4.464 The truth of tautology is certain, of propositions possible, of contradiction impossible.
(Certain, possible, impossible: here we have an indication of the gradation we need in the theory of probability.)
It’s dodgy though, isn’t it? The certain must belong to the class of the possible, surely, not be a separate class from it.
No article before “tautology” or “contradiction” here, or in 4.463, as per Wittgenstein’s wishes in Letters to