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S. Austin Allibone, comp. Prose Quotations from Socrates to Macaulay. 1880.

Logic

Logic differeth from rhetoric as the fist from the palm; the one close, the other at large.

Logic does not pretend to invent science, or the axioms of science.

If a man can play the true logician, and have as well judgment as invention, he may do great matters.

Those who in a logical dispute keep in general terms would hide a fallacy.

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

Sir William Hamilton.

A man knows first, and then he is able to prove syllogistically; so that syllogism comes after knowledge, when a man has no need of it.

I find that laying the intermediate ideas naked in their due order shows the incoherence of the argumentations better than syllogisms.

Reason by its own penetration, where it is strong and exercised, usually sees quicker and clearer without syllogism.

The syllogistical form only shows, that if the intermediate idea agrees with those it is on both sides immediately applied to, then those two remote ones, or, as they are called, extremes, do certainly agree.

A man unskilful in syllogism, at first hearing, could perceive the weakness and inconclusiveness of a long, artificial, and plausible discourse, wherewith some others, better skilled in syllogism, have been misled.

He that will look into many parts of Asia and America will find men reason there perhaps as acutely as himself, who yet never heard of a syllogism.

Syllogism is of necessary use, even to the lovers of truth, to show them the fallacies that are often concealed in florid, witty, or involved discourses.

If ideas and words were distinctly weighed and duly considered, they would afford us another sort of logic and critic than what we have been hitherto acquainted with.

Those that are not men of art, not knowing the true forms of syllogism, cannot know whether they are made in right and conclusive modes and figures.

However it be in knowledge, I may truly say it is of no use at all in probabilities; for the assent there being to be determined by the preponderancy, after a due weighing of all the proofs on both sides, nothing is so unfit to assist the mind in that as syllogism.

General observations drawn from particulars are the jewels of knowledge, comprehending great store in a little room; but they are therefore to be made with the greater care and caution, lest, if we take counterfeit for true, our shame be the greater when our stock comes to a severe scrutiny.

Though they are not self-evident principles, yet what may be made out from them by a wary deduction may be depended upon as certain and infallible truths.

We must own that we entertain the same opinion concerning the study of Logic which Cicero entertained concerning the study of Rhetoric. A man of sense syllogizes in celarent and cesare all day long without suspecting it, and, though he may not know what an ignoratio elenchi is, has no difficulty in exposing it whenever he falls in with it; which is likely to be as often as he falls in with a Reverend Master of Arts nourished on mode and figure in the cloisters of Oxford. Considered merely as an intellectual feat, the Organum of Aristotle can scarcely be admired too highly. But the more we compare individual with individual, school with school, nation with nation, generation with generation, the more do we lean to the opinion that the knowledge of the theory of logic has no tendency whatever to make men good reasoners.

Lord Thomas Babington Macaulay: Lord Bacon, July, 1837.

For me, who only desire to become more wise, not more learned or eloquent, these logical or Aristotelian dispositions of parts are of no use. I would have a man begin with the main proposition; and that wherein the force of the argument lies: I know well enough what death and pleasure are, let no man give himself the trouble to anatomize them to me: I look for good and solid reasons at the first dash to instruct me how to stand the shock, and resist them; to which purpose, neither grammatical subtilties, nor the queint contexture of words and argumentations, are of any use at all: I am for discourses that give the first charge into the heart of the doubt: his [Cicero’s] languish about his subjects, and delay our expectation.

Michel de Montaigne: Essays, Cotton’s 3d ed., ch. lxvii.

Pure logic is a science of the form, or of the formal laws, of thinking, and not of the matter. Applied logic teaches the application of the forms of thinking to those objects about which men do think.

Archbishop William Thomson.

Grammar is the logic of speech, even as logic is the grammar of reason.

Richard C. Trench.

Logic is to teach us the right use of our reason, or intellectual powers.

Dr. Isaac Watts.

Logic helps us to strip off the outward disguise of things, and to behold and judge of them in their own nature.

Dr. Isaac Watts.

It was a saying among the ancients, Truth lies in a well; and, to carry on this metaphor, we may justly say that logic does supply us with steps, whereby we may go down to reach the water.

Dr. Isaac Watts.

Men have endeavoured to transform logic into a kind of mechanism, and to teach boys to syllogize, or frame arguments and refute them, without real knowledge.

Dr. Isaac Watts.

The sense of these propositions is very plain, though logicians might squabble a whole day whether they should rank themselves under negative or affirmative.

Dr. Isaac Watts.

Though the terms of propositions may be complex, yet, where the composition of the argument is plain, the complexion does not belong to the syllogistic form of it.

Dr. Isaac Watts.

Where the respondent limits or distinguishes any proposition, the opponent must prove his own proposition according to that member of the distinction in which the respondent denied it.

Dr. Isaac Watts.

The word abstraction signifies a withdrawing some part of an idea from other parts of it; by which means such abstracted ideas are formed as neither represent anything corporeal or spiritual; that is, anything peculiar or proper to mind or body.

Dr. Isaac Watts.

Abstract terms signify the mode or quality of a being, without any regard to the subject in which it is; as whiteness, roundness, length, breadth, wisdom, mortality, life, death.

Dr. Isaac Watts.

As a science, logic institutes an analysis of the process of the mind in reasoning, and investigates 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. Some are disposed to view logic as a peculiar method of reasoning, and not, as it is, a method of unfolding and analyzing our reason. They have, in short, considered logic as an art of reasoning, whereas (so far as it is an art) it is the art of reasoning; the logician’s object being, not to lay down principles by which one may reason, but by which all must reason, even though they are not distinctly aware of them,—to lay down rules not which may be followed with advantage, but which cannot possibly be deviated from in sound reasoning.

Richard Whately.