§137

'True' and 'false' might be said to fit the concept of a proposition in the sense that 'l' fits 'k' when we remind ourselves of the order of the alphabet. 'True' and 'false' don't fit the concept 'proposition' in the way that one cogwheel fits another. We might discover that one cogwheel fits another but we don't discover that 'l' comes after 'k'.