The Relevance of Human Nature

The so-called "Human Nature Constraint" holds that if an agent is unable, due to features of human nature, to bring herself to act in a certain way, then this suffices to block or negate the claim that the agent is required to act in that way. David Estlund (2011) has recently mounted a forceful objection to the Human Nature Constraint. I argue that Estlund’s objection fails – but instructively, in a way that gives Estlund resources for a different way of resisting attempts to negate normative claims by deploying the Human Nature Constraint.