 Of course, there are difficulties with appeal to an evolutionary account of the source of our beliefs about our obligations. All that such an appeal does is to propose a causal hypothesis about the genesis of our beliefs. Even if that causal hypothesis is true, it does not show that the belief that we have special obligations is false. People often acquire true beliefs as a result of mechanisms that do not provide any evidence or justification for the belief. For all that we know, our acceptance of modus ponens as an inferential rule might be due to the selective advantage accruing to those who use that rule, but, I take it, few would see that as undermining the validity of that rule of inference.