Why do philosophers seem to object to anthropomorphic moral and value claims? In other words, what's wrong embracing our parochial human interests completely? Say for instance a rare slug which we know conclusively to have no non-aesthetic value occupies space that prevents the construction of a hydroelectric dam. Why should we not say, "Screw the slug, humanity is more important" and proceed accordingly? More abstractly, why has morality (excepting maybe Nietzsche) not attempted to reconcile humanity's obvious selfishness, bias, violence and greed with what we might call "pure" ethics. Moreover, what's to stop us from simply re-defining our philosophical terms in order to make this more palatable, e.g. by defining "free will" as "whatever it is that humans do/experience" as an easy out from some sticker philosophical dilemmas? Thanks in advance for any responses.