Psychologism is very appealing. For it seems right that when an agent acts for a reason, he acts motivated by an end that he desires (an end towards which he has a “pro-attitude”) and guided by a belief about how to achieve that end. Because of this, it is possible to explain his action by citing his desiring and his believing the relevant things. To return to our example, we can explain why Othello kills Desdemona by citing his wanting to defend his honour and his believing that, given that Des