  Armstrong's central state materialism involved identifying beliefs and desires with states of the brain (1968a). Smart came to agree with this. On the other hand Place resisted the proposal to extend the identity theory to dispositional states such as beliefs and desires. He stressed that we do not have privileged access to our beliefs and desires. Like Ryle he thought of beliefs and desires as to be elucidated by means of hypothetical statements about behaviour and gave the analogy of the horsepower of a car (Place 1967). However he held that the dispute here is not so much about the neural basis of mental states as about the nature of dispositions. His views on dispositions are argued at length in his debate with Armstrong and Martin (Armstrong, Martin and Place, T. Crane (ed.) 1996). Perhaps we can be relaxed about whether mental states such as beliefs and desires are dispositions or are topic neutrally described neurophysiological states and return to what seems to be the more difficult issue of consciousness. Causal identity theories are closely related to Functionalism, to be discussed in the next section. Smart had been wary of the notion of causality in metaphysics believing that it had no place in theoretical physics. However even so he should have admitted it in folk psychology and also in scientific psychology and biology generally, in which physics and chemistry are applied to explain generalisations rather than strict laws. If folk psychology uses the notion of causality, it is no matter if it is what Quine has called second grade discourse, involving the very contextual notions of modality.