Common sense supposes thoughts can cause bodily movements and thereby bring about changes in where the agent is or how his surroundings are. Many philosophers suppose that any such outcome is realized in a complex state of affairs involving only microparticles; that previous microphysical developments were sufficient to cause that state of affairs; hence that, barring overdetermination, causation by the mental is excluded. This paper argues that the microphysical swarm that realizes the outcome is an accident (Aristotle) or a coincidence (...) (David Owens) and has no cause, though each component movement in it has one. Mental causation faces no competition “from below”. (shrink)