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It is to be regretted, as a circumstance unfavourable to the reception of Dr. Beattie's valuable essay among accurate reasoners, that, in the outset of his discussions, he did not confine himself to some such general explanation of this phrase as is given in the foregoing extracts from Buffier and Reid, without affecting a tone of logical precision in his definitions and distinctions, which, so far from being necessary to his intended argument, were evidently out of place, in a work designed as a popular antidote against the illusions of metaphysical scepticism. The very idea, indeed, of appealing to common sense, virtually implies that these words are to be understood in their ordinary acceptation, unrestricted and unmodified by any technical refinements and comments. This part of his essay, accordingly, which is by far the most vulnerable part of it, has been attacked with advantage, not only by the translator of Buffier, but by Sir James Steuart, in a very acute letter published in the last edition of his works.*
While I thus endeavour, however, to distinguish Dr. Reid's definition of common sense from that of Dr. Beattie, I am far from considering even the language of the former on this subject, as in every instance unexceptionable; nor do I think it has been a fortunate circumstance (notwithstanding the very high authorities which may be quoted in his vindication,) that he attempted to incorporate so vague and ambiguous a phrase with the appropriate terms of logic. My chief reasons for this opinion I have stated at some length, in an account published a few years ago of Dr. Reid's Life and Writings.†
What each must act was yet unknown,
Till all was moved by Chance alone.
Blest for his sake be human reason,
Which cane at last though late, in season."-Alma, Canto I.
To the honour of Dr. Beattie it must be remarked, that his reply to this letter (which may be found in Sir James Steuart's works) is written in a strain of forbearance and of good humour, which few authors would have been able to maintain, after being handled so roughly.
In consequence of the ambiguous meaning of this phrase, Dr. Reid sometimes falls into a sort of play on words, which I have often regretted. "If this be philosophy (says he, on one occasion) I renounce her guidance. Let my soul dwell with common sense.' (Inquiry into the Human Mind, chap. i. sect. 3. See also sect. 4 of the same chapter.) And in another passage, after quoting the noted saying of Hobbes, that "when reason is against a man, a man will be against reason;" he adds: "This is equally applicable to common sense." (Essays on the Intellectual Powers, p. 530, 4to. edition.) In both of these instances, and indeed in the general strain of argument which runs through his works, he understands common sense in its ordinary acceptation, as synonymous, or very nearly synonymous, with the word reason, as it is now most frequently employed. In a few cases, however, he seems to have annexed to the same phrase a technical meaning of his own, and has even spoken of this meaning as a thing not generally understood. Thus, after illustrating the different classes of natural signs, he adds the following sentence: "It may be observed, that as the first class of natural signs I have mentioned is the foundation of true philosophy, and the second of the fine arts or of taste, so the last is the foun dation of common sense; a part of human nature which hath never been explained."— Inquiry, chap. v. sect. 3.
See Note (D.)
One very unlucky consequence has unquestionably resulted from the coincidence of so many writers connected with this northern part of the island, in adopting, about the same period, the same phrase, as a sort of philosophical watch-word;-that, although their views differ widely in various respects, they have in general been classed together as partisans of a new sect, and as mutually responsible for the doctrines of each other. It is easy to perceive the use likely to be made of this accident by an uncandid antagonist.
All of these writers have, in my opinion, been occasionally misled in their speculations, by a want of attention to the distinction between first principles, properly so called, and the fundamental laws of human belief. Buffier himself has fallen into the same errour; nor do I know of any one logician, from the time of Aristotle downwards, who has entirely avoided it.
The foregoing critical remarks will, I hope, have their use in keeping this distinction more steadily in the view of future inquirers; and in preventing some of the readers of the publications to which they relate, from conceiving a prejudice, in consequence of the looseness of that phraseology which has been accidentally adopted by their authors, against the just and important conclusions which they contain.
OF REASONING AND OF DEDUCTIVE EVIDENCE.
Doubts with respect to Locke's Distinction between the Powers of Intuition and of Reasoning.
ALTHOUGH, in treating of this branch of the Philosophy of the Mind,
I have followed the example of preceding writers, so far as to speak Intuition: of intuition and reasoning as two different faculties of the understand
ing, I am by no means satisfied that there exists between them that reasoning radical distinction which is commonly apprehended. Dr. Beattie, in not distinct his Essay on Truth, has attempted to show, that, how closely soever
they may in general be connected, yet that this connexion is not ne- famultin. cessary; in so much, that a being may be conceived endued with' the one, and at the same time destitute of the other.* Something
*Beattie's Essay, p. 41. 2d edit.
of this kind, he remarks, takes place in dreams and in madness; in In madness both of which states of the system, the power of reasoning appears dreams occasionally to be retained in no inconsiderable degree, while the reasoning power of intuition is suspended or lost. But this doctrine is liable and to insurmountable objections; and has plainly taken its rise from the vagueness of the phrase common sense, which the author employs through the whole of his argument, as synonymous with the power of intuition. Of the indissoluble connexion between this last power and that of reasoning, no other proof is necessary than the following consideration, that, "in every step which reason "makes in demonstrative knowledge, there must be intuitive cer"tainty;" a proposition which Locke has excellently illustrated, and which, since his time, has been acquiesced in, so far as I know, by philosophers of all descriptions. From this proposition (which, properly interpreted, appears to me to be perfectly obviously follows, that the power of reasoning presupposes the intuition about which any doubt can be entertained is, Whether the power of intuition (according to Locke's idea of it) does not also imply that of reasonciu usa opinion is, that it at least, when combined with the faculty of memory. In examining those processes of thought which conduct the mind by a series of consequences from premises to a conclusion, I can detect no intellectual act whatever, which the joint operation of intuition and of memory does not sufficiently explain.
Before, however, proceeding farther in this discussion, it is proper for me to observe, by way of comment on the proposition just quoted from Locke, that, although, "in a complete demonstration, low for "there must be intuitive evidence at every step," it is not to be supposed, that, in every demonstration, all the various intuitive intuitive judgments leading to the conclusion are actually presented to our wuption thoughts. In by far the greater number of instances, we trust entirely to judgments resting upon the evidence of memory; by the na dumon help of which faculty, we are enabled to connect together the most tration? remote truths, with the very same confidence as if the one were an immediate consequence of the other. Nor does this diminish, in the smallest degree, the satisfaction we feel in following such a train of reasoning. On the contrary, nothing can be more disgusting than a demonstration where even the simplest and most obvious steps are brought forward to view; and where no appeal is made to that stock of previous knowledge which memory has identified with the operations of reason. Still, however, it is true, that it is by a continued chain of intuitive judgments, that the whole science of geometry hangs together; in as much as the demonstration of any one proposition virtually includes all the previous demonstrations to which it refers.
Hence it appears, that, in mathematical demonstrations, we have not, at every step, the immediate evidence of intuition, but only the evidence of memory. Every demonstration, however, may be re
remory supplin place of intuition some part.
solved into a series of separate judgments, either formed at the moment, or remembered as the results of judgments formed at some preceding period; and it is in the arrangement and concatenation of these different judgments, or media of proof, that the inventive and reasoning powers of the mathematician find so noble a field for their exercise.
With respect to these powers of judgment and of reasoning, as 9 Mustration they are here combined, it appears to me, that the results of the
former may be compared to a collection of separate stones prepared of jud by the chisel for the purposes of the builder; upon each of which sing stones, while lying on the ground, a person may raise himself, as upon a pedestal, to a small elevation. The same judgments, when combined into a train of reasoning, terminating in a remote conclusion, resemble the formerly unconnected blocks, when converted into the steps of a staircase leading to the summit of a tower, which would be otherwise inaccessible. In the design and execution of this staircase, much skill and invention may be displayed by the architect; but, in order to ascend it, nothing more is necessary than a repetition of the act by which the first step was gained. The fact I conceive to be somewhat analogous, in the relation between the power of judgment, and what logicians call the discursive processes of the understanding.
Mr. Locke's language, in various parts of his Essay, seems to accord with the same opinion. "Every step in reasoning, (he ob"serves) that produces knowledge, has intuitive certainty; which, "when the mind perceives, there is no more required but to remember it, "to make the agreement or disagreement of the ideas, concerning "which we inquire, visible and certain. This intuitive perception "of the agreement or disagreement of the intermediate ideas, in "each step and progression of the demonstration, must also be car"ried exactly in the mind, and a man must be sure that no part is “left out; which, in long deductions, and in the use of many proofs, "the memory does not always so readily and exactly retain: there"fore it comes to pass, that this is more imperfect than intuitive "knowledge, and men embrace often falsehood for demonstra❝tions."*
The same doctrine is stated elsewhere by Mr. Locke, more than once, in terms equally explicit ; and yet his language occasionally favours the supposition, that, in its deductive processes, the mind exhibits some modification of reason essentially distinct from intuition. The account, too, which he has given of their respective provinces, affords evidence that his notions concerning them were not sufficiently precise and settled. "When the mind (says he) "perceives the agreement or disagreement of two ideas immediately "by themselves, without the intervention of any other, its know"ledge may be called intuitive. When it cannot so bring its ideas
"together as, by their immediate comparison, and, as it were, juxta"position, or application one to another, to perceive their agree"ment or disagreement, it is fain, by the intervention of other ideas, "(one or more as it happens) to discover the agreement or disagree, "ment which it searches; and this is that which we call reasoning." According to these definitions, supposing the equality of two lines A and B to be perceived immediately in consequence of their coincidence; the judgment of the mind is intuitive: supposing A to coincide with B, and B with C; the relation between A and C is perceived by reasoning. Nor is this a hasty inference from Locke's accidental language. That it is perfectly agreeable to the foregoing definitions, as understood by their author, appears from the following passage, which occurs afterwards: "The principal act of ratio"cination is the finding the agreement or disagreement of two ideas, 66 one with another, by the intervention of a third. As a man, by a "yard, finds two houses to be of the same length, which could not "be brought together to measure their equality by juxta-position."t This use of the words intuition and reasoning, is surely somewhat Lockis arbitrary. The truth of mathematical axioms has always been supposed to be intuitively obvious; and the first of these, according to ure of intu· Euclid's enumeration, affirms, That if A be equal to B, and B to C, ition and A and C are equal. Admitting, however, Locke's definition to be just, it only tends to confirm what has been already stated with respect to the near affinity, or rather the radical identity of intuition and of reasoning. When the relation of equality between A and B has once been perceived, A and B are completely identified as the same mathematical quantity; and the two letters may be regarded as synonymous wherever they occur. The faculty, therefore, which perceives the relation between A and C, is the same with the faculty which perceives the relation between A and B, and between B and C.
In farther confirmation of the same proposition, an appeal might be made to the structure of syllogisms. Is it possible to conceive an understanding so formed as to perceive the truth of the major and of the minor propositions, and yet not to perceive the force of the conclusion? The contrary must appear evident to every person who knows what a syllogism is; or rather, as in this mode of stating an argument, the mind is led from universals to particulars, it must appear evident, that, in the very statement of the major proposition, the truth of the conclusion is presupposed; in so much, that it was not without good reason Dr. Campbell hazarded the epi
* B. IV. chap. ii. §§ 1. and 2.
B. IV. chap. xvii. § 18.
Dr. Reid's notions, as well as those of Mr. Locke, seem to have been somewhat unsettled with respect to the precise line which separates intuition from reasoning. That the axioms of geometry are intuitive truths, he has remarked in numberless passages of his works; and yet, in speaking of the application of the syllogistic theory to mathema tics, be makes use of the following expression: "The simple reasoning, A is equal to B, and B to C, therefore A is equal to C,' cannot be brought into any syllogism in figure and mode."-See his Analysis of Aristotle's Logic.