If humans have an evolved moral psychology, then we should not expect it to function in an identical way between individuals. Instead, we should expect a diversity in the function of our moral psychology between individuals that varies along genetic lines, and a corresponding diversity of moral attitudes and moral judgements that emerge from it. This is because there was no one psychological type that would reliably produce adaptive social behaviour in the highly heterogeneous environments in which our minds evolved. As such, there was no single psychological type towards which evolution could gravitate. Instead we evolved a stable polymorphism of psychological types, maintained by frequency-dependent selection, each predisposed towards particular social and moral attitudes and behaviours. This can help explain the existence of moral diversity, particularly intra-cultural moral diversity, and seemingly intractable moral disagreement.

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Alford, J. R., Funk, C. L. & Hibbing, J. R. 2005. 'Are Political Orientations Genetically Transmitted?' American Political Science Review 99, no. 2: 153–167.

Altemeyer, B. 1998. 'The Other Authoritarian Personality'. Advances in experimental social psychology 30: 47–92.

Axelrod, R. 1987. 'The evolution of strategies in the iterated prisoner's dilemma'. Genetic algorithms and simulated annealing 3: 32–41.

Axelrod, R. & Hamilton, W. D. 1981. 'The evolution of cooperation'. Science 211, no. 4489: 1390–1396.

Bateson, P. 2004. 'The origins of human differences'. Daedalus 133, no. 4: 36–46.

Binmore, K. G. 1998. Game Theory and the Social Contract: Just Playing. MIT Press.

Bloomfield, P. 2001. Moral reality. Oxford University Press, USA.

Bouchard, T. 1994. 'Genes, environment, and personality'. Science 264: 1700–1701.

Bouchard, T. & McGue, M. 2003. 'Genetic and environmental influences on human psychological differences'. Journal of neurobiology 54, no. 1: 4–45.

Boyd, R. & Lorberbaum, J. P. 1987. ‘No pure strategy is evolutionarily stable in the repeated Prisoner’s Dilemma game’. Nature Publishing Group.

Buss, D. M. 2009. 'How can evolutionary psychology successfully explain personality and individual differences?' Perspectives on Psychological Science 4, no. 4: 359–366.

Casebeer, W. D. & Churchland, P. S. 2003. 'The Neural Mechanisms of Moral Cognition: A Multiple-Aspect Approach toMoral Judgment and Decision-Making'. Biology and Philosophy 18, no. 1: 169–194.

Cosmides, L. & Tooby, J. 2004. ‘Knowing thyself: The evolutionary psychology of moral reasoning and moral sentiments’. Business, science, and ethics 4: 91–127.

Duckitt, J. 2001. 'A dual-process cognitive-motivational theory of ideology and prejudice'. Advances in experimental social psychology 33: 41–113.

Frenkel-Brunswik, E. 1948. 'Tolerance toward ambiguity as a personality variable'. American Psychologist 3: 250.

Gill, M. B. & Nichols, S. 2008. 'Sentimentalist Pluralism: Moral Psychology and Philosophical Ethics'. Philosophical Issues 18, no. 1: 143–163.

Godfrey-Smith, P. 1998. Complexity and the Function of Mind in Nature. Cambridge University Press.

Greene, J. & Haidt, J. 2002. 'How (and where) does moral judgment work?' Trends in Cognitive Sciences 6, no. 12: 517–523.

Haidt, J. 2001. 'The emotional dog and its rational tail: A social intuitionist approach to moral judgment'. Psychological Review 108, no. 4: 814–834.

Haidt, J. 2003. ‘The moral emotions’. In R. J. Davidson, K. R.Scherer & H. H. Goldsmith (eds.) ‘Handbook of affective sciences’, 852–870. Oxford University Press, USA.

Haidt, J. & Graham, J. 2007. ‘Planet of the Durkheimians, where community, authority, and sacredness are foundations of morality’. Social and psychological bases of ideology and system justification (December 11, 2006) 371–401.

Huebner, B., Dwyer, S. & Hauser, M. 2009. 'The role of emotion in moral psychology'. Trends in cognitive sciences 13, no. 1: 1–6.

Jost, J. T., Glaser, J., Kruglanski, A. W. & Sulloway, F. J. 2003. 'Political conservatism as motivated social cognition'. Psychological Bulletin 129, no. 3: 339–375.

Jost, J. T., Napier, J. L., Thorisdottir, H., Gosling, S. D., Palfai, T. P. & Ostafin., B. 2007. 'Are needs to manage uncertainty and threat associated with political conservatism or ideological extremity?' Personality and social psychology bulletin 33, no. 7: 989–1007.

Kitcher, P. 2011. The Ethical Project. Cambridge, MA: Harvard University Press.

Lakoff, G. 1996. Moral politics. University of Chicago Press.

Lieberman, D. 2008. 'Moral Sentiments Relating to Incest: Discerning Adaptations from By-products'. In W. Sinnott-Armstrong (ed.) 'Moral Psychology vol. 1.', 165–190. Cambridge, MA: The MIT Press.

Lieberman, D., Tooby, J. & Cosmides, L. 2003. 'Does morality have a biological basis? An empirical test of the factors governing moral sentiments relating to incest.' Proceedings. Biological sciences / The Royal Society 270, no. 1517: 819–26.
PMid:12737660 PMCid:1691313

Lomborg, B. 1996. 'Nucleus and Shield: The Evolution of Social Structure in the Iterated Prisoner's Dilemma'. American Sociological Review 61, no. 2: 278–307.

McCoy, S. & Major, B. 2007. 'Priming meritocracy and the psychological justification of inequality'. Journal of Experimental Social Psychology 43, no. 3: 341–351.

McCrae, R. R. & Costa, P. T. 2003. Personality in adulthood: A five-factor theory perspective. The Guilford Press.

McElreath, R., Boyd, R. & Richerdson, P. J. 2003. 'Shared Norms and the Evolution of Ethnic Markers'. Current Anthropology 44, no. 1: 341–351.

Mitchell, G. & Tetlock, P. E. 2009. ‘Disentangling reasons and rationalizations: Exploring perceived fairness in hypothetical societies’. Social and psychological bases of ideology and system justification 1, no. 9: 126–158.

Mondak, J. J. 2010. Personality and the foundations of political behavior. Cambridge Univ Pr.

Nettle, D. 2005. 'An evolutionary approach to the extraversion continuum'. Evolution and Human Behavior 26, no. 4: 363–373.

Penke, L., Denissen, J. J. A. & Miller, G. F. 2007. 'The evolutionary genetics of personality'. European Journal of Personality 21, no. 5: 549–587.

Plomin, R., Owen, M. J. & McGuffin, P. 1994. 'The genetic basis of complex human behaviors'. Science 264, no. 5166: 1733–1739.

Richerdson, P. J. & Boyd, R. 2001. ‘The evolution of subjective commitment to groups: A tribal instincts hypothesis’. In R. M. Nesse (ed.) ‘The Evolution of Subjective Commitment’, 186–220. Russell Sage Foundation Publications.

Richerdson, P. J., Boyd, R. & Henrich, J. 2002. ‘Cultural Evolution of Human Cooperation’. In P. Hammerstein (ed.) ‘Genetic and Cultural Evolution of Cooperation’, 1–33. MIT Press.

Sripada, C. S. 2005. 'Punishment and the strategic structure of moral systems'. Biology and Philosophy 20, no. 4: 767–789.

Sripada, C. S. & Stich, S. 2005. 'A Framework for the Psychology of Norms'. In P. Carruthers, S. Laurence & S. Stich (eds.) 'The Innate Mind: Structure and Contents', 1–40. Oxford University Press, UK.

Sterelny, K. 2007. 'Social intelligence, human intelligence and niche construction'. Philosophical transactions of the Royal Society of London. Series B, Biological sciences 362, no. 1480: 719–30.
PMid:17255005 PMCid:2346527

Sterelny, K. 2012. The Evolved Apprentice. Cambridge, MA: The MIT Press.

Tetlock, P. E. 1983. 'Cognitive style and political ideology'. Journal of Personality and Social Psychology 45, no. 1: 118–126.

Thorisdottir, H., Jost, J. T. & Kay, A. C. 2009. 'On the Social and Psychological Bases of Ideology and System Justification'. In J. T. Jost, A. C. Kay & H. Thorisdottir (eds.) 'Social and Psychological Bases of Ideology and System Justification', 1. Oxford University Press, USA.

Trivers, R. L. 1971. 'The evolution of reciprocal altruism'. The Quarterly review of biology 46, no. 1: 35–57.

Turkheimer, E. 2000. 'Three laws of behavior genetics and what they mean'. Current Directions in Psychological Science 9, no. 5: 160–164.

Zaller, J. 1992. The nature and origins of mass opinion. Cambridge University Press.