This paper develops an account of core criminal terms like ‘murder’ that parallels Williamson’s account of knowledge. It is argued that while murder requires that the murderer killed, and that they did so with a certain state of mind, murder cannot be regarded as the conjunction of these two elements. Rather murder should be seen as a primitive notion, which entails each of them. This explains some of the problems around criminal attempt. Attempted murder cannot be seen simply as involving the state of mind of murder minus success; rather, it has to be seen as a self-standing offence, that of attempting to commit the murder.