Abstract

Hume's theory of practical rationality, it has been claimed, fails to account for the intrinsically social character of practical deliberation and of the norms governing action. While the standard way of pressing this critique is unsuccessful, it can be advanced in another way. It is alleged that Hume cannot explain how it is possible to act contrary to reason because he holds that practical reasons are grounded in brute desires which are beyond the reach of rational criticism. But Hume offers a rich explanation of practical irrationality. To show that Hume's theory of practical reason is too individualistic, a problem in his account of theoretical reason must first be appreciated. Hume thinks that rational agents should only trust in testimony about matters of fact when that trust can be reductively justified on the basis of their own observations. Such a stringently individualistic criterion would shrink the scope of human knowledge beyond recognition. Similarly, Hume thinks that rational agents should only trust advice---testimony about what is valuable or desirable---when that trust can be instrumentally justified in terms of their own antecedent values or desires. Individuals bound by this criterion would be unable to deliberate rationally when faced with novel and challenging circumstances. Humean theories must treat trust in advice as default justified if this problem is to be avoided.