Kitap 11
4
Now those who intend to join in discussion must understand one another to some extent; for without this how can there be any common discussion between them? Therefore each of the terms which they use must be intelligible and signify something; not several things, but one only; or if it signifies more than one thing, it must be made clear to which of these the term is applied.
5
Now he who says that A is and is not denies what he asserts, and therefore denies that the term signifies what it does signify. But this is impossible. Therefore if to be so-and-so has a definite meaning, the opposite statement about the same subject cannot be true.
6
Again, if the term has a definite significance and this is truly stated, it must of necessity be so.sect. 6=Aristot. Met. 4.4.14-16. But that which of necessity is can never not be. Hence opposite statements about the same subject cannot be true.
6
Again, if the assertion is no more true than the negation, it will be no more true to say A is man than to say A is not man. With this section cf. Aristot. Met. 4.4.26-30.
7
But it would also be admitted that it is more or at least not less true to say that a man is not a horse than to say that he is not a man; and therefore, since it was assumed that opposite statements are equally true, it will be true to say that the same person is also a horse. It follows therefore, that the same person is a man and a horse, or any other animal.
