 The first argument is (what I will call) The Argument from Causal Closure. The first premise of this argument is the thesis of the Causal Closure of the Physical — that is, the thesis that every event which has a cause has a physical cause. The second premise is that mental events cause physical events — for example we normally think that events such as wanting to raise your arm (a mental event) cause events such as the raising of your arm (a physical event). The third premise of the argument is a principle of causation that is often called the exclusion principle (Kim 1993, Yablo 1992, Bennett 2003). The correct formulation of the exclusion principle is a matter of some controversy but a formulation that is both simple and plausible is the following: