“Without God, anything goes,” or so some say. This claim of moral relativism is often found clinging to the belly of evolutionary theories of morality, like some kind of parasitic lamprey, sucking the blood from the very body that hosts it. Yet evolutionary ethics doesn’t necessarily imply moral relativism. Here’s why:
Say we accept the evolutionary ethics picture that morality is a device used to promote pro-social behaviour and solve the problems of cooperation, because doing so lends its adherents greater reproductive success. And the way evolution promotes moral behaviour is by endowing us with a spectrum of moral sentiments that encourage pro-social behaviour – things like empathy and guilt.
But that’s not the end of morality. We also have our rational capacity, which enables us to predict future outcomes of actions, abstract moral principles away from individual actions and deliberate about the best course of action. Between these two faculties – the moral sentiments and reason – we develop normative codes that are spread amongst our community. However, other communities might settle upon different moral norms, perhaps ones that contradict our own.
Now, some claim this picture endorses moral relativism because there is nowhere a single moral authority that can arbitrate between the various moral norms held in different cultures. But this is not entirely true. For if one accepts the premise of what morality is for – i.e. promoting pro-social behaviour and cooperation – then one can review the various moral norms and assess whether they are better or worse at promoting these ends.