If Descartes is prepared to attribute a range of cognitive and affective states to animals, including some kind of reasoning processes, even if unconscious ones, the problem is less that he makes animals into mere machines, but rather that animal faculties are capable of so much that the line between animals and human beings becomes blurred. Could not the account of animal faculties be extended into the explanation of human behaviour? La Mettrie's Cartesian-inspired doctrine of ‘man machine’ may have been the only significant positive construal along these lines, but the opprobrium that Descartes' doctrine of the ‘animal machine’ attracted over more than two centuries was not due to the fact that his critics were animal lovers who thought him unfair to animals, but to the fact that the sharp distinction between animals and humans seemed to have been compromised. In fact, in Descartes' view, the gulf was as wide as ever, and indeed it rested on the very traditional basis of human beings being unique in having the faculty of free will, although, when it came to the detail, what Descartes had to offer on the question of what made human beings different from animals was a novel and uncompromising theory about the unity of one's mental life, for it is this unity that ultimately supplies the possibility of moral responsibility, something that is lacking in animals.

There is, nevertheless, something distinctive about human cognitive states that marks them out from the cognitive states of automata.