Syllogism Quotes (8 quotes)
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.
A System of Logic, Ratiocinative and Inductive (1858), 122.
LOGIC, n. The art of thinking and reasoning in strict accordance with the limitations and incapacities of the human misunderstanding. The basic of logic is the syllogism, consisting of a major and a minor premise and a conclusion—thus:
Major Premise: Sixty men can do a piece of work sixty times as quickly as one man.
Minor Premise: One man can dig a post-hole in sixty seconds; therefore—
Conclusion: Sixty men can dig a post-hole in one second.
This may be called the syllogism arithmetical, in which, by combining logic and mathematics, we obtain a double certainty and are twice blessed.
Major Premise: Sixty men can do a piece of work sixty times as quickly as one man.
Minor Premise: One man can dig a post-hole in sixty seconds; therefore—
Conclusion: Sixty men can dig a post-hole in one second.
This may be called the syllogism arithmetical, in which, by combining logic and mathematics, we obtain a double certainty and are twice blessed.
The Collected Works of Ambrose Bierce (1911), Vol. 7, The Devil's Dictionary, 196.
Mathematics … belongs to every inquiry, moral as well as physical. Even the rules of logic, by which it is rigidly bound, could not be deduced without its aid. The laws of argument admit of simple statement, but they must be curiously transposed before they can be applied to the living speech and verified by observation. In its pure and simple form the syllogism cannot be directly compared with all experience, or it would not have required an Aristotle to discover it. It must be transmuted into all the possible shapes in which reasoning loves to clothe itself. The transmutation is the mathematical process in the establishment of the law.
From Memoir (1870) read before the National Academy of Sciences, Washington, printed in 'Linear Associative Algebra', American Journal of Mathematics (1881), 4, 97-98.
Slavery in America was perpetuated not merely by human badness but also by human blindness. … Men convinced themselves that a system that was so economically profitable must be morally justifiable. … Science was commandeered to prove the biological inferiority of the Negro. Even philosophical logic was manipulated [exemplified by] an Aristotlian syllogism:
All men are made in the image of God;
God, as everyone knows, is not a Negro;
Therefore, the Negro is not a man.
All men are made in the image of God;
God, as everyone knows, is not a Negro;
Therefore, the Negro is not a man.
'Love in Action', Strength To Love (1963, 1981), 44.
SYLLOGISM, n. A logical formula consisting of a major and a minor assumption and an inconsequent. (See LOGIC.)
The Collected Works of Ambrose Bierce (1911), Vol. 7, The Devil's Dictionary, 335.
The maxim is, that whatever can be affirmed (or denied) of a class, may be affirmed (or denied) of everything included in the class. This axiom, supposed to be the basis of the syllogistic theory, is termed by logicians the dictum de omni et nullo.
A System of Logic, Ratiocinative and Inductive (1858), 117.
The Syllogism consists of propositions, propositions consist of words, words are symbols of notions. Therefore if the notions themselves (which is the root of the matter) are confused and over-hastily abstracted from the facts, there can be no firmness in the superstructure. Our only hope therefore lies in a true induction.
From Novum Organum (1620), Book 1, Aphorism 14. Translated as The New Organon: Aphorisms Concerning the Interpretation of Nature and the Kingdom of Man), collected in James Spedding, Robert Ellis and Douglas Heath (eds.), The Works of Francis Bacon (1857), Vol. 4, 49.
When someone says “I am thinking, therefore I am, or I exist,” he does not deduce existence from thought by means of a syllogism, but recognises it as something self-evident by a simple intuition of the mind. This is clear from the fact that if he were deducing it by means of a syllogism, he would have to have had previous knowledge of the major premiss 'Everything which thinks is, or exists'; yet in fact he learns it from experiencing in his own case that it is impossible that he should think without existing. It is in the nature of our mind to construct general propositions on the basis of our knowledge of particular ones.
Author's Replies to the Second set of Objections to Meditations on the First Philosophy (1641), in The Philosophical Writings of Descartes (1985), trans. J. Cottingham, R. Stoothoff and D. Murdoch, Vol. 2, 100.
In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion.
(1987) -- 
