Getting on in a varied world

Are greed and ruthlessness contrary to reason? Is immorality a form of irrationality? Much of contemporary ethical theory is a debate between Kantians, who argue that the dictates of morality are dictates of reason, and Humeans, who argue that reason is neutral between morality and immorality. The Kantian and Humean positions assume that the above questions can be answered uniformly for all possible rational agents. Recently, however, the Aristotelian view that the dictates of reason can vary depending on the agent's species has gained some ground. If such variation is possible, then it might be that greed and mthlessness are contrary to reason for agents of a certain species, rationally required for agents of another species, and rationally optional for agents of yet a third species.