Deepest thanks to Eric Posner at the University of Chicago for his helpful advice and suggestions. Thank you also to Neil Duxbury at the London School of Economics for reviewing an earlier draft of the present article.

1. Robert Ellickson writes, “ … the law-and-economics scholars believe that the law-and-society group is deficient in both sophistication and rigor, and the law-and-society scholars believe that the law-and-economics theorists are not only out of touch with reality but also short on humanity.” Ellickson, R.C., Order Without Law (Cambridge, MA: Harvard University Press, 1991) at 7.Google Scholar

2. McAdams, Richard H., “Signaling Discount Rates: Law, Norms, and Economic Methodology” (2001) 110 Yale L.J. 625 at 681CrossRefGoogle Scholar.

3. As Posner says, “ … people bound by [norms] feel an emotional or psychological compulsion to obey the norms; norms have moral force.” Posner, Eric A., “Law, Economics, and Inefficient Norms” (1996) 144 U. Pa. L. Rev. 1697 at 1709CrossRefGoogle Scholar. The literature sometimes makes a distinction with regard to what I am here referring to broadly as internalization. For instance, Peter Huang speaks of emotions, specifically the moralistic kind. Huang, Peter H., “Reasons Within Passions: Affects and Attributions in Property Rights Bargaining” (2000) 79 Or. L. Rev. 435 Google Scholar; Huang, Peter & Wu, Ho-Mou, “More Order Without More Law: A Theory of Social Norms and Organizational Cultures” (1994) 10 J. L. Econ. & Org. 390 Google Scholar. McAdams cites the importance of the psychological need for esteem from others in his Esteem Theory of Norms. See McAdams, Richard H., “The Origin, Development, and Regulation of Norms” (1997) 96 Mich. L. Rev. 338 at 355-57CrossRefGoogle Scholar.

4. “The rational-actor model has two basic underlying tenets. It assumes, first, that each individual pursues self-interested goals and, second, that each individual rationally chooses among various means for achieving those goals.” Ellickson, supra note 1 at 156.

5. Posner, Eric A., Law and Social Norms (Cambridge, MA: Harvard University Press, 2000).Google Scholar

6. Posner, supra note 5 at 24-25.

7. Ibid. at 19-21.

8. Ibid. at 8.

9. Ibid. at 46.

10. Indeed, internalization lies embedded at the heart of the natural law position, and it in fact explains the persistence of the embattled belief within jurisprudential circles.

11. Gintis, Herbert, “The Hitchhiker’s Guide to Altruism: Gene-culture Coevolution, and the Internalization of Norms” (2003) 220 J. Theor. Biol. 407 at 417CrossRefGoogle Scholar; see also Leary, Mark R., “Digging Deeper: The Fundamental Nature of ‘Self-Conscious’ Emotions” (2004) 15 Psych. Inquiry 129 at 129Google Scholar.

12. Leary, ibid. (“Since Darwin … all theories of emotion have assumed that the capacity for emotional experience evolved because it had adaptive value in helping organisms deal with recurrent challenges and opportunities in their physical and social environments.” [footnotes omitted]).

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14. Scott, ibid.

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16. Posner, Eric A., “Signaling Model of Social Norms: Further Thoughts” (2002) 36 U. Rich. L. Rev. 465 at 467Google Scholar; see also Posner, supra note 5 at ch. 3.

17. Ibid.

18. Ibid.

19. This is not to deny that some norms may arise due to their inherent survival value, or as solutions to coordination dilemmas—but these norms are nevertheless also co-opted as signals. And their function as signals contributes greatly to their persistence. Not all norms may start off as signals, but all norms end that way. See infra notes 103-07 and accompanying text.

20. See Ellickson, Robert C., “The Evolution of Social Norms: A Perspective from the Legal Academy” in Hechter, Michael & Karl-Dieter, Opp, eds., Social Norms (New York: Russell Sage Foundation, 2005) 35 at 36Google Scholar (“The new norms scholars all hew to a rational-choice model of human behavior. This methodological individualism … supposes that each individual generally is both rational and self-interested.”).

21. Though, admittedly, what I go on to contend below might be accused of being no more than a slightly more nuanced foray into reductionism.

22. Of course, that the rational choice model is entirely safe even within the field of economics is debatable.

23. Elster, Jon, “Fairness and Norms” (2006) 73 Social Research 365 at 368Google Scholar.

24. For those unfamiliar with game theory, McAdams provides a concise summary: “ … two prisoners, A and B, are suspected of committing a crime together. If neither confesses, each knows they will each be convicted of a lesser offense and serve (say) three years in prison. The prosecutor then offers each the following deal, and each knows it is offered to the other: If you confess and the other does not, we will let you off with only one year in prison; if the other confesses and you do not, we will punish you with ten years in prison; if you both confess, you both will serve five years in prison. Confessing is the dominant strategy because it is the best strategy no matter what the other prisoner does. From A’s perspective, if B confesses, A is better off confessing and getting five years instead of ten; if B does not confess, A is better off confessing and getting one year instead of three. The reasoning is the same for B.” McAdams, supra note 2 at 628; see also Druzin, Bryan, “Law Without the State: The Theory of High Engagement and the Emergence of Spontaneous Legal Order within Commercial Systems” (2010) 41 Geo. J. Int’l L. 1 at 559, 599-605.Google Scholar

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28. Of course the intensity of internalization is another matter: if the tip was fifteen thousand dollars, more people might be inclined to not tip. Murder is deeply internalized but most would still not murder someone for fifteen thousand dollars. For an interesting discussion of tipping practices in this respect, see Levmore, Saul, “Norms as Supplements” (2000) 86 Va. L. Rev. 1989 at 1997CrossRefGoogle Scholar.

29. This is the perennial problem for rational choice theorists of a second-order collective action problem—the irrationality of 3rd party norm enforcers willing to pay the cost of sanctioning with no clear individual benefit when they can simply free-ride on others enforcement. For second-order problems, see, e.g., Mahoney, Paul G. & Sanchirico, Chris. W., “Norms, Repeated Games, and the Role of Law” (2003) 91 Cal. L. Rev. 1281 CrossRefGoogle Scholar.

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42. See Thaler, Richard H., The Winner’s Curse: Paradoxes and Anomalies of Economic Life (Princeton, NJ: Princeton University Press, 1996)Google Scholar, especially chapters two and three for a good review of these findings.

43. See, e.g., Korobkin, Russell B. & Ulen, Thomas S., “Law and Behavioral Science: Removing the Rationality Assumption from Law and Economics” (2000) 88 Cal. L. Rev. 1051 CrossRefGoogle Scholar (arguing for fundamental modifications to the assumption of rationality); Ostrom, Elinor, “A Behavioral Approach to the Rational Choice Theory of Collective Action,” Presidential Address Before the American Political Science Association (1997), in 92 Am. Pol. Sci. Rev. 1 (1998)Google Scholar (stating the need for a “second-generation” rational choice model).

44. Wendel, W. Bradley, “Mixed Signals: Rational-Choice Theories of Social Norms and the Pragmatics of Explanation” (2002) 77 Ind. L.J. 1 at 10Google Scholar.

45. Scott, supra note 13; see also Sunstein, supra note 36 at 909.

46. Ellickson, supra note 1 at 156, n.3. However, this failure is, perhaps, matched equally by those on the Law and Society side in their failure to adequately explain the nature of these preferences, simply adducing concepts like “norm of cooperation” to explain cooperation. See Wendel, supra note 44 at 6. Elster compares this approach to explaining the soporific effects of opium in terms of its “dormative principle.” Elster, supra note 13 at 186. Indeed, as Ellickson explains, “A key shortcoming of the law-and-society school has been its failure to develop a theory of the content of norms … sociologists and other law-and-society scholars have tended to treat observed norms as exogenous, rather than as dependent variables whose contents are to be explained.” Ellickson, supra note 1 at 149.

47. Scott, supra note 13 at 134; see also Cook, K.S. & Emerson, R.M., “Power, Equity and Commitment in Exchange Networks” (1978) 43 American Sociological Rev. 721 CrossRefGoogle Scholar.

48. Duxbury, Neil, “Signaling and Social Norms” (2001) 21 Oxford J. Legal Stud. 719 CrossRefGoogle Scholar; see also, e.g., Rachlinsky, Jeffrey J., “The Limits of Social Norms” (2000) 74 Chicago-Kent L. Rev. 1537 Google Scholar; Scott, Robert E., “The Limits of Behavioural Theories of Law and Social Norms” (2000) 86 Va. L. Rev. 1603 CrossRefGoogle Scholar.

49. Posner acknowledges that people do behave in this fashion. Posner, supra note 5 at 38, 43. Note that this dilemma applies equally to norm enforcement. Posner responds by stating that “rational choice theory can be used to explain some social phenomena but not other social phenomena.” Ibid.

50. Some norm scholars make a distinction between shame and guilt, pointing out that shame is related to compliance, while guilt brings up issues of voluntary conformity. See, e.g., ibid. at 43. For our purposes, however, both are expressions of internalization.

51. I am in good company: Cooter also asserts a norm only exists if it has been internalized. Cooter, Robert D., “Decentralized Law for a Complex Economy: The Structural Approach to Adjudicating the New Law Merchant” (1996) 144 U. Pa. L. Rev. 1643 at 1661—66 Google Scholar.

52. Posner, supra note 5 at 46.

53. Posner, supra note 16 at 477.

54. McAdams, supra note 2 at 679.

55. Posner, supra note 5 at 26.

56. Posner, supra note 16 at 472.

57. Posner, supra note 5 at 43.

58. Ibid. at 43-44.

59. Ibid. at 44.

60. Interestingly, Posner’s earlier work did not exhibit this rejection of all things normative: “ … even a complete game-theoretic account of cooperative behavior would miss some essential aspects of norms. We say about most norms that people bound by them feel an emotional or psychological compulsion to obey the norms; norms have moral force … Game theory does not explain these phenomena.” Posner, supra note 3 at 1709.

61. For a critique of Posner’s theory in this respect, see McAdams, supra note 2 at 678-87.

62. Besides Cooter, McAdams, and Elster are perhaps the two most prominent. See Elster, supra note 46; Elster, Jon, “Norms of Revenge” (1990) 100 Ethics 862 CrossRefGoogle Scholar; McAdams, supra note 3 at 338; see also Pettit, Philip, “Virtus Normativa: Rational Choice Perspectives” (1990) 100 Ethics 725 at 730CrossRefGoogle Scholar.

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64. Bicchieri’s criticism of such an approach applies: “Yet to maintain that we conform to social norms because of the disapproval involved in violating them is of little help in explaining why norms are there, how they emerged, and why they persist.” Bicchieri, Cristina, “Norms of Cooperation” (1990) 100 Ethics 838 at 839CrossRefGoogle Scholar.

65. McAdams, supra note 2 at 687.

66. Cooter, Robert, “Do Good Laws Make Good Neighbors? An Economic Analysis of Internalized Norms” (2000) 86 Va. L. Rev. 1577 at 1601CrossRefGoogle Scholar.

67. Many rational choice theorists in fact employ evolutionary models that presuppose this kind of bounded rationality to explain norm emergence. See, e.g., Axelrod, Robert, The Complexity of Cooperation: Agent-Based Models of Competition and Collaboration (Princeton, NJ: Princeton University Press, 1997)Google Scholar; Skyrms, Brian, Evolution of the Social Contract (Cambridge: Cambridge University Press, 1996)CrossRefGoogle Scholar; H. Young, Peyton, Individual Strategy and Social Structure: An Evolutionary Theory of Institutions (Princeton, NJ: Princeton University Press, 1998)Google Scholar. See also, e.g., Sunstein, Cass R., Behavioral Law & Economics (Cambridge: Cambridge University Press, 2000)CrossRefGoogle Scholar; Korobkin & Ule, supra note 43.

68. Indeed, Frank sees the emotions as the progenitor of moral behavior rather than rational decisions. Frank, Robert H., Passions Within Reason: The Strategic Role of the Emotions (New York: W. W. Norton & Co., 1988) at 51—56 Google Scholar.

69. “Individuals do not eat in response to a rational calculus of caloric need. Instead, a complex set of forces causes one to ‘feel hungry.’” Scott, Robert E., “The Limits of Behavioral Theories of Law and Social Norms” (2000) 86 Va. L. Rev. 1603 at 1606CrossRefGoogle Scholar (referencing Frank, supra note 68).

70. Robert Trivers famously presented a similar idea in his 1971 paper The Evolution of Reciprocal Altruism. Trivers argued that due to the difficulty involved in computing the complex cost-benefit ratios that underpin long-term reciprocity, human emotions evolved as a regulating mechanism. See Trivers, R.L., “The Evolution of Reciprocal Altruism” (1971) 46 Q. Rev. Biology 35 CrossRefGoogle Scholar. To facilitate this system of reciprocal altruism, “feelings and emotions—including guilt, fairness, moralistic aggression, gratitude, and sympathy—are part of the normal repertoire of human responses and are evoked in predictable situations.” Holcomb, Harmon & Bryon, Jason, “Sociobiology” (Stanford CA: Stanford Encyclopedia of Philosophy, 2005).Google ScholarPubMed

71. Posner, supra note 5 at 25.

72. See Gintis, supra note 11(arguing that the ability to internalize norms evolves as it enhances individual fitness in situations where social behavior has become too complex to be evaluated piecemeal through individual rational assessment).

73. McAdams, supra note 3 at 376; see also Franks, supra note 68 at 152-61; Ellickson, Robert, “Bringing Culture and Human Frailty to Rational Actors: A Critique of Classical Law and Economics” (1989) 65 Chicago-Kent L. Rev. 23 at 45—46 Google Scholar.

74. Scott makes a similar point, though he is speaking about internalization in general: Scott, supra note 48 at 1621 (“There is long-term advantage in moral behavior. But in order for emotions, such as guilt, to work as self-enforcing commitments, satisfaction must be intrinsic in the act of compliance and not premised on the possibility that material gains may follow.”).

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79. See Hirshleifer, J., “On the Emotions as Guarantors of Threats and Promises” in Dupre, John, ed., The Latest on the Best: Essays on Evolution and Optimality (Cambridge, MA: The MIT Press, 1987) 307 Google Scholar; Hirshleifer, J., “The Affections and the Passions: Their Economic Logic” (1993) 5 Rationality Soc. 185 CrossRefGoogle Scholar; Hirshleifer, J., “Evolutionary Models in Economics and Law: Cooperation Versus Conflict Strategies” in Hirshleifer, J., ed., The Dark Side of the Force: Economic Foundations of Conflict Theory (Cambridge: Cambridge University Press, 2001) 183 Google Scholar; see also Margolis, H., Selfishness, Altruism and Rationality: A Theory of Social Choice (Chicago, IL: University of Chicago Press, 1982)Google Scholar; R. Frank, supra note 68; Sugden, Robert, The Economics of Rights, Co-Operation and Welfare (Oxford: Blackwell, 1986) at 145—47 Google Scholar; Cooter, supra note 51 at 1662 (discussing the psychological underpinning that induces norm compliance).

80. See Plutchik, R., Emotion: A Psychoevolutionary Synthesis (New York: Harper & Row, 1980)Google Scholar (positing an evolutionary model of emotion in which primary emotions are distinguished from more complex emotions); see also Panskepp, J., “Toward a General Psychobiological Theory of Emotions” (1982) 5 Behavioral and Brain Sciences 407 Google Scholar.

81. See Elster, Jon, Strong Feelings: Emotion, Addiction, and Human Behavior (Cambridge, MA: The MIT Press, 2000) at 98 Google Scholar (citing emotions as supporting social norms).

82. See Mealey, L., “The Sociobiology of Sociopathy: An Integrated Evolutionary Model” in Baron-Cohen, Simon, ed., The Maladapted Mind: Classic Readings in Evolutionary Psychopathology (East Sussex, UK: Psychology Press, 1997) 133 at 170Google Scholar at n.2.

83. Posner gives an illuminating explanation of racist norms as discount rate signals. See Posner, supra note 5 at 133-43.

84. Ibid. at 112-19.

85. See infra notes 161-68 and accompanying text.

86. Asch, S.E., “Opinions and Social Pressure” (1955) 193 Scientific American 31 CrossRefGoogle Scholar; Sherif, M., “An Experimental Approach to the Study of Attitudes” (1937) 1 Sociometry 90 CrossRefGoogle Scholar.

87. Posner, supra note 5 at 46.

88. Ibid.

89. Buss, David M., Evolutionary Psychology: The New Science of the Mind (Boston, MA: Allyn & Bacon, 2004) at 50.Google Scholar

90. See Frank, supra note 68 at 5-7.

91. Scott, supra note 48 at 1606 (“Salient emotional reactions-such as guilt, anger, or empathy-mark one as a ‘cooperator’ who is able to make credible commitments concerning her future actions.”).

92. A point adamantly made by Wendel in his critique of Posner, see Wendel, supra note 44 at 30 (“ … it matters critically whether the theory is radically at odds with one’s subjective experiences. In these contexts, we may have reason to reject the rational-choice model in favor of one that employs explanatory concepts that are congruent with those actually deployed by the deliberating individual.”).

93. Cooter, Robert, “The Normative Failure of Law” (1997) 82 Cornell L. Rev. 947 at 952Google Scholar; see, e.g., Grief, Avner, Milgrom, Paul & Weingast, Barry, “Coordination, Commitment, and Enforcement: The Case of the Merchant Guild” (1994) 102 J. Pol. Economy 745 at 764—71 Google Scholar; Milgrom, Paul, North, Douglass, & Weingast, Barry, “The Role of Institutions in the Revival of Trade: The Law Merchant, Private Judges, and the Champagne Fairs” (1990) 2 Economy & Politics 1 at 6—14 Google Scholar.

94. Cooter being one notable exception. See Cooter, supra note 51 at 1690-94; Cooter, supra note 66; Cooter, supra note 93.

95. Baird, Douglas G., Gertner, Robert H., & Picker, Randal C., Game Theory and the Law (Cambridge, MA: Harvard University Press, 1994) at 125.Google Scholar

96. For example, animals certainly kill, but it is unclear if an animal can commit murder; we don’t have the moral language for this, as we don’t impose norms on animal behavior in the way we do for human conduct.

97. A bold assertion could be made here that follows from this line of reasoning: Morality does not exist outside the world of these discount signals. The arc of our moral universe is wholly constructed from this signaling game—morality is an emergent property. When one considers that approximately 4% of all males (sociopaths) do not experience moral sentiment at all, the onus would seem to rest with those claiming its objective validity—if they cannot meet this burden, one would have to conclude that it is not an objective truth but rather a subjective concoction. However, a Kantian universal moral truth is not necessarily denied here. One could equally make the case that evolution merely provides otherwise selfish organisms a degree of clarity in regards to certain moral truths where and when it confers an evolutionary advantage.

98. Sugden, Robert, “Spontaneous Order” (1989) J. Economic Perspectives 85 at 95CrossRefGoogle Scholar. Sugden uses the term “convention”.

99. An important point regarding rational choice theory should, however, be understood here. Arguably, behavior based upon self-interest is just as much a product of internalization as selfless behavior. It is simply the internationalization of a different order, one that imparts a normative quality to self-interest. Indeed, a rational calculus is employed, but it is predicated on a fundamental assumption that is no less normative in nature. The tremendous survival advantage of selfishness ensured it was evolutionarily selected for to a degree. The rationality of rational choice is that decisions are made through a careful cost benefit analysis; however, the basis for this analysis (self-interest) is still very much normative. My point here is that in either case—rational choice, or the blind internalization of norms—internalization is present. Even the most self-serving individuals believe they are normatively justified in their self-interest. Indeed, an argument could be made that the difference is more the nature of the internalization then the presence or absence of it.

100. See supra note 12.

101. Or not internalize as in the case of pure opportunists. What is therefore meant here is the degree of internalization has been selected for.

102. Posner, supra note 5 at 37 (“[W]hat might emerge as a conventional signal in any group is to a certain extent arbitrary.”).

103. For a good overview of the literature regarding this distinction, see Cialdini, Robert B. & Trost, Melanie R., “Social Influence: Social Norms, Conformity, and Compliance” in Gilbert, Daniel T., Fiske, Susan T. & Lindzey, Gardner, eds., The Handbook of Social Psychology, vol. 2 (New York: Oxford University Press, 1998) 151 at 152-53.Google Scholar

104. Posner, supra note 5 at 25.

105. Ibid. See also Sugden, supra note 79 at 47-52, where he speaks of “focal points.” Schelling was perhaps the first to articulate this idea of salience or focal points, facilitating coordination. See Schelling, Thomas C., The Strategy of Conflict (Cambridge, MA: Harvard University Press, 1980) at 53—80, 83-118Google Scholar.

106. Posner, supra note 5 at 29-32.

107. We can see this clearly with norms of an aesthetic nature. For example, the sexualizing of woman’s breasts might be explained in this manner. Likewise, aesthetic offenses such as facial pimples, obesity, and male-pattern baldness might be attributed to their common characteristic of obviousness. To be sure, it would be hard to imagine a norm of this nature arising that could not be plainly seen by others. Research regarding the difficulty in creating a brand image for “invisible” products that are not readily observable, such as men’s underwear, illustrates this point in the context of fashion norms (though even here a select few will see the product). See Yen, Jui-Yen & Chen, Mei-Liang, “Creating Brand Value in Third Countries: A Case of Underwear Industry” (2007) J. International Management Studies 133 Google Scholar (concluding that there is a necessity to place an inordinate emphasis on quality in marketing as a way of overcoming branding difficulties related to invisible products).

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112. Spence, supra note 110.

113. Posner, supra note 5.

114. Posner, supra note 3; see also Mahoney, Paul & Sanchirico, Chris William, “Competing Norms and Social Evolution: Is the Fittest Norm Efficient?” (2001) 149 U. Pa. L. Rev. 2027 CrossRefGoogle Scholar; Posner, supra note 5 at 169-84; Sugden, supra note 98; Bicchieri, supra note 33 at 838.

115. Sugden, supra note 98 at 93.

116. Posner, supra note 5 at 8.

117. Ibid. at 172.

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120. Mahoney et al., supra note 114 at 2027.

121. Ibid. at 2062.

122. Ibid. at 2027.

123. Sugden, supra note 98 at 97.

124. Elster, supra note 13 at 125-51.

125. Elster, supra note 81 at 88.

126. Bicchieri, supra note 64 at 838.

127. Ibid.

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130. Nielsen, supra note 76 at 271.

131. Posner, supra note 114 at 1723.

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141. Elster, supra note 81 at 101.

142. McAdams, supra note 2 at 637.

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147. Sripada et al., supra note 136 at 284.

148. Ibid. at 283.

149. Ibid. at 299.

150. Ibid.

151. Ibid.

152. Ibid. at 282.

153. Ibid.

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158. Kilborne & Langness, eds., supra note 143 at 137.

159. Nucci, supra note 154.

160. Ibid. at 78.

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163. Sherif, supra note 86.

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174. Fehr & Fischbacher, supra note 111.

175. Dawkins, supra note 172; Wilson, supra note 172; Smith, supra note 172.

176. Gintis et al., supra note 103; see also McAndrew, supra note 111; Fehr & Fischbacher, supra note 111 at 789.

177. Using both hands when presenting someone with money or a gift is a norm in some parts of China. Having lived in China for the better part of decade, I personally internalized this norm.

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186. Ibid.

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191. In terms of human normative behavior.

192. For social learning, see Bandura, A., Social Learning Theory (Saddle River, NJ: Prentice Hall, 1977)Google ScholarPubMed (giving an overview of theoretical and experimental advances in the field of social learning); see also Zentall, T.R., “Imitation: Definitions, Evidence, and Mechanisms” (2006) 9 Animal Cognition 335 CrossRefGoogle Scholar (presenting an overview of various types of social learning).

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194. The basic premise of Dual Inheritance Theory is that human behavior evolves through both genetic and cultural processes. For Dual Inheritance Theory, see Lumsden, C. & Wilson, E., Genes, Mind and Culture: The Coevolutionary Process (Cambridge, MA: Harvard University Press, 1981)Google Scholar (formulating a series of mathematical models for how genes and culture might coevolve); Cavalli-Sforza, L. & Feldman, M., Cultural Transmission and Evolution: A Quantitative Approach (Princeton, NJ: Princeton University Press, 1981)Google Scholar (presenting a mathematical theory concerning the spread of cultural traits); Boyd, R. & Richerson, P., Culture and the Evolutionary Process (Chicago, IL: University of Chicago Press, 1985)Google Scholar (examining the relationship between culture as a transmission system and genetic evolution); see also Richerson, Peter J. & Boyd, Robert Not by Genes Alone: How Culture Transformed Human Evolution (Chicago, IL: University of Chicago Press, 2004)CrossRefGoogle Scholar (presenting an excellent overview of the current state of cultural evolution research).

195. For the concept of an evolutionarily stable strategy (ESS), see Smith, supra note 77.

196. The existence of sociopaths, perhaps the quintessential pure opportunist, attests to the viability of a non-cooperative strategy in evolutionary game theoretical terms. Sociopaths comprise a sizable percentage of the population, roughly 3-4% of the male population and approximately 1% of the female population. Davison, G.C. & Neale, J.M., Abnormal Psychology, 6th ed., (New York: John Wiley & Sons, 1994)Google Scholar; Robins, L.N., Tipp, J. & Przybeck, T., “Antisocial Personality” in Robins, L.N. & Regier, D.A., eds., Psychiatric Disorders in America (New York: Free Press, 1991) 258.Google Scholar Sociopaths demonstrate a “marked degree of impulsivity,” which makes sense for an individual with an enormously high discount rate. See Mealey, supra note 82 at 134.

197. See Posner, supra note 5 at 112-19.

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214. Ibid. at 398.

215. Ibid. at 397.

216. Ibid. at 398.

217. Ibid.

218. Ibid.

219. Cleckley, Hervey, Mask of Sanity: An Attempt to Clarify Some Issues about the so-called Psychopathic Personality, 5th ed. (Augusta, GA: 1988 [1941]) at 338—39 Google Scholar.

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223. Correctional Service of Canada, “A Mental Health Profile of Federally Sentenced Offenders” (1990) 2 Forum on Corrections Research 7 Google Scholar. Note that I am here using antisocial personality disorder synonymously with sociopathy.

224. Becker, Gary S., Grossman, Michael & Murphy, Kevin M., “Rational Addiction and the Effect of Price on Consumption” (1991) 81 Aea Papers and Proceedings 237 Google Scholar; see also Glaeser, Edward L., “Economic approach to crime and punishment” in Newman, Peter, ed., The New Palgrave Dictionary of Economics and the Law (New York: Palgrave Macmillan, 1998).Google Scholar

225. Posner, supra note 5 at 1-8, 49-50, 122-24, 133.

226. Ibid. at 35.

227. McAdams, supra note 2 at 672.

228. See Posner, supra note 5 at 18.

229. Ibid. at 43.

230. Ibid. at 44.

231. See Mealey, L., “The Sociobiology of Sociopathy: An Integrated Model” (1995) 18 Behavioral and Brain Sciences 523 CrossRefGoogle Scholar (identifying hypothetical ancestral conditions that would make sociopathy adaptive); but see Crusio, Wim E., “The Sociopathy of Sociobiology” (1995) 18 Behavioral & Brain Sciences 552 CrossRefGoogle Scholar (charging that Mealey’s evolutionary reasoning is logically flawed, and the import of the cited genetic evidence exaggerated).

232. The gender gap in sociopathy rates is interesting (“3%-4% of the male population and less than 1% of the female population”). See Mealey, supra note 82 at 133. One possible explanation for this gap is that as the physically stronger gender, males were evolutionarily better positioned to pursue an opportunist strategy based on aggression. This could go far in explaining the higher rates of criminality and propensity towards violence found in males.

233. The limits of even deeply internalized norms speaks to this fact. Even the strongest cooperators may abandon their moral convictions given the right circumstances. Consider situations of mass panic, or life and death me-or-you situations, where feelings of right and wrong fall by the wayside to facilitate survival. We even accept this inherent normative flexibility to a degree in others; for instance, we judge less harshly an individual who takes an innocent life when a gun is held to their own head. This assumption is so deep-seated in fact, this is a legal defense, i.e. the defense of necessity. See infra notes 241-42 and accompanying text.

234. Posner, supra note 5 at 19.

235. See Mealey’s concept of secondary sociopaths, Mealey, supra note 82 at 163; see also the “Mach” scale (as in Machiavellian) developed by Christie & Geis, supra note 221.

236. Smith, J. Maynard, Evolutionary Genetics (Oxford: Oxford University Press, 1989) at 126—36 Google ScholarPubMed; see also Hawkes, K., “Sharing and Collective Action” in Smith, Eric A. & Winterhalder, Bruce, eds., Evolutionary Ecology and Human Behavior (New York: Walter de Gruyter, 1992) 269 Google Scholar at 281.

237. Nielsen, supra note 76 at 278.

238. See Smith, supra note 77 at 164-66.

239. Mealey, supra note 82 at 135 (speaking about sociopathy).

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242. Ibid.

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246. Mealey, supra note 82 at 163.

247. Ibid. at 138.

248. Posner, supra note 5 at 22.

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250. Posner, supra note 5 at 22.

251. Ibid. 19-21.

252. Wendel, supra note 44 at 40.

253. Kahan, supra note 200.

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255. See Wendel, supra note 44 at 27; Duxbury, supra note 48 at 725-33.

256. Wendel, supra note 44 at 36.

257. Duxbury, supra note 48 at 732.

258. Ibid. at 725.

259. Ibid. at 727.

260. Ibid. at 733.

261. See Wendel, supra note 44 at 25, 29; Madison, supra note 198.

262. Wendel, supra note 44 at 37.

263. Madison, supra note 198; see also Schaefer, Elmer J., “Predicting Defection” (2002) 36 U. Rich. L. Rev. 443 at 445-46Google Scholar (pointing out that people signal to communicate other characteristics besides discount rates).

264. Wendel, supra note 44 at 29.

265. Ibid. at 25.

266. Ibid. at 34.

267. See supra notes 161-68, 205-08 and accompanying text.

268. Wendel, supra note 44 at 32.

269. McAdams, supra note 2 at 666.

270. Ibid.

271. See Luce, R. & Raiffa, H., Games and Decisions: An Introduction and Critical Survey (New York: John Wiley & Sons, 1957) at 98—99 Google Scholar.

272. McAdams, supra note 2 at 664.

273. Mahoney, Paul G., “Norms and Signals: Some Skeptical Observations” (2002) 36 U. Rich. L. Rev. 387 at 392Google Scholar.

274. Ibid. at 391.

275. Ibid. at 394.

276. McAdams, supra note 2 at 666.

277. Ibid. at 655.

278. Wendel, supra note 44 at 31.

279. McAdams, supra note 2 at 655.

280. Wendel, supra note 44 at 31.

281. Hardin, supra note 204 at 1826.

282. Ibid. at 1826-27.

283. Ibid. at 1826.

284. McAdams agrees: “Absent a highly predictive alternative theory, I think one can justify cutting normative motivations out of the explanation only if one of the following is true: (1) normative motivations do not actually exist, or (2) normative motivations, while they exist, are unrelated to the behavior we call norms. Posner explicitly rejects the first proposition, and the second is simply not tenable.” McAdams, supra note 2 at 681.

285. Cooter, supra note 157.