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sort of discourse, as a subordinate end conducive to the advancement of the principal. If, then, it is the business of logic to evince the truth, to convince an auditory, which is the province of eloquence, is but a particular application of the logician's art. As logic, therefore, forges the arms which eloquence teacheth us to wield, we must first have recourse to the former, that, being made acquainted with the materials of which her weapons and armour are severally made, we may know their respective strength and temper, and when and how each is to be used.
Now, if it be by the sense or soul of the discourse that rhetoric holds of logic, or the art of thinking and reasoning, it is by the expression or body of the discourse that she holds of grammar, or the art of conveying our thoughts in the words of a particular language. The observation of one analogy naturally suggests another. As the soul is of heavenly extraction and the body of earthly, so the sense of the discourse ought to have its source in the invariable nature of truth and right; whereas the expression can derive its energy only from the arbitrary conventions of men, sources as unlike, or, rather, as widely different, as the breath of the Almighty and the dust of the earth. In every region of the globe we may soon discover that people feel and argue in much the same manner, but the speech of one nation is quite unintelligible to another. The art of the logician is, accordingly, in some sense, universal; the art of the grammarian is always particular and local. The rules of argumentation laid down by Aristotle, in his Analytics, are of as much use for the discovery of truth in Britain or in China as they were in Greece; but Priscian's rules of inflection and construction can assist us in learning no language but Latin. In propriety, there could not be such a thing as a universal grammar, unless there were such a thing as a universal language. The term hath sometimes, indeed, been applied to a collection of observations on the similar analogies that have been discovered in all tongues, ancient and modern, known to the authors of such collections. I do not mention this liberty in the use of the term with a view to censure it. In the application of technical or learned words, an author hath greater scope than in the application of those which are in more frequent use, and is only then thought censurable, when he exposeth himself to be inisunderstood. But it is to my purpose to observe, that as such collections convey the knowledge of no tongue whatever, the name grammar, when applied to them, is used in a sense quite different from that which it has in the common acceptation; perhaps as different, though the subject be language, as when it is applied to a system of geography.
Now the grammatical art hath its complexion in syntax; the oratorical, as far as the body or expression is concerned,
m style. Syntax regards only the composition of many words into one sentence; style, at the same time that it attends to this, regards, farther, the composition of many sentences into one discourse. Nor is this the only difference: the grammarian, with respect to what the two arts have in common, the structure of sentences, requires only purity; that is, that the words employed belong to the language, and that they be construed in the manner, and used in the signification, which custom hath rendered necessary for conveying the sense. The orator requires also beauty and strength. The highest aim of the former is the lowest aim of the latter; where grammar ends, eloquence begins.
Thus, the grammarian's department bears much the same relation to the orator's which the art of the mason bears to that of the architect. There is, however, one difference, that well deserves our notice. As in architecture it is not necessary that he who designs should execute his own plans, he may be an excellent artist in this way who would handle very awkwardly the hammer and the trowel. But it is alike incumbent on the orator to design and to execute. He must, therefore, be master of the language he speaks or writes, and must be capable of adding to grammatic purity those higher qualities of elocution, which will render his discourse graceful and energetic.
So much for the connexion that subsists between rhetoric and these parent arts, logic and grammar.
OF THE DIFFERENT SOURCES OF EVIDENCE, AND THE DIFFERENT SUBJECTS TO WHICH THEY ARE RESPECTIVELY ADAPTED.
LOGICAL truth consisteth in the conformity of our conceptions to their archetypes in the nature of things. This conformity is perceived by the mind, either immediately on a bare attention to the ideas under review, or mediately by a comparison of these with other related ideas. Evidence of the former kind is called intuitive; of the latter, deductive.
OF INTUITIVE EVIDENCE.
Or intuitive evidence there are different sorts. One is that which results purely from intellection.* Of this kind is the
I have here adopted the term intellection, rather than perception, because,
evidence of these propositions: "One and four make five. Things equal to the same thing are equal to one another. The whole is greater than a part ;" and, in brief, all axioms in arithmetic and geometry. These are, in effect, but so many different expositions of our own general notions, taken in different views. Some of thein are no other than definitions, or equivalent to definitions. To say "One and four make five," is precisely the same as to say, "We give the name five to one added to four." In fact, they are all, in some respect, reducible to this axiom, "Whatever is, is." I do not say they are deduced from it, for they have in like manner that original and intrinsic evidence, which makes them, as soon as the terms are understood, to be perceived intuitively. And if they are not thus perceived, no deduction of reason will ever confer on them any additional evidence. Nay, in point of time, the discovery of the less general truths has the priority, not from their superior evidence, but solely from this consideration, that the less general are sooner objects of perception to us, the natural progress of the mind in the acquisition of its ideas being from particular things to universal notions, and not inversely. But I affirm that, though not deduced from that axiom, they may be considered as particular exemplifications of it, and coincident with it, inasmuch as they are all implied in this, that the properties of our clear and adequate ideas can be no other than what the mind clearly perceives them to be.
But, in order to prevent mistakes, it will be necessary farther to illustrate this subject. It might be thought, that if axioms were propositions perfectly identical, it would be impossible to advance a step, by their means, beyond the simple ideas first perceived by the mind. And it must be owned, if the predicate of the proposition were nothing but a repetition of the subject, under the same aspect, and in the same or synonymous terms, no conceivable advantage could be made of it for the furtherance of knowledge. Of such propositions as these, for instance, "Seven are seven," "eight are eight," and "ten added to eleven are equal to ten added to eleven," it is manifest that we could never avail ourselves for the improvement of science. Nor does the change of the name make any alteration in point of utility. The propositions,
though not so usual, it is both more apposite and less equivocal. Perception is employed alike to denote every immediate object of thought, or whatever is apprehended by the mind, our sensations themselves, and those qualities in body, suggested by our sensations, the ideas of these upon reflection, whether remembered or imagined, together with those called general notions, or abstract ideas. It is only the last of these kinds which are considered as peculiarly the object of the understanding, and which, therefore, require to be distinguished by a peculiar name. Obscurity arising from an uncommon word is easily surmounted, whereas ambiguity, by misleading us, ere we are aware, confounds our notion of the subiect altogether.
"Twelve are a dozen," "twenty are a score," unless considered as explications of the words dozen and score, are equally insignificant with the former. But when the thing, though in effect coinciding, is considered under a different aspect; when what is single in the subject is divided in the predicate, and conversely; or when what is a whole in the one, is regarded as a part of something else in the other; such propositions lead to the discovery of innumerable, and apparently remote relations. One added to four may be accounted no other than a definition of the word five, as was remarked above. But when I say, "Two added to three are equal to five," I advance a truth, which, though equally clear, is quite distinct from the preceding. Thus, if one should affirm, "twice fifteen make thirty," and again, "thirteen added to seventeen make thirty," nobody would pretend that he had repeated the same proposition in other words. The cases are entirely similar. In both, the same thing is predicated of ideas which, taken severally, are different. From these, again, result other equations, as, "One added to four are equal to two added to three," and "twice fifteen are equal to thirteen added to seventeen."
Now it is by the aid of such simple and elementary principles that the arithmetician and the algebraist proceed to the most astonishing discoveries. Nor are the operations of the geometrician essentially different. By a very few steps you are made to perceive the equality, or, rather, the coincidence of the sum of the two angles, formed by one straight line falling on another, with two right angles. By a process equally plain, you are brought to discover, first, that if one side of a triangle be produced, the external angle will be equal to both the internal and opposite angles; and then, that all the angles of a triangle are equal to two right angles. So much for the nature and use of the first kind of intuitive evidence, resulting from pure intellection.
PART II. Consciousness.
The next kind is that which ariseth from consciousness. Hence every man derives the perfect assurance that he hath of his own existence. Nor is he only in this way assured that he exists, but that he thinks, he feels, that he sees, that he hears, and the like. Hence his absolute certainty in regard to the reality of his sensations and passions, and of everything whose essence consists in being perceived. Nor does this kind of intuition regard only the truth of the original feelings or impressions, but also many of the judgments that are formed by the mind, on comparing these one with another. Thus, the judgments we daily and hourly form concerning resemblances or disparities in visible objects, or size in things tangible, where the odds is considerable, darker
or lighter tints in colours, stronger or weaker tastes or smells, are all self-evident, and discoverable at once. It is from the same principle that, in regard to ourselves, we judge infallibly concerning the feelings, whether pleasant or painful, which we derive from what are called the internal senses, and pronounce concerning beauty or deformity, harmony or discord, the elegant or the ridiculous. The difference between this kind of intuition and the former will appear on the slightest reflection. The former concerns only abstract notions or ideas, particularly in regard to number and extension, the objects purely of the understanding; the latter concerns only the existence of the mind itself, and its actual feelings, impressions, or affections, pleasures or pains, the immediate subjects of sense, taking that word in the largest acceptation. The former gives rise to those universal truths, first principles, or axioms, which serve as the foundation of abstract science; whereas the latter, though absolutely essential to the individual, yet, as it only regards particular perceptions, which represent no distinct genus or species of objects, the judgments resulting thence cannot form any general positions to which a chain of reasoning may be fastened, and, consequently, are not of the nature of axioms, though both similar and equal in respect of evidence.
PART III. Common Sense. ·
The third sort is that which ariseth from what hath been termed, properly enough, common sense,* as being an original
The first among the moderns who took notice of this principle, as one of the genuine springs of our knowledge, was Buffier, a French philosopher of the present century, in a book entitled Traité des Premières Véritez; one who, to an uncommon degree of acuteness in matters of abstraction, added that solidity of judgment which hath prevented in him, what had proved the wreck of many great names in philosophy, his understanding becoming the dupe of his ingenuity. This doctrine hath lately, in our own country, been set in the clearest light, and supported by invincible force of argument, by two very able writers in the science of man, Dr. Reid, in his Inquiry into the Human Mind, and Dr. Beattie, in his Essay on the Immutability of Truth. I beg leave to remark in this place, that though, for distinction's sake, I use the term common sense in a more limited signification than either of the authors last mentioned, there appears to be no real difference in our sentiments of the thing itself. I am not ignorant that this doctrine has been lately attacked by Dr. Priestley in a most extraordinary manner, a manner which no man who has any regard to the name of Englishman or of philosopher will ever desire to see imitated in this or any other country. I have read the performance, but have not been able to discover the author's sentiments in relation to the principal point in dispute. He says, expressly, [Examination of Dr. Reid's Inquiry, &c., p. 119], "Had these writers," Messieurs Reid, Beattie, and Oswald, "assumed, as the elements of their common sense, certain truths which are so plain that no man could doubt of them (without entering into the ground of our assent to them), their conduct would have been liable to very little objection." And is not this the very thing which these writers have done? What he means to signify by the parenthesis ("without entering into the ground of our assent to