It is often argued that evolutionary materialism – the belief that we are simply the sum of our component parts, without any metaphysical attributes whatsoever – is incompatible with moral realism, as it reduces our nature to purely chemical and physical terms. It is tempting therefore to argue that foundations so basic (and shared not only amongst humans, but also all animals) cannot possible logically lead to a convincing moral framework, which in itself seems to be connected with metaphysical connotations such as consciousness.
However, it seems to me that the compatibility between these two areas greatly relies on one’s moral approach or ethical theory. In particular, a convincing account can be made for the compatibility between evolutionary materialism and ethical naturalism, a metaethical theory which states that the term ‘morality’ describes a natural, objective quality such as pleasure, therefore overcoming the gap between nature and morality. In this way, it could also be argued that utilitarianism, another similar and highly subscribed to ethical theory, can also be compatible with evolutionary materialism.
Evolution, in a general sense, puts humans on par with other animals, a view which is often strayed from in a metaphysical approach to human nature which tends to place humans above their fellow species as a result of their rational faculties and consciousness. However, the one uniting factor that undoubtedly drives the nature of both humans and all other living animals the possession of the intrinsic values of pleasure and pain. These two values can be logically found in all actions, both of humans and animals, most visibly in the survival instinct and the (almost universal) natural disposition to reproduction. As is argued in approaches such as utilitarianism and ethical naturalism, all actions – including their subsequent morality – can be logically reduced to these two universal factors of pleasure and pain, therefore causing the two (evolutionary materialism and morality) to be logically compatible.
Although utilitarianism can be viewed as subjective, and therefore fundamentally incompatible with the moral realism that we are trying to reconcile with evolutionary materialism in the first place, a broader and fundamentally objective approach such as ethical naturalism does not fall short of this necessary factor.
In terms of consciousness, which is arguably incompatible itself with forms of evolutionary materialism and reductionism as it goes beyond the capacities of Darwinian-style evolutionary thought, I would hasten also to reject this assumption. I would instead propose that consciousness itself is, perhaps, an evolved attribute and development that serves to enhance these aforementioned instincts of pleasure and pain. For example, although these instincts are universal throughout the entirety of the animal kingdom, they cannot be rationally achieved and maximised due to this lack of consciousness. Moths, for example, would perhaps better achieve their ultimate goal of pleasure that they perceive to be a burning light as something else, due to the fact that pursuing this end often leads to their death (obviously something they do not naturally seek). Humans, therefore, have an advantage not in a metaethical, ‘made in the image of God’ sense, but in a purely evolutionary, material sense of improving our ability to achieve our ultimate, shared goal of the greatest amount of pleasure over pain possible.