Aristotle is often credited with views about practical reasoning, desire, and action collectively referred to as the theory of the practical syllogism.Some commentators are skeptical about the existence of any such general theory, but most would agree that a theory of some sort is outlined in the De Motu Animalium and that it influences Aristotle’s account of akrasia in the icomachean Ethics.This paper will begin by describing the most important ideas in the De Motu Animalium discussion of the practical syllogism. (...) The ideas are simple but I think that their implications and philosophical importance have not been appreciated. I will suggest that the practical syllogism is Aristotle’s model for the rational explanation of action. Other commentators have made this claim, but I think that it can be given a very precise sense. Aristotle thinks that an action can be rationally explained if the agent acts in response to the strength of the reasons that he sees for acting. The practical syllogism is an argument that expresses the reasons in favor of the action, so if the agent acts for those reasons the action is explained by the practical syllogism. The second part of the paper considers the work that the practical syllogism does in Aristotle’s account of akrasia. I will argue that in akrasia—at least in the most extreme kind of akrasia—the agent acts intentionally to satisfy a desire but the action cannot be explained by a practical syllogism. Aristotle distinguishes between explanation by the motivational strength of desires and explanation by a practical syllogism. The last part of this paper comments on David Charles’s interpretation of Aristotle’s views about desire, practical reason, and akrasia. Charles discusses the traditionally disputed questions in a provocative way, and more importantly his suggestions fit together into a complex and philosophically sophisticated reading of Aristotle. I disagree with his most important claims, but I can best explain and defend my own interpretation by contrasting it with his. (shrink)