The Notion of a Proposition

It was argued in the third section of Chapter Two that belief-states must be assumed to have an internal complexity, a complexity corresponding to the content of the proposition believed. Thoughts, at least in the narrow sense which we have given to the term, also involve propositions, and so must also be credited with an internal complexity. Hence, if we wish to cast light on the nature of belief (and thought), it seems important to understand what propositions are, and in what way they enter beliefs and thoughts.

The notion of a proposition seems forced upon us when we consider beliefs, thoughts and also assertions.

It is clear that different people may all believe the same thing. Suppose, for instance, that nine men believe that the earth is flat. We have nine different beliefs. There is A's belief, B's belief, C's belief… If what we have said about belief already is correct, then there are nine numerically different states. (Whether these states are to be conceived of as purely physical states of the brain, or as states of a spiritual substance, or in some other way, is not at issue here.)

However, we distinguish between a man's belief-state and the thing he believes: between the believing and what is believed: between the state of affairs Bap and p. In the case of the nine men, what is believed is the same thing in each case: that the earth is flat.