Copyright © 1985 The Columbia Law Review.

                                      Columbia Law Review

                                        JANUARY, 1985

                                       85 Colum. L. Rev. 38

 LENGTH:32975 words




* Copyright © 1985 by E. Donald Elliott. All rights reservedto the author.

E. Donald Elliott **


** Professor of Law, Yale University. B.A. 1970, J.D. 1974,Yale University. A faculty seminar on evolutionary models andmetaphors in the social sciences at Yale's Institute for Social and PolicyStudies first sparked by interest in evolutionary models.This article is a condensation of a chapter of a forthcoming book, edited byRichard Nelson and Greg Dow, which grew out of the seminarand reviews the influence of evolutionary models in various disciplines. Igratefully acknowedge the support of the Sloan Foundation,and the research assistance of Adeeb Fadil, Yale Law School class of 1984.


  ...This Article begins to fill that void by considering how the most influentialidea of the last century, Charles Darwin's theory ofbiological evolution, has affected the way lawyers think about law. ... Thefountainhead for Anglo-American theories of legalevolution of the "social" variety was the nineteenth century German"historical school" of jurisprudence, founded byFriedrich Karl von Savigny. ... Rather, legal evolution means only that the lawcontinually adapts to changes in the environment. ... Bymaking assumptions and developing a formal, mathematical model of common lawevolution, Cooter and Kornhauser prove that evolutionarypressures arising from settlement decisions by litigants "are insufficientto cause the legal system to adopt and retain the bestlegal rule without the help of judges. ... Keller introduces his sociobiologicaltheory of legal evolution by quoting Holmes, andannouncing that he is planning on "asserting and maintaining" Holmes'implication "that law is evolutionary. ... Except forBrown's comment, Keller's theory of legal evolution attracted surprisinglylittle attention even though it anticipated many of thethemes of sociobiology which were to create a storm of intellectual controversyhalf a century later. ...  

The government of the United States was constructed upon theWhig theory of political dynamics, which was a sort of unconsciouscopy of the Newtonian theory of the universe. In our own day, whenever wediscuss the structure or development of anything, whetherin nature or in society, we consciously or unconsciously follow Mr. Darwin . . .Woodrow Wilson (1908). n1


[*38]  Law is ascavenger. It grows by feeding on ideas from outside, not by inventing new onesof its own. How borrowed ideas -- not political and socialtheories, but abstract ideas borrowed from other disciplines -- affect the lawis a topic scholars have overlooked. This Article beginsto fill that void by considering how the most influential idea of the lastcentury, Charles Darwin's theory of biological evolution,has affected the way lawyers think about law.

Today the idea that law "evolves" is so deeplyingrained in Anglo-American legal thought that most lawyers are no longereven conscious of it as a metaphor. n2 We speak of the law"adapting" to its social, cultural, and technological environmentwithout the slightest awareness of the jurisprudential traditionwe are invoking. The central purpose of this Article is to bring tolight the evolutionary tradition in Anglo-American jurisprudence, whichunderlies many of our assumptions about law.

The first step will be to trace the metaphor of biologicalevolution as used by legal writers who have influenced American law.Reviewing evolutionary theories of law has several purposes. The first isessentially archival: to reclaim from obscurity and toevaluate several evolutionary theories of law which have either been forgottenor misunderstood. But there is also a second, more subtlegoal: to define -- and thereby to create -- an evolutionary tradition injurisprudence with a cumulative power that transcends theindividual works.  [*39] 

In an earlier Article, I observed that academic lawyers,unlike historians, philosophers and literary critics, rarely "cultivate atradition." n3 The present Article is an experiment with anapproach to legal scholarship that regards works by legal writers notas islands, but as stages in an intellectual tradition which itself evolves.

The present essay will not evaluate whether the law reallydoes evolve, or speculate about what mechanisms might be responsibleif it does. Instead the goals are to trace the idea of evolution as the commonunderpinning for a number of different theories of law,and to account, if possible, for the peculiar fascination that evolutionarymetaphors have held for legal thinkers.

I consider theories about the nature and sources of law to be"evolutionary" if they propose that the law is shaped by its environmentin a way that is analogized explicitly to the theory of evolution in biology:namely, the theory, usually attributed to Charles Darwin,that the forms of living things are shaped by environmental conditions, not bythe design choices of a Creator. By referring to legal theories as"evolutionary," I do not mean to imply, however, that they are basedon a correct understanding of evolutionary theory inbiology. My central concern is the effect that evolutionary ideas have had onlegal thought, not whether the lawyers got their biologyright.

Necessarily omitted from this review is the much larger bodyof legal theories that express parallel thoughts but without explicitreference to the biological theory of evolution. n4 Nor is it possible in a workof this length to undertake the more basic anthropologicalinquiry into how lawyers and judges use evolutionary metaphors. Instead, thefocus here in on formal theories of law based onself-conscious analogies to  [*40] evolutionary theory in biology. n5  

It is possible to subdivide theories of legal evolution intofour basic groups, which I shall call the social, the doctrinal, the economic,and the sociobiological approaches to legal evolution. These four categoriesrepresent different schools of evolutionary thought; eachdraws a different analogy between biological evolution and law. n6


The "social" approach to legal evolution is theoldest of the four. It is characterized by the assertion that law is not anautonomous system, but an integral part of the social life of acommunity. In these theories, it is not so much the law that evolves,as it is society. As the language, culture, political system, and economicstructure of society evolve, the law changes with them.

A. Savigny

The fountainhead for Anglo-American theories of legalevolution of the "social" variety was the nineteenth century German"historical school" of jurisprudence, founded byFriedrich Karl von Savigny. n7 The historical school proposed that, ratherthan building on abstract  [*41] speculation about states of nature, jurisprudence should study thehistorical foundations of law. Savigny, a professor ofRoman law at the University of Berlin from 1810 through 1842, wrote severalmulti-volume treatises on Roman legal history, but hisinfluence on Anglo-American jurisprudence rests primarily on a minor politicaltract, published in 1814, and translated into English in 1831under the title Of the Vocation of Our Age for Legislation and Jurisprudence.n8

Savigny advocates "an organically progressivejurisprudence," n9 an idea that struck a responsive chord for English andAmerican lawyers. They interpreted Savigny as defending thecommon law, as opposed to civil law codes. Savigny's argument,however, is not actually a brief for the common law method. Savigny wrote toattack a proposal that all the German principalitiesshould adopt one unified code of laws following the overthrow of Napoleon. n10He claimed that the present age was "not qualified toframe a code" which would establish the law for all time. n11 Drawing onRoman legal history, Savigny argued that legal systemspass through several stages before they reach a period in which codification isappropriate. Early nineteenth century Germany, according toSavigny, had not yet reached the stage of mature legal developmentnecessary before codification would be successful.

Savigny's theory of stages of legal development is built on aself-conscious analogy to evolution in nature, albeit the pre-Darwinianunderstanding of evolution which lacked the concept of natural selection: n12"In recent times, the view has become common that inthe beginning all societies lived in an animalistic state, and from there havecome to a tolerable existence through gradual evolution,and finally to the heights upon which we now stand." n13 The word whichSavigny uses again and again to describe legal charge isEntwicklung, which in context should be translated as "evolution." n14

Savigny attacks the proposal to codify German law as anoutgrowth  [*42] of the spirit of radical change which swept acrossEurope following the French Revolution, claiming that, in a "blind rage forimprovement, [all] sense and feeling of the greatness bywhich other times were characterized, as also of the natural [evolution] ofcommunities and institutions, all, consequently, that iswholesome and profitable in history, was lost." n15 He sees this spirit ofradical change as reflecting a false, positivist n16jurisprudence: "According to this theory, all law, in its concrete form, isfounded upon the express enactments of the supremepower." n17 Savigny proposes that law is not the arbitrary creation ofgovernment officials, but an integral part of the"spirit of a people," what we would now call "culture." n18According to Savigny, law and culture evolve together:

But this organic connection of the law with the essence andcharacter of a people manifests itself also over time, and here alsoit is to be compared to language. As with language, so too the law does notstand absolutely still for even an instant, but undergoesthe same movement and evolution as every other aspect of a people, and thisevolution is subject to the same law of internal necessityas every earlier development, therefore, the law grows forward with a people,constitutes itself out of them, and finally becomesextinct as a people lose their individuality. n19

Although Savigny does not present any evidence to support histheories, he does identify two distinct forces which he maintainsunderlie the evolution of law: "[A]ll law . . . is first developed bycustom and [conventional morality], next by jurisprudence,-- everywhere, therefore, by internal silently-operating powers, not by thearbitrary will of a law-giver." n20 [*43] 

Savigny's theory was revolutionary for its suggestion that lawwas not the intentional creation of governors, but somehow evolvedout of the common spirit of a people. Nevertheless, by modern standardsSavigny's work seems hopelessly metaphorical andunscientific. Savigny is vague about the mechanisms which cause law to evolve(and indeed, about what the concept of legal evolutionreally means). Moreover, he never explains why the codification movement whichhe opposed was not as "natural" an outgrowth ofthe spirit of the people as any other change.

B. Maine

Savigny's historical approach to the evolution of legalsystems was extended and refined by Sir Henry James Sumner Maine, whose mostinfluential book, Ancient Law, n21 was published in 1861, two years afterDarwin's Origin of the Species. Whether Darwin's workactually influenced Maine's has been the subject of speculation. n22 Whateverthe connection, Maine's theories about the stages of legaldevelopment are only "mildly evolutionary." n23 Maine identifiessuccessive stages  [*44] through which all "progressive societies" must pass. n24 Eachof these stages grows our of the one prior, and lays thegroundwork for its own transformation into the next.

The key to an understanding of the evolution of law, hecontends, lies in the "early forms of jural conceptions," n25 which"are to the jurist what the primary crusts of the earth areto the geologist. They contain, potentially, all the forms in which law hassubsequently exhibited itself." n26 The most primitive jurisprudentialstage, according to Maine, is a legal system based on thejudgments of kings. n27 Since the pronouncements of kings are not connected toone another in any "orderly sequence," for Mainethey do not qualify as a true law, but are mere commands. n28

The second stage, which grows our of heroic kingship and thensupplants it, is "the dominion of aristocracies," when the "officeof the king [is] usurped by [a] council of chiefs." n29 In this era, theconception of law as a body of rules is born, and with itthe power of a "juristical oligarchy" whose power is founded on theclaim "to monopolise the knowledge of the laws, tohave the exclusive possession of the principles by which quarrels aredecided." n30 Out of aristocracy in turn grows the "epochof Customary Law," n31 and finally, "codification." n32

The evolutionary bent in Maine's thinking may also be seen inhis Partiarchal Theory that the state evolves out of the family. n33Maine claims the "eldest male parent" is "absolutely supreme inhis household." n34 Society is organized not as a collectionof individuals but "an aggregation of families," n35 the Gens orHouse, and finally the Tribe. n36 At this point, LegalFictions enter which "permit[ ] family relations to be createdartificially"; n37 this idea of artificial kinship, Maine argues,is the seed for the idea of the social contract and the modern state. n38 Hetraces transformations of customs and legal forms to reachone of his  [*45]  mostfamous conclusions, the supposed progression of law "from Status toContract." n39

Some aspects of Maine's work have withstood the test of time.His insights into the role legal fictions play in facilitating changesin the law, for example, are as brilliant today as when they were written. Onthe other hand, Maine's broad, evolutionarygeneralizations -- that all societies evolve from family ties to individualism,from status to contract, from penal legislation to civil-- now seem embarrassingly simplistic. n40

Frederick Pollock, the great English legal historian, hassuggested charitably that "[m]uch trouble and confusion might have beensaved if Maine had in the first place expressly confined his [patriarchal]thesis . . . to the Indo-European family of nations."n41 But the difficulty is more fundamental than Pollock acknowledges: Maine didexplicitly limit his claims "nearly exclusively"to "the institutions of societies belonging to the Indo-Europeanstock." n42 The problem instead is that Maine foundit inconceivable that societies could develop along different paths, withoutpassing through the same stages. n43

Despite his emphasis on empiricism, and the importance ofdrawing evidence from different cultures, Maine had not assimilatedthe Darwinian concept of evolutionary change as variation in the distribution ofcharacteristics within populations. n44 Maine stillthought in terms of the iron laws of the machine, or the inflexible stages ofdevelopment in embryology, [*46]  which were the modelfor Herbert Spencer's theory of evolution, not Darwin's. n45

Moreover, like Savigny, Maine describes patterns of legalchange without paying much attention to the processes that producethem. Maine asserts, for example, that there is a natural progression fromheroic kingship to aristocracy, but does not tell us howor why. In one exceptional passage in Ancient Law, however, Maine does avert tothe mechanisms of legal change in terms that suggest atleast a veiled reference to Darwin: The usages which aparticular community is found to have adopted in its infancy and in itsprimitive seats are generally those which are on the wholebest suited to promote its physical and moral well-being; and, if they areretained in their integrity until new social wants havetaught new practices, the upward march of society is almost certain. n46 Darwinnever defined fitness in terms that made the "upward march of society . . .almost certain." If Maine is indeed referring toDarwinism here, it is not good Darwinism. In addition, Maine merely asserts thatsocieties tend to adopt practices that promote theirphysical and moral well-being; he tells us nothing about why this should be so.

Despite these shortcomings, Maine's methods were extremelyinfluential in English and American legal scholarship of the late nineteenthand early twentieth centuries. By 1890, Pollock could declare: "Thedoctrine of evolution is nothing else than the historicalmethod applied to the facts of nature; the historical method is nothing elsethan the doctrine of evolution applied to known societiesand institutions." n47

C. Wigmore

John Henry Wigmore's n48 ten-volume treatise on the law ofevidence n49  [*47] remains a standard reference work. While courts andlawyers continue to cite Wigmore On Evidence, most are not aware that anexplicitly evolutionary theory of jurisprudence lay at thefoundation of Wigmore's approach to law. Between 1915 and 1918, Wigmore and acolleague, professor of jurisprudence Albert Kocourek,published a 2100-page, three-volume set of readings, Evolution of Law. n50 Theirgoal was to take up "Maine's inspiring call" by "tracing . . .the evolution of universal legal ideas." n51

The first two volumes of Evolution of Law collect primarysources. n52 In the third volume, Formative Influences of Legal Development,Kocourek and Wigmore develop a comprehensive theory of legal evolution. Theirargument begins with several introductory chapters on"criteria of legal evolution and methods of its study." n53 Next, theycollect articles describing the influence on the law ofvarious environmental factors -- geophysical, economic, racial, religious, andpolitical factors, as well as physical force. An articleby Belgian law professor Edmond Picard, called "Factors of LegalEvolution," n54 introduces the substance of Kocourekand Wigmore's theory of legal evolution. It identifies ten factors thatsupposedly influence legal evolution, including race, theenvironment, foreign intrusion and imitation, great jurists, and density ofpopulation. n55 Unlike earlier theories, which were not stronglyinfluenced by Darwin, n56 this one is tied explicitly to Darwin'stheory that environmental conditions are responsible for the forms of animalsand plants. For example, the section on the influence ofthe natural environment on the development of law begins by quoting Darwin onhow  [*48]  plantsadapt to differing light conditions in a forest, andargues that law also responds to a "geographic imperative," n57 amongother factors.

The rest of Kocourek and Wigmore's third volume elaborates onPicard's theory. Many of the pieces anticipate themes that haveonly recently begun to be reexplored under the rubric of sociobiology. n58 Onearticle describes the development of something akin toproperty rights among animals. n59 Another comes close to outlining the moderntheory of "reciprocal altruism" and theevolution of cooperation. n60 A third anticipates economic theories of legalevolution by suggesting that the law evolves as a moreefficient mechanism for reducing intra-group conflict. n61

The final part of the volume consists of general articles onthe "process of legal evolution." Perhaps the most interesting is byWigmore himself, the "Planetary Theory of the Law'sEvolution." n62 Wigmore proposed this "planetary theory" as aresponse to Maine and other writers who "commit certainfallacies" n63 by reducing the concept of legal evolution to a simplisticprogression from one stage to another. Wigmore strongly attacks this vision oflegal evolution, providing counterexamples from the law oftestamentary transfers to show that legal systems do not move in lock-stepthrough the same stages, or even in the same directions.n64 In place of the crude evolutionary model proposed by Maine, Wigmore developsan analogy to the complex interaction of forces influencing the movement of theplanets.

Wigmore stresses that law represents only a temporary"equilibrium" n65 among competing social forces: Lawis usually a series of wrestling bouts; the prize to the final [*49]  winner signifies the enactment of the winning force as a ruleof law . . . . But the victory does not signify the annihilation of the losingforce; it signifies only a slight overbalance in the winningforce, followed by a more or less temporary rest . . . . n66 Heconcludes that "to solve the problem of evolution of a legal rule, we mustfirst analyze fully the respective social forces whichwere struggling underneath the surface." n67 But these underlying socialforces differ with place and time. Thus, Wigmore argues,we should not expect that law would always evolve along the same path.

Consider "the evolution of marriage," which Maineand others argue "passes from promiscuity through polygamy to monogamy."n68 This formulation, Wigmore maintains, "ignores the contrary localvariations . . . and therefore fails to represent thewhole truth." n69 The weakness in this and similar theories of stages oflegal evolution, he says, is that they "fail[ ] tostate anything about the outside factors which cause the movement; for example,local poverty of economic resources may make polygamyimpossible, or local moral precepts may make monogamy impossible; and thus theabstract formula becomes fallacious." n70 For Wigmore,the true study of legal evolution does not simply identify and universalizeabstract patterns of legal change; it must relate changes in thelaw to the local environmental conditions which cause them. Nordoes he believe that evolution in the law implies progress in a normative sense.Rather, legal evolution means only that the lawcontinually adapts to changes in the environment. n71

In place of Maine's progressive stages, Wigmore suggests an"analogy of the planetary system with its numerous interdependentmotions." n72 The law is a body in motion produced bya force, this motion modified by other immediate forces, and this body and itsmotions being one part only of a larger body which isitself in one or more motions produced by other forces and modifying the firstmotions; and this system as one part only of a larger system offorces and motions; and so on, indefinitely. n73

Wigmore's planetary analogy may strike some modern readers astoo mechanical, but his conception of legal evolution is surprisinglymodern. In emphasizing the role of environmental variation, Wigmore [*50]  is a true Darwinian ina way that Savigny and Maine were not. n74 moreover, hisconception of evolution in the law as a sequence of temporary equilibria amongopposing forces, n75 and of law as a system nested within a series of largersystems, makes his "planetary" conception oflegal evolution consistent with modern mathematical models of evolution. n76 Yetlike his predecessors, Wigmore has very little to sayabout how it is that environmental factors shape the law.

Overall, the "social" evolutionists made a majorcontribution to jurisprudence by proposing an alternative to the positivistconception of law as an artifact made by the will of governors.By focusing attention on social and cultural factors, they laid thefoundations for modern sociological and anthropological jurisprudence. However,their work suffers from a lack of empirical rigor, andtheir analogies between law and biological evolution are not well-defined.


Both Savigny and Maine focused primarily on the historicalevolution of whole societies and what they claimed were the correspondingchanges in the gross structure of the legal order. Oliver Wendell Holmes, Jr., acommanding figure, n77 who is the source of most attitudeswhich dominate orthodox American legal thought, inherited the "social"concept of legal evolution, n78 but transformed it intowhat I call the "doctrinal" approach to legal evolution. Holmesasserted that evolution took place not only at the levelof societies, but also on the more detailed lebel of specific statements oflegal rules and principles -- what lawyers generally call"legal doctrines." Those writers who follow Holmes in portraying legalevolution at the level of specific legal doctrines withina legal system constitute the doctrinal school of legal evolutionists. [*51] 

A. Holmes

One great idea attributable to Holmes is that judges make law;a second is that the law evolves to adapt to the "felt necessitiesof the time." Whether both can be true simultaneously is perhaps thecentral paradox of our jurisprudence, and it accounts inlarge part for the continuing fascination that Holmes' work has held forgenerations of scholars.

The theory of legal evolution most lawyers associate withHolmes is the one that begins The Common Law:

The life of the law has not been logic: it has beenexperience.

The felt necessities of the time, the prevalent moral andpolitical theories, intuitions of public policy, avowed or unconscious, eventhe prejudices which judges share with their fellow-men, have had a good dealmore to do than the syllogism in determining the rules bywhich men should be governed. n79 Holmes' claim that legaldoctrines evolve in response to changes in the social environment has becomevirtually a canon of professional faith for Americanlawyers. n80

Most commentators have seen strong evolutionary undercurrentsin The Common Law. n81 In one famous passage, Holmes analogizes legal doctrinesto the "clavicle of a cat," arguing that just as evolution adaptsexisting biological structures to different uses in different time periods, n82so too the functions of legal doctrines evolve from one period to another. n83Holmes' thesis -- that societies are constantly reinterpreting [*52]  legal forms to servenew purposes -- has been labelled "evolutionarypragmatism." n84 However, the analogy Holmes draws between the common lawprocess and biological evolution in The Common Law is atbest vague and indirect. Nor is Holmes particularly clear in The Common Lawabout what forces cause the law to evolve.

Almost two decades later, Holmes articulated a second theoryof common law evolution in an article entitled Law in Science and Science inLaw. n85 Elsewhere I have argued that Law in Science and Science in Lawrepresents a "more mature, and in some ways a more sophisticated"theory of common law evolution than The Common Law, although the latter isbetter known. n86 Be that as it may, Holmes' analogies to biological evolutionin Law in Science and Science in Law are sharper and more explicit than those inThe Common Law.

Law in Science and Science in Law traces examples of thehistorical "transformations" n87 of legal doctrines and compares themto the evolution of biological structures. "Surely a flower is not moreunlike a leaf, or a segment of a skull more unlike a vertebra, than the executoras we know him is remote from his prototype, the saleman of the Salic law."n88 Echoing Maine's notion that the "rudimentary ideas" of primitivelegal systems "contain, potentially, all the forms in which law hassubsequently exhibited itself," n89 Holmes writes that one sees similartransformations of legal ideas "all through the law" due to "thepaucity of original ideas in man, and the slow, coasting way in which he worksalong from rudimentary beginnings to the complex and artificial conceptions ofcivilized life." n90 This process of gradual transformation of ideas in thelaw Holmes analogizes to evolution in nature: It is likethe niggardly uninventiveness of nature in its other manifestations, with itsfew smells or colors or types, its short list of elements,working along in the same slow way from compound to compound until the dramaticimpressiveness of the most intricate compositions, which we call organic life, [*53]  makes them seemdifferent in kind from the elements out of which they are made, when setopposite to them in direct contrast. n91 Holmes goes on to draw an explicitcomparison between the evolution of complex legal concepts and evolution innature: "We have evolution in this sphere of conscious thought and actionno less than in lower organic stages, but an evolution which must be studied inits own field." n92

In the balance of Law in Science and Science in Law, Holmessets out to describe how the evolutionary process n93 accounts for change in thelaw and to identify certain pathologies which can impede the adaptation of law.In my view, Holmes' theory of legal evolution combines two different conceptionsof evolution, one derived from Spencer and one from Darwin. n94 In the first,which Holmes identifies using Spencer's term, "Integration," n95 legalconcepts expand and become more general through theextension of their internal logic. n96 The second, the analogy to Darwiniannatural selection, Holmes calls "the struggle for life among competingideas," n97 which he illustrates with the evolution of contract law. Holmesmaintains that while a number of primitive legal ideas might have served as thebasis for a theory of contract law, there was a "struggle for life amongthese competing ideas" and "an ultimate victory and survival of thestrongest." n98

Choices by judges in individual cases are responsible n99 forboth "Integration" and "the struggle among competing ideas":[I]nasmuch as the real justification of a rule of law, ifthere be one, is that it helps to bring about a social end which we desire, itis no less necessary that those who make and develop [*54]  the law should havethose ends articulately in their minds . . . . whenever a doubtful case arises,with certain analogies on one side and other analogies on the other, . . . whatreally is before us is a conflict between two social desires, each of whichseeks to extend its dominion over the case, and which cannot both have their way. . . . [t]he simple tool of logic does not suffice, and even if it is disguisedand unconscious the judges are called on to exercise the sovereign prerogativeof choice. n100

Holmes' emphasis on choices by judges who have social"ends articulately in their minds" has led some scholars to suggestthat at maturity, Holmes' theory of the common law is no longer evolutionary butinstrumental. n101 There is no inconsistency, however, between evolution andconscious choice; rather, the two may describe the same phenomenon on twodifferent levels. This point can be clarified by considering evolutionary modelsin other disciplines. In economics, for example, evolutionary metaphors havesometimes been used to describe the behavior of a population of firms within themarket system as a whole. n102 This is not to deny, however, that individualactors are making conscious choices at the level of individual economicdecisions within the economic system. Conscious choice operates at the level ofindividual decisions; evolution describes the patterns of those decisions at thelevel of a system.

Holmes seems to intend a similar distinction in hisdescription of the law. A judge who decides an individual case admittedlyexercises the "sovereign prerogative of choice," n103 and according toHolmes, ought therefore to have policy considerations clearly in mind. But froma scholarly perspective, "[t]he interesting issue is not why an individualjudge decides as he does, but why others follow." n104 Here, at the moregeneral level of patterns of decisions within the law, Holmes sees theevolutionary forces of "Integration" and the "struggle amongcompeting ideas" operating.

In general, the peculiar appeal of evolutionary models arisesin part from their power to explain "the achievement of purposive or [*55]  ends-guided processesthrough a mechanism involving blind, stupid, unforesightful elements." n105One reason Darwin's theory of the origin of the species was a watershed inintellectual history was its ability to explain complex structures in naturewithout invoking design choices by a Creator. But the ability of evolutionarymodels to explain apparently purposeful behaviors without invoking consciousactors should not obscure the fact that evolution may also take place in systemscomposed of conscious actors. A great deal of controversy about evolutionaryexplanations in the legal literature has been devoted to a false dichotomybetween evolutionary models of law and policy choices by judges. n106 At leastin Holmes' vision of common law evolution, there is no dichotomy between thetwo.

Holmes' theory is coherent in positing that conscious choicesby judges and evolutionary forces work simultaneously in the law. He neverdefines satisfactorily, however, what he means by the "strongest"legal idea surviving. Holmes describes two different kinds of evolution withinthe common law, corresponding roughly to policy and precedent, or the"logic" and "experience" with which he began The Common Law.But he is never able to explain when judges are to follow one as opposed to theother. n107 I have argued elsewhere that Holmes' dilemma cannot be solved inprinciple within a common law system, n108 and there is at least a hint in TheCommon Law that Holmes realized this. "[T]he law is always approaching, andnever reaching, consistency. It is forever adopting new principles from life atone end, and it always retains old ones from history at the other . . . . Itwill become entirely consistent only when it ceases to grow." n109

B. Corbin

Holmes' evolutionary approach to legal doctrine was extendedby Arthur Linton Corbin, n110 author of the famous treatise on the law ofcontracts. n111 As was Wigmore's, n112 Corbin's work was built on an [*56]  explicitlyevolutionary theory of jurisprudence.

In The Law and the Judges, n113 published in 1914, Corbinappears to build on Holmes' Law in Science and Science in Law n114 with anargument that "the growth of the law is an evolutionary process." n115Quoting Pollock and Maitland, Corbin describes the forms of action as"living things. . . . A few are still-born, some are sterile, others liveto see their children and children's children in high places. The struggle forlife is keen among them and only the fittest survive." n116 Corbin insiststhat this metaphor is "not to be taken solely in a figurative sense; itstates truly the life-story of our legal principles also." n117 He thendistinguishes, even more clearly than did Holmes, n118 between the law asapplied in individual cases, which judges make as an act of will, and legaldoctrines or "rules" of law which evolve in populations of cases.

A judge's declared rules must compete for their lives with therules declared by other judges and by all other persons. In the judicial world,as in the animal and vegetable world, the ultimate law is the law of thesurvival of the fittest.

Do the judges make the law? Undoubtedly they do, so far as thelitigating parties are concerned. As to the parties to the suit, the court oflast resort can and does lay down the rule according to its will. . . . n119

For Corbin, the fact that a legal principle has been declaredover and over is no guarantee that it will continue to be recognized. As newcases arise, other judges decide whether to follow the law as stated previouslyor to modify it in the case before them: "[H]owever 'well-settled' therules may be, their application to life is always uncertain. A rule lives onlyin its application; apart from that, it is a dead, inert thing. A new anddifferent application of the rule is the creation of a new rule." n120 Asdo contemporary theorists of cultural evolution, n121 Corbin [*57]  appears to use"survival of the fittest" to mean only that some doctrines are morelikely than others to gain acceptance. He never claims clearly that some legaldoctrines are "fitter" in the strict, biological sense of enhancingthe chance that the society which adopts them will itself survive. n122

Like Savigny, Corbin emphasizes the role of the community inmaking law. Judges have power, writes Corbin, only "from some sort ofconsent and acquiescence of all the active forces of the community." n123Judges "may lead the multitude," but their "leading can bejustified only by success," n124 that is, by community acceptance of theprinciples they declare. n125

Corbin's theory moves beyond those of Savigny and of Holmes,n126 however, by embracing variation as a creative force in the law. True to the"leading case" theory of law dominant at Harvard during his tenurethere, n127 Holmes, like Savigny, conceives of variation in the law as largelysequential, with one rule of law supplanting another over time. n128 Holmeslacks Corbin and Wigmore's n129 sense of the law as a broad distribution ofcompeting answers about how to resolve a given dispute, rather than as a singleunitary "rule." Corbin sees past judicial decisions as a valuablestorehouse of wisdom, but emphasizes that the law never speaks with a singlevoice. "The records of a million cases" in the law reports, he says,are "instructive," but never "harmonious." n130 [*58] 

The variation in precedents that Corbin views as a creativeforce is not his only source of "mutant" legal types engaged in acompetition for survival. An equally important part of Corbin's contribution totheories of legal evolution is his assertion that "there are many sourcesof law other than statute and precedent." n131 According to Corbin, legalevolution also occurs as principles from outside enter the law. n132 Inextending the theory of legal evolution to include community norms as sources oflaw, The Law and the Judges is more sophisticated than its predecessors. n133

In the final analysis, however, Corbin is also vague aboutwhat makes one principle of law "fitter" than another to winacceptance by the community, and about how the community's preferences aretranslated into law by judges. n134

Corbin First asks, "When someone declares a new principleof law, how can we tell whether or not it is fit?" n135 The "newprinciple," he tells us, is rarely really new; we can consult history forguidance. n136 If history is unilluminating, however, "we must compare itwith other doctrines, make applications of it to hypothetical cases, try it inactual cases, experiment, and await the result." n137 But Corbin neverreally explains what "result" we are waiting for; what kind ofcommunity  [*59] response signifiesthat a principle is "fit"; or how the community's response caninfluence the law. In the end, he retreats into generalities like his assertionsthat the "test of judicial action is criticism" n138 and the "aimof any legal system is general satisfaction." n139 Corbin does say thatwhen a judge refuses to follow the community's wishes and "is a law untohimself," the community may "criticise and recall and impeach and evenhang him." n140 These remedies are not particularly useful ways to guidejudicial discretion. n141 At most, the fear of hanging may constrain judges fromflagrantly disregarding the will of powerful segments of the community; it doesnot explain why the finer details of law evolve in response to the communalwill, as Corbin claims.

C. Clark

For reasons that remain somewhat mysterious, n142 referencesto evolution in Anglo-American jurisprudence are few and far between during thehalf-century from the middle 1920s to the middle 1970s. The rebirth of anevolutionary tradition in legal scholarship began in 1977 with the work ofRobert Charles Clark. Like Holmes and Corbin, Clark focuses on the evolution oflegal doctrines but extends their argument beyond the common law to propose thatstatutes also evolve.

Clark first proposed the concept of statutory evolution in ananalysis of subchapter C of the Internal Revenue Code, the corporate income tax.n143 Clark acknowledges that the corporate income tax is an artifact produced byhuman minds, n144 but maintains that the corporate income tax, like the designsof pottery, arrowheads, or other cultural artifacts, is subject to a process of"cultural evolution." n145

Clark begins with a question: Were the "majortraits" of the corporate income tax "determined by a set of genesfixed in its infancy," or does it "grow in a passive, mechanisticway" with its parts "constantly shaped and re-shaped in response tothe shifting pressures of a changing environment?" n146 Clark's answer isthat the "genes" of  [*60]  corporateincome tax law -- a "few basic decisions" n147 made early on -- ratherthan environmental factors, are primarily responsible for its development.

Clark's thesis is that a pattern on interactions betweentaxpayers, the Internal Revenue Service (IRS), the courts and Congress repeatsitself over and over within a framework established by seven fundamentalstructural decisions. "Taxpayers and their lawyers continually seek todiscover, invent, and exploit ways of reducing their taxes," n148 while theIRS "continually counters these new modes of tax reduction." n149Courts and Congress "arbitrate" and act as "shapers of thecultural environment." n150 Courts tend to resolve new tax issues byapplying vague, "open-ended judicial policies and rules." n151 As aresult of entreaties by taxpayers and the IRS, Congress creates "morecertainty" by adopting "mechanical rules," n152 and then thecycle begins again.

Even if Clark's model is valid, however, it is not entirelyclear in what sense the process he describes is evolutionary. Despite hisreferences to "genes" and to "cultural evolution," it ishard to see in what way the interactions among taxpayers, the IRS, the courtsand Congress that Clark describes are analogous to biological evolution. Ifthere is an analogy to Darwinian natural selection, it is vague and undeveloped.n153

Clark's repeated references to evolution are made all the moreenigmatic by his insistence that changes brought about by "environmentalpressures" are somehow "mechanistic," rather than evolutionary.n154 Yet the essence of the Darwinian theory of evolution is selection by theenvironment. The process of evolution Clark describes in The Morphogenesis ofSubchapter C actually owes less to Darwin than to Herbert Spencer's notion ofevolution as cycles of Integration and Disintegration. n155

Clark's 1977 article on statutory evolution left a number ofkey questions unanswered. Since then, he has not published a  [*61] comprehensive theory of legal evolution, n156 preferring instead to writea series of articles which describe distinctive patterns of legal evolution indifferent areas of law. In one article, n157 for example, he claims that thesuccession in the dominant forms of capitalist enterprise -- from privately-heldcorporations, to publicly-held corporations, to institutional investors, topension funds -- shows an evolution "in the direction of increasingspecialization and professionalization [in] decisionmaking" accompanied by"increasing scope for citizen participation" in the income from realcapital investment. n158 In another article, n159 he argues that the successionof legal principles for determining priority among secured creditors shows anevolution toward reducing "fraud and 'unfixity' costs in securedtransactions" while reacting to "technological innovations." n160

In his most comprehensive published work of evolutionarytheory, The Interdisciplinary Study of Legal Evolution, n161 published in 1981,Clark summarizes six different examples of legal evolution which he and othershad identified in corporate and commercial law. n162 He maintains that these sixinstances examplify two "apparently general patterns of change." n163The first general pattern of change is "cost reduction" in response tosocial or technological changes. n164 The second involves "the closeconnection between changes in the size of economic units of transactions and thesubsequent development of new  [*62] institutions and rules." n165 However, this second phenomenon maynot really be a separate category. Large scale economic units or transactionsseem to be merely a particular instance of Clark's "technological, social,or other external changes . . . that create new opportunities for legal rules toreduce costs." n166

While Clark's theory amounts to an assertion that a generalpattern of cost reduction appears to underlie most of the instances of legalevolution he has identified, Clark has not yet suggested any explanation for whythe law evolves toward less costly arrangements. He does, however, attack thecausal theories proposed by others explain this supposed tendency of the law.n167 Clark is apparently content to observe that the law generally seems to bemoving toward cost reduction in those instances he has identified. Presumably,however, one also might be able to identify other areas (for example, discoveryproceedings in civil litigation) in which the law is evolving toward increasedcosts. Clark himself acknowledges that the pattern of evolution towarddecreasing costs is not universal, and insists that the type of legal evolutionhe identified in his 1977 article on The Morphogenesis of Subchapter C cannotproperly be interpreted in terms of cost-reduction. n168 Clark has not proposedany systematic theory of when the law evolves in a direction that reduces costs,and when it does not.

Overall, the strength of Clark's work is in its attention tothe substance of legal doctrine in a number of areas. Like Wigmore, Clarkattempts to relate trends in the law to external factors. Despite the oddpassage from his 1977 article in which Clark appears to denigrate"environmental pressures" as a source of legal change, n169 most ofClark's work seems to document precisely that pattern -- the law graduallyaccommodating itself to changes in the environment. However, what mechanisms areresponsible, and to what degree they are analogous to biological evolution, innot clear from Clark's work.


An important difference of focus separated economic theoriesof legal evolution from the doctrinal theories which preceded them. Economictheorists of legal evolution are not particularly interested in identifyingpatterns of changes in legal doctrine. Their primary concern has been modelingthe processes that cause legal doctrines to change. The economic school of legalevolution has argued that processes akin to natural selection in biology are atwork in the law. The basic thesis is that people share a desire to eliminateunnecessary  [*63] costs, and that over time the shared goal of reducing unnecessary costscauses the law to evolve toward rules of law that are less wasteful or,conversely, rules that increase economic efficiency.

These contemporary economic theories of legal evolution arenot necessarily inconsistent with earlier theories of legal evolution. Rather,the economic theorists claim to have solved the riddle that baffled Holmes andCorbin: why one legal rule ultimately proves "stronger" than anotherin the competition to survive. In general, the economists' answer is that a ruleof law is "stronger" if it reduces social costs.

The shift from a doctrinal conception of legal evolution to aneconomic one can be seen in Professor Clark's work. His 1977 article on theevolution of the corporate income tax is typical of doctrinal approaches tolegal evolution, such as Holmes' or Corbin's. It described a pattern of changein legal principles analogous to the results of biological evolution in nature,without saying much about the processes that produce these evolutionary changesin the law. To the extent that he addresses the issue, Clark, like Holmes,maintains only that groups compete, with the "strongest" winning out.n170 By 1981, however, Clark adopted a perspective more typical of the economicschool, describing a general pattern of "cost reduction" as the forcebehind many patterns of legal evolution. n171

To identify certain premises shared by the economic school oflegal evolution is not to say that the economists have no differences amongthemselves. On the contrary, a burgeoning literature has developed in recentyears proposing, controverting, and modifying economic theories of legalevolution. n172 The technical differences between various economic theorists arenot essential to the present discussion; it will suffice to describe the basicevolutionary hypothesis that underlies most of the economic theories of legalevolution, and to review some of the major criticisms that have been made ofthis school.  [*64] 

A. Rubin

The cornerstone of virtually all economic theories of legalevolution is that decisions by litigants, not judges, determine which legalprinciples survive. n173 This evolutionary hypothesis was proposed in 1977 byeconomist Paul Rubin n174 and refined and elaborated by law professor GeorgePriest. n175 Stripped to its essence, Rubin's insight is that judges only decidethose cases that somebody takes to court. Thus, law cannot be produced by judgesalone; it is necessarily a joint product of the pattern of decisions bydisputants to bring cases to court, and the pattern of decisions by judges oncecases reach them. Perhaps, Rubin suggests, a systematic pattern in decisions bylitigants about which cases to settle has more to do with forming the law thanwhat judges decide once cases reach them. Rubin argues that the law is shaped byan "evolutionary mechanism," n176 becausedecisions by citizens to settle disputes serve to select from among the existingpopulation of legal doctrines those which will survive and those which will"mutate" as they are reexamined by the courts.

Beginning from Richard Posner's thesis that "the commonlaw can best be understood as an attempt to achieve economic efficiency,"n177 Rubin argues that this "presumed efficiency" n178 is due to"the utility maximizing decisions of disputants rather than . . . thewisdom of judges." n179 Rubin significantly qualifies Posner's broadassertion that the common law is efficient, however, by stating that anefficient outcome is achieved only if "both parties . . . have asubstantial interest in future cases of this sort." n180 Unless theanticipated "efficiency savings" [*65]  from a change in therule of law are large enough to outweigh attorneys' fees and other direct costsof litigation, parties will, if rational, settle for the result dictated byexisting precedents to avoid court costs, rather than litigate in the hope ofpersuading the court to alter the law. However, if both sides have an interestin the future effect of the legal rule that is relatively substantial comparedto the costs of litigation, one or the other will always force litigation untilan equilibrium is reached at or near an "efficient" solution. n181Rubin contends that this evolutionary process will drive the law towardeconomically efficient rules despite the motivations of judges: "If judgesdecide independently of efficiency, we would still find efficient rules.Intelligent judges may speed up the process of attaining efficiency; they do notdrive the process." n182

Rubin's thesis is both too broad and too narrow. His claimsare too broad in asserting that the law will evolve toward economic efficiencydespite judicial opposition. n183 Nothing in his argument justifies the claimthat the evolutionary process he identifies is strongenough to overcome all contrary biases in the decisions of judges. At most,Rubin's process gives judges greater opportunities tochange inefficient rules of law; it does not require them to do so. n184 If thedistribution of other factors affecting judges' decisions-- tradition, political ideology, class bias -- were essentially random, thesefactors would tend to cancel one another out, and the selective pressures whichRubin identifies might tend to promote economic efficiency in the law. But ifconsistent biases affect the distribution of judicial decisions, it is anempirical questionwhether they or Rubin's evolutionary forces would have astronger influence on the law. Thus, Rubin is not justified in asserting thatevolutionary forces generated by settlement decisions are necessarily strongerthan any other forces that may affect the law.

On the other hand, Rubin's model of litigation decisions maybe too narrow in assuming that disputants are always rational and"utility maximizing." n185 What little we know about why people go tocourt rather than settling their differences privatelysuggests that the decision  [*66] to litigate is not always a logical one, taken after a dispassionatecalculation of costs and benefits. A variety of norms in addition to rationalself-interest in the narrow economic sense may enter into decisionsto settle or litigate. n186

In addition to these problems, there are also substantialweaknesses in Rubin's evolutionary model on its own terms. It seems unlikelythat a pattern of settlement decisions, as Rubin models them, could be a verystrong force toward economic efficiency in the common law. Rubin's model dependson litigants having relatively similar stakes in the future consequences of alegal rule -- a situation which probably does not occur very frequently. Even inthose few cases in which both litigants do have substantial stakes in futureapplications of the law, Rubin's model assumes naively that there is a clear-cutcorrespondence between a legal "rule" adopted in one case and resultsin future cases. In fact, however, the diversity and "richness of factualdetail in . . . judicial opinions" make it difficult to predict the futureapplicability of many legal principles. n187 Moreover,even where the future effect of a legal rule can be predicted, incentives tolitigate to overturn an inefficient rule would be limited. According to Rubin'smodel, cases will be settled unless the anticipated future costs from aninefficient legal rule, discounted by the expected probability of obtaining achange in the rule through litigation, outweigh the expenses of litigation.Legal rules which are grossly inefficient in the aggregate would nonethelesstend to persist as long as they did not impose a cost on any single litigantlarge enough to make it worthwhile to go to court to try to change the law.

Overall, Rubin's general observation that settlement decisionsby litigants may create evolutionary pressures in the law may be more importantthan the specifics of his model of the settlement process.  

B. Priest

In a comment on Rubin's paper, law professor George L. Priestproposed a variation which "simplifies and extends [Rubin's] . . .important insight." n188 The central evolutionary logic of Priest's modelof common law is the same as Rubin's. Both maintain that inefficient rules oflaw are more likely than efficient ones to be "relitigated" andeventually changed by courts. The primary difference between their theories ofcommon law evolution lies in Rubin and Priest's explanations of why inefficientrules are more likely to be relitigated until they are changed.

Rubin's argument was subject to the important qualificationthat  [*67]  both parties to litigation must be sufficiently affected by aparticular rule of law that they are willing to invest in litigation in the hopethat courts will use their case to replace that rule with a more efficient one.Priest's theory eliminates this constraint. n189 "[E]fficient rules,"Priest announces, "will bemore likely to endure as controlling precedentsregardless of the attitudes of individual judges toward efficiency, the abilityof judges to distinguish efficient from inefficient outcomes, or the interest oruninterest of litigants in the allocative effects of the rules." n190"The only assumption necessary for the hypothesis," Priest claims,"is that transaction costs in the real world are positive." n191Therefore, [i]t follows . . . that inefficient legal ruleswill impose greater costs than efficient rules on the parties subject to them.Since litigation is more likely than settlement where, ceteris paribus, thestakes of a case are greater, disputes arising under inefficientrules will be more likely to be relitigated than disputes arising underefficient rules. n192

Priest's argument boils down to a deceptively simple chain ofreasoning: inefficient rules increase costs, which increases the stakes inlitigation, which in turn increases the rate of litigation as opposed tosettlement. Therefore, Priest asserts, cases involving inefficient rules aremore likely to be litigated than cases involving efficient ones.

Priest argues that "[i]nefficient assignments ofliability by definition impose greater costs" n193 than efficientallocations of liability. Even if parties are free to bargain to reallocatecosts to those who can bear them most cheaply, assuming that bargaining itselfis not costless, "the costs imposed by inefficient rules will always behigher than the costs imposed by efficient rules." n194 Therefore, Priesasserts, the "stakes" in litigation will be greater when theprevailing legal rule is inefficient than if the rule were efficient, becausethe amount at stake is increased by what it would cost to overcome the initial,inefficient assignment of liability through private bargaining. But "if allother factors and held constant, those cases in which the stakes are higher aremore likely than those in which the stakes are lower to be litigated rather thansettled." n195 Therefore, Priest concludes, "inefficient rules as aclass will be more likely than efficient rules to generate litigation and thusto be  [*68] subjected to judicial reexamination." n196

Strictly speaking, however, Priest's reasoning does notsupport the proposition underlying his evolutionary thesis: namely, that theclass of disputes arising under inefficient legal rules is more likely to belitigated than the class of disputes arising under efficient rules. Priest'sargument shows only that more will be at stake in any particular case if theapplicable rule of law is inefficient than would have been at stake in that casehad the legal rule been more efficient. Priest commits the logical "fallacyof composition" n197 by jumping from the statement that an inefficient ruleof law increases costs in individual cases to the quite different conclusionthat costs are greater in the class of disputes arising under inefficient rules.

An illustration may clarify why Priest's conclusion does notfollow. Suppose that the rules of law relating to securities fraud are highlyefficient and that the rules of divorce law are not. The stakes in divorce casesmay be somewhat larger than they would have been if the rules of divorce law hadbeen more efficient, but that does not imply that the stakes in divorce casesare larger than the stakes in securities fraud cases. As this example shows, theclass of disputes arising under inefficient rules does not necessarily involvelarger stakes than does the class arising under efficient rules. n198

A second problem with Priest's argument arises from one of itsseeming virtues. Priest tones down Rubin's (and Posner's) position that thecommon law is efficient and specifically disavows having shown that "therules of the common law are or ever will be completely efficient." n199Instead, Priest restricts his thesis to the claim that the set of "legalrules in force will consist of a larger proportion of efficient rules than thebias or the incapacity of judges might otherwise permit." n200 He contendsonly that the evolutionary process inherent in the common law is one factorwhich influences the law. n201

By toning down Rubin's claim that the common law iseconomically efficient to the weaker claim that an evolutionary process merely [*69]  moves the common lawcloser to economic efficiency than it would otherwise be, Priest's thesis vergeson the meaningless. Literally, Priest claims only that the existing common lawcomes closer to economic efficiency than would some imaginary common lawdeveloped by judges with no settlement decisions by litigants. But the contentof that imaginary common law is unknowable; speculation about whether it wouldbe more or less efficient has no point of contact with reality.

Priest has subsequently refined and elaborated his analysis ofthe effect of settlement decisions on the law. In a later article, he arguedthat "substantive indeterminancy," rather than economic efficiency,characterizes the influence of settlement decisions on the common law. n202 Inhis recent work, Priest has continued to explore the factors that influencesettlement decisions, and has tested his predictions by analyzing data obtainedfrom court records. n203

C. Cooter and Kornhauser

 Athird economic theory of common law evolution has been developed by RobertCooter, an economist, and Lewis Kornhauser, a professor of law and economics, inan article n204 criticizing the thesis that the common law can achieve economicefficiency without the help of judges.

By making assumptions and developing a formal, mathematicalmodel of common law evolution, n205 Cooter and Kornhauser prove thatevolutionary pressures arising from settlement decisions by litigants "areinsufficient to cause the legal system to adopt and retain the best legal rulewithout the help of judges." n206 On the other hand, they do concede:"At least, for simple processes of legal change, evolutionary forces canimprove the legal system relative to what it would be otherwise." n207 Inother words, if the selective relitigation effect proposed by Rubin and Priestdoes exist -- an issue on which Cooter and Kornhauser take no position n208 --Cooter and Kornhauser agree that it would tend to increase the proportion ofefficient rules in the law.

Cooter and Kornhauser conclude that evolutionary forces in the [*70]  law cannot lead to a single efficient rule; rather, they willlead to an "equilibrium" in which both "best" and"worst" legal rules "recur." n209 These results contradictthe more extreme and simplistic claims that have been made for evolutionarymodels of law, but they are not at all inconsistent with the evolutionarytradition as such. n210 Wigmore's "planetary theory" of legalevolution, n211 for example, was a less mathematical way of stating that law isnot a single rule, but a distribution of competing principles. Similarly, modernevolutionary theory in biology does not posit that only the single"fittest" form will survive; rather, it recognizes that evolutionnecessarily leads to a broad distribution of varying solutions to particularsurvival problems. n212

Rather than refuting evolutionary theories of law, Cooter andKornhauser actually enrich the evolutionary tradition by showing that it ispossible to model legal evolution as an equilibrium in which various legalprinciples compete for survival, rather than as a simplistic process in whichonly a single efficient rule survives.

D. A Retrospective on Economic Theories of Legal Evolution

Economic theories of common law evolution have provoked alarge critical literature. n213 Some of the criticisms are particularapplications of more general objections to "law and economics" as anapproach to legal scholarship. n214 Other critics take issue with the ways thatRubin and/or Priest model the settlement process, and propose their ownalternative theories of the factors that induce parties to settle rather thanlitigate particular disputes. n215

Perhaps the most extensive criticism of the Rubin-Priestthesis is made by Professor Clark, n216 himself the proponent of an evolutionaryapproach to law. Clark raises a number of objections to the Rubin-Priestapproach, including that "the selective relitigation effect could be a realbut trivial factor in the actual evolution of the common law." n217

Despite their many substantial shortcomings, however, economictheories of common law evolution represent a remarkable step forward in theevolutionary tradition. They have focused attention on the [*71]  mechanisms that mayaccount for the patterns of evolutionary change that earlier authors observed inthe law. Moreover, the economic school of evolution has broadened our view ofthe legal system to include the role of litigants, as well as judges, in makinglaw.

It is unfortunate that economic theories of legal evolutionhave not yet been seen as part of an evolving tradition of evolutionary modelsin law. Rather, they have been written off as an isolated chapter in the debatewithin the law and economics movement over whether the common law iseconomically efficient. n218 That focus is understandable, since the economictheory of common law evolution was originally advanced by Rubin and Priest as acorollary to Posner's thesis that the common law waseconomically efficient. n219 However, in this instance, the power of thecorollary does not depend on the truth of the propositionit was devised to explain. The significance of the Rubin-Priest hypothesis isnot restricted to explaining how public concern with economic efficiency mightshape the law; "[i]n principle, . . . any values that are systematicallyheld by the community could make themselves felt on the law" through aprocess like that described by Rubin and Priest. n220 Thus, their hypothesis maybe understood more broadly as a theory of how the values of a community --Savigny's "spirit of a people" -- might shape the law.

The economic account of legal evolution, however, remainsincomplete. First, economic theories of legal evolution depend on a number ofcontroversial assumptions: that individuals are motivated by a desire tomaximize their wealth (or utility); that they behave rationally; that outcomesin a legal system are (or are perceived to be) based on rules derived fromprecedents. Economic theories of legsl evolution also depend on the assumptionthat a legal system already exists. As George Priest himself points out,"There is no good economic theory of how individual, utility-mazimizing[sic] behavior generates a legal system." n221


In recent years, several theories of legal evolution have beenproposed which attempt to remedy these shortcomings n222 in the economic [*72]  approach to legalevolution. Economist Jack Hirshleifer, n223 and law professors Richard Epsteinn224 and William H. Rodgers, Jr. n225 have advanced independent theories oflegal evolution which, in a sense, pick up where the economic theories leaveoff. I will call the Hirshleifer-Epstein-Rodgers approach to legal evolution"sociobiological" to reflect the common debt these theories owe to thesociobiology movement. n226  

Sociobiology is less a formal discipline than an intellectualperspective. Sociobiologists believe that the effect of evolution are notrestricted to biological structures but that many aspects of behavior are alsoshaped by natural selection. n227 Many of the evolutionary explanations thatsociobiologists have advanced for particular behaviors are deeply controversialamong scientists, n228 although there is broad agreement among most biologiststhat at least some aspects of behavior may have evolutionary foundations.Perhaps the best way to capture the flavor of sociobiology is to say thatsociobiologists are willing to presume that evolutionary forces explain a broadspectrum of individual and cultural practices, based on fragmentary andanecdoctal evidence not regarded as convincing by more mainstream scientists.  

Sociobiological theories of legal evolution apply theconclusions of sociobiology to law. The sociobiological school of legalevolution sees evolution not merely as a metaphor for the internal dynamics of alegal system; its members believe that evolution is the causal process whichaccounts for the existence of law and, to some extent, for the law's form andcontent. What distinguishes sociobiological theories of legal evolution is notthe claim that law evolves, but the claim that law has evolved; that law isitself a product of evolution.  

A. Keller

A sociobiological approach may be beneath the surface of anumber of earlier theories of legal evolution. It is at least implicit in [*73]  Maine's notion of anevolutionary progression from governance by heroic kingship to law. n229 Thepremises of sociobiology also may lie behind Corbin's allusion to legalprocesses enabling societies to escape being torn apart by conflict. n230 Atmost, these are only fragments. The essential elements for a full-blownsociobiological theory of legal evolution were stated clearly, however, in anextraordinary article published half a century ago by A. G. Keller. n231 Kellerwas Professor of the Science of Society in Yale University, and a friend ofArthur Corbin, who may have stimulated his interest in legal evolution. Kellertheorized that a Darwinian process of evolutionary selection operates to shapecultural mores in general and law in particular.  

Keller introduces his sociobiological theory of legalevolution by quoting Holmes, and announcing that he is planning on"asserting and maintaining" Holmes' implication "that law isevolutionary." n232 By evolutionary, Keller means that "humaninstitutions, and, among them, law show adjustment to life-conditions by way ofthe stock Darwinian factors of variation, selection and transmission." n233In a passage that reads as though it had been written half a century later bysociobiologist E. O. Wilson, Keller describes cultural mores as "anevolutionary product": n234  

Man's diversities of structural modification are by no meanssufficient to secure his adjustment to the extremes of environment in which helives. His typical mode of adjustment is mental . . . . [The products ofevolution] cover systems and economies and organizations that develop in thestruggle for existence and the competition with fellow-creatures. They thereforeembrace, in short, all the folkways and mores, and whatever develops out ofthese in the way of more definite and settled social forms. [Cultural] mores areas much evolutionary products as are the horse's hoof and the camel's foot . . .. They are equally adjustments to life-conditions, possessing survival-value andthus characteristic of the fitter societies. It is by adjustments in its moresthat a human group adapts itself to environment; the slower method by way ofstructural change is superseded by the swifter action of a specilized organ ofadjustment, the mind. Adjustment may be mental without being deliberate,purposeful, rational, or even conscious. Folkways are empirical, not planful.n235  

According to Keller, the same evolutionary pressures thatshape  [*74]  cultural mores also operate on the law. n236 Law evolves whenthe power of the state stands behind particular cultural mores. n237 Butevolution accounts for the growth of law as well as its birth, Keller argues,for if any society is to survive, it must develop mores which permit it to meetthreats from within and without. Keller does not maintain that all laws are theproducts of evolutionary forces, only those "elements common to all codesof laws, over all earthly space and . . . time." n238 Keller claims thatthese elements have survived because "they respond to a perennial necessityfor the very self-preservation of society. In that sense they are natural andnot Natural law; but now we know what the 'natural' means." n239 Keller'sonly illustrations are a brief reference to prohibitions of murder, which hesees as "the very essence of social necessity, if internal cohesion andorder are to be maintained" n240 and stealing, which "establishes theright to property, thus excluding aggressions, reprisals, and consequent chaosand disorganization." n241 According to Keller, "[n]o society can longpersist in the competition without such inhibitions. Here are laws, then, whichhave an external survival-value in them . . . ." n242  

Keller's theory suffers from a number of shortcomings. By itsown terms, the theory lacks power to explain any but the most basic features oflaw. Keller gives only two examples of laws which are arguably necessary to the"self-preservation" of society -- criminal laws concerning murder andstealing. They constitute only a tiny fraction of the matters touched by law.Even in the narrow areas addressed by his theory, Keller is vague about whyevolution would mandate particular legal solutions. For example, Keller's ideathat societies must enforce a rule against "stealing" to minimizeconflict, may explain why they need some definition of property rights inthings; it does not explain why private, as opposed to communal, property wouldemerge.  

An additional limitation is that Keller's thesis is entirelyspeculative. He cites no evidence that murder and stealing have in fact beendealt with by all societies as he assumes that evolution dictates. Nor does hedemonstrate that even these few, arguably universal features of legal codes wereproduced by natural selection at the group level, a theory which would implythat societies became extinct because they lacked particular laws.  

The shortcomings in Keller's article are serious, but do notgo to the heart of his theory. For example, Keller's remarkable assertion thatthere are features of law which are similar in all societies at all times is [*75]  as unnecessary as itis dubious. Variations in laws are not inconsistent with evolution, as Kellerseems to assume. Differences in laws among societies may be explained either bydifferences in environmental conditions, or by the fact that a variety ofsatisfactory solutions are available to particular survival problems. Evolutionmay indeed require that in order to survive as a community every society mustdevelop a collective response to the crisis posed when one member of thecommunity kills another. There is no reason to suppose, however, that only oneparticular code of laws will achieve this goal well enough to enable a societyto survive.  

Keller vacillates on the related problem of the degree towhich change in the law is the result of conscious choices. At one point, hestates that "[m]uch" of the selection in the law "has beenautomatic and unconscious, not rational and planned." n243 This formulationimplies, however, that to some extent selection in the law is rational andplanned. Doesn't conscious choice undermine Keller's evolutionary thesis?  

This question provoked an interesting comment on Keller'sarticle by W. Jethro Brown, an Australian scholar and judge. Brown's articlen244 provides what is still the best explanation in the literature of why it isa false dichotomy to insist that change in the law must result either fromconscious choice or from evolution. Brown considers the "breeding ofanimals in an environment where one of the factors of the process is the mind ofthe breeder" n245 and concludes that when we speak ofthe evolution of a particular species, there is not excluded the possibility ofmental or quasi-mental processes in the course of adjustment to the environment.If the fittest survive, the result is not invariably due to extraneous causes .. . . [T]he existence and degree of the element of purpose in legal change arenot, per se, an answer to the appropriateness of the use of the term "legalevolution." All that we are justified in saying is that in the case of lawconscious, if unformulated, purposes play a more important and a more apparenttole than in biological evolution. n246  

Except for Brown's comment, Keller's theory of legal evolutionattracted surprisingly little attention even though it anticipated many of thethemes of sociobiology which were to create a storm of intellectual controversyhalf a century later. Part of the explanation for the relative obscurity ofKeller's theory lies in its inherent weaknesses and his failure to provideempirical support. An equally important factor, however, may be the controversysurrounding Social Darwinism which  [*76]developed in the years following Keller's article. n247 Despite Keller'sprotestations that his theory of legal evolution was based on Darwin's versionof evolution, not Spencer's, n248 by the first half of this century, theories ofsocial evolution were so firmly associated with Spencer's racist and imperialistideologies that any evolutionary theory of social phenomena was perceived asreactionary. n249 Outside biology, evolutionary models were in a state ofintellectual banishment for over half a century.  

B. Hirshleifer  

After a fifty year hiatus, interest in evolutionary models oflaw has recently been reborn. This resurgence was not fed by the work of priorlegal theorists; indeed, most contemporary theorists are unaware of theevolutionary tradition which precedes them. Instead, it was a by-product of thelaw and economics movement, n250 which drew on a tradition of evolutionarymodels in economics.  

The first modern author to propose an explicitlysociobiological theory of legal evolution was Jack Hirshleifer, professor ofeconomics at UCLA. Hirshleifer, an early contributor to the law and economicsmovement, grew dissatisfied with the narrowness of classical microeconomicmodels for describing human behavior. Like other applications of microeconomictheory, economic theories of law develop formal models based on assumptionsabout how hypothetical people behave in hypothetical social structures, whichmay or may not correlate usefully with the way real people behave in the socialstructures that actually exist. Even at their best, however, classical economictheories do not purport to have anything to say about why people and socialstructures are as they are. Hirshleifer expresses his dissatisfaction with thisaspect of classical microeconomic theory as a criticism of the typicaleconomist's conception of "tastes." n251 "The use of thistrivializing word, suggestive of the choice of French dressing versus ThousandIsland, is itself an evasion. If we spoke of human drives or aims, of [*77]  ingrained ethics, orof value systems or goals for living, we would be more inclined to treat thesubject with more respect." n252 Sociobiology was attractive to Hirshleiferprecisely because it seemed to transcend the arbitrary treatment of tastes andto return to the insights of "the master, Adam Smith, who did not regardthe fundamental drives of men as arbitary  and inexplicable, [but as]ultimately adaptive responses shaped by man's biological nature and situation onearth." n253  

Hirshleifer's first articles on sociobiology focus on therelationship between evolution and economic theory. n254 He quickly extends hisanalysis, however, to propose a sociobiological explanation for the developmentof law:  Withina social group, law emerges when what might be called "moralisticaggression" by third-party intervenors serves to control internal conflict.We see this already when parents regulate offspring rivalry -- behaviorwidespread in the animal kingdom. Government may be said to exist when, ingroupings larger than a single family, control tasks are performed byspecialists in that function. In the biological realm, some species havedominant individuals or cliques that approach primitive government within packsor troops. The immunities from invasions thus created prefigure the humaninstitution of property.  

The political-economy institutions provide two classes ofadvantages. On the first level, law and government deter or limit the internalfighting and consequent losses of strength that would be disfunctional for thegroup as a whole. Individuals need not divert effort to continual patrolling andmonitoring. This is a king of minimal or negative co-operation. On the secondlevel, positive co-operation in the form of exchange or resource entitlementsbecomes a possibility -- and, ultimately, the more sophisticated dealings indeferred reciprocations that constitute the essence of contract. n255  

Although Hirshleifer does not cite the work of earlier legalevolutionists, there are a number of parallels between his theory and theirs.Like Maine, Hirshleifer sees law developing as an extension of behavior patternslearned in the family. Both theories also portray contract law as the foundationfor an "advanced" society. Hirshleifer's vision of legal evolution isalso reminiscent of Keller's in claiming that by reducing internal conflict, lawgives certain groups an advantage in the evolutionary struggle to survive.However, this aspect of Hirshleifer's theory is much more powerful than itspredecessors. Keller merely suggested  [*78] that a group would be more likely to survive if it were able to maintaina shared definition of behavior appropriate in conflict-prone areas of life; hehad no logical basis for contending that any one particular definition of rightswas more likely to contribute to group survival than any other. n256 Hirshleifergoes further, suggesting that certain laws are indeed more likely than others topromote group survival. Combining economics and sociobiology, he maintains thata legal system that promotes mutually beneficial exchanges while keeping thepeace provides an additional survival advantage over a system that merelysupresses conflict. n257  

Hirshleifer's thesis is disputable, of course. He offersnothing but intuition to support his claim that a legal system that promotesresource exchange enhances group survival. Despite the lack of support for thisaspect of his theory, the empirical flavor of Hirshleifer's work generally doesset it apart from most earlier theories of legal evolution. Hirshleifer attemptsto support his theories with numerous references to parallels in the animalkingdom. Like most sociobiologists, however, Hirshleifer's use of evidence issuggestive rather than definitive. His work nonetheless is innovative as thefirst theory of legal evolution to propose an essential contimuity between lawand forms of social organization among animals. In fact, he probably goes toofar in extrapolating from animal behaviors to human institutions. Unlike Kellerand Brown, n258 Hirshleifer does not explicitly leave room for consciousmotivation, intelligence, and planning by human beings in his theory of legalevolution.

Hirshleifer does not restrict the scope of his sociobiologicalapproach to legal evolution to explaining the genesis of legal systems as such,or to a few major concepts such as contract or property. He also attempts toextend the logic of legal evolution to explain the finer texture of legaldoctrines in certain fields of law; for example, he proposes a sociobiologicalexplanation of the law of privacy. n259 Hirshleifer begins this analysis byattacking the previous economic theories of privacy law n260 as based on a"more or less inexplicable 'taste'" for seclusion. n261 On thecontrary, Hirshleifer contends, tastes are not arbitrary at all but are based on"what has been found by natural selection to work" as a successfulmotivator in the past. n262

Rather than make the straightforward argument that evolution [*79]  favors the survival ofgroups that recognize privacy rights, Hirshleifer takes a more subtle tack,arguing that the law of privacy is an outgrowth of "a particular kind ofsocial structure together with its supporting social ethic." n263 The lawof privacy develops not because it, in itself, increases the chance that a groupwill survive, but because it is integral to a social ethic which enhancessurvival. Bodies of law are thus shaped by evolutionary forces, but onlyindirectly.  

Hirshleifer outlines three social ethics, which he calls theGolden Rule of "communal sharing," the Silver Rule of "privaterights," and the Iron Rule of "dominance." n264 "Thesestructures and ethics have evolved, each only in particular ecological contexts,because individuals so organized turned out to have a survival advantage(through group selection) over those expressing different behavioraltraits." n265 Hirshleifer sees the "privacy ethic" as associatedwith a particular balance between "autonomy and sociality" typical ofsocieties organized according to the Silver Rule of private rights. n266 In suchsocieties, individuals are taught to "insist on [their] own claims ofinviolability of persons and property while being prepared to concedecorresponding rights to other." n267  

It is not altogether clear what significance Hirshleiferascribes to his three "Rules." or to what degree he acknowledges thatforms of social organization may deviate from his categories. At one point, heconcedes that his three types are oversimplified, "since none of these areprobably ever observed as pure forms." n268 Elsewhere, however, he appearsto make more imperious claims. Hirshleifer goes to some length in an attempt toprove that a "social system of private rights" tends to evolvenaturally, n269 and even asserts, without supporting citations, that "[e]ssentiallyall known primitive communities have been found to possess relatively elaboratestructures of property rights." n270 At the same time, however, Hirshleiferpoints out -- again without citations -- that "[i]n primitive humansocieties, anthropologists have emphasized, patterns of redistribution arenearly universal as limitations upon property rights." n271  

These inconsistences and ambiguitie are symptoms of a [*80]  fundamental dilemma.To the extent that Hirshleifer maintains that his three metallic rulesconstitute progressive stages through which all societies must evolve, histheory, like Maine's, is both ethnocentric and unsupportable. On the other hand,when Hirshleifer backs away from a strong version of evolutionary determinism,he runs the risk that his theory will degenerate into a personal, metaphoricalsystem for classifying differing social value systems. n272  

Sociobiology is still a long way from the comprehensiveaccount of human motivations necessary for the kind of positive theory of socialevolution that Hirshleifer seeks. Nonetheless, biology and sociobiology docaution the legal scholar that the model of human motivations proposed byconventional microeconomic theory is too narrow. The law and economics traditionin legal scholarship has typically modeled human behavior as self-seeking.Evolutionary biology teaches, however, that human beings are not motivated onlyby the desire to maximize their personal well-being. In some circumstances,evolution selects for altruism n273 -- self-sacrifice to benefit the group ofwhich one is a member. n274 Thus, the picture of individual and socialmotivation that emerges from evolutionary biology differs in critical respectsfrom that assumed by the law and economics movement in legal scholarship.Hirshleifer clearly agrees with those -- including proponents of the"critical legal studies" movement n275 -- who suggest that law cannotbe understood without incorporating noneconomic motivations such as altruism,n276 redistribution, n277 and paternalism. n278 [*81]   

The aspiration in Hirshleifer's most recent work is toreconstruct traditional microeconomic models to incoporate the more complexmotivations suggested by evolutionary biology. n279 Whether this effort willultimately bear fruit remains to be seen. Whatever the outcome of that work,however, Hirshleifer's sociobiological theory of legal evolution remainsimportant. It points out a central weakness in the law and economics approach tolegal scholarship and suggests possible directions that legal scholarship maytake to overcome it.  

C. Epstein  

Hirshleifer's 1980 article on privacy law n280 stimulatedRichard Epstein, a professor of law at the University of Chicago, to propose hisown theory of legal evolution. n281 Epstein's article began as a comment onHirshleifer's evolutionary theory of privacy law, but grew into a fullfledged"speculative" exploration of the extent to which "an evolutionarytheory of behavior" can explain "not only [privacy but] manysubstantive legal issues." n282  

Epstein criticizes Hirshleifer's conception of privacy lawn283 and argues that "it is most unlikely that any set of selectionpressures have fostered . . . preference for the right of privacy." n284However, he does agree with Hirshleifer's general position that in other areasof law, natural selection may "play a powerful role" n285 by selectingin favor of human beings with "tastes for legal rules." n286 Epsteinproposes four categories of law which he believes have evolutionary roots. n287For each of these four areas, the thrust of Epstein's argument is the same: [*82]  human beings whofollow certain rules of conduct are more likely to survive and reproduce thanare those who do not. Over time, natural selection operates so that most humanbeings share norms as "common instinctive responses" to recurringsituations. n288 The final step in Epstein's argument is not spelled out; hesimply assumes that if norms are shared, somehow they find their way into thelaw. n289  

Epstein's theory of legal evolution bears at least asuperficial resemblance to Hirshleifer's. Both see evolution creating sharedtastes which are in turn reflected in the law. Epstein places primary relianceon natural selection at the individual level, however, while Hirshleiferemphasizes group selection. Neither marshals evidence in support of his thesis,but Epstein's theory that the evolution of shared values takes place throughselection at the individual level seems more plausible. It is difficult toimagine, for example, that at one time there was a random distribution ofattitudes toward murder, but that those groups which legitimated the practicegradually died out while those which banned it survived. It is more probablethat individual human beings who experience revulsion at killing, and fleesituations in which killing may occur, are more likely to survive than theirpeers. Ultimately, however, the distinction between individual and groupselection may not be of too much importance. The two processes are not mutuallyexclusive but may simultaneously shape the social attitudes reflected in law.  

Epstein is among the first to tell a credible story about howbiological evolution might produce inborn attitudes which account for certainfeatures of the law. However, the negative implications of Epstein's theory areat least as important as the positive ones. While recognizing that some basicprinciples of law may be based on attitudes which are [*83]  built into humanbeings by evolution, n290 Epstein denies that evolution has any material effecton most of the law, including the law of privacy. His argument here is alsointuitive: it seems implausible that evolution can have much to do with the bulkof the law, which deals with issues "too far removed" from survivaland reproduction. n291 "The gene-environment interactions that drive natualselection are strongest in matters that . . . come closest to the raw nerve ofsurvival and propagation. The questions of privacy are simply too far removedfrom these dominating concerns to have much imprint upon the development oftastes for any given normative orders." n292  

Neither Hirshleifer nor any other evolutionary theorist hasyet made a case that all, or even most, areas of law are shaped by evolution.However, to the extent that Epstein goes beyond a verdict of "notproved" to a claim that evolution cannot affect the law except in the fewareas which he has identified, his analysis overlooks several important factors.Like eighteenth century "state of nature" theories, Epstein's accountof legal evolution describes human beings competing for survival in an imaginarytabula rasa. Because his description of the environment is impoverished, it isnot surprising that he is able to identify only a few basic behavior patternswhich enhance survival universally. If one posits a more detailed set ofenvironmental conditions, however, it may be possible to extend Epstein's theoryof legal evolution to additional areas of law.  

For example, the difference between the laws governing waterrights in the eastern and western parts of the United States may be a result ofevolutionary adaptation under different environmental conditions. In the east,water rights are generally governed by the "riparian rights" system,inherited from English common law, under which each landowner along a watercourse is equally entitled to reasonable use of the stream flow past his land.n293 On the other hand, throughout most of the western United States, waterrights are generally determined according to the doctrine of "priorappropriation." Under a prior appropriation system, the first person to putwater to a beneficial use acquires a vested right to continue to use that amountof water. n294  

The difference between the two systems may be partlyhistorical, but it may also be attributed to the differences in theenvironmental conditions that prevailed in those regions when water law wasbeing formed. In the east, water was generally not scarce, but it was [*84]  important to maintainstream flows in order to ensure a continuing source of water power to mills andother industries. Hence, the doctrine developed that each abutting land owner isentitled to use water but not to divert it outside the watershed. In the morearid west, on the other hand, water has always been a scarce resource. Bygranting vested rights to those who put the water to beneficial uses, the lawpromoted the "mission of regional settlement and development." n295With the spread of industry, the differences in water usage between the west andthe east have become less pronounced, and the water law doctrines of the twoareas have gradually tended to converge. n296  

It is not necessary to invoke the spectre of societies orindividuals becoming extinct because they picked the wrong system of waterrights to see an evolutionary process shaping water law. Broadening the argumentof the economic evolutionary theorists, one might assume that the law rejectsprinciples that are not successful at resolving conflicts. n297 Under thistheory, the riparian rights system of the east did not spread to the westbecause it could not successfully resolve conflicts in that environment,although it worked tolerably well in New England.  

Epstein's argument that evolutionary forces only operate inareas close to the "raw nerve" of survival and propagation overlooksthe fact that evolution may build into a society's value system adaptivecriteria which are proxies for the results of past evolutionary selection. n298To take a simple analogy, it has been suggested that some substances -- such asrotting carrion -- are unappetizing to most human beings because pastevolutionary "processes . . . build in internal selective criteria, liketaste buds, which are vicarious representatives of external selectors."n299 Similarly in the law, evolution may operate in terms of intermediate norms,which embody the results of past adaptation, as well as through outrightextinction of individuals or groups. For example, natural selection may havelong ago eliminated societies which did not develop a legal system whichrecognized the importance of minimizing internal strife. Once the fundamentalnorm n300 of minimizing internal struggle is built into the legal system byevolution, it is possible to derive subsidiary legal principles from it. We donot need to play the evolutionary game through to extinction each time.Variations of water law which ultimately would have led to range wars and groupextinction do not have to be pursued to their bloody conclusion; they can be [*85]  rejected at a morepreliminary stage on the grounds that they are inconsistent with norms alreadyembodied in the legal system.  

Therefore, it is not true, as Epstein evidently supposes, thatevolutionary forces can only be at work in the law in a few areas which impingedireclty on procreation and survival. Indeed, Hirshleifer's thesis that the lawof privacy may be an outgrowth of the "Silver Rule" of private rightsn301 is an attempt to illustrate that the law may be shaped by intermediatestructures, which he calls "ethics," which are themselves the resultsof past evolutionary selection.  

D. Rodgers

A more recent sociobiological theory of law was proposed in1982 by William H. Rodgers, Jr. n302 Rodgers, like Hirshleifer, turned tosociobiology out of a belief that contemporary legal scholarship is built onfalse conceptions of human motivations. n303 On one side are the economists, whoattempt to understand law by assuming that people are rational maximizers ofself-interest, an image which Rodgers denigrates as bearing "scantresemblance to the thinkers and actors known to social investigators." n304Opposing the economists are the followers of philosophers such as John Rawls,n305 whose theories of justice based on a "calculated social contract"are, Rodgers maintains, "utterly at odds with what paleoanthropology knowsof the evolution of the human species." n306  

Rather than build our legal theories on these misleading"caricatures" of human nature, Rodgers proposes to use the lessons ofsociobiology to "bring people back" into legal analysis and draw uponthe behavioral preferences of human beings as revealed by "the laws ofbiology." n307 Rodgers cites E. O. Wilson n308 as the source for hisassumption that biological laws control social behavior, but fails to note thatsociobiology is very controversial among scientists. n309  

Rodgers proposes to test his thesis that the law is shaped bycharacteristics that evolution builds into human beings by applying it toexplain "property rights in natural resources." n310 Rodgers firstdevelops  [*86] his own "comprehensive theory of property" which he relates toprecepts derived from sociobiology. n311  

A property rights holder may possess three types of property:a core "human" property, which may be taken only upon the terms of theholder; private property or entitlements that may be taken only withcompensation; and a "social" or provisional property interest in theresource commons, which may be redefined to the detriment of the holder withoutcompensation. n312 Rodgers develops these categories by analogy to the "[s]paceand territorial needs of animals," asserting that "biologists haveidentified similar needs in humans." n313 The type of property historicallygiven the greatest legal protection under this analysis is"biologically-justified property," n314 which includes"maintenance of a food base, provision of security and identity, andprotection of privacy" through a "microspace" and a "mesospace."n315  

Rodgers proposes to "test[ ] this comprehensive theoryagainst legal experience in the natural resources field." n316 Heacknowledges that this strategy will provide only weak confirmation for hissociobiological theories. All he purports to show is that it is possible to givea parsimonious explanation of certain areas of property law in terms of theprecepts of sociobiology, and that the sociobiological explanation fitsreasonably well with the legal principles that are actually observed. Rodgersmaintains, however, that "at the point of confirmation theory . . .normative social science is severely impoverished," and that his, as a"descriptive theory," is actually far more scientific than "muchlaw review analysis." n317  

The balance of Rodgers' article is a rich and sophisticatedtour of property law, with particular attention to conflicts over the use ofnatural resources. No summary will do justice to Rodgers' full argument, but byfocusing on Rodgers' sociobiological interpretation of the traditional law ofnuisance as an illustration, it may be possible to suggest its flavor.  

Overall, Rodgers sees nuisance law as confirming his generalthesis "that human property is protected by right and . . . social propertyis vulnerable to uncompensated redefinition." n318 Nuisance law has astrong "absolutist" component, Rodgers writes, which is reflected by  [*87]  thetraditional right of a successful plaintiff to obtain an injunction requiringthe abatement of a nuisance even though the defendant loses more in an economicsense than the plaintiff gains. n319 Rodgers attributes this absolutistcomponent in nuisance law to the fact that "[f]or most nuisance plaintiffs. . . the core interests protected in the face of utilitarian objections includehealth, abode, and other essentials of living . . . ." n320 Such interestsare "reminiscent" of the interests which form the basis of Rodgers'biologically-based theory of rights in human property. n321  

Rodgers does acknowledge that nuisance law is not absolute buthas traditionally compromised the protection given to individuals, even inmatters affecting life and health, by balancing a number of factors under therubric of "reasonableness." n322 Rodgers interprets this aspect of thetraditional law of nuisance as an illustration of conflict-avoidance. n323Finally, Rodgers relates the features of nuisance law to the precepts ofsociobiology, n324 including theories of reciprocal altruism which he, likeHirshleifer, regards as a key to understanding law: Aftertheir basic needs are satisfied, individuals in human society long have beenexpected to sacrifice for the benefit of neighbors. Human altruistic behaviorextends to a variety of activities . . . and is thought to have evolved beauseof the wide range of human reciprocal relations. . . . Biological theorysupports a rule of best efforts to prevent resource usage from working to thedisadvantage of another member of the society. Thus, in protecting humanproperty and in enforcing reciprocity, nuisance law confirms the themes ofbiological property theory adverted to earlier. n325 Rodgers conceives ofnuisance law, then, as a social mechanism by which communities enforce anobligation of reciprocal altruism for the benefit of the group as a whole.  

The upshot of Rodgers' argument is that judges decide propertylaw cases as if they believed in the principles of sociobiology. n326 [*88]  Rodgers is not veryilluminating, however, about what mechanisms supposedly produce this result. Atone point, he admits frankly that he simply "assumes" that courtsadopt property justifications "strongly held by the population." n327This comes close to Keller's metaphorical assumption that community moressomehow "crystallize" to become the law. n328 Alternatively, citingPriest, Rodgers suggests that "courts might be led unknowingly tobiological sharing rules because departures from the biological optimum would bechallenged repeatedly by those suffering the deprivation." n329  

Rodgers' difficulty in identifying a mechanism which wouldcause judges to decide cases according to the principles of sociobiology iscompounded by his reluctance to assert that evolutionary imperatives are theonly factors at work in the law. Rodgers specifically warns his readers:"Biological theory offers no all-encompassing explanation of legaloutcomes, although it offers important, and partial explanations." n330Rodgers insists that his theory is not nominalistic or tautological, but"descriptive," and therefore that it is falsifiable. n331 However, ifby a "partial" explanation Rodgers means that the drives evolutionbuilds into human nature are only one factor among many which combine to producelegal outcomes, it is doubtful that the evolutionary aspects of Rodgers' theoryreally can be falsified: any deviations from what his theory predicts couldalways be attributable to the unspecified "other factors" which lieoutside his theory. n332  

Despite this shortcoming, Rodgers' sociobiological theory ofproperty rights is one of the first attempts by a modern legal scholar to movebeyond generalities to explain the details of particular bodies of law in termsof evolutionary theory. In particular, Rodgers' theory is probably moresuccessful than any competing legal theory at rationalizing the confusing welterof "takings" cases, in which courts attempt to define thecircumstances under which governmental interference with private property is sogreat that compensation must be paid. n333 Rodgers does [*89]  provide relativelyparsimonious explanations for many existing legal doctrines in property law interms of sociobiology. The history of ideas, however, is strewn with relativelyparsimonious explanations that turned out to be wrong.  

Ultimately, the value of a sociobiological theory of law likeRodgers' is not descriptive, but normative. Ideally, his notion that there is a"biological optimum" in the structure of property rights could be usednot simply to describe how courts do decide "takings" cases, but totell them how they should decide these cases. Rodgers admits that he aspires touse sociobiology as the foundation for a prescriptive theory of law based on"positive rights" as a "counterpoise to economic analyses."n334  

Here Rodgers ventures into exciting but treacherous territory.In the past, many have aspired to transform law into a rational science ofsocial engineering, based on the application of one version or another ofabsolute truth. There is little reason to suppose that sociobiology will succeedat defining uncontroversial goals for society where so many other disciplineshave failed. Consider that Epstein and Rodgers both propose theories of propertybased on sociobiology, and that both then derive interpretations of the takingsclause of the Constitution to strike the proper balance between public andprivate rights. n335 To Epstein, it is clear that the law should enhance theprotection it gives to  [*90] private property; to Rodgers, it is equally clear that communal claims toresources should be dominant over private rights.  

Evidently, the "laws of biology" have not yet beenheard to speak with a single voice on the issues of social justice that underlielaw.  


A surprising number of writers over the years have proclaimedthat law evolves. What explains this peculiar fascination with evolutionarymetaphors among legal scholars?  

In part, the fascination with evolution in jurisprudence isnot peculiar at all. Most realms of thought have been deeply influenced byDarwin. Evolutionary metaphors are part of the zeitgeist. It would be strange ifthere were no evolutionary theories in jurisprudence. Yet there are also specialreasons for the affinity for evolutionary metaphors in American jurisprudence.  

To understand the special appeal that evolutionary models andmetaphors hold for legal scholars, one must first appreciate that scholars meansomething quite different by "the law" than do most lawyers orcitizens. To someone who may be affected by a legal decision, the importantissue is to predict how a particular case will be decided. This rarely interestslegal scholars. They typically focus on patterns in legal decisions which emergeover longer time periods. When scholars claim to see evolutionary forces at workin the law, they see them in the patterns of decisions over many decades.  

Thus, the claim that law evolves is not inconsistent with thebelief that judges are affected by economics, by ideology and class bias, by therhetoric of lawyers, or by a host of other factors that may influence theoutcome in particular cases. Theories of legal evolution simply do not speak tolaw at retail. They claim to identify patterns of change that become visiblewhen one views the law from altitude, not at groundlevel.  

Evolutionary models and metaphors are a particularly usefuldevice for talking about changes of this sort in the law. One of the distinctivefeatures of evolutionary theories is that they may be used to describe thenature and direction of changes in a complex phenomenon even though little isknown about its constituent parts and the mechanisms connecting them. Darwinknew almost nothing about the mechanisme of heredity; he was ignorant of theexistence of genes, much less of DNA and the genetic code. Nor could he havespecified the precise conditions which account for the death or survival of eachmember of even a single species. Yet despite Darwin's ignorance of theseparticulars, he was able to formulate simple, powerful statements at higherlevels of abstraction about the patterns of change that result from theseforces.  

Similarly, writers in the evolutionary legal tradition -- fromSavigny and Maine to Hirshleifer and Rodgers -- aspire to describe global [*91]  patterns of change inthe law without specifying the details of why particular officials decideparticular cases as they do. Evolutionary models are almost uniquely adaptableto these purposes. Very few other modeling traditions require so little by wayof specification of input functions and almost none are available to lawyers.Thus, when Holmes, Corbin, and Wigmore describe legal evolution without definingprecisely why some legal doctrines are "stronger" than others, theyare not abusing evolutionary metaphors. Rather, they are attempting to use anunique aspect of the power of evolutionary models to make relatively refinedstatements at an abstract level when little is known about the determinants ofspecific cases. n336  

To say that evolutionary models have particular advantages fordescribing gradual patterns of change in the law is not, however, to assert thatthe function of jurisprudence is primarily descriptive. Theories of law arerarely written to describe; their aim is more often to advocate and tolegitimate. n337 Here too, on a normative level, evolutionary models haveparticular appeal, although an appeal which has both positive and negativeaspects. To understand the strong normative appeal of evolutionary models, onemust first appreciate that American law, like biology at the time of Darwin,faces the problem of providing a theory of creation which does not invoke aSupreme Being.  

A central question for any jurisprudence is why people shouldobey the law. If the populace believes that the local despot rules as God'semissary on earth, the answer is relatively easy. Without God as the ultimatecreator of the legal universe, however, it becomes more difficult to justify lawas something people have a moral obligation to obey. In the United States, wehave several different approaches for justifying the creation of the legaluniverse. The Constitution begins with the first, and most successful: "We,the people . . . ." n338 The explanation that the people, acting throughtheir elected representatives, have created our legal universe workssurprisingly well, and it is rare that the legitimacy of laws enacted bydemocratically elected legislatures is questioned. When courts and bureaucratsmake law, however, it is less persuasive to assert that they speak by authorityof "We, the people . . . ."  

In one guise or another, the question, "by what right docourts and bureaucrats make law?" has occupied a large percentage of theenergy of American legal scholars. n339 In the twentieth century, the dominant [*92]  answers have beenessentially "positivism" and its second cousin, "legalrealism." Law is conceived of as the behavior of certain powerfulofficials: "The prophecies of what the courts will do in fact, and nothingmore pretentious." n340 It is obeyed because "behind every finaljudgment procured in any court in this country stands, ultimately, the UnitedStates Army." n341  

Many American lawyers are not entirely comfortable with theextreme positivist position that law and power are synonyms, and there have beennumerous attempts to provide alternative explanations for the legal order. Iflaw is to be more than the record of commands backed by superior force, ajurisprudential theory is needed which explains why there is an obligation toobey law, and which gives meaning to arguments that law is right or wrong(rather than simply is). One alternative is the "natural law"tradition. Natural lawyers claim that there is some set of principles -- some"higher law" -- by which the law declared by government officials canbe judged. n342 The problem with natural law theories comes in defining thenature and sources of this higher law. Most modern natural law theories areeither intuitive, or assert that some goal, such as economic efficiency, isuncontroversial among all sane people. n343  

It is here that the normative power of evolutionary theoriesof law comes into play. In much the same way that Darwin invoked evolution toexplain the order of creation without a Creator, or Julian Huxley sought to useevolution as the basis for religion without revelation, n344 lawyers havefastened on evolution as an alternative to intuition, or economics as a sourceof natural law principles by which human law may be judged. Of the legalevolutionists, perhaps A. G. Keller saw this point most clearly, writing thatthe legal principles he had described were "natural and not Natural law;but now we know what the 'natural' means." n345 But even at its veryinception, the evolutionary tradition in law was proposed as an alternative topositivism; Savigny declared his purpose was to attack the positivist theorythat law "is founded upon the express enactments of the supremepower." n346  

In my opinion, it would be a fundamental mistake to evaluateevolutionary theories of jurisprudence as true or false. Jurisprudentialtheories are not true or false in the same sense that scientific theories are. [*93]  Instead, we shouldjudge evolutionary jurisprudence as we judge any creation myth, by whether it isuseful. As the foregoing pages show, the evolutionary tradition does not dictatea single definite theory of law; at most, an evolutionary approach to lawcreates a context, a distinctive kind of conversational setting, within whichdialogue about law may occur.  

As a context for thinking about law, however, evolutionarymetaphors offer both perils and strengths. The peril is insidious, if wellknown. Evolutionary biologists Steven J. Gould and R. C. Lewontin identify it asthe "adaptationist programme" in evolutionary theory. n347 Legalhistorian Robert W. Gordon calls it "adaptation theory," n348 or"evolutionary functionalism" in law. n349 Perhaps Voltaire captured itbest in Professor Pangloss, who assured his listeners: "'[T]hings cannot beotherwise . . . everything is necessarily for the best end. Observe that noseswere made to support spectacles; and so we have spectacles. Legs were visiblyinstituted to be breeched, and we have breeches.'" n350  

No doubt evolutionary models in law can be, and have been,invoked to maintain that existing legal arrangements are the natural, eveninevitable, products of evolution. Perhaps the Panglossian side to legalevolution is clearest in Maine, to whom it seemed self-evident that a societyorganized along the lines of nineteenth century England was evolution's highestcreation. A similar, though more subtle, penchant to see a familiar legalarrangement as the best of all possible worlds is also present in Keller andHirshleifer, and perhaps in Epstein and Rubin as well.  

But it does not follow that an evolutionary jurisprudenceleads inevitably to legal scholarship which rationalizes the status quo. On thecontrary, the striking thing about the scholars who have shared an evolutionaryapproach to jurisprudence is that they have been among America's most creativelegal scholars. They have not accepted legal doctrines in their fields blindly,but engaged them in vigorous debate. I want to maintain that this is not merehappenstance; there is a connection between an evolutionary jurisprudence andlegal scholarship which is at once constructive and creative, critical andvigorous. n351  

At its best, an evolutionary jurisprudence leads scholars totake legal doctrine seriously but not to glorify it. To scholars who share anevolutionary approach to jurisprudence, reported cases are not [*94]  collections ofimmutable rules, but are, as they were for Corbin, a storehouse of wisdom. n352Scholars whose work grows out of an evolutionary approach to jurisprudence donot worship the past; they must, as Wigmore reminded, n353 strive to relatelegal principles to the ends they serve, and to criticize existing law when itdoes not serve valid goals or when conditions have changed. This lays thejurisprudential foundation for the work of scholars like Holmes, Corbin, andWigmore, work which is both critical and creative.  

There are, to be sure, alternative theories which others claimmay serve as the foundations for a positive, constructive legal scholarship,such as law and economics, n354 or intuitive theories which imagine how humanbeings might think about social justice in rarefied states of nature. n355However, as Rodgers points out, n356 these alternative approaches initiateconversations about law which involve types of human beings and environmentsradically different from those we know.  

Evolutionary approaches to jurisprudence are not a panacea,but neither are they prescriptions that the law adopt "pig ethics" orthe rule of the bloody tooth and claw. Evolutionary approaches to jurisprudencechallenge us to consider human nature, and the relationships between humanbeings and the environment as they really are.  


n1 W. Wilson, Constitutional Government in the United States54-55 (1908).

n2 See Epstein, The Static Conception of the Common Law, 9 J.Legal Stud. 253, 253-54 (1980).

n3 Elliott, Holmes and Evolution: Legal Process as ArtificialIntelligence, 13 J. Legal Stud. 113, 114 (1984); see also Elliott, TheDis-Integration of Administrative Law: A Comment on Shapiro, 92 Yale L.J. 1523,1524 (1983) (contrasting power of "organized bodies of knowledge" withlegal scholarship which continually "reinvent[s] in new words theinsights" of the past).

n4 Many legal writers, including Aristotle, Montesquieu, andBurke, have expressed ideas similar to those in the evolutionary traditionwithout drawing explicit analogies to the theory of evolution in biology. For arecent example of a theory of law that exploits evolutionary ideas without usingthe language of evolution, see Teubner, Substantive and Reflexive Elements inModern Law, 17 Law & Soc'y Rev. 239 (1983); see also Gordon, Critical LegalHistories, 36 Stan. L. Rev. 57 (1984) (surveying works of "evolutionaryfunctionalism").  

Other writers make casual references to evolution or uselanguage of evolution without developing the sustained analogies between law andbiological evolution that characterize the evolutionary tradition. See, e.g., L.Friedman, A History of American Law 14, 18 (1973); L. Rosdorff, The Framework ofLegal Evolution (1974).  

One author whose theories of legal evolution are not discussedin this Article, but perhaps should be, is Friedrick Hayek. See F. Hayek, Law,Legislation and Liberty (1973) (3 vols.). Hayek's theories do include explicitlyevolutionary elements, but they are inseparable from his comprehensive theory ofjustice and the role of the state, making them virtually impossible to integrateinto a work such as the present Article.  

n5 Even that subject turns out to be surprisingly vast. PeterStein, professor of civil law at Cambridge University, has already written afine book tracing the idea of legal evolution in 18th and 19th century Europeanjurisprudence. P. Stein, Legal Evolution: The Story of an Idea (1980). ProfessorStein inaccurately concludes that theories of legal evolution "wereessentially a nineteenth-century pheonomenon and did not long survive the end ofthe century." id. at 122. As will become clear, however, there has been amajor resurgence of interest in evolutionary theories of law in the 20thcentury, particularly in America. Nevertheless, modern proponents ofevolutionary theories of law seem strangely unaware of the evolutionarytheorists who preceded them. See, e.g., Manne, Introduction to Symposium, 8. J.Legal Stud. 231 (1979) ("[I]t is peculiar that an evolutionary theory ofour legal process, with its strong emphasis on the survival of certainprecedents, had not developed heretofore."); see also Ghiselin, SummaryComments in 4 Research in Law and Economics 203, 204 (P. Rubin ed. 1982)("[W]e have an opportunity to found a new branch of knowledge, namely, anevolutionary science of the law.").  

n6 While the groupings are useful for indentifying certaincommon features of theories of legal evolution, they should not be misunderstoodas implying that the differences among the theorists within each group areinsignificant. Nor are the four categories intended to be mutually exclusive. Adifferent analogy between law and evolution typifies each group, but often asingle evolutionary theorist may draw several different comparisons between lawand evolution. Thus that theorist's work might legitimately be categorized inmore than one group.  

n7 Both Maine, see infra notes 21-47 and accompanying text,and Holmes, see infra notes 77-109 and accopanying text, cite Savigny, althoughRudolph von Jhering, who followed and extended Savigny's ideas, appears to havehad a more direct influence on their work. See J. Burrow, Evolution and Society:A Study in Victorian Social Theory 142-43 (1966). For a summary of thesimilarities and differences between the jurisprudential theories of Savigny andvon Jhering with particular attention to their theories of legal evolution, seeP. Stein, supra note 5, at 65-68.  

n8 F. von Savigny, Of the Vocation on Our Age for Legislationand Jurisprudence (A. Hayward trans. London 1831 & Arno Press reprint 1975). 

n9 Id. at 182.  

n10 See Thibaut, Uber die Notwendigkeit eines allgemeinenburgerlichen Rechts fur Deutschland (Heidelberg 1814).  

n11 F. von Savigny, supra note 8, at 183.  

n12 Darwin did not invent, but inherited and refined theconcept of evolution. Darwin proposed natural selection as the mechanism whichexplains evolutionary change in nature and suggested that the existence ofseparate species of animals and plants could be explained as the result ofevolution. Prior to Darwin, however, numerous authors had described evolutionarychange in nature. See G. Daniels, Darwinism Comes to America xii (1967);Lewontin, Darwin's Revolution, N.Y Rev. Books, June 16, 1983, at 21.  

n13 F. von Savigny, Vom Beruf unserer Zeit fur Gesetzgebungund Rechtswissen-schaft 8-9 (3d ed. 1840) (author's translation).  

n14 The New Schoeffler-Weiss German and English Dictionary 111(Chicago 1974). Hayward's translation, see F. von Savigny, supra note 8, isinconsistent in its translation of the word Entwicklung but usually renders itas "development." The translation as "evolution" isconfirmed by the context; Savigny repeatedly uses words like "organic"and "natural" to modify Entwicklung.  

n15 F. von Savigny, supra note 8, at 20-21 (modified to renderEntwicklung as "evolution").  

n16 The term "positivism" is generally used bymodern legal writers to describe a variety of positions which share the viewthat law can be defined in terms of the acts of government officials. SeeColeman, Negative and Positive Positivism, 11 J. Legal Stud. 139 (1982).  

n17 F. von Savigny, supra note 8, at 22-23 (Originaltranslation by the present author, based on an earlier translation.).  

n18 in the earliest times to which authentic history extends,the law will be found to have already attained a fixed character, peculiar tothe people like their language, manners and constitution. Nay, these phenomenahave no separate existence. . . . That which binds them into one whole is thecommon conviction of the people, the kindred consciousness of an inwardnecessity, excluding all notion of an accidental and arbitrary origin. F. vonSavigny, supra note 8, at 24.  

n19 F. von Savigny, supra note 13, at 11.  

n20 F von Savigny, supra note 8, at 30. For Savigny's wordVolksglaube (literally, "people's belief"), I have substituted theterm "conventional morality," which is used by certain modern legalwriters, see, e.g., Wellington, Common Law Rules and Constitutional DoubleStandards: Some Notes on Adjudication, 83 Yale L.J. 221, 284-85 (1973). Savignyexplained that law developed through jurisprudence in this fashion: Withthe progress of civilization, national tendencies become more and more distinct,and what otherwise would have remained common, becomes appropriated toparticular classes; the jurists now become more and more a distinct class of thekind; law perfects its language, takes a scientific direction, and, as formerlyit existed in the consciousness of the community, it now devolves upon thejurists, who thus, in this department, represent the community. Law ishenceforth more artificial and complex, since it has a twofold life; first, aspart of the aggregate [life] of the community, which it does not case to be;and, secondly, as a distinct branch of knowledge in the hands of the jurists.All the latter phenomena are explicable by the co-operation of these two [vital]principles; and it may now be understood, how even the whole of that immensedetail might arise from organic causes, without any exertion of arbitrary willor intention. For the sake of brevity, we call, technically speaking, theconnection of the law with the general [life] of the people -- the politicalelement; and the distinct scientific [life] of law -- the technical element. F.von Savigny, supra note 8, at 28-29. The words in brackets Hayward (mis)translatesas "existence" (Leben in the German).  

n21 H. Maine, Ancient Law: Its Connection with the EarlyHistory of Society and its Relation to Modern Ideas (Beacon ed. 1963) (1st ed.London 1861). Maine lived from 1822 to 1888, and was professor of law at Oxfordand Cambridge and legal advisor to the Viceroy's Council in India. 

n22 The substance of Maine's ideas had already formed a decadeearlier. See J. Burrow, supra note 7, at 139-40. By choosing Darwin's publisher,John Murray of Albemarle Street, Piccadilly, Maine may have implied that AncientLaw did for law what Darwin's book had done for natural science. See G. Feaver,From Status to Contract: A Biography of Sir Henry Maine 1822-1888 at 41 (1969).  

n23 Firth, Preface to H. Maine, supra note 21, at xxix.  

n24 H. Maine, supra note 21, at 23. Not all societies are"progressive," according to Maine, China being one which he deemedstatic. Id. at 22.  

n25 Id. at 3.  

n26 Id.  

n27 Maine finds the "earliest notions . . . of a law orrule of life" lie in the Homeric concept Themis, a "divineagent"; when the king passes judgment, he is presumed to do so by"direct inspiration." Id. at 3-4.  

n28 Id. at 8.  

n29 Id. at 9.  

n30 Id. at 11 (emphasis omitted).  

n31 Id.  

n32 Id. at 14.  

n33 Id. at 119.  

n34 Id. In fact, Maine cited Darwin's work, G. Feaver, note22, at 167, to rebut the matriarchal thesis of development. See infra note 43.  

n35 Id. at 121 (emphasis omitted)  

n36 Id. at 124.  

n37 Id. at 125.  

n38 Id. at 126-28.  

n39 The movement of the progressive societies has been uniformin one respect. . . . [F]rom a condition of society in which all the relationsof Persons are summed up in the relations of Family, we seem to have steadilymoved towards a phase of social order in which all these relations arise fromthe free agreement of individuals. . . . [W]e may say that the movement of theprogressive societies has hitherto been a movement from Status to Contract. Id.at 163-65 (emphasis in original).  

n40 See Firth, Preface to H. Maine, supra note 21, at xviii-xx. 

n41 Pollock, Appendix to H. Maine, supra note 21, at 415, n.K.  

n42 H. Maine, supra note 21, at 118.  

n43 Cf. F. Pollock Sir Henry Maine and His Work, OxfordLectures and Other Discourses 147, 164 (1890) ("A given result may beproduced in one community by straightforward development; in another by somehighly artificial adaptation; and in a third by direct importation or imitationof a foreign model. And a series of apparently continuous forms may have no realhistorical connection at all.").  

Ironically, Maine himself voiced a similar criticism of Morganand McLennan, two of his critics who advanced a martriarchal theory of theevolution of societies: "So far as I am aware, there is nothing in therecorded history of society to justify the belief that, during that vast chapterof its growth which is wholly unwritten, the same transformations of socialconstitution succeeded one another everywhere, uniformly if notsimultaneously." H. Maine, Dissertations on Early Law and Custom 218-19(1883). Maine apparently distinguished his own conclusion that societiesnecessarily proceed in sequence through particular stages from the similartheory of Morgan and McLennan because he worked from written records andconfined his theories to "Aryan societies, [while] his opponents speculatedon a much grander scale." G. Feaver, supra note 22, at 167; see supra note34.  

n44 Biologist R. C. Lewontin has argued that the truesignificance of "Darwin's revolution" is the introduction ofprobabilistic thinking. In the past, science had generally attempted to supressvariation by imposing mechanical models on nature.  

Before Darwin, the central issue for science was to discoverthe Platonic form that lay behind the imperfect reality, as Newton in the firstbook of the Prinicipia treated ideal bodies moving in perfect voids, and onlylater considered the disturbing effects of friction and vicosity. . . . Darwinrevolutionized our study of nature by taking the actual variation among actualthings as central to the reality, not as an annoying and irrelevant disturbanceto be wished away. Lewontin, supra note 12, at 27.  

n45 For a summary of the differences between Spencer's conceptof evolution and Darwin's, see J.D.Y. Peel, Herbert Spencer: The Evolution of aSociologist 141-46 (1971); see also Landman, Primitive Law, Evolution and SirHenry Summer Maine, 28 Mich. L. Rev. 404, 425 (1930) (attacking Maine's theorybased on "innate evolutionary laws" as "not warranted by thefacts").  

n46 H. Maine, supra note 21, at 18.  

n47 F. Pollock, English Opportunities in Historical andComparative Opportunities, Oxford Lectures and Other Discourses 37, 41 (1870).  

n48 Wigmore was graduated from Harvard Law School in 1887,seven years after Holmes gave the lectures which became The Common Law. Seeinfra note 77. After briefly teaching Anglo-American law in Japan, Wigmorebecame a professor of law at Northwestern University in 1893. He remained atthat institution throughout his career, serving as dean of its law school from1901 to 1929.  

n49 J. Wigmore, A Treatise on the Anglo-American System ofEvidence in Trials at Common Law (1st ed. 1904; 2d ed. 1923; 3d ed. 1940; supp.1964) (commonly known as "Wigmore on Evidence").  

N50 Evolution of Law: Select Readings on the Orgin andDevelopment of Legal Institutions (A. Kocourek & J. Wigmore eds. 1915-1918)(3 vols.) [hereinafter cited as A. Kocourek & J. Wigmore]. The three volumesin the series are respectively subtitled: Sources of Ancient and Primitive Law,Primitive and Ancient Legal Institutions, and Formative Influences of LegalDevelopment.  

n51 1 A. Kocourek & J. Wigmore, supra note 50, at xi-xii.  

n52 Volume one consists of 24 readings, each describing adifferent ancient legal system, including Homer, the Bible, the Code ofHammurabi, and the seventh century Anglo-Saxon King Aethelbirht. The secondvolume contains translations of articles by continental jurisprudential writersof an evolutionary bent, including Josef Kohler, Rudolph Sohm, and Fustel deCoulanges, as well as several articles by Maine. The third volume,"Formative Influences of Legal Development," is analytical.  

n53 3 A. Kocourek & J. Wigmore, supra note 50, at xi.  

n54 Picard, Factors of Legal Evolution in 3 A. Kocourek &J. Wigmore, supra note 50, at 163.  

n55 Id.  

n56 See supra text accompanying notes 12, 23.  

n57 Environment includes certain main factors, which byinfluencing . . . the customary behavior of a people, affect its Law. . . .These include: climate . . .; land-level . . .; distance from the sea . . .;nature of the surface . . .; quality of soil. All these and other variations ofland and of atmosphere show their traces in the jural system, either by creatingspecies or by modifiying varieties. Picard, Factors of Legal Evolution in 3 A.Kocourek & J. Wigmore, supra note 50, at 170.  

n58 See generally infra text accompanying notes 222-335.  

n59 Petrucci, Natural Origin of Property Among Birds, Beasts,and Fishes in 3 A. Kocourek & J. Wigmore, supra note 50, at 288.  

n60 Page Sympathy in Group and Institutional Survival in 3 A.Kocourek & J. Wigmore, supra note 50, at 393; see R. Axelrod, The Evolutionof Cooperation (1984).  

n61 Richard, Arbitrament and Guaranty in the Origin of Law in3 A. Kocourek & J. Wigmore, supra note 50, at 485.  

n62 Wigmore, Planetary Theory of the Law's Evolution in 3 A.Kocourek & J. Wigmore, supra note 50 at 531. Wigmore first offered thetheory in a lecture at the Univerity of Virginia. Wigmore, Problems the Law'sEvolution, 4 Va. L. Rev. 247 (1917). Pages 253 to 266 of that article arereprinted with minor changes as the Planetary Theory of the Law's Evolution.  

n63 Wigmore, Planetary Theory of the Law's Evolution in 3 A.Kocourek & J. Wigmore, supra note 50, at 532.  

n64 Id. at 539-41.  

n65 Id. at 531.  

n66 Id.  

N67 Id.  

n68 Id. at 532.  

n69 Id.  

n70 Id. at 533.  

n71 "The evolution of law, which we seek to discover,does not imply progress, either morally or otherwise, but merely movement; . . .but always including the cause with the effect." Id. (emphasis inoriginal).  

n72 Id. at 536.  

n73 Id. at 541.  

n74 See supra notes 12-20, 40-46 and accompanying text.  

n75 See infra notes 204-12 and accompanying text.  

n76 See, e.g., R. Nelson & S. Winter, An EvolutionaryTheory of Economic Change 163-92 (1982).  

n77 Holmes lived from 1841 to 1935. His profound influence onAmerican legal thought was due less to the profundity of his thought than thepower of his pen. A pungent Holmes aphorism is available on almost every legaltopic -- often on both sides of the issue. As a professor at Harvard, Holmeswrote the most celebrated American law book of all times, The Common Law. Helater served on the Supreme Judicial Court of Massachusetts for 20 years, andthe United States Supreme Court for 30 years.  

n78 Holmes built on the evolutionary theories of Savigny andMaine, and cites them both in The Common Law. According to Mark DeWolfe Howe,Holmes' editor and biographer, "[i]t would not . . . be a greatexaggeration to say" that in The Common Law "Holmes borrowed fromMaine the spectacles which the Englishman had used for observing the law ofancient Rome and looked through them at the common law of England." Howe,Introduction to O. Holmes, The Common Law xiv (M. Howe ed. 1963). Holmes wasalso a friend of legal historian Frederick Pollock, and the two of themcorresponded for over falf a century. See Holmes-Pollock Letters: TheCorrespondence of Mr. Justice Holmes and Sir Frederick Pollock 1874-1932 (M.Howe ed. 1941).  

n79 O. Holmes, supra note 78, at 5.  

n80 See, e.g., E. Levi, An Introduction to Legal Reasoning102-04 (1949). Even changes in technical legal doctrine, such as rules governingin personam jurisdiction over out of state parties, are attributed to thechanging needs of society. See, e.g., Shaffer v. Heitner, 433 U.S. 186, 202(1977) ("The advent of automobiles, with the concomitant increase in theincidence of individuals causing injury in States where they were not subject toin personam actions under Pennoyer, required further moderation of theterritorial limits on jurisdictional power."). But see Epstein, supra note2 (legal change infrequently occurs due to changes in social conditions;instead, change is more often simply a response to laws which were incorrect inthe first place).  

n81 See e.g., Gordon, Holmes' Common Law as Legal and SocialScience, 10 Hofstra L. Rev. 719, 739 (1982) (Holmes' jurisprudence was "notliberal at all, but Darwinian."); Howe, Introduction to O. Holmes, supranote 78, at xxvi-xxvii (concluding that the "collectivism andDarwinism" of The Common Law "deserve special attention").  

n82 Compare Holmes' modern analogy to biologist Ernst Mayr'snotion of "evolutionary pathways." Mayr's "central point was thatevolution is not infinitely resourceful. It is not possible for organisms toevolve in any direction, since their evolution is constrained by existingstructures and functions. The seeds of the new structure must already bepresent." C. Wills, Genetic Variability 8 (1981).  

n83 The official theory [of the development of law] is thateach new decision follows syllogistically from existing precedents. But just asthe clavicle in the cat only tells of the existence of some earlier creature towhich a collarbone was useful, precedents survive in the law long after the usethey once served is at an end and the reason for them has been forgotten. . . .[A]s the law is administered by able and experienced men, who know too much tosacrifice good sense to a syllogism, it will be found that, when ancient rulesmaintain themselves . . ., new reasons more fitted to the time have been foundfor them, and that they gradually receive a new content, and at last a new form,from the grounds to which they have been transplanted. O. Holmes, supra note 78,at 31-32.  

n84 P. Wiener, Evolution and the Founders of Pragmatism 172(1949).  

n85 Holmes, Law in Science and Science in Law, 12 Harv. L.Rev. 443 (1899), reprinted in O. Holmes, Collected Legal Papers 210-43 (1920).  

n86 Elliott, supra note 3. For a view contrary to my own,which maintains that there is essential continuity between Holmes' views in TheCommon Law and his views in Law in Science and Science in Law, see Gordon, supranote 81, at 743-45.  

n87 Holmes, supra note 85, at 446.  

n88 Id.  

n89 H. Maine, supra note 21, at 3.  

n90 Holmes, supra note 85 at 446.  

n91 Id. at 446-47.  

n92 Id. at 447.  

n93 Id.  

n94 Elliott, supra note 3, at 138.  

n95 Holmes, supra note 85 at 450. ("[I]f we turn to thelaw of torts we find there . . . another evolutionary process which Mr. HerbertSpencer has made familiar to us by the name of Integration."). According toHolmes' biographer, Holmes found in Spencer a comprehensive evolutionary view ofthe world that remained a "fixed element" in his thinking throughouthis career. 1 M. Howe, Justice Oliver Wendell Holmes: The Shaping Years1841-1870, at 156 (1957); see also Elliott, supra note 3, at 126-27 (discussingHolmes' application of the constructive, "Integration" phase ofSpencer's life cycle to the development of the law).  

n96 See Elliott, supra note 3, at 126-29.  

n97 Holmes, supra note 85, at 449.  

n98 Id.  

n99 Holmes' theory that two different kinds of evolutionaryforces are at work since simultaneously, in the law bears a close resemblance toSavigny's idea that the law is the joint product of two forces which Savignyreferred to as the "technical element" and the "politicalelement." F. von Savigny, supra note 8, at 29; see supra note 20. However,while Savigny is somewhat mystical about how the "political element"representing the "spirit of the people" is incorporated into the law,Holmes finds clear resonsibility in the choices of judges.  

n100 Holmes, supra note 85, at 460-61.  

n101 See, e.g., Gordon, supra note 81, at 744 ("Holmessometimes used that old chestnut, the idea of the natural, evolutionaryadaptiveness of the common law, whereby the judge would unconsciously refashionthe law to suit the felt necessities of the time . . . . He made clear, however,that unconscious evolution belonged to the prescientific state of law; the newgrounds of legal policy should be conscious and articulate."); Tushnet, TheLogic of Experience: Oliver Wendell Holmes on the Supreme Judicial Court, 63 Va.L. Rev. 975, 1044-51 (1977) (The Holmes of The Common Law "presented thelaw as organically derived from the society" while the Holmes of The Pathof the Law "presented it much more as a positive phenomenon of articulatehuman choice.").  

n102 See, e.g., R. Nelson & S. Winter, supra note 76;Alchian, Uncertainty, Evolution and Economic Theory, 58 J. Pol. Econ. 211(1950).  

n103 Holmes, supra note 85, at 461.  

n104 Elliott, supra note 3, at 142.  

n105 Campbell, Variation and Selective Retention inSocio-Cultural Evolution in Social Changes in Developing Areas: AReinterpretation of Evolutionary Theory 19, 26-27 (H. Barringer, G. Blanksten& R. Mack eds. 1965); see also R. Nozick, Anarchy, State and Utopia 18-22(1974) (discussing special appeal of "invisible hand" explanations).  

n106 See e.g., Cooter & Kornhauser, Can Litigation Improvethe Law Without the Help of Judges?, 9 J. Legal Stud. 139 (1980).  

n107 See Elliott, supra note 3, at 139-46.  

n108 Id.  

n109 O. Holmes, supra note 78, at 32.  

n110 Corbin was born in 1874. A member of the Class of 1899 atthe Yale Law School, he joined the faculty in 1910, see Kessler, Arthur LintonCorbin, 78 Yale L.J. 517, 517-18 (1969), and continued his active scholarly workuntil 1964, when his eyesight failed. Id. at 519.  

n111 A. Corbin, Contracts (1960).  

n112 See supra notes 48-76 and accompanying text.  

n113 Corbin, The Law and the Judges, 3 Yale Rev. 234 (1914).The publication of this article only four years into his academic career nearlycost Corbin his job. The controversy stemmed not from its evolutionary overtonesbut because the article enunciated the then-heretical, now othodox propositionthat a "judge is a lawmaker." Id. at 235; Kessler, supra note 110, at518 ("[T]he powerful backing of William Howard Taft, Kent Professor of Lawat Yale College . . . effectively neutralized the opposition.").  

n114 Corbin does not attribute the evolutionary aspects of histheory to Holmes, although he does quote from one of Holmes' other essays. A.Corbin, supra note 113, at 238 (quoting Holmes, the Path of the Law, 10 Harv. L.Rev. 457, 461 (1897)). Undoubtedly Corbin also knew Holmes' The Common Law.While there is no direct evidence that Corbin was familiar with Law in Scienceand Science in Law, the article appeared in the Harvard Law Review in 1899,Corbin's last year in law school, and it seems likely Corbin read it and it leftan unconscious impression.  

n115 A. Corbin, supra note 113, at 249.  

n116 Id. at 237. The source of the metaphor is 2 F. Pollock& F. Maitland, The History of English Law 561 (2d ed. 1899).  

n117 A. Corbin, supra note 113, at 237.  

n118 See supra text accompanying note 100.  

n119 A. Corbin, supra note 113, at 238.  

n120 Id. at 239.  

n121 See L. Cavalli-Sforza & M. Feldman, CulturalTransmission and Evolution: A Quantitative Approach (1981).  

n122 Compare id. at 15-17 (distinguishing between"cultural fitness," the probability that practice will be followed byothers in the future, and "Darwinian fitness," which increases theability of an organism or culture to survive), with A. Corbin, supra note 113,at 247 ("What is the test of right and wrong, of truth and error, of soundlaw and bad law? The final test is survival in conflict. The fittestsurvive.") But see id. at 248 ("The aim of any legal system is generalsatisfaction . . . because it is general satisfaction that supports thesystem.").  

n123 A. Corbin, supra note 113, at 240.  

n124 Id. at 250.  

n125 In general [the judge] must let the multitude lead him.That judge is just and wise who draws from the weltering mass the principleactually immanent therein and declares it as the law. This has always been thejudicial function in all countries, and for its performance the judge must bearthe responsibility. Id.  

n126 See supra text accompanying notes 12, 94-98.  

n127 See, e.g., C. Langdell, A Selection of Cases on the Lawof Contracts vii-ix (1879).  

n128 See, e.g., O. Holmes, supra note 78, at 63-120(describing historical evolution of tort law as a process in which one rulesucceeds another); see also Elliott, supra note 3, at 122 ("lack of acontinuing source of variation is a substantial problem" for the Holmes'theory of common law evolution).  

n129 See supra text accompanying notes 73-76.  

n130 A. Corbin, supra note 113, at 246.  

In [the law reports] are the records of a million cases, eachwith dozens of facts, each with its history of a dispute between men, and eachwith a judge's decision as to what justice required and why he thought so. Theyare not harmonious; in them can be found authority for both sides of almost anyquestion. But they are instructive: . . . they present material for testing aproposed rule by applying it to a great variety of cases; . . . they supplyarguments of learned and experienced men on both sides of vast numbers ofquestions. Id.  

n131 Id. at 245.  

n132 The rules [of law declared by judges] come from allpossible sources -- from constitutions and statutes; from the decisions of otherjudges; from legal writers, ancient and modern, in this and other countries;from books of religion and morality; from the general principles of right andwrong in which the judge was trained from his youth up; from the rules of actioncustomarily followed in the community . . .; from the judge's own practice andinterest and desire. The judge, if honest, lays down either a rule that has beenapproved or acquiesced in by the community in the past, or a rule to which hebelieves the community will in the future give approval and acquiesence. Indeclaring the rule by which the parties are to be governed, he must beclare therule that is the resultant of all the foregoing forces. It can easily be seenhow wide a variation this allows. Id. at 240.  

n133 Professor Robert Cover has recently advanced a theory oflaw similar to this aspect of Corbin's theory. See Cover, The Supreme Court,1982 Term -- Foreword: Nomos and Narrative, 97 Harv. L. Rev. 4 (1983) ("Noset of legal institutions or prescriptions exists apart from the narratives thatlocate it and give it meaning.").  

n134 See supra note 125 and accompanying text.  

n135 A. Corbin, supra note 113, at 247.  

n136 Id.  

n137 Id.  

n138 Id. at 248.  

n139 Id.  

n140 Id. at 242.  

n141 See J. Ely, Democracy and Distrust 45-47 (1980).  

n142 The association of evolutionary models of law with SocialDarwinism may have tended to discredit them, see infra notes 247-49 andaccompanying text. The demise of the evolutionary tradition in legal scholarshipwas not, however, marked by the sort of violent controversies that havesurrounded sociobiology in recent years. See infra note 228. Rather, as otherapproaches to legal scholarship such as "legal realism" became morepopular, works embracing evolutionary approaches to law simply seem not to havebeen read or written.  

n143 Clark, The Morphogenesis of Subchapter C: An Essay inStatutory Evolution and Reform, 87 Yale. L.J. 90 (1977).  

n144 Id. at 90.  

n145 Id. at 91-93.  

n146 Id. at 90.  

n147 Id. at 92.  

n148 Id. at 95.  

n149 Id.  

n150 Id.  

n151. Id.  

n152 Id. at 96.  

n153 It is possible to interpret the taxpayers in Clark'smodel as the source of variations -- "mutations" -- which must"survive" competition from the IRS, in an "environment"defined by courts and Congress, to become law. Clark does not draw theseparallels to Darwinian evolutionary theory, however, and in a later articleappears to maintain that a Darwinian theory of natural selection is not anappropriate way to conceptualize the evolution of the corporate tax culture.Clark, The Interdisciplinary Study of Legal Evolution, 90 Yale L.J. 1238,1255-56 (1981).  

n154 See supra text accompanying note 146.  

n155 See H. Spencer, First Principles § 95 at 258 (6th ed.1901). Clark's concept of legal evolution also bears some resemblance to theprocesses of "Integration" that Holmes described in Law in Science andScience in Law, see supra text accompanying note 95.  

n156 Clark has proposed a more ambitious theory of legalevolution which he has cited but never published. Clark, Notes Toward a Theoryof Legal Evolution (1978) (unpublished manuscript), cited in Clark, supra note153, at 1256 n.30. One of the issues addressed there is "Why dodevelopments in some legal fields seem endogenous, that is explainable with fewreferences to changes in non-legal influences, while those in other fields donot?" Clark, supra note 153, at 1256.  

n157 Clark, The Four Stages of Capitalism: Reflections onInvestment Management Treatises, 94 Harv. L. Rev. 561 (1981).  

n158 Clark, supra note 153, at 1247-48.  

n159 Clark, Abstract Rights Versus Paper Rights under Article9 of the Uniform Commercial Code, 84 Yale L.J. 445 (1975).  

n160 Clark, supra note 153, at 1254.  

n161 Clark, supra note 153.  

n162 Id. at 1242-56.  

n163 Id. at 1241.  

n164 First, technological, social, or other external changesoccur that create new opportunities for legal rules to reduce costs ordisutilities . . . . Second, a responsive legal invention occurs . . . [which]reduces the costs or disutilities better than indentifiable alternatives; andinstances of the principle or institution proliferate. One is inevitably temptedto analogize the process to Darwin's natural selection view of the origin ofspecies. Third, the rise of the successful legal principle or institution itselfcreates new needs and opportunities for cost reduction. Fourth, substantiallegal activity occurs . . . to exploit these opportunities . . . [which] is aptto involve fairly obvious struggles over the distribution of cost savings. Id.(footnote omitted).  

n165 Id. at 1242.  

n166 Id. at 1241; see supra note 164.  

n167 Id. at 1266-72 (criticizing George Priest's theory). Fora discussion of Priest's work, see infra text accompanying notes 188-203.  

n168 Id. at 1255-56.  

n169 See supra note 153.  

n170 See supra text accompanying notes 146-52.  

n171 See supra text accompanying note 164.  

n172 In chronological order, the more significant papers areRubin, Why Is the Common Law Efficient?, 6 J. Legal Stud. 51 (1977); Priest, TheCommon Law Process and the Selection of Efficient Rules, 6 J. Legal Stud. 65(1977); Goodman, An Economic Theory of the Evolution of the Common Law, 7 J.Legal Stud. 393 (1978); Cooter, Kornhauser & Lane, Liability Rules, LimitedInformation and the Role of Precedent, 10 Bell J. Econ. 366 (1979); Landes &Posner, Adjudication as a Private Good, 8 J. Legal Stud. 235 (1979); Cooter& Kornhauser, supra note 106; Terrebonne, A Strictly Evolutionary Model ofCommon Law, 10 J. Legal Stud. 397 (1981); Note, The Inefficient Common Law, 92Yale L.J. 862 (1983). For a capsule summary of the differences among three ofthe leading theories -- those of Rubin, Priest, and Goodman -- see the remarksof George Priest, in Hirshleifer, Evolutionary Models, in Economics and Law, 4Research in Law and Economics 167, 171-72 (1982).  

n173 The suggestion that community reaction helps to shape thelaw was not entirely new. See A. Bickel, The Morality of Consent (1975); 2 F.Hayek, Law, Legislation and Liberty (1976); R. Jhering, The Struggle for Law (J.Lalor trans. 2d. ed. 1915). Rubin, however, made more extreme claims for theeffect of decisions by litigants than previous writers, he expressed his thesisas a formal, evolutionary model.  

n174 Rubin, supra note 172.  

n175 Priest, supra note 172. As will become apparent, thereare significant differences between Rubin's and Priest's theories of legalevolution. Moreover, Priest subsequently renounced his original theory of legalevolution as too simple, and turned in his later work to modeling the settlementprocess, see infra text accompanying notes 202-03. For purposes of comparingtheories of legal evolution, however, it is useful to group together certaincommon elements to Rubin's theory and Priest's early evolutionary theories.  

n176 Rubin, supra note 172, at 51.  

n177 Id.  

n178 Id.  

n179 Id.  

n180 Id. at 53. According to Rubin's theory the outcomes oflitigation would be inefficient, however, when "repeat players" suchas insurance companies litigate against "one-shotters" such asconsumers, since the repeat player would have an incentive to "invest"in litigation in order to purchase a favorable precedent, while the one-shotterwould not, id. at 55-56. Rubin also says that his analysis applies tolegislation, as well as litigation, and predicts that "laws would be passedat the expense of large groups which would not be able to effectively lobbyagainst their passage because of free rider problems." Id. at 61; see alsoWilson, The Politics of Regulation in The Politics of Regulation (J. Wilson ed.,1980) (interest groups have incentive to form only when costs and benefits arenarrowly concentrated).  

n181 Rubin, supra note 172, at 54-55.  

n182 Id. at 55.  

n183 Id. at 55.  

n184 Rubin may assume that only inefficient rules of law evercome to court. This conclusion depends on the assumption that all litigants areperfectly rational and have perfect information about the effect of legal rules.Even in that unrealistic world, however, nothing requires judges to abandoninefficient rules of law. They might simply reiterate them. If courts repeatedlyrefuse to abandon an inefficient rule of law, presumably at some point rationallitigants would cease challenging it, since the incentive to litigate dependsupon some likelihood a court may abandon the inefficient rule.  

n185 See supra text accompanying note 179.  

n186 A broad variety of social and cultural norms -- such asemotions, community values, and peer pressure -- may influence settlementdecisions. See H. Ross, Settled Out of Court (rev. ed. 1980); Eisenberg, PrivateOrdering Through Negotiation: Dispute Settlement and Rulemaking, 89 Harv. L.Rev. 637 (1976).  

n187 See Deutsch, Law as Metaphor: A Structural Analysis ofLegal Process, 66 Geo. L.J. 1339, 1340 (1978).  

n188 Priest, supra note 172 at 65.  

n189 "It is unnecessary to assume, as might have beenimplied by Professor Rubin's discussion, for example, that the parties agree onthe probability of a given verdict, that transaction costs are greater than thesavings from voluntary shifts in liability, or, as was crucial to ProfessorRubin's results, that both parties to the dispute have continuing interest inthe legal outcome." Id. at 66 (footnote omitted).  

n190 Id. at 65 (emphasis added).  

n191 Id.  

n192 Id.  

n193 Id. at 67.  

n194 Id.  

n195 Id.  

n196 Id. at 68.  

n197 See Mackie, Fallacies in 3 Encyclopedia of Philosophy169, 173 (1967).  

n198 Priest attempts to surmount this difficulty by assumingthat "[o]ther characteristics . . . that influence thelitigation-settlement ratio . . . are unlikely to differ systemtically betweendisputes arising under inefficient and those arising under efficientrules." Priest, supra note 172, at 67-68. But, since Priest has not shownthat the stakes differ systematically between disputes arising under inefficientand efficient rules, this does not save his argument.  

n199 Id. at 81.  

n200 Id. at 66.  

n201 Priest believes, to be sure, that the evolutionary forcesmoving the law toward efficiency are strong, and he develops a numerical examplewhich shows that for one assumed rate of selective relitigation, a strong biasby judges against efficiency would be necessary to counteract the evolutionarypressures. Id. at 68-71. Ultimately, however, it is an empirical question forPriest how strong the forces propelling the law toward economic efficiency maybe compared to other forces in the law.  

n202 Priest, Selective Characteristics of Litigation, 9 J.Legal Stud. 399, 421 (1980).  

n203 See Priest & Klein, The Selection of Disputes forLitigation, 31 J. Legal Stud. 1 (1984).  

n204 Cooter & Kornhauser, supra note 106.  

n205 The cooter and Kornhauser model of legal evolution iscomposed of Markov matrices in which the vectors represent the degree to whichlegal rules prevailing at any given moment approach efficiency. Cooter andKornhauser then assume that inefficient rules are selectively relitigated, butadd that judges have no insight into which rules are better. They claim theirmathematics prove that legal rules prevailing at any time do not improvemonotonically, but instead the result is "indecomposable and aperiodic withall the rules regularly recurrent." Id. at 160.  

n206 Id. at 145.  

n207 Id.  

n208 Id. at 150, 157.  

n209 Id. at 144.  

n210 See Hirshleifer, supra note 172, at 191.  

n211 See supra text accompanying notes 62-76.  

n212 See Gould & Lewontin, The Spandrels of San Marco andthe Panglossian Paradigm: A Critique of the Adaptationist Programme, 205 Proc.R. Soc. Lond. 581 (1979).  

n213 See supra note 172.  

n214 E.g., Duncan Kennedy's point that the concept of"cost" is not self-defining, see Kennedy, Cost-Reduction asLegitimation, 90 Yale L.J. 1275, 1278 (1981); see also Rizzo, The Mirage ofEfficiency, 8 Hofstra L. Rev. 641 (1980) (criticizing the economists fortreating moral issues in an incomplete and tautological fashion).  

n215 See, e.g., Landes & Posner, supra note 172.  

n216 Clark, supra note 153, at 1266-72.  

n217 Id. at 1270.  

n218 See, e.g., Cooter & Kornhauser, supra note 106;Hirshleifer, supra note 172, at 167-208.  

n219 R. Posner, Economic Analysis of Law (2d ed. 1977).  

n220 Elliott, INS v. Chadha: The Administrative Constitution,the Constitution and the Legislative Veto, 1983 Sup. Ct. Rev. 125, 149 n.116.  

n221 Priest, Social Science Theory and Legal Education: TheLaw School as University, 33 J. Legal Educ. 437, 438 (1983).  

n222 By pointing out that the economic account of legalevolution is radically incomplete, I do not mean to imply that this is its onlyshortcoming.  

As this Article went to press, the author first became awareof the proceedings of a symposium on the biological and evolutionary roots oflaw. See Law, Biology & Culture: The Evolution of Law (M. Gruter & P.Bohannan, eds. 1983).  

n223 Hirshleifer, Privacy: Its Origin, Function and Future, 9J. Legal Stud. 649 (1980); Hirshleifer, supra note 172.  

n224 Epstein, A Taste for Privacy?: Evolution and theEmergence of a Naturalistic Ethic, 9 J. Legal Stud. 665 (1980).  

n225 Rodgers, Bringing People Back: Toward a ComprehensiveTheory of Taking in Natural Resources Law, 10 Ecology L.Q. 205 (1982).  

n226 Hirshleifer, Epstein, and Rodgers all cite theoreticalworks by sociobiologists, of whom E. O. Wilson is perhaps best-known, in supportof their theories of legal evolution. See E. Wilson, Sociobiology (1975); seealso D. Barash, Sociobiology and Behavior (2d ed. 1982); C. Lumsden & E.Wilson, Genes, Mind, and Culture: The Coevolutionary Process (1981).  

n227 See, e.g., C. Lumsden & E. Wilson, supra note 226,passim; E. Wilson, supra note 226, passim.  

n228 For a strong attack on sociobiology in general andWilson's work in particular, see R. Lewontin, S. Rose & L. Kamin, Not in OurGenes: Biology, Ideology and Human Nature (1984).  

n229 See supra text accompanying note 29.  

n230 See supra note 122.  

n231 Keller, Law in Evolution, 28 Yale L.J. 769 (1919). I amgrateful to Ralph Sharp Brown, Jr., Professor Emeritus at the Yale Law School,for informing me that Corbin and Keller were friends.  

n232 Keller, supra note 231, at 769.  

n233 Id. at 773.  

n234 Id. at 775.  

n235 Id.  

n236 Id. at 781.  

n237 Id. at 775.  

n238 Id. at 783.  

n239 Id.  

n240 Id. at 782.  

n241 Id.  

n242 Id.  

n243 Id. at 778.  

n244 Brown, Law and Evolution, 29 Yale L.J. 394 (1920).  

n245 Id. at 398.  

n246 Id.  

n247 Keller himself notes that "so deeply did Spencerimpress his stamp upon the social thought of his age that to most students ofsocial phenomena, evoluation means Spencerian evolution." Id. at 772.  

n248 Keller, supra note 231, at 772-73. Keller consideredSpencer's "propositions" to be "tenuous and unscientific."Id. at 772.  

n249 For a convincing refutation of the idea that evolutionarytheories are necessarily racist, sexist and politically reactionary, see D.Barash, The Whisperings Within 231-43 (1979).  

n250 "Law and economics" a highly influentialmovement in legal scholarship during the last fifteen years, is characterized bythe attempt to illuminate legal problems by analyzing them in terms ofmicroeconomic models. See Priest, The Rise of Law and Economics (Yale Law SchoolCivil Liability Program, working paper #7, Oct., 1982). Among the moreinfluential early works in the area are G. Calabriesi, The Costs of Accidents(1970) and R. Posner, Economic Analysis of Law (1972).  

n251 Hirshleifer, supra note 223, at 651 (1980).  

n252 Id.  

n253 Hirshleifer, Natural Economy versus Political Economy, 1J. Soc. & Biological Structures 319, 321 (1978).  

n254 See Hirshleifer, Economics from a Biological Viewpoint,20 J. Law Econ. 1 (1977); Hirshleifer, supra note 253.  

n255 Hirshleifer, supra note 253, at 321-22 (citationsomitted).  

n256 See supra text accompanying notes 240-42.  

n257 See supra text accompanying note 255.  

n258 See supra text accompanying notes 243-46.  

n259 Hirshleifer, supra note 223.  

n260 Posner, Privacy, Secrecy and Reputation, 28 Buffalo L.Rev. 1 (1979); Posner, The Right of Privacy, 12 Georgia L. Rev. 393 (1978);Stigler, An Introduction to Privacy in Economics and Politics, 9 J. Legal Stud.623 (1980).  

n261 Hirshleifer, supra note 223, at 650.  

n262 Id. at 652.  

n263 Hirshleifer, supra note 223, at 649.  

n264 Id. at 655.  

n265 Id.  

n266 Id. at 653.  

n267 Id. (emphasis in original).  

n268 Id. at 655.  

n269 Id. at 657. The essence of Hirshleifer's argument is theclaim that "a territory is worth more to its proprietor than to theintruder," because the "proprietor" will have more accurate"knowledge" of its resources and because the amount of adaptationbetween proprietor and territory will be greater than that between intruder andterritory. Id.  

n270 Id. at 659.  

n271 Id. at 661 (emphasis in original).  

n272 Cf. Leff, Economic Analysis of Law: Some Realism AboutNominalism, 60 Va. L. Rev. 451, 459 (1974) (law and economics movementsubstitutes definitions for both normative and empirical propositions).  

n273 Although the term "altruism" is established inthe biological literature, Hirshleifer dislikes it because it carriesunfortunate psychological implications. He prefers "helping," which heconsiders an "entirely objective phenomenon." Hirshleifer, supra note223, at 326.  

n274 Cf. Hamilton, The Genetical Evolution of Social Behavior,7 J. Theoretical Biology 1 (1964) (relatives of the self-sacrificing organismwill be more likely to survive because of that sacrifice; these relativespossess and will transmit similar genes). Others, however, reject the notionthat any sort of group advantage is necessary to explain altruistic behavior.See R. Dawkins, The Selfish Gene (1976); Trivers, The Evolution of ReciprocalAltruism, 46 Q. Rev. Biology 35 (1971). They argue that reciprocal altruism --that is, where an organism helps others who have helped or will help it -- canbe selected for genetically. They conclude, therefore, that reciprocal altruismis consistent with self-interest.  

n275 For a brief description of the critical legal studiesmovement, see Kennedy, Cost-Reduction Theory as Legitimation, 90 Yale L.J. 1275(1981). For a more extensive statement of its philosophical basis, see Unger,The Critical Legal Studies Movement, 96 Harv. L. Rev. 563 (1983).  

n276 See Kennedy, Form and Substance in Private LawAdjudication, 89 Harv. L. Rev. 1685 (1976) (proposing "individualism andaltruism" as two "opposed rhetorical modes" of dealing withsubstantive issues in private law).  

n277 Kennedy, Cost/Benefit Analysis of Entitlement Programs: ACritique, 33 Stan. L. Rev. 387 (1981).  

n278 Kennedy, Distributive and Paternalistic Motives inContract and Tort Law, With Special Reference to Compulsory Terms and UnequalBargaining Power, 41 Maryland L. Rev. 563 (1982).  

Hirshleifer has written that: Economicstudy of market interactions may yield satisfactory results while postulatingpurely egoistic men, acting within an unexplained social environment ofregulatory law. But as the power of eocnomic anlaysis comes to be employedoutside the traditional market context, for example, in the area of publicchoice, the egoistic model of man . . . will not suffice. Hirshleifer, supranote 223, at 663.  

n279 Hirshleifer, supra note 172.  

n280 Hirshleifer, supra note 223.  

n281 Epstein, supra note 224.  

n282 Id. at 666.  

n283 Epstein borrows a typology of privacy law proposed byWilliam Prosser, see Prosser, Privacy, 48 Calif. L. Rev. 383, 389 (1960), quotedin Epstein, supra note 224, at 667, and argues that the right to privacyactually breakes down into four separate interests.  

n284 Epstein, supra note 224, at 669.  

n285 Id. at 669-70.  

n286 Id.  

n287 The four categories are: (a)the prohibition on the use of force against strangers in the same species exceptin self-defense; (b) the rule of first possession of an unowned thing as theroot of title; (c) the status obligations of parents to their offspring; and (d)promissory obligations. Id.  

n288 Id. at 672; see also id. at 673 ("collectiveconsensus . . . on instinctive and nonintellectual grounds"). However,Epstein does not imagine that evolution will ever result in all human beingssharing exactly the same values: It is most unlikely underany set of environmental conditions that all organisms will develop a natural oruniform inclination against aggression. To the contrary,any unanimous preference in that direction, even if achieved, should proveunstable over time . . . . In the end some sort of equilibrium should emerge inwhich some members of society prefer to use force, while most remain inclined toresist its use. The preference against the unrestrained use of force will not beunanimous, but it will in most cases be widespread enought to create apredisposition to regard its use as wrongful. Id. at 671-72.  

n289 See, e.g., id. at 673 ("The tendency to respectfirst possession will not be universal within any group for the same reasonsdiscussed above in connection with the use of force. Yet a collective consensusin favor of the rule is apt to emerge, thus accounting for the broad acceptancethat the rule receives in the legal order, ususally on instinctive andnonintellectual grounds.").  

n290 On at least one occasion Epstein explicitly states hisbelief that there is a "genetic variation" in the inclination ofindividuals to use force. Id. at 671.  

n291 Id. at 670.  

n292 Id. at 669-70.  

n293 See Hanks, The Law of Water in New Jersey, 22 Rutgers L.Rev. 621, 627-32 (1968).  

n294 See Tarlock, Appropriations for Instream FlowMaintenance: A Progress Report on "New" Public Western Water Rights,1978 Utah L. Rev. 211, 211-12.  

n295 Id.  

n296 Id. (describing development of doctrines to protectinstream flows in western water law).  

n297 See supra text accompanying note 220.  

n298 See supra text accompanying note 292.  

n299 See Campbell, Variation and Selective Retention inSocio-Cultural Evolution in Social Change in Developing Areas 19, 33 (1965).  

n300 See H. Kelsen, General Theory of Law and State (1945).  

n301 See supra text accompanying notes 264-67.  

n302 Rodgers, supra note 225.  

n303 Id. at 205 ("Contemporary legal theory . . . hasdegenerated into a contest of false modeling.").  

n304 Id.  

n305 J. Rawls, A Theory of Justice (1971); see also R. Nozick,Anarchy, State and Utopia (1975). For a attempt to synthesize welfare economicsand Rawlsian theories of social justice, the two schools of thought Rodgers seesas irreconciable, see B. Ackerman, Social Justice in the Liberal State (1981).  

n306 Rodgers, supra note 225, at 205.  

n307 Id. & n.6 (citing E. Wilson, supra note 226).  

n308 Id.  

n309 See supra note 228 and accompanying text.  

n310 Rodgers, supra note 225, at 206.  

n311 Id.  

n312 Id. at 207.  

n313 Id. at 211.  

n314 Id.  

n315 Id.  

n316 Id. at 206.  

n317 Id. at 206 n.6. But cf. Priest, The New Scientism inLegal Scholarship, 90 Yale L.J. 1284 (1981) (criticizing "a growingadoption of the scientific style in legal scholarship").  

n318 Rodgers, supra note 225, at 218.  

n319 Id. at 219. For a case which has fascinated legalscholars, particularly economists, because the court substituted monetarydamages for nuisance law's traditional injunctive remedy, see Boomer v. AtlanticCement Co., 26 N.Y.2d 219, 257 N.W.2d 870, 309 N.Y.S.2d 312 (1970); see alsoPolinsky, Resolving Nuisance Disputes: The Simple Economics of Injunctive andDamage Remedies, 32 Stan. L. Rev. 1075 (1980).  

n320 Rodgers, supra note 225, at 219.  

n321 Id. at 218.  

n322 See Rabin, Nuisance Law: Rethinking FundamentalAssumptions, 63 Va. L. Rev. 1299 (1977).  

n323 "Nuisance case law discloses a distinct preferencefor technological or operational solutions short of ouster of one of theprincipals. This search for conflict avoidance postpones the issue of limits ofavailable resources." Rodgers, supra note 225, at 219.  

n324 Id. at 220.  

n325 Id. (footnotes omitted).  

n326 See text accompanying note 316.  

n327 Rodgers, supra note 225, at 220, n.66.  

n328 See Keller, supra note 231.  

n329 Rodgers, supra note 225, at 221, n.66. This argument isbased by analogy to the work of George Priest, see supra text accompanying notes188-203, but unlike Priest, Rodgers does not support his supposition that legalrules that deviate from the "biological optimum" would be selectivelyrelitigated. But cf. supra text accompanying note 220 (suggesting that legaloutcomes which deviate in any respect from values held systematically bylitigants should be subject to selective relitigation under Priest's reasoning). 

n330 Rodgers, supra note 225, at 221.  

n331 Cf. supra text accompanying note 272 (criticizingHirshleifer's theory as a system of personal metaphors); see also Rodgers, supranote 225, at 218 & nn.52 & 53 (criticizing Posner's economic theories oflaw as nonfalsifiable).  

n332 Cf. Priest, Selective Characteristics of Litigation, 9 J.Legal Stud. 399, 418 (1980) (effect of efficiency considerations on legal rulesis indeterminant because both procedural and substantive law combine to produceoutcomes).  

n333 Compare Pennsylvania Central Transp. Co. v. New York, 438U.S. 104 (1978) (no compensation due for ordinance which preserves historicfacade of Grand Central Terminal, thereby precluding construction of officebuilding) with United States v. Causby, 328 U.S. 256 (1946) (Compensation duefor frequent overflights by military planes); see also Pennsylvania Coal Co. v.Mahon, 260 U.S. 393, 415 (1922) (government regulation of private property isnot a taking unless it "goes too far").  

For a frank concession that "takings" law is ashambles and that a new theory is needed to enable courts to distinguishlegitimate from illegitimate encroachments on private rights, see Epstein, NotDeference But Doctrine: The Eminent Domain Clause, 1982 Sup. Ct. Rev. 315, 355.  

n334 Sociobiology is a science that draws upon the behavior ofsocial species, especially humans, to gain insight into the rules that governsocial interaction. . . . A sociobiological legal theory could be based uponhuman preferences expressed through nonmarket channels. . . . At a minimum, areliable science of human behavior offers empirical insight into whether aparticular legal option goes with or against the grain of human nature. Withmuch greater difficulty, a sociobiological ethical theory could be constructedaround the idea that the law should tilt towards the biological preferences ofthe species. . . . In my view there is empirical evidence for absolutist humanvetoes in [property law] doctrines [of nuisance, waste and reserved rights], andthey can be read as validating positive rights theories. . . . They clearlyreflect ideas of nonmarket preferences, needs, deserts, and ultimately anonmarket allocation of scarce goods. Rodgers, Building Theories of JudicialReview in Natural Resources Law, 53 U. Colo. L. Rev. 213, 214-15 (1982)(footnote omitted).  

n335 Compare Epstein, supra note 333, with Rodgers, supra note225.  

n336 Cf. Clark, supra note 153, at 1272 (questioning the valueof "very general theory built by speculative reasoning upon a small numberof concepts" since "[r]egrettably, . . . there is no way one can pulla rabbit out of an empty hat.").  

n337 See Kennedy, supra note 214, at 1276.  

n338 See Ackerman, The Storrs Lectures: Discovering theConstitution, 93 Yale L.J. 1013, 1017-18 (1984).  

n339 The problem is particularly intense, of course, in thecase of judicial review under the Constitution, in which the courts assert theright to strike down laws made by popularly elected legislatures. See A. Bickel,The Least Dangerous Branch 16 (1962) (posing the "counter-majoritariandifficulty" of judicial review).  

n340 Holmes, The Path of the Law, 10 Harv. L. Rev. 457, 461(1897).  

n341 Leff, Injury, Ignorance and Spite -- the Dynamics ofCoercive Collection, 80 Yale L.J. 1, 8 (1970).  

n342 See, e.g., L. Fuller, The Law in Quest of Itself (1940);Dworkin, "Natural" Law Revisited, 34 U. Fla. L. Rev. 165 (1982).  

n343 See, e.g., B. Ackerman, Reconstructing American Law 23-45(1984).  

n344 See J. Huxley, Religion with Revelation 106-07, 181-86(1957).  

n345 Keller, supra note 231 at 783; see supra textaccompanying note 239.  

n346 See supra text accompanying note 17.  

n347 Gould & Lewontin, supra note 212.  

n348 Gordon, Historicism in Legal Scholarship, 90 Yale L.J.1017, 1028-36 (1981).  

n349 Gordon, Critical Legal Histories, 36 Stan. L. Rev. 57,59-65 (1984).  

n350 Voltaire, Candide 9-10 (Random House ed. 1929).  

n351 For a general argument that there is a connection betweentheories of jurisprudence and the forms of legal literature, see Simpson, TheRise and Fall of the Legal Treatise: Legal Principles and the Forms of LegalLiterature, 48 U. Chi. L. Rev. 632 (1981).  

n352 See supra text accompanying note 130.  

n353 See supra text accompanying note 71.  

n354 See B. Ackerman, supra note 343.  

n355 See, e.g., B. Ackerman, supra note 305.  

n356 See supra text accompanying notes 304-06.