Acting on true belief

This paper critically examines Timothy Williamson’s claim that knowledge figures essentially in explanations of behavior. Since this claim implies that knowledge is causally efficacious in bringing about actions, it plays a key role in Williamson’s case for knowledge being a mental state. I first discuss a central example of Williamson, in which a burglar ransacks a house. I dispute Williamson’s claim that the best explanation of the burglar’s behavior invokes the burglar’s state of knowledge as he enters the house, by arguing that there is a better explanation that only mentions the burglar’s beliefs. Since the reasons that explain the superiority of my proposed explanation generalize, I conclude that one does not have to invoke a subject’s state of knowledge to explain behavior. Nevertheless, Williamson’s explanation is superior to belief-based explanations if one only considers facts that obtain before the action takes place. In the final part of the paper, I argue that this fact does not help Williamson’s case for considering knowledge as a mental state.