2 th - century mental causation debates appeal to its physiological antecedents, the full explanatory picture has been completed, leaving no room for a further explanation couched in terms of reasons.13 With Kim’s principle of explanatory realism, Malcolm’s problem of explanatory exclusion becomes the problem of causal exclusion According to this principle, certain structural features of the world (‘truthmakers’) underwrite the correctness and truth of an explanation Thus, the question of whether we can have distinct explanations for a single explanans becomes the question of whether we can have distinct causes of a single effect This is the principle of causal exclusion: Exclusion: If a property F is causally sufficient for a property G, then no property F* distinct from F is causally relevant to G Epiphenomenalism results from applying this principle to the currently popular metaphysics of non-reductive physicalism, which consists of these two theses: Causal Completeness of the Physical: For every physical property P, there is a physical property P* that is causally sufficient for P.14 Irreducibility of the Mental: For every mental property M and physical property P, M is distinct from P.15 According to the irreducibility thesis, your desire to turn on the switch is not reducible to any physical property The subsequent motion of your arm moving towards the switch has a fully sufficient physical cause, according to the causal completeness thesis Since no effect requires more than its sufficient cause, your desire is ‘excluded’ from contributing to your behavior, according to the exclusion principle, rendering your desire epiphenomenal The exclusion principle does not rule out the possibility of overdetermination It is only supposed to cast suspicion on systematic overdetermination For instance, a single case where a person dies because she is both shot in the heart and suffers a brain aneurysm, both of which would have been independently sufficient for her death at exactly the same time is permitted under the principle What is not permitted is when every assassination is also overdetermined by a fatal aneurysm Without something tying the two types of events together, there is no basis for postulating such a cosmically improbable pairing of outcomes Likewise, while it would not strain credulity to think that on a certain occasion, one’s turning on the light switch is caused by the right neurophysiological processes, and independently of those processes, by one’s having the desire to turn on the switch, one certainly would not want to postulate a framework that magically coordinates parallel causation for every instance of mental causation The point of the principle of exclusion is to rule out extensive parallel causation The exclusion problem casts a wide net Its epiphenomenalist conclusion applies not just to mental properties, but to all properties not strictly reducible to 185