Book 3
1.54
And again: If man is not an animal, he will be either a stick or a stone. But he is not a stick or a stone; for he is animate and self-moved. Therefore he is an animal. But if he is an animal, and if a dog or an ox is also an animal, then man by being an animal will be a dog and an ox as well. This is the kind of induction which proceeds by contradiction and dispute, and Plato used it, not for laying down positive doctrines but for refutation. The other kind of induction by agreement appears in two forms, the one proving the particular conclusion under discussion from a particular, the other proceeding by way of the universal [by means of particular facts]. The former is suited to rhetoric, the latter to dialectic. For instance, under the first form the question is raised, Did so-and-so commit a murder? The proof is that he was found at the time with stains of blood on him.
