Practical reasoning is reasoning directed toward decision or action, as contrasted with theoretical reasoning, which is directed toward belief. Deciding to pass your dinner companions the salt instead of the sugar, because you've always meant to find out if they would notice the difference, and now, you realize, is your chance, would be an example of practical reasoning, though not, perhaps, of the best table manners. Since everyone is an agent, everyone has a fairly direct interest in understanding the forms that practical reasoning takes: just as understanding the logic of theoretical reasoning can lead to better arguments and better beliefs, a like grasp of the logic of practical reasoning might improve one's decisions. Moral philosophers, however, have, in addition, a more focused and professional interest in the workings of practical rationality, in virtue of its consequences for systematic ethics.

It should not be surprising that a theory of practical reasoning can have consequences for moral philosophy. Moral reasoning is reasoning about what to do in which specifically moral issues are at stake. Because moral reasoning is practical reasoning, practical reasoning stands (or should stand) to moral theory as process to product. So a moral philosopher's view of practical reasoning is likely to account for many of the deeper structural features of his or her moral theory.

By way of an example, consider instrumentalism, which is still, despite a certain amount of recent dissent, the default view of the subject. The instrumentalist holds that practical reasoning is simply means-end reasoning: that what practical reasoning is for is to figure out how to get whatever it is you happen to want.