Arthur Conan Doyle Quotes

SYLLOGISM, n. A logical formula consisting of a major and a minor assumption and an inconsequent.

Contrariwise, if it was so, it might be; and if it were so, it would be; but as it isn't, it ain't. That's logic.

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

Logic: The art of thinking and reasoning in strict accordance with the limitations and incapacities of the human misunderstanding.

Reasoning draws a conclusion, but does not make the conclusion certain, unless the mind discovers it by the path of experience.

It is true the orator may make a myriad replica of his own passion out of those who listen to him. But that does not prove he is right or they are not fools.

Logic is like the sword - those who appeal to it, shall perish by it.

You should carefully study the Art of Reasoning, as it is what most people are very deficient in, and I know few things more disagreeable than to argue, or even converse with a man who has no idea of inductive and deductive philosophy.

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

To reason logically is so to link one's propositions that each should contain the reason for the one succeeding it, and should itself be demonstrated by the one preceding it. Or at any rate, whatever the order adopted in the construction of one's own exposition, it is to demonstrate judgments by each other.

It must be granted that in every syllogism, considered as an argument to prove the conclusion, there is a petitio principii. When we say, All men are mortal Socrates is a man therefore Socrates is mortal; it is unanswerably urged by the adversaries of the syllogistic theory, that the proposition, Socrates is mortal.

When you get me a good man made out of arguments, I will get you a good dinner with reading you the cookery book.

Before anything can be reasoned upon to a conclusion, certain facts, principles, or data, to reason from, must be established, admitted, or denied.

Logic is the art of convincing us some truth.

Logic is the art of going wrong with confidence.

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 bad; but in order that the bearing of the case may not escape us, and that when another makes an unfair use of these reasonings, we may be able to solve them.

If the reason I give is a good one, you will act upon it. If it is a bad one I cannot make it better by piling epithet upon epithet. There is no logic in abuse; there is no argument in an epithet.

Inference is always an invasion of the unknown, a leap from the known.

To admit one's own presuppositions and to point out the presuppositions of others is therefore to maintain that all reasoning is, in the nature of the case, circular reasoning. The starting-point, the method, and the conclusion are always involved in one another.

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

That's the way most everyone gets here. It's really quite simple: every time you decide something without having a good reason, you jump to Conclusions whether you like it or not. It's such an easy trip to make that I've been here hundreds of times.

But Carroll's were more convoluted, and they struck me as funny in a new way: 1) Babies are illogical. 2) Nobody is despised who can manage a crocodile. 3) Illogical persons are despised. Therefore, babies cannot manage crocodiles. And: 1) No interesting poems are unpopular among people of real taste. 2) No modern poetry is free from affectation. 3) All of your poems are on the subject of soap bubbles. 4) No affected poetry is popular among people of taste. 5) Only a modern poem would be on the subject of soap bubbles. Therefore, all your poems are uninteresting.

Analogy cannot serve as proof.

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.

In every chain of reasoning, the evidence of the last conclusion can be no greater than that of the weakest link of the chain, whatever may be the strength of the rest.