4.243 Can we understand two names without knowing whether they signify the same thing or two different things? -- Can we understand a proposition, in which two names occur, without knowing if they mean the same or something different?
If I know the meaning [Bedeutung] of an English word and of a synonymous German word, then it is impossible that I do not know that they are both synonymous; it is impossible that I cannot translate them by each other.
Expressions like “a = a,” or those derived from such expressions, are neither elementary propositions nor otherwise signs with sense [sinnvolle Zeichen]. (This will be shown later.)
Black (p. 211): “The questions are, of course, rhetorical (cf. 5.5303).” What is to be shown later is so, he presumes, at 5.531-5.533.
If Black is right, then the intended answer to the questions posed above seems to be “No.” In the case of Tractarian names this would make sense. But the reference to English words and German words complicates things. Couldn't I know the English name of some mythical creature and the German name of a mythical creature without knowing that they are names of one and the same mythical creature? Not if by Bedeutung we mean what Frege means by it.
I'm not entirely sure what would count as expressions like "a = a". Does "a = b" lack sense? Presumably not, given 4.242.