original_query: What is the position of moral nihilism and why is it warranted in light of the evolutionary process instantiating objective morality in humans?
query: What is the position of moral nihilism and why does Alexander Rosenberg consider it warranted based on the evolutionary process and its instantiation of objective morality in humans?
answer: Moral nihilism rejects the existence of objective morality.  Alexander Rosenberg argues that this is warranted because neither horn of the Euthyphro dilemma (is something moral because evolution discovered it, or did evolution discover it because it's moral?) adequately explains how evolution could produce objective morality, given the existence of traits like xenophobia and sexism that aren't objectively moral.