 Many philosophers think that agent-causation is either incoherent or impossible, due to considerations about causation. What sense does it make to say that a person, as opposed to a change in a person, or the state of a person at a time, is a cause? (Bok 1998). (See also Clarke 2003 for a detailed and sympathetic examination of the metaphysics of agent-causation, which ends with the conclusion that there are, on balance, reasons to think that agent-causation is impossible.)