More on Wittgenstein, continuing the line started last month. Read it if you're interested.
The account of propositions as a kind of expression repeats and deepens the lacuna in the picture theory (its omission of display and perception of logical pictures). The proposition is an expression of a thought, which is in turn a "logical picture" by which we "picture to ourselves" the facts which make up the world. First of all there is the fact, or, as far as thought with logical form is concerned, it might be better to say the elementary binary node of possibility. This node is what we picture to ourselves and determine positively or negatively. The binary node of possibility which is one point in the world appears to us in our picturing it to ourselves in logical space. The world is not a logical picture but finds expression in one, and this is what it means for a logical picture to be "of" facts.
Now the words "node," "point," "appears," "picturing," and "space" above all seem to be metaphors transferring the material of the senses into the structure of thinking. On the basis of this metaphoricity, it would be necessary to qualify also the statement that the world finds "expression" in thought (Such an analysis would be in accord with the traditional interpretation of intellectual perception as a metaphor). However, to posit a metaphysical rift between sense and thinking will make it impossible to explain how it is that the expression of a thought "can be perceived by the senses" in a proposition.
The thought may be a picture but does the thought then think itself? (Does a picture perceive itself and display itself?) We cannot neglect this question by chalking it up to the penumbras of the metaphoricity of "logical pictures," as though we were looking for a correlative in thinking to the production and reception of pictures only because we had been deceived by the metaphor into expecting everything to be the same "over there" in thinking as it is "over here" in sensing. Rather, it is the very gap in correspondence between sense and thinking which requires us to ask about the thinking of a thought. We can be satisfied, at first, with the substantial existence of sensible pictures. A thought, however, is not already "out there" but comes about simultaneously with the thinking of it. The phrase "picture...to ourselves" nicely reproduces the ambiguity of "machen uns Bilder," which in good usage means that we get an idea of something, but taken word for word also attributes the production of ideas to us as simultaneous with our receiving them. Wittgenstein's usage here points to a critical difference in the nature of a thought and the nature of a picture; the latter is produced and subsequently received, and stands in the meantime waiting in the world, ready to be seen.
The picture-theory of the Tractatus persistently treats the logical picture as though it were something substantial--that is, perduring in a meantime between production and perception, and says nothing about what it means to see a logical picture, or to display it. These, however, are the real moments of thinking, of which "the thought" is a fleeting shadow. What thinking is, then, remains fundamentally unclear in the Tractatus, and this leads to a deeper unclarity in what seems clearest: the senses. Here it must be admitted that we have no clear way of discerning whether the static interpretation of thought is responsible for the static interpretation of the proposition, or the other way around. At any rate, that an expression of a thought can be perceived by the senses proves that the senses no more receive a ready object than does thinking. Thinking must already somehow have a hand in saying and hearing for perception of a proposition to come about.