Philosophical Logic Quotes

Aristotle can be regarded as the father of logic. But his logic is too scholastic, full of subtleties, and fundamentally has not been of much value to the human understanding. It is a dialectic and an organon for the art of disputation.

Eventually, Aristotle appeared among the Greeks. He improved the methods of logic and systematized its problems and details. He assigned to logic its proper place as the first philosophical discipline and the introduction to philosophy. Therefore he is called the First Teacher.

Neither Aristotelian nor Russellian rules give the exact logic of any expression of ordinary language; for ordinary language has no exact logic.

Formal logic is mathematics, and there are philosophers like Wittgenstein that are very mathematical, but what they're really doing is mathematics - it's not talking about things that have affected computer science; it's mathematical logic.

The true function of logic ... as applied to matters of experience ... is analytic rather than constructive; taken a priori, it shows the possibility of hitherto unsuspected alternatives more often than the impossibility of alternatives which seemed prima facie possible. Thus, while it liberates imagination as to what the world may be, it refuses to legislate as to what the world is

...logical validity is not a guarantee of truth.

I am God. So it’s easy to play him. They say God is in all things. So if God is in me, then I am in God. Therefore, I am God. God does not exist without me.

There is no exception to the rule that every rule has an exception.

Every philosophical problem, when it is subjected to the necessary analysis and justification, is found either to be not really philosophical at all, or else to be, in the sense in which we are using the word, logical.

Logic is not a body of doctrine, but a mirror-image of the world. Logic is transcendental.

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.

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

Frege has the merit of ... finding a third assertion by recognising the world of logic which is neither mental nor physical.

I've always felt like we're all human beings and we're all basically given the tools to make whatever choices we want to make. How we treat other people. How we treat ourselves. Just the whole philosophy of that and the philosophical logic of that is that we're all capable of great acts of evil, and we're all capable of great acts of good.

If truth doesn't exist, then it would be true that truth doesn't exist, and once again we arrive at truth. There is no alternative; truth must exist.

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.

The so-called law of induction cannot possibly be a law of logic, since it is obviously a proposition with a sense.--Nor, therefore, can it be an a priori law.

Reason is just as cunning as she is powerful. Her cunning consists principally in her mediating activity, which, by causing objects to act and re-act on each other in accordance with their own nature, in this way, without any direct interference in the process, carries out reason's intentions.

There are also two kinds of truths: truth of reasoning and truths of fact. Truths of reasoning are necessary and their opposite is impossible; those of fact are contingent and their opposite is possible.

The logic of the world is prior to all truth and falsehood.

In it he proves that all things are true and states how the truths of all contradictions may be reconciled physically, such as for example that white is black and black is white; that one can be and not be at the same time; that there can be hills without valleys; that nothingness is something and that everything, which is, is not. But take note that he proves all these unheard-of paradoxes without any fallacious or sophistical reasoning.

The Occultists, however, know that the traditions of Esoteric Philosophy must be the right ones, simply because they are the most logical, and reconcile every difficulty.

There are also two kinds of truths, those of reasoning and those of fact. Truths of reasoning are necessary and their opposite is impossible, and those of fact are contingent and their opposite is possible. When a truth is necessary its reason can be found by analysis, resolving it into more simple ideas and truths until we reach those which are primitive.

In [Aristotle's] formal logic, thought is organized in a manner very different from that of the Platonic dialogue. In this formal logic, thought is indifferent toward its objects. Whether they are mental or physical, whether they pertain to society or to nature, they become subject to the same general laws of organization, calculation, and conclusion - but they do so as fungible signs or symbols, in abstraction from their particular "substance." This general quality (quantitative quality) is the precondition of law and order - in logic as well as in society - the price of universal control.