which philosophers used to consider essential for the philosophy of logic. But it has the great advantage of excluding any psychological investigations, which belong to the province of psychology. All that is presupposed by the study of logic is that names have meanings and propositions sense. Just as it is not the business of the philosopher of logic to give us examples of elementary propositions, since this is a matter of the application of logic (TLP 5.557-5.5571)—which Wittgenstein deferred until the abortive 'Some Remarks on Logical Form' of 1929—so too it is not the business of the philosopher of logic to investigate the nature of psychological processes. But the Tractatus Logico-Philosophicus, the Logisch-philosophische Abhandlung, is a treatise on logic. That is why Wittgenstein could be so insouciant in replying to Russell 'I don't know what the constituents of a thought are but I know that it must have constituents which correspond to the words of Language. Again the kind of relation of the constituents of the thought and of the pictured fact is irrelevant. It would be a matter of psychology to find out' (NB 129). The psychological processes of thinking, meaning, and understanding do indeed underpin the use of language, but they are of no concern to logic.
In MS 165, 9-11, probably composed in 1944, Wittgenstein wrote:
Doesn't the sentence have a sense because I am conscious and I mean it? (And, of course, I can't mean a senseless combination of words.) And this meaning is, of course, something mental. And it is something private. It is the elusive object.
What happens when I mean a sentence? I say, e.g. 'I don't feel very well', and mean it. But it can't actually be like that; for can't I mean the sentence even though it is a lie? I would, when I mean it, e.g. pull a face corresponding to the sense. But we can suppose that it is true, and then the meaning seems like an arrow or arrows, which point at something from the sentence. What a strange phenomenon this is (almost like a fever // like a dream in a fever //).
Here too, I think, there is little doubt that the dream is a dream that Wittgenstein himself had dreamt and it had left its mark upon the Tractatus. But by the time he wrote the above passage, of course, he had long cured himself of the fever that had once beset him, and adumbrated a host of prophylactic arguments. It is sad that the very same fever still rages among philosophers, who hypothesize a language of thought in order to explain the learning of a language and the nature of thought, belief, and judgement.
The interpretation of the Tractatus given in the above article was criticized by Professor Cora Diamond in a lecture she delivered at the