Christine Korsgaard argues that Humean views of both action and rationality jointly imply the impossibility of irrational action, allowing us only to perform actions that we deem rational. Humeans can answer Korsgaard’s objection if their views of action and rationality measure agents’ actual desires differently. What determines what the agent does are the motivational forces that desires produce in the agent at the moment when she decides to act, as these cause action. What determines what it is rational to do should be the agent’s dispositional desire strengths, as our normative intuitions respond to these