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source of knowledge common to all mankind. I own, indeed, that in different persons it prevails in different degrees of them") it is not easy to guess. By a ground of assent to any proposition is commonly understood a reason or argument in support of it. Now, by his own hypothesis, there are truths so plain, that no man can doubt of them. If so, what ground of assent beyond their own plainness ought we to seek? what besides this can we ever hope to find, or what better reason need be given for denominating such truths the dictates of common sense? If something plainer could be found to serve as evidence of any of them, then this plainer truth would be admitted as the first principle, and the other would be considered as deduced by reasoning. But notwithstanding the mistake in the instance, the general doctrine of primary truths would remain unhurt. It seems, however, that though their conduct would have been liable to very little, it would have been liable to some objection. "All that could have been said would have been, that, without any necessity, they had made an innovation in the received use of a term" I have a better opinion of these gentlemen than to imagine, that if the thing which they contend for be admitted, they will enter into a dispute with any person about the name; though in my judgment, even as to this, it is not they, but he, who is the innovator. He proceeds, "For no person ever denied that there are self-evident truths, and that these must be assumed, as the foundation of all our reasoning. I never met with any person who did not acknowledge this, or heard of any argumentative treatise that did not go upon the supposition of it." Now if this be the case, I would gladly know what is the great point he controverts. It is, whether such self-evident truths shall be denominated principles of common sense, or be distinguished by some other appellation. Was it worthy any man's while to write an octavo of near 400 pages for the discussion of such a question as this? And if, as he assures us, they have said more than is necessary in proof of a truth which he himself thinks indisputable, was it no more than necessary in Dr. Priestley to compose so large a volume, in order to convince the world that too much had been said already on the subject? I do not enter into the examination of his objections to some of the particular principles adduced as primary truths. An attempt of this kind would be foreign to my purpose: besides that the authors he has attacked are better qualified for defending their own doctrine, and, no doubt, will do it, if they think there is occasion, I shall only subjoin two remarks on this book. The first is, that the author, through the whole, confounds two things totally distinct-certain associations of ideas, and certain judgments implying belief, which, though in some, are not in all cases, and, therefore, not necessarily connected with association. And if so, merely to account for the association, is in no case to account for the belief with which it is attended. Nay, admitting his plea, [page 86], that, by the principle of association, not only the ideas, but the concomitant belief may be accounted for, even this does not invalidate the doctrine he impugns. For, let it be observed, that it is one thing to assign a cause which, from the mechanism of our nature, has given rise to a particular tenet or belief, and another thing to produce a reason by which the understanding has been convinced. Now, unless this be done as to the principles in question, they must be considered as primary truths in respect of the understanding, which never deduced them from other truths, and which is under a necessity, in all her moral reasonings, of founding upon them. In fact, to give any other account of our conviction of them, is to confirm, instead of confuting the doctrine, that in all argumentation they must be regarded as primary truths, or truths which reason never inferred, through any medium, from other truths previously perceived. My second remark is, that though this examiner has, from Dr. Reid, given us a catalogue of first principles, which he deems unworthy of the honourable place assigned them, he has nowhere thought proper to give us a list of those self-evident truths which, by his own account, and in his own express words,
strength; but no human creature hath been found originally and totally destitute of it, who is not accounted a monster in his kind: for such, doubtless, are all idiots and changelings. By madness, a disease which makes terrible havoc on the faculties of the mind, it may be in a great measure, but is never entirely lost.
It is purely hence that we derive our assurance of such truths as these: "Whatever has a beginning has a cause. "When there is, in the effect, a manifest adjustment of the several parts to a certain end, there is intelligence in the cause. "The course of nature will be the same to-morrow that it is to-day; or, the future will resemble the past.' "There is such a thing as body; or, there are material substances independent of the mind's conceptions." "There are other intelligent beings in the universe besides me.' "The clear representations of my memory, in regard to past events, are indubitably true." These, and a great many more of the same kind, it is impossible for any man by reasoning to evince, as might easily be shown, were this a proper place for the discussion. And it is equally impossible, without a full conviction of them, to advance a single step in the acquisition of knowledge, especially in all that regards mankind, life, and conduct.
I am sensible that some of these, to men not accustomed to inquiries of this kind, will appear, at first, not to be primary principles, but conclusions from other principles; and some of them will be thought to coincide with the other kinds of intuition above mentioned. Thus the first, "Whatever hath a beginning hath a cause," may be thougnt to stand on the same footing with mathematical axioms. I acknowledge that, in point of evidence, they are equal, and it is alike impossible, in either case, for a rational creature to withhold his assent. Nevertheless, there is a difference in kind. All the axioms in mathematics are but the enunciations of certain properties in our abstract notions, distinctly perceived by the mind, but have no relation to anything without themselves, and can never be made the foundation of any conclusion concerning actual existence; whereas, in the axiom last specified, from the existence of one thing we intuitively conclude the exist"must be assumed as the foundation of all our reasoning." How much light might have been thrown upon the subject by the contrast? Perhaps we should have been enabled, on the comparison, to discover some distinctive characters in his genuine axioms, which would have preserved us from the danger of confounding them with their spurious ones. Nothing is more evident than that, in whatever regards matter of fact, the mathematical axioms will not answer. These are purely fitted for evolving the abstract relations of quantity. This he in effect owns himself [page 39]. It would have been obliging, then, and would have greatly contributed to shorten the controversy, if he had given us, at least, a specimen of those self-evident principles, which, in his estimation, are the non plus ultra of moral reasoning.
ence of another. This proposition, however, so far differs in my apprehension, from others of the same order, that I cannot avoid considering the opposite assertion as not only false, but contradictory; but I do not pretend to explain the ground of this difference.
The faith we give to memory may be thought, on a superficial view, to be resolvable into consciousness, as well as that we give to the immediate impressions of sense. But on a little attention one may easily perceive the difference. To believe the report of our senses doth, indeed, commonly imply, to believe the existence of certain external and corporeal objects, which give rise to our particular sensations. This, I acknowledge, is a principle which doth not spring from consciousness (for consciousness cannot extend beyond sensation), but from common sense, as well as the assurance we have in the report of memory. But this was not intended to be included under the second branch of intuitive evidence. By that firm belief in sense, which I there resolved into consciousness, I meant no more than to say, I am certain that I see, and feel, and think, what I actually see, and feel, and think. As in this I pronounce only concerning my own present feelings, whose essence consists in being felt, and of which I am at present conscious, my conviction is reducible to this axiom, or coincident with it, "It is impossible for a thing to be and not to be at the same time." Now when I say, I trust entirely to the clear report of my memory, I mean a good deal more than, "I am certain that my memory gives such a report, or represents things in such a manner," for this conviction I have, indeed, from consciousness, but I mean, “I am certain that things happened heretofore at such a time, in the precise manner in which I now remember that they then happened." Thus there is a reference in the ideas of memory to former sensible impressions, to which there is nothing analogous in sensation. At the same time, it is evident that remembrance is not always accompanied with this full conviction. To describe, in words, the difference between those lively signatures of memory which command an unlimited assent, and those fainter traces which raise opinion only, or even doubt, is perhaps impracticable; but no man stands in need of such assistance to enable him, in fact, to distinguish them for the direction of his own judgment and conduct. Some may imagine that it is from experience we come to know what faith in every case is due to memory. But it will appear more fully afterward that, unless we had impli citly relied on the distinct and vivid informations of that faculty, we could not have moved a step towards the acquisition of experience. It must, however, be admitted, that experience is of use in assisting us to judge concerning the more languid and confused suggestions of memory; or, to speak
more properly, concerning the reality of those things of which we ourselves are doubtful whether we remember them or not.
In regard to the primary truths of this order it may be urged, that it cannot be affirmed of them all, at least, as it may of the axioms in mathematics, or the assurances we have from consciousness that the denial of them implies a manifest contradiction. It is, perhaps, physically possible that the course of nature will be inverted the very next moment; that my memory is no better than a delirium, and my life a dream; that all is mere allusion; that I am the only being in the universe, and that there is no such thing as body. Nothing can be juster than the reply given by Buffier: "It must be owned," says he,* "that to maintain propositions the reverse of the primary truths of common sense, doth not imply a contradiction, it only implies insanity." But if any person, on account of this difference in the nature of these two classes of axioms, should not think the term intuitive so properly applied to the evidence of the last mentioned, let him denominate it, if he please, instinctive: I have no objection to the term; nor do I think it derogates in the least from the digni、 ty, the certainty, or the importance of the truths themselves. Such instincts are no other than the oracles of eternal wisdom.
For, let it be observed farther, that axioms of this last kind are as essential to moral reasoning, to all deductions concerning life and existence, as those of the first kind are to the sciences of arithmetic and geometry. Perhaps it will appear afterward, that, without the aid of some of them, these sciences themselves would be utterly inaccessible to us. Besides, the mathematical axioms can never extend their influence beyond the precincts of abstract knowledge, in regard to number and extension, or assist us in the discovery of any matter of fact: whereas, with knowledge of the latter kind, the whole conduct and business of human life is principally and intimately connected. All reasoning necessarily supposes that there are certain principles in which we must acquiesce, and beyond which we cannot go; principles clearly discernible by their own light, which can derive no additional evidence from anything besides. On the contrary supposition, the investigation of truth would be an endless and a fruitless task; we should be eternally proving, while nothing could ever be proved; because, by the hypothesis, we could never ascend to premises which require no proof. "If there be no first truths," says the author lotely quoted, "there can be no second truths, nor third, nor, indeed, any truth at all.”
So much for intuitive evidence, in the extensive meaning which hath here been given to that term, as including every
* Premières Véritez, part i., chap. xi. † Ib., Dessein de l'ouvrage.
thing whose evidence results from the simple contemplation of the ideas or perceptions which form the proposition under consideration, and requires not the intervention of any third idea as a medium of proof. This, for order's sake, I have distributed into three classes-the truths of pure intellection, of consciousness, and of common sense. The first may be denominated metaphysical, the second physical, the third moral; all of them natural, original, and unaccountable.
OF DEDUCTIVE EVIDENCE.
PART I. Division of the Subject into Scientific and Moral, with the principal Distinctions between them.
ALL rational or deductive evidence is derived from one or other of these two sources: from the invariable properties or relations of general ideas; or from the actual, though perhaps variable connexions, subsisting among things. The former we call demonstrative; the latter, moral. Demonstration is built on pure intellection, and consisteth in an uninterrupted series of axioms. That propositions formerly demonstrated are taken into the series, doth not in the least invalidate this account; inasmuch as these propositions are all resolvable into axioms, and are admitted as links in the chain, not because necessary, but merely to avoid the useless prolixity which frequent and tedious repetitions of proofs formerly given would occasion. Moral evidence is founded on the principles we have from consciousness and common sense improved by experience; and as it proceeds on this general presumption or moral axiom, that the course of nature in time to come will be similar to what it hath been hitherto, it decides, in regard to particulars, concerning the future from the past, and concerning things unknown from things familiar to us. The first is solely conversant about number and extension, and about those other qualities which are measurable by these. Such are duration, velocity, and weight. With regard to such qualities as pleasure and pain, virtue and vice, wisdom and folly, beauty and deformity, though they admit degrees, yet, as there is no standard or common measure by which thei differences and proportions can be ascertained and expressed in numbers, they can never become the subject of demonstrative reasoning. Here rhetoric, it must be acknowledged, hath little to do. Simplicity of diction and precision in arrangement, whence results perspicuity are, as was observed already,* all the requisites. er province of rhetoric is the second or moral evidence; for to the second belong all decisions concerning fact, and thing without us.
* Chap. i.