Abstract: Given the view urged in Chs. 3 to 5, a bodily motion (say, the rising of someone's arm) can have mental causes distinct from any of its biochemical causes. But effects of mental causes are not overdetermined, in any objectionable way, given a proper understanding of the relevant counterfactuals. A deeper question, stressed by Kim and others, is why the mental supervenes on the physical, if identity theories are false. But supervenience may reflect the nature of possibility: if a ‘possible world’ w1 is physically indiscernible from a possible world w2, then w1 is w2; in which case, w1 is mentally indiscernible from w2. This is a defensible view given by Kripke's, as opposed to Lewis's conception of possibility.

Keywords: counterfactuals, individuation, Kim, Kripke, David Lewis, mental causation, modality, overdetermination, possibility, possible worlds, supervenience,