logical principles Quotes

Logic is an old subject, and since 1879 it has been a great one.

Logic is the science of the laws of thought, as thought,--that is of the necessary conditions to which thought considered in itself is a subject.

Our reasonings are grounded upon two great principles, that of contradiction, in virtue of which we judge false that which involves a contradiction, and true that which is opposed or contradictory to the false.

Since at least the Middle Ages, philosophers and philologists have dreamed of curing natural languages of their flaws by constructing entirely new idioms according to orderly, logical principles.

As a science, logic institutes an analysis of the process of the mind in reasoning, and investigating the principles on which argumentation is conducted; as an art, it furnishes such rules as may be derived from those principles, for guarding against erroneous deductions.

The true function of philosophy is to educate us in the principles of reasoning and not to put an end to further reasoning by the introduction of fixed conclusions.

Certain characteristics of the subject are clear. To begin with, we do not in this subject deal with particular things or particular properties: we deal formally with what can be said about any thing or any property. We are prepared to say that one and one are two, but not that Socrates and Plato are two.

... the laws of physics and of logic ... the number system ... the principle of algebraic substitution. These are ghosts. We just believe in them so thoroughly they seem real.

The principle of contradiction establishes merely the agreement of concepts, but does not itself produce concepts.

you are never called upon to prove a negative. that's a law of logic.

True to her inveterate habit, rationalism reverts to 'principles,' and thinks that when an abstraction once is named, we own an oracular solution.

I am opposed to looking upon logic as a kind of game. ... One might think that it is a matter of choice or convention which logic one adopts. I disagree with this view.