Psychological and evolutionary evidence for altruism

Sober and Wilson have recently claimed that evolutionary theory can do what neither philosophy nor experimental psychology have been able to, namely, "break the deadlock" in the egoism vs. altruism debate with an argument based on the reliability of altruistic motivation. I analyze both their reliability argument and the experimental evidence of social psychology in favor of altruism in terms of the folk-psychological "laws" and inference patterns underlying them, and conclude that they both rely on the same patterns. I expose the confusions that have led Sober and Wilson to defend a reliability argument while rejecting the experimental evidence of social psychology.