esis is that objective standards of human morality can be uncovered by locating the epigenetic source(s) of morality. As they put it, "'epigenetic rules' . . . predispose us to think that certain courses of action are right and certain courses of action are wrong" (RW, 426). They cite evidence of altruistic and reciprocal behavior among lower species as well as human beings--behavior that may objectively seem against individual self-interest--to show a tendency toward what they term naturalistic ethics, as a support mechanism for generally approved or agreed upon social norms. Thus for example the individual who sacrifices himself can be understood to do so for the long-term biological survival and stability of his society (tribe, culture). They reject the idea that ethical action comes about as a result of nonbiological experience of the world.
The thesis argues in a way for a priori moral reasoning. But in the realm of naturalistic ethics, such reasoning is not simply a feature of rational processes but rather is an attribute of biological evolution, and its implication goes beyond individual organisms, reaching into the culture. Materialistic rather than nonmaterialistic explanations for moral codes make sense, say Ruse and Wilson, because they lend themselves to empirical understanding. Nonmaterialistic explanations fall before the demonstrable weakness of emotional and psychological moral reasoning and thus the indeterminate nature of moral understanding. The more concrete the explanation for moral development, the more likely it is that more enduring moral codes ca
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