On the whole, I find citing evolutionary claims in arguments about ethics to be unproductive, because to me, such a move undermines the nature of ethical inquiry: trying to figure out what the right thing is to do in the circumstances at hand. Citing evolutionary arguments undermines this effort because it moves the argument from a prospective, deliberative point of view to a retrospective, explanatory point of view.
Both kind of perspectives have their uses, but to cite evolutionary claims when deciding what to do seems to miss the point.
For example, there has been no lack of articles and academic papers that seek to interpret altruism and acts motivated by altruism as evolutionary vestiges. Now, there is nothing wrong with this, if one’s aim is to explain something which already exists: namely, that a lot of people act for altruistic reasons. Then the evolutionary claims cited are perfectly reasonable.
However, I find empirical/scientific explanations not at all helpful from the agent’s perspective when he’s trying to decide what to do. So when I find myself in a situation in which one possible way to act is to act altruistically, knowing the fact that altruism is an evolutionary response doesn’t help me decide whether I should act altruistically or not.
One might, however, make the argument that knowing altruism is an evolutionary response does in fact help me make a decision. After all, the reasoning goes, if altruism comes about as an evolutionary mechanism that helps the survival of the species, why not continue? My reason for rejecting this line of reasoning is that evolution is a random, blind process. It is not that evolution chose altruism among a list of options; rather, altruism survives because those ancient human beings who are altruistic have survived this far.
But because this claim is based on past experiences, it is inductive by nature; and by its inductive nature, there is absolutely no a priori guarantee that in this day and age that those who act altruistically are more likely to survive in the future than those who do not. Evolution helps us understand why it is that some species survive long-term whereas others do not, but this explanation is always retrospective and after the fact. And evolution also does not rule out the possibility that those traits conducive to individual survival are in fact harmful to the species as a whole.
My point is that moral deliberation is always about what one will do in any given situation in which no definite possibilities are immediately obvious. Moral decisions are decisions about the future, and as such, evolutionary claims don’t help the moral agent in his deliberative process. Even if we agree that the survival of the species can act as a normative guideline, among many other normative guidelines, there is no way to judge whether a specific act done by a specific moral agent at a specific point in time will meet the normative goal of species-survival until much later after the fact (essentially thousands of years later, probably even longer).
Therefore, evolutionary considerations don’t really help the agent to decide. Because of this, using evolutionary claims in ethical considerations do not serve the purpose that ethical consideration is aiming at.