Mental causation and exclusion: why the difference making account of causation is no help

Peter Menzies has developed a novel version of the exclusion principle that he claims to be compatible with the possibility of mental causation. Menzies proposes to frame the exclusion principle in terms of a difference-making account of causation, understood in counterfactual terms. His new exclusion principle appears in two formulations: upwards exclusion — which is the familiar case in which a realizing event causally excludes the event that it realizes — and, more interestingly, downward exclusion, in which an event causally excludes its realizer. This paper shows that one consequence of Menzies’s proposed solution to the problem of mental causation is a ubiquitous violation of the principle of closure — a fact that forces him into a trilemma to which we see no satisfactory response.