Abelard makes another leap forward when it comes to the question of negating a proposition. For Boethius, the negation of the proposition “A giraffe is in the kitchen cooking dinner” would be “A giraffe is not in the kitchen cooking dinner.” Which looks reasonable enough, and not just because giraffes are notoriously bad cooks. But it has a disadvantage. In stating this denial I seem to be saying something about a certain giraffe, namely that she is not cooking dinner. But what if I wanted to deny the proposition without talking about any giraffe at all? Abelard gives
