5.551 Our fundamental principle is that every question that can be decided at all with logic must be decidable without anything else.

(And if we get into a state of things where we need to answer such a problem by looking at the world, then this shows that we are on a fundamentally wrong track.)

Exactly! Logic is logic, not metaphysics.

Black notes (p. 303) that Wittgenstein got onto precisely this “wrong track” in his remarks on logical form. “This must be regarded as a temporary aberration, which he later repudiated,” according to Black.