This paper offers an interpretation of Jaegwon Kim’s “Causal Exclusion” and “Causal Inheritance” arguments for reductionism about special science properties, and defends these arguments against standard “compatibilist” responses on behalf of nonreductive physicalism. I interpret Kim’s arguments as relying on an implicit account of causal efficacy of properties. Understood in this way, I argue, compatibilist responses deny Kim’s account of efficacy, and propose weaker accounts which can be satisfied by special science properties. But in weakening Kim’s account of efficacy, I argue, compatibilist views threaten to count nonsupervenient dualist qualia as efficacious, or at least to have no good reason not to. I pose a challenge for these views: why should it be necessary for a property to be efficacious that it is metaphysically necessitated by physical properties? I argue that compatibilist views have no good answer. Then I argue that at least at present, Kim’s overall argument appears to be the only good argument for physicalism itself. In the absence of an answer to my challenge, the compatibilist cannot offer this argument for physicalism. The more general challenge for nonreductive physicalism is to find a principled middle ground between dualism and reductive physicalism. My overall conclusion is that the compatibilist response does not answer this general challenge: it blocks the argument for reductive physicalism only by giving up on the argument for physicalism itself.