6.12
The fact that the propositions of logic are tautologies shows the formal—logical—properties of language, of the world. That its constituent parts connected together in this way give a tautology characterizes the logic of its constituent parts. In order that propositions connected together in a definite way may give a tautology they must have definite properties of structure. That they give a tautology when so connected shows therefore that they possess these properties of structure.