logic Quotes

To say of what is that it is not, or of what is not that it is, is false, while to say of what is that it is, and of what is not that it is not, is true.

If then it be possible that one contrary should exist, or be called into existence, the other contrary will also appear to be possible.

Persuasion is clearly a kind of proof, because we are most convinced when we feel something has been proven.

Now all orators effect their demonstrative proofs by allegation either of enthymems or examples, and, besides these, in no other way whatever.

Finally, if nothing can be truly asserted, even the following claim would be false, the claim that there is no true assertion.

In inventing a model we may assume what we wish, but should avoid impossibilities.

Accordingly, the poet should prefer probable impossibilities to improbable possibilities. The tragic plot must not be composed of irrational parts.

It is a part of probability that many improbable things will happen.

We ought to be able to persuade on opposite sides of a question; as also we ought in the case of arguing by syllogism: not that we should practice both, for it is not right to persuade to what is... ...

A statement is convincing and believable either because it's obviously true or because it seems proven by other statements that are true.

The arousing of prejudice, pity, anger, and similar emotions has nothing to do with the essential facts, but is merely a personal appeal to the man who is judging the case.

"There is no logical way to the discovery of these elemental laws. There is only the way of intuition, which is helped by a feeling for the order lying behind the appearance."