Journal for the Theory of Social Behaviour 39:1 0021–8308 © 2009 The Author Journal compilation © The Executive Management Committee/Blackwell Publishing Ltd. 2009. Published by Blackwell Publishing, 9600 Garsington Road, Oxford, OX4 2DQ UK and 350 Main Street, Malden, MA 02148, USA. Blackwell Publishing Ltd Oxford, UK JTSB Journal for the Theory of Social Behaviour 0021-8308 1468-5914 © 2008 The Author Journal compilation © The Executive Management Committee/Blackwell Publishing Ltd. 2008 XXX Original Article Sex Differences in Moral Interests Deborah Mower Sex Differences in Moral Interests: The Role of Kinship and the Nature of Reciprocity DEBORAH MOWER 1. INTRODUCTION The idea that there are sex differences in moral reasoning, interests, or values is not new. Kohlberg’s (1973) work in moral stage theory appeared to offer solid evidence that males achieve a higher stage of moral reasoning than females, and that they have greater interests in abstract reasoning and principles of justice. In their responses to moral dilemmas, males explained their decisions using abstract and impartial principles, while many females based their decisions on values inherent in maintaining relationships. In a groundbreaking work, Carol Gilligan (1982) protested that the stages of moral development merely reflected the moral reason- ing of males, and that the moral reasoning of females was not inferior or less developed, but just different. Gilligan argued that while justice may be a primary moral value for males, care is a primary moral value for females. The notion of an “ethic of care” as established by Gilligan is now firmly entrenched in moral theory, and there has been much research and continuing debate on sex differences in moral development, reasoning, values, and interests in the past thirty years. Although moral psychologists and feminist moral theorists emphasize males’ interest in justice or fairness and females’ interest in care or empathy, recent work in evolutionary psychology links females’ interests in care and empathy for others with interests in fairness and equality. In an important work on sex differences in cognitive abilities, David Geary (1998) argues that the evolutionary mechanism of sexual selection drives the evolution of particular cognitive abilities and selection for particular interests. He uses the notions of kin selection and reciprocal altruism to argue that the nature of the social and intrasexual competitive environments for males and females differ. These differences in male and female environments drive the selection of traits and lead to a divergence of interests, in which females have greater interests in empathy, fairness, and equality, and males have greater interests in dominance (for a similar argument, see Knickmeyer et al., 2006). I mount two main challenges to Geary’s claims. First, I argue that female social and intrasexual competitive environments evolve, which challenges the assumption