LEXIS-NEXIS® Academic
Copyright © 1985 The Columbia Law Review.
Columbia Law Review
JANUARY, 1985
85 Colum. L. Rev. 38
LENGTH:32975 words
ARTICLE:THE EVOLUTIONARY TRADITION IN JURISPRUDENCE *
* 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.
SUMMARY:
...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
TEXT:
[*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
I. SOCIAL THEORIES OF LEGAL EVOLUTION
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.
II. DOCTRINAL THEORIES OF LEGAL EVOLUTION
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.
III. ECONOMIC THEORIES OF LEGAL EVOLUTION
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
IV. SOCIOBIOLOGICAL THEORIES OF LEGAL EVOLUTION
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.
V. WHY EVOLUTION?
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 parti