  Construing attributions of belief as statements of attitudes towards sentences gives them a syntax and an ontology that Quine can accept. That does not, however, show that the idiom “A believes that p” satisfies his physicalistic criterion, i.e. that all statements of this form correspond to (physical) facts. The matter is complicated. Quine certainly accepts that most uses of this idiom are factual. The relevant facts are neurophysiological states of the person concerned, and those states are causally connected with actions which the person performs, or would perform under certain circumstances, and which we would count as manifestations of the belief, or lack of belief. (Assenting or dissenting when asked is one such action, but only one among a myriad.) In cases where we have evidence for or against the ascription of a belief to someone, the evidence consists in behaviour and there are presumably neurophysiological states which explain the behaviour. Those states are not in practice specifiable in neurophysiological terms. Nevertheless, the person’s being in those states is the physical fact in which the truth of the ascription consists. Even where there is no behaviour of the relevant kind, there may still be dispositions to behave in those ways under certain unrealized circumstances. The dispositions are the physical states in which the truth of the ascription consists. So in most cases where we ascribe belief, there is a fact of the matter which makes the ascription true or false. (More on dispositions a few paragraphs hence.)