Anscombe and the difference rationality makes

Anscombe famously argues that to act intentionally is to act under a description, and that “it is the agent's knowledge of what he is doing that gives the descriptions under which what is going on is the execution of an intention.”1 Further, she takes ‘knows’ to mean that the agent can give these descriptions herself.2 Since non-rational animals (hereafter ‘animals’) cannot describe anything, it would seem to follow that animals cannot act intentionally. However, she denies this, insisting that although animals cannot express intentions, they can have them.3 And she speculates that those who have a problem with this assume that the relevant description must “in some sense [be] written into something inside the agent.”4 But this is an odd charge for her to make, given that she herself holds that a human agent can have an intention only if they can express it. In fact, the difficulty surrounding the idea of animal intention is not the result of any facile assumption, but indicative of a genuine philosophical puzzle, one that—if the argument to follow is correct—Anscombe’s approach to action helps us resolve. To resolve it is to understand the difference that rationality makes to intentional action.