Front Page Titles (by Subject) CHAPTER VI.: Reflections on the Utility of Logic, and the Means of its improvement. - Sketches of the History of Man, vol. 3
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CHAPTER VI.: Reflections on the Utility of Logic, and the Means of its improvement. - Henry Home, Lord Kames, Sketches of the History of Man, vol. 3 
Sketches of the History of Man Considerably enlarged by the last additions and corrections of the author, edited and with an Introduction by James A. Harris (Indianapolis: Liberty Fund, 2007). 3 Vols. Vol. 3.
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Reflections on the Utility of Logic, and the Means of its improvement.
Of the Utility of Logic.
Men rarely leave one extreme without running into the contrary. It is no wonder, therefore, that the excessive admiration of Aristotle, which continued for so many ages, should end in an undue contempt; and that the high esteem of logic as the grand engine of science, should at last make way for too unfavourable an opinion, which seems now prevalent, of its being unworthy of a place in a liberal education. Those who think according to the fashion, as the greatest part of men do, will be as prone to go into this extreme, as their grandfathers were to go into the contrary.
Laying aside prejudice, whether fashionable or unfashionable, let us consider whether logic is, or may be made, subservient to any good purpose. Its professed end is, to teach men to think, to judge, and to reason, with precision and accuracy. No man will say that this is a matter of no importance; the only thing therefore that admits of doubt, is, whether it can be taught.
To resolve this doubt, it may be observed, that our rational faculty is the gift of God, given to men in very different measure. Some have a large portion, some a less; and where there is a remarkable defect of the natural power, it cannot be supplied by any culture. But this natural power, even where it is the strongest, may lie dead for want of the means of improvement: a savage may have been born with as good faculties as a Bacon or a Newton: but his talent was buried, being never put to use; while theirs was cultivated to the best advantage.
It may likewise be observed, that the chief mean of improving our rational power, is the vigorous exercise of it, in various ways and in different subjects, by which the habit is acquired of exercising it properly. Without such exercise, and good sense over and above, a man who has studied logic all his life, may after all be only a petulant wrangler, without true judgement or skill of reasoning in any science.
I take this to be Locke’s meaning, when in his Thoughts on Education he says, “If you would have your son to reason well, let him read Chillingworth.” The state of things is much altered since Locke wrote. Logic has been much improved, chiefly by his writings; and yet much less stress is laid upon it, and less time consumed in it. His counsel, therefore, was judicious and seasonable; to wit, That the improvement of our reasoning power is to be expected much more from an intimate acquaintance with the authors who reason the best, than from studying voluminous systems of logic. But if he had meant, that the study of logic was of no use nor deserved any attention, he surely would not have taken the pains to have made so considerable an addition to it, by his Essay on the Human Understanding, and by his Thoughts on the Conduct of the Understanding. Nor would he have remitted his pupil to Chillingworth, the acutest logician as well as the best reasoner of his age; and one who, in innumerable places of his excellent book, without pedantry even in that pedantic age, makes the happiest application of the rules of logic, for unravelling the sophistical reasoning of his antagonist.
Our reasoning power makes no appearance in infancy; but as we grow up, it unfolds itself by degrees, like the bud of a tree. When a child first draws an inference, or perceives the force of an inference drawn by another, we may call this the birth of his reason: but it is yet like a new-born babe, weak and tender; it must be cherished, carried in arms, and have food of easy digestion, till it gather strength.
I believe no man remembers the birth of his reason: but it is probable that his decisions are at first weak and wavering; and, compared with that steady conviction which he acquires in ripe years, are like the dawn of the morning compared with noon-day. We see that the reason of children yields to authority, as a reed to the wind; nay, that it clings to it, and leans upon it, as if conscious of its own weakness.
When reason acquires such strength as to stand on its own bottom, without the aid of authority or even in opposition to authority, this may be called its manly age. But in most men, it hardly ever arrives at this period. Many, by their situation in life, have not the opportunity of cultivating their rational powers. Many, from the habit they have acquired of submitting their opinions to the authority of others, or from some other principle which operates more powerfully than the love of truth, suffer their judgement to be carried along to the end of their days, either by the authority of a leader, or of a party, or of the multitude, or by their own passions. Such persons, however learned, however acute, may be said to be all their days children in understanding. They reason, they dispute, and perhaps write: but it is not that they may find the truth; but that they may defend opinions which have descended to them by inheritance, or into which they have fallen by accident, or been led by affection.
I agree with Mr. Locke, that there is no study better fitted to exercise and strengthen the reasoning powers, than that of the mathematical sciences; for two reasons; first, Because there is no other branch of science which gives such scope to long and accurate trains of reasoning; and, secondly, Because in mathematics there is no room for authority, nor for prejudice of any kind, which may give a false bias to the judgement.
When a youth of moderate parts begins to study Euclid, every thing at first is new to him. His apprehension is unsteady: his judgement is feeble; and rests partly upon the evidence of the thing, and partly upon the authority of his teacher. But every time he goes over the definitions, the axioms, the elementary propositions, more light breaks in upon him: the language becomes familiar, and conveys clear and steady conceptions: the judgement is confirmed: he begins to see what demonstration is; and it is impossible to see it without being charmed with it. He perceives it to be a kind of evidence that has no need of authority to strengthen it. He finds himself emancipated from that bondage; and exults so much in this new state of independence, that he spurns at authority, and would have demonstration for every thing; until experience teaches him, that this is a kind of evidence that cannot be had in most things; and that in his most important concerns, he must rest contented with probability.
As he goes on in mathematics, the road of demonstration becomes smooth and easy: he can walk in it firmly, and take wider steps: and at last he acquires the habit, not only of understanding a demonstration, but of discovering and demonstrating mathematical truths.
Thus, a man, without rules of logic, may acquire a habit of reasoning justly in mathematics; and, I believe, he may, by like means, acquire a habit of reasoning justly in mechanics, in jurisprudence, in politics, or in any other science. Good sense, good examples, and assiduous exercise, may bring a man to reason justly and acutely in his own profession, without rules.
But if any man think, that from this concession he may infer the inutility of logic, he betrays a great want of that art by this inference: for it is no better reasoning than this, That because a man may go from Edinburgh to London by the way of Paris, therefore any other road is useless.
There is perhaps no practical art which may not be acquired, in a very considerable degree, by example and practice, without reducing it to rules. But practice, joined with rules, may carry a man on in his art farther and more quickly, than practice without rules. Every ingenious artist knows the utility of having his art reduced to rules, and by that means made a science. He is thereby enlightened in his practice, and works with more assurance. By rules, he sometimes corrects his own errors, and often detects the errors of others: he finds them of great use to confirm his judgement, to justify what is right, and to condemn what is wrong.
Is it of no use in reasoning, to be well acquainted with the various powers of the human understanding, by which we reason? Is it of no use, to resolve the various kinds of reasoning into their simple elements; and to discover, as far as we are able, the rules by which these elements are combined in judging and in reasoning? Is it of no use, to mark the various fallacies in reasoning, by which even the most ingenious men have been led into error? It must surely betray great want of understanding, to think these things useless or unimportant. These are the things which logicians have attempted; and which they have executed; not indeed so completely as to leave no room for improvement, but in such a manner as to give very considerable aid to our reasoning powers. That the principles laid down with regard to definition and division, with regard to the conversion and opposition of propositions and the general rules of reasoning, are not without use, is suffi-ciently apparent from the blunders committed by those who disdain any acquaintance with them.
Although the art of categorical syllogism is better fitted for scholastic litigation, than for real improvement in knowledge, it is a venerable piece of antiquity, and a great effort of human genius. We admire the pyramids of Egypt, and the wall of China, though useless burdens upon the earth. We can bear the most minute description of them, and travel hundreds of leagues to see them. If any person should with sacrilegious hands destroy or deface them, his memory would be had in abhorrence. The predicaments and predicables, the rules of syllogism, and the topics, have a like title to our veneration as antiquities: they are uncommon efforts, not of human power, but of human genius; and they make a remarkable period in the progress of human reason.
The prejudice against logic has probably been strengthened by its being taught too early in life. Boys are often taught logic as they are taught their creed, when it is an exercise of memory only, without understanding. One may as well expect to understand grammar before he can speak, as to understand logic before he can reason. It must even be acknowledged, that commonly we are capable of reasoning in mathematics more early than in logic. The objects presented to the mind in this science, are of a very abstract nature, and can be distinctly conceived only when we are capable of attentive reflection upon the operations of our own understanding, and after we have been accustomed to reason. There may be an elementary logic, level to the capacity of those who have been but little exercised in reasoning; but the most important parts of this science require a ripe understanding, capable of reflecting upon its own operations. Therefore to make logic the first branch of science that is to be taught, is an old error that ought to be corrected.
Of the Improvement of Logic.
In compositions of human thought expressed by speech or by writing, whatever is excellent and whatever is faulty, fall within the province, either of grammar, or of rhetoric, or of logic. Propriety of expression is the province of grammar; grace, elegance, and force, in thought and in expression, are the province of rhetoric; justness and accuracy of thought are the province of logic.
The faults in composition, therefore, which fall under the censure of logic, are obscure and indistinct conceptions, false judgement, inconclusive reasoning, and all improprieties in distinctions, definitions, division, or method. To aid our rational powers, in avoiding these faults and in attaining the opposite excellencies, is the end of logic; and whatever there is in it that has no tendency to promote this end, ought to be thrown out.
The rules of logic being of a very abstract nature, ought to be illustrated by a variety of real and striking examples taken from the writings of good authors. It is both instructive and entertaining, to observe the virtues of accurate composition in writers of fame. We cannot see them, without being drawn to the imitation of them, in a more powerful manner than we can be by dry rules. Nor are the faults of such writers, less instructive or less powerful monitors. A wreck, left upon a shoal or upon a rock, is not more useful to the sailor, than the faults of good writers, when set up to view, are to those who come after them. It was a happy thought in a late ingenious writer of English grammar, to collect under the several rules, examples of bad English found in the most approved authors. It were to be wished that the rules of logic were illustrated in the same manner. By these means, a system of logic would become a repository; wherein whatever is most acute in judging and in reasoning, whatever is most accurate in dividing, distinguishing, and defining, should be laid up and disposed in order for our imitation; and wherein the false steps of eminent authors should be recorded for our admonition.
After men had laboured in the search of truth near two thousand years by the help of syllogisms, Lord Bacon proposed the method of induction, as a more effectual engine for that purpose. His Novum Organum gave a new turn to the thoughts and labours of the inquisitive, more remarkable and more useful than that which the Organum of Aristotle had given before; and may be considered as a second grand aera in the progress of human reason.
The art of syllogism produced numberless disputes; and numberless sects who fought against each other with much animosity, without gaining or losing ground, but did nothing considerable for the benefit of human life. The art of induction, first delineated by Lord Bacon, produced numberless laboratories and observatories; in which Nature has been put to the question by thousands of experiments, and forced to confess many of her secrets, that before were hid from mortals. And by these, arts have been improved, and human knowledge wonderfully increased.
In reasoning by syllogism, from general principles we descend to a conclusion virtually contained in them. The process of induction is more arduous; being an ascent from particular premises to a general conclusion. The evidence of such general conclusions is probable only, not demonstrative: but when the induction is sufficiently copious, and carried on according to the rules of art, it forces conviction no less than demonstration itself does.
The greatest part of human knowledge rests upon evidence of this kind. Indeed we can have no other for general truths which are contingent in their nature, and depend upon the will and ordination of the Maker of the world. He governs the world he has made, by general laws. The effects of these laws in particular phenomena, are open to our observation; and by observing a train of uniform effects with due caution, we may at last decypher the law of nature by which they are regulated.
Lord Bacon has displayed no less force of genius in reducing to rules this method of reasoning, than Aristotle did in the method of syllogism. His Novum Organum ought therefore to be held as a most important addition to the ancient logic. Those who understand it, and enter into its spirit, will be able to distinguish the chaff from the wheat in philosophical disquisitions into the works of God. They will learn to hold in due contempt all hypotheses and theories, the creatures of human imagination; and to respect nothing but facts sufficiently vouched, or conclusions drawn from them by a fair and chaste interpretation of nature.
Most arts have been reduced to rules, after they had been brought to a considerable degree of perfection by the natural sagacity of artists; and the rules have been drawn from the best examples of the art, that had been before exhibited: but the art of philosophical induction was delineated by Lord Bacon in a very ample manner, before the world had seen any tolerable example of it. This, altho’ it adds greatly to the merit of the author, must have produced some obscurity in the work, and a defect of proper examples for illustration. This defect may now be easily supplied, from those authors who, in their philosophical disquisitions, have the most strictly pursued the path pointed out in the Novum Organum. Among these Sir Isaac Newton appears to hold the first rank; having, in the third book of his Principia and in his Optics, had the rules of the Novum Organum constantly in his eye.
I think Lord Bacon was also the first who endeavoured to reduce to a system the prejudices or biasses of the mind, which are the causes of false judgement, and which he calls the idols of the human understanding. Some late writers of logic have very properly introduced this into their system; but it deserves to be more copiously handled, and to be illustrated by real examples.
It is of great consequence to accurate reasoning, to distinguish first principles which are to be taken for granted, from propositions which require proof. All the real knowledge of mankind may be divided into two parts: the first consisting of self-evident propositions; the second, of those which are deduced by just reasoning from self-evident propositions. The line that divides these two parts ought to be marked as distinctly as possible; and the principles that are self-evident reduced, as far as can be done, to general axioms. This has been done in mathematics from the beginning, and has tended greatly to the advancement of that science. It has lately been done in natural philosophy: and by this means that science has advanced more in an hundred and fifty years, than it had done before in two thousand. Every science is in an unformed state until its first principles are ascertained: after which, it advances regularly, and secures the ground it has gained.
Although first principles do not admit of direct proof, yet there must be certain marks and characters, by which those that are truly such may be distinguished from counterfeits. These marks ought to be described, and applied, to distinguish the genuine from the spurious.
In the ancient philosophy, there is a redundance, rather than a defect, of first principles. Many things were assumed under that character without a just title: That nature abhors a vacuum; That bodies do not gravitate in their proper place; That the heavenly bodies undergo no change; That they move in perfect circles, and with an equable motion. Such principles as these were assumed in the Peripatetic philosophy, without proof, as if they were self-evident.
Des Cartes, sensible of this weakness in the ancient philosophy, and desirous to guard against it in his own system, resolved to admit nothing until his assent was forced by irresistible evidence. The first thing that he found to be certain and e-vident was, that he thought, and reasoned, and doubted. He found himself under a necessity of believing the existence of those mental operations of which he was conscious: and having thus found sure footing in this one principle of consciousness, he rested satisfied with it, hoping to be able to build the whole fabric of his knowledge upon it; like Archimedes, who wanted but one fixed point to move the whole earth. But the foundation was too narrow; and in his progress he unawares assumes many things less evident than those which he attempts to prove. Altho’ he was not able to suspect the testimony of consciousness; yet he thought the testimony of sense, of memory, and of every other faculty, might be suspected, and ought not to be received until proof was brought that they are not fallacious. Therefore he applies these faculties, whose character is yet in question, to prove, That there is an infinitely perfect Being, who made him, and who made his senses, his memory, his reason, and all his faculties; That this Being is no deceiver, and therefore could not give him faculties that are fallacious; and that on this account they deserve credit.
It is strange, that this philosopher, who found himself under a necessity of yielding to the testimony of consciousness, did not find the same necessity of yielding to the testimony of his senses, his memory, and his understanding: and that while he was certain that he doubted, and reasoned, he was uncertain whether two and three made five, and whether he was dreaming or awake. It is more strange, that so acute a reasoner should not perceive, that his whole train of reasoning to prove that his faculties were not fallacious, was mere sophistry; for if his faculties were fallacious, they might deceive him in this train of reasoning; and so the conclusion, That they were not fallacious, was only the testimony of his faculties in their own favour, and might be a fallacy.
It is difficult to give any reason for distrusting our other faculties, that will not reach consciousness itself. And he who distrusts the faculties of judging and reasoning which God hath given him, must even rest in his scepticism, till he come to a sound mind, or until God give him new faculties to sit in judgement upon the old. If it be not a first principle, That our faculties are not fallacious, we must be absolute sceptics: for this principle is incapable of proof; and if it is not certain, nothing else can be certain.
Since the time of Des Cartes, it has been fashionable with those who dealt in abstract philosophy, to employ their invention in finding philosophical arguments, either to prove those truths which ought to be received as first principles, or to overturn them: and it is not easy to say, whether the authority of first principles is more hurt by the first of these attempts, or by the last: for such principles can stand secure only upon their own bottom; and to place them upon any other foundation than that of their intrinsic evidence, is in effect to overturn them.
I have lately met with a very sensible and judicious treatise, wrote by Father Buffier about fifty years ago, concerning first principles and the source of human judgements, which, with great propriety, he prefixed to his treatise of logic. And indeed I apprehend it is a subject of such consequence, that if inquisitive men can be brought to the same unanimity in the first principles of the other sciences, as in those of mathematics and natural philosophy, (and why should we despair of a general agreement in things that are self-evident?), this might be considered as a third grand aera in the progress of human reason.
END of the Third Volume.
HISTORY OF MAN.
by the last additions
of the author.
in four volumes.
printed for a. strahan and t. cadell, london;
and for william creech, edinburgh.
Principles and Progress of Morality
The principles of morality are little understood among savages: and if they arrive at maturity among enlightened nations, it is by slow degrees. This progress points out the historical part, as first in order: but as that history would give little satisfaction, without a rule for comparing the morals of different ages, and of different nations, I begin with the principles of morality, such as ought to govern at all times, and in all nations. The present sketch accordingly is divided into two parts. In the first, the principles are unfolded; and the second is altogether historical.