In The Methods of Ethics Henry Sidgwick argued against deontology and for consequentialism. More specifically, he stated four conditions for self-evident moral truth and argued that, whereas no deontological principles satisfy all four conditions, the principles that generate consequentialism do. This article argues that both his critique of deontology and his defence of consequentialism fail, largely for the same reason: that he did not clearly grasp the concept W. D. Ross later introduced of a prima facie duty or duty other (...) things equal. The moderate deontology Ross's concept allows avoids many of Sidgwick's objections. And Sidgwick's statements of his own axioms equivocate in exactly the same way for which he criticized deontological ones. Only if they are read as other things equal can they seem intuitive and earn widespread agreement; but that form is too weak to ground consequentialism. And in the form that does yield consequentialism they are neither intuitive nor widely accepted. Sidgwick's arguments against a rival view and for his own were, in multiple ways, unfair. (shrink)