Reply to Haldane 157the football. Contexts such as ‘Joe believes that.. .’ and ‘Joe desires that.. .’
are examples of intensional contexts. We can get round the difficulty roughly
by saying with Quine ‘Joe believes-true S’ where S might be the sentence ‘The
head of the philosophy department is the dean of the faculty of arts’.^11 This
sentence is certainly different from the tautologous sentence ‘The head of the
philosophy department is the head of the philosophy department’. And we
could say ‘Joe wants-true of himself “possesses a unicorn” ’.^12 ‘Wants-true of
himself ’ signifies a relation between Joe and a predicate. Sentences and pre-
dicates certainly exist. We can of course say this whether or not Joe knows
English, and we can talk in this way even of the beliefs and desires of cats.
The sentence just serves vaguely to single out a belief or desire, a mental
state, and in my opinion a brain state. (If someone prefers to think of beliefs
and desires as functional states which are multiply realized by brain states,
I can agree without compromising my materialism. Incidentally ‘functional’
here is more like ‘function’ in mathematics: it is not a teleological notion.)
The development of this sort of approach in a sophisticated way would go
beyond the confines of the present book, but the general approach suggests
how it can remove some mystery from both intensionality (with an ‘s’) and
consequently ‘intentionality’ (with a ‘t’).^13
Thus when I use the word ‘unicorn’ I do not refer to a unicorn because
there are no unicorns to be referred to. ‘Cat’ refers to the set of cats, past,
present and future. It does not refer to counterfactual cats because there
are no such. I here differ from David Lewis^14 who has a realistic theory
of possible worlds other than the actual world. I deal with counterfactuals
in a different way, following Quine.^15 ‘If it had been the case that p then
it would have been the case that q’ said by me to you is true relative to
me, you and the context if and only if qfollows by first order logic from p
together with contextually agreed background assumptions. Because counter-
factuals have this contextual and relativist character they are to be avoided,
where possible, in science and metaphysics. Thus I disagree with Haldane
when he speaks of future and counterfactual cats (see p. 106). I believe in
future cats (there they are up ahead of us in space–time) but not in counter-
factual cats.
3 Consciousness
Consciousness may be thought to provide a particular difficulty for a physicalist
philosophy of mind. I concede that there seems to be something mysterious
about the fact of consciousness, as if some strange supernatural light was lit
up in our minds. I hold that all the properties of immediate experience are
‘topic neutral’ ones, neutral between materialism and mind–body dualism.