5.451

If logic has primitive ideas these must be independent of one another. If a primitive idea is introduced it must be introduced in all contexts in which it occurs at all. One cannot therefore introduce it for one context and then again for another. For example, if denial is introduced, we must understand it in propositions of the form “ ~ p ”, just as in propositions like “ ~ ( p ∨ q ) ”, “ ( ∃ x ) . ~