The overdetermination problem has long been raised as a challenge to nonreductive physicalism. Nonreductive physicalists have, in various ways, tried to resolve the problem through appeal to counterfactuals. This essay does two things. First, it takes up the question whether counterfactuals can yield an appropriate notion of causal redundancy and argues for a negative answer. Second, it examines how this issue bears on the mental causation debate. In particular, it considers the argument that the overdetermination problem simply does not arise (...) on a dependency conception of causation and shows why this idea, though initially appealing, does not address the real problem. As the essay shows, the idea derives its spurious plausibility from the fact that the dependency conception cannot even make sense of our pretheoretic idea of causal redundancy. The essay concludes by briefly discussing a possible picture of mental causation that suggests itself in light of these results. (shrink)