Quotes About Logic

for it is the mark of an educated man to look for precision in each class of things just so far as the nature of the subject admits; it is evidently equally foolish to accept probable reasoning from a mathematician and to demand from a rhetorician scientific proofs.

For nothing is moved at haphazard, but in every case there must be some reason present [1071b]

Avoid the enthymeme form when you are trying to rouse feeling; for it will either kill the feeling or will itself fall flat: all simultaneous motions tend to cancel each other either completely or partially.

Further, the orator should be able to prove opposites, as in logical arguments;

Now the proofs furnished by the speech are of three kinds. The first depends upon the moral character of the speaker, the second upon putting the hearer into a certain frame of mind, the third upon the speech itself, in so far as it proves or seems to prove. [4]

rhetoric was to be surveyed from the standpoint of philosophy.

since we are most strongly convinced when we suppose anything to have been demonstrated; that rhetorical demonstration is an enthymeme

Dialectic as a whole, or of one of its parts, to consider every kind of syllogism in a similar manner, it is clear that he who is most capable of examining the matter and forms of a syllogism will be in the highest degree a master of rhetorical argument, if to this he adds a knowledge of the subjects with which enthymemes deal and the differences between them and logical syllogisms.

wherefore one who divines well in regard to the truth will also be able to divine well in regard to probabilities. It

not that we should do both (for one ought not to persuade people to do what is wrong), but that the real state of the case may not escape us, and that we ourselves may be able to counteract false arguments, if another makes an unfair use of them.

The smallest number, strictly speaking, is two.

The law is reason unaffected by desire.

a man investigating principles cannot argue with one who denies their existence.

It is plain then that they all in one way or another identify the contraries with the principles. And with good reason. For first principles must not be derived from one another nor from anything else, while everything has to be derived from them. But these conditions are fulfilled by the primary contraries, which are not derived from anything else because they are primary, nor from each other because they are contraries.

But of Reason this too does evidently partake, as we have said: for instance, in the man of self-control it obeys Reason: and perhaps in the man of perfected self-mastery, or the brave man, it is yet more obedient; in them it agrees entirely with the Reason.

And here we must not forget the difference between reasoning from principles, and reasoning to principles:

Art, then, as has been said, is a state concerned with making, involving a true course of reasoning, and lack of art on the contrary is a state concerned with making, involving a false course of reasoning; both are concerned with the variable

I'm not ruthless. It's common sense that's ruthless.

No electronic computer can match the human brain at associating apparently irrelevant facts.

there's something fundamentally wrong with the wiring of our brains, which makes us incapable of consistent logical thinking. To make matters worse, though all creatures need a certain amount of aggressiveness to survive, we seem to have far more than is absolutely necessary. And no other animal tortures its fellows as we do. Is this an evolutionary accident—a piece of genetic bad luck?

there's something fundamentally wrong with the wiring of our brains, which makes us incapable of consistent logical thinking. To make matters worse, though all creatures need a certain amount of aggressiveness to survive, we seem to have far more than is absolutely necessary. And no other animal tortures its fellows as we do.

He might himself be putting on a superb act, following the performance by logic alone and with his own strange emotions completely untouched, as an anthropologist might take part in some primitive rite. The fact that he uttered the appropriate sounds, and made the expected responses, really proved nothing at all.

The hypothesis you refer to as God, though not disprovable by logic alone, is unnecessary for the following reason. "If you assume that the universe can be quote explained unquote as the creation of an entity known as God, he must obviously be of a higher degree of organization than his product. Thus you have more than doubled the size of the original problem, and have taken the first step on a diverging infinite regress.

I'd hate to do arithmetic, George thought to himself, in a system based on fourteen.