I just had this idea/realization: Utilitarianism a form of normative evolutionary ethics because it argues that the way one ought to act is based on certain facts about human nature, namely, how man has evolved to desire pleasure and avoid pain.
I can accept that the desire for pleasure and avoidance of pain is a fact about human nature for the sake of argument. However, all that can be said of this is that evolution selected for innate behavioral mechanisms in humans that produced the desire for pleasure and avoidance of pain. But this does not offer any moral justification for these behaviors. Additionally, evolutionary psychology argues that there are many innate mechanisms in humans. This means that Utilitarianism would also need to provide an explanation for why the desire for pleasure and avoidance of pain is the only fact about human nature that is relevant to the discussion of morality. In other words, Utilitarianism connects human nature to moral goodness but only focuses on one aspect of human nature.
What are your thoughts on this? I'm sure I'm not the first one to say these sort of things about Utilitarianism so if you know of anyone who made similar points I'd appreciate it if you posted them in the thread.