SARTRE'S BEING AND NOTHINGNESS
account from which it follows that thirst 'as an organic phe nomenon, as a "physiological" need of water, does not exist' (87/130). In §41 we will see in more detail what this involves. A full survey of the topics in the philosophy of mind approached in this manner by Sartre would be extensive. In the previous chapter we mentioned Sartre's early treatments of imagination and emotion. Sartre also mounts, we will see in §37, a critical challenge to the concept of character, or at any rate to its putative empirical explanatory employment. In the chap ter on the body, Sartre discusses at length the psychological conception of sensory experience and concept of sensation (310-20/372-83). Regarding action and its explanation, we will see (§32) that Sartre argues in Part Four in the context of his theory of freedom that psychological causal determination is strictly inconceivable, and later this is followed by a critique of the attempt to explain individuals in terms of psychological laws (§34). It is notable, therefore, and important for the strength of his case, that Sartre takes the trouble to argue in two direc tions - both down from metaphysics to ordinary concepts of the mental, and upwards from a critique of these to his meta physics - and both directions need to be taken account of in assessing Sartre's position. It is often observed that elements in Sartre's view of the men tal agree strikingly with many of Wittgenstein's observations regarding the logical peculiarities or distinctive 'grammar' of mental concepts. But in pursuing this comparison the difference should not be lost sight of that, in Sartre's view, the grounds of the grammar must be rediscovered in the phenomena, and that Sartre considers that nothing short of a metaphysical system can provide the therapy which Wittgenstein thinks we stand in philosophical need of. In part this is because Sartre regards our need for existential transformation as much greater than Wittgenstein supposes it to be, but it is also because, according to Sartre, mental phenomena make sense only if their subject is grasped as having the strange metaphysical form of non-self identity which Part Two has attempted to bring to light, and this form in turn makes sense, Sartre believes, only on the basis of his metaphysics of nothingness. 1 20