Abraham Lincoln Quotes

Euclid taught me that without assumptions there is no proof. Therefore, in any argument, examine the assumptions.

I am bound to furnish my antagonists with arguments, but not with comprehension.

We cannot ... prove geometrical truths by arithmetic.

The knowledge of the theory of logic has no tendency whatever to make men good reasoners.

Bad reasoning as well as good reasoning is possible; and this fact is the foundation of the practical side of logic.

A philosopher once said, 'Half of good philosophy is good grammar.'

And for mathematical science, he that doubts their certainty hath need of a dose of hellebore.

Whoever in discussion adduces authority uses not intellect but rather memory.

By free-thinking I mean the use of the understanding in endeavoring to find out the meaning of any proposition whatsoever, in considering the nature of the evidence for or against it, and in judging of it according to the seeming force or weakness of the evidence.

[Logic and philosophy] were of no use, in the church or the state, in the cloister or the court, in peace or war, at home or abroad or anywhere but in the schools

Use your logick, and then your rhetorick. Rhetorick without logick, is like a tree with leaves and blossoms, but no root; yet I confess more are taken with rhetorick than logick, because they are catched with a free expression, when they understand not reason. Logick must be natural, or it is worth nothing at all: Your rhetorick figures may be learned.

To convince someone of the truth, it is not enough to state it, but rather one must find the path from error to truth.

Logic can become enormously difficult, and it would undoubtedly be well to produce more assurance in its use.

We cannot infer that because sciences of things divine and human are full of controversies and quarrels, therefore their whole subject-matter is uncertain ; for there have been many persons so enamoured of contradiction, as to turn into ridicule geometrical axioms.

It's really important when we're writing our opinions to be transparent about what our decision method in the case is and how we get from Point A to B to C in the analysis.

I enjoy a good reasoned argument. I love the power of logic.

Facts are not truths; they are not conclusions; they are not even premises, but in the nature and parts of premises.

If someone doesn’t value evidence, what evidence are you going to provide that proves they should value evidence. If someone doesn’t value logic, what logical argument would you invoke to prove they should value logic?

Rhetoric is the counterpart of logic; since both are conversant with subjects of such a nature as it is the business of all to have a certain knowledge of, and which belong to no distinct science. Wherefore all men in some way participate of both; since all, to a certain extent, attempt, as well to sift, as to maintain an argument; as well to defend themselves, as to impeach.

Reason is non-negotiable. Try to argue against it, or to exclude it from some realm of knowledge, and you've already lost the argument, because you're using reason to make your case. ... We don't "believe" in reason.

One cannot refute what one has not thoroughly understood.

Whoever in debate quotes authority uses not intellect, but memory.

Arithmetic is where the content lies, and not logic; but logic prompts certainty, and not arithmetic.

A skeptic, I would ask for consistency first of all.

Logic is the art of convincing us some truth.