There is increasing evidence that there is an evolved "moral grammar" in
human brains (which in some respects resembles Kantian moral philosophy). My question is, is it possible to have an ethical system that is entirely rational and unreliant on "hardwired" beliefs? Obviously any moral theory that relies on evolution commits the naturalistic fallacy (what helps animals to survive and reproduce has no bearing on what is good and bad).
Case in point is utilitarianism, trumpeted as an entirely secular and rational moral philosophy. But why would "anti-utilitarianism"--the ethical theory that prescribes the greatest pain for the greatest number--be, logically speaking, any less valid than utilitarianism? The assumption that pain is bad and pleasure is good appears to be "hardwired" and without rational basis. These questions leave me in some doubt about the viability of moral philosophy, since all moral theories seem to include premises that I have no reason to accept.