Most theories of rationality take it for granted that rationality is always a matter of conformity to certain principles, or responding to reasons. I argue that (non-trivial) principles of rationality cannot fully capture the nature of our instrumentally rational powers. A full theory of rationality must also make room for what I call “instrumental virtues”. An agent suffers a defect of rationality insofar as she fails to have one of these virtues, or insofar as she manifests one of its corresponding vices. However, an agent can manifest instrumental vices without failing to conform to any principle of rationality. I argue that the virtue of courage is a paradigmatic instance of such a virtue.