First paragraph: Most work in cognitive science and naturalistic philosophy of mind is unashamedly internalist in outlook, in at least the following sense: the parts of the physical world where psychological states occur and where psychological processes happen are held to be located entirely inside the head. One’s first reaction to this sort of internalism about the mind might well be that it must be right. Indeed, given all those wonderful ‘pictures of the brain thinking’ that have been delivered over the past few years by contemporary neuroimaging techniques, where else could the material machinery of mind be? Enter the hypothesis of extended cognition (henceforth ExC). If ExC is true, there are actual (in this world) c...