so vigorously forwarded, and so often renewed, that they now constitute a great part of what is called the philosophy of the human mind. It is difficult, perhaps impossible, to give a logical definition of Truth. But we shall endeavour to give such a description of it, as may make others understand what we mean by the word. The definitions of former writers are not so clear, nor so accurate as could be wished. These therefore we shall overlook, without seeking either to explain or to correct them ; and shall satisfy ourselves with taking notice of some of the mental phenomena that attend the perception of truth. This seems to be the safest way of intro ducing the subject. CHAPTER I. On the Perception of Truth in general. N hearing these propositions: I exist,-Things equal to one and the same thing are equal to one another,―The sun rose to-day,There is a GodIngratitude ought to be blamed and punished, The three angles of a triangle are equal to two right angles, &c.-I am conscious, that my mind readily admits and acquiesces in them. I say, that I believe them to be true; that is, I conceive them to express something conformable to the nature of things *. Of the contrary propositions I should say, that my mind. does not acquiesce in them, but disbelieves them, and conceives them to express something not conformable to the nature of things. My judgment in this case, I conceive to be the same which I should form in regard to these propositions, if I were perfectly acquaint * ώσθ' έκασον ὡς ἔχει τε ἄἶναι, οὕτω καὶ τῆς ἀληθείας. Aristot. Metaph. lib. 2. cap. 1. C ed with all nature, in all its parts, and in all its laws *. If I be asked, what I mean by the nature of things, I cannot otherwise explain myself, than by saying, that there is in my mind something which induces me to think, that every thing existing in nature, is determined to exist, and to exist after a certain manner in consequence of established laws; and that whatever is agreeable to those laws is agreeable to the nature of things, because by those laws the nature of all things is determined. Of those laws I do not pretend to know any thing, except so far as they seem to be intimated to me by my own feelings, and by the suggestions of my own understanding. But these feelings and suggestions are such, and affect me in such a manner, that I cannot help receiving them, and trusting in them, and believing that their intimations are not fallacious, but such as I should approve if I were perfectly acquainted with every thing in the universe, and such as I may approve, and admit of, and regulate my conduct by, without danger of any inconvenience. It is not easy on this subject to avoid identical expressions. I am not certain that I have been able to avoid them. And perhaps I might have expressed my meaning more shortly and more clearly, by saying, that I account That to be truth which the constitution of our nature determines us to believe, and That to be falsehood which the constitution of our nature determines us to disbelieve. Believing and disbelieving are simple acts of the mind; I can neither define nor describe them in words; and therefore the * This remark, when applied to truth in general, is subject to certain limitations; for which see part 2, chap. 1. sect. 3.*. reader must judge of their nature from his own experience. We often believe what we afterwards find to be false; but while belief continues, we think it true; when we discover its falsity, we believe it no longer. Hitherto we have used the word belief, to denote that act of the mind which attends the perception of truth in general. But truths are of different kinds; some are certain, others only probable: and we ought not to call that act of the mind which attends the perception of certainty, and that which attends the perception of probability, by one and the same name. Some have called the former conviction, and the latter assent. All convictions are equally strong; but assent admits of innumerable degrees, from moral certainty, which is the highest degree, downward, through the several stages of opinion, to that suspense of judgment which is called doubt. We may, without absurdity, speak of probable truth as well as of certain truth. Whatever a rational being is determined, by the constitution of his nature, to admit as probable, may be called probable truth; the acknowledgment of it is as universal as rational nature, and will be as permanent. But, in this. inquiry, we propose to confine ourselves chiefly to that kind of truth which may be called certain, which enforces our conviction, and the belief of which, in a sound mind, is not tinctured with any doubt or uncertainty. The investigation and perception of truth is commonly ascribed to our rational faculties; and these have by some been reduced to two; Reason, and Judgment; the former being supposed to be conversant about certain truths, the latter chiefly about pro babilities. But certain truths are not all of the same kind; some being supported by one sort of evidence, and others by another: different energies of the understanding must therefore be exerted in perceiving them; and these different energies must be expressed by different names, if we would speak of them distinctly and intelligibly. The certainty of some truths, for instance, is perceived intuitively; the certainty of others is perceived, not intuitively but in consequence of a proof. Most of the propositions of Euclid are of the latter kind; the axioms of geometry are of the former. Now, if that faculty by which we perceive truth in consequence of a proof, be called Reason, surely that power by which we perceive self-evident truth, ought to be distinguished by a different name. It is of little consequence what name we make choice of, provided that in chusing it we depart not from the analogy of language; and, that, in applying it, we avoid equivocation and ambiguity *. Some philosophers of note † have given the name of Common Sense to that faculty by which we perceive selfevident truth; and, as the term seems proper enough, we shall adopt it. But in a subject of this kind, there is great danger of our being imposed upon by words; we cannot therefore be too much upon our guard against that species of illusion. We mean to draw some important inferences from this doctrine of the distinction between Reason and Common Sense. Now these words are not always used in the strict signification we have here assigned them: let us *We might call the one Reason, and the other Reasoning; but the similarity of the terms would frequently occasion both obscurity in the sense, and harshness in the sound. † Buffer, Dr Reid, &c. therefore take a view of all the similar senses in which they are commonly used, and let us explain more particularly that sense in which we are to use them; and thus we shall take every method in our power to secure ourselves against the impropriety of confounding our notions by the use of ambiguous and indefinite language. These philological discussions are indeed no part of philosophy; but they are very necessary to prepare us for it. "Qui ad interpretandam naturam accesserit," says Bacon, " verborum mixtam "naturam, et juvamenti et nocumenti imprimis par"ticipem, distincte sciat *" 66 This distinction between Common Sense and Reason is no modern discovery †. The ancient geome * De interpetatione Naturæ, sent. 9. †The vaporùm of the Greek Stoics seems to mean that benevolent affection which men owe to society and to one another. Some modern moralists have called it the Public Sense. But the notion or idea we mean to express by the term Common Sense is quite different, The Sensus Communis of the Latins hath several significations. 1. It denotes this Public Sense, or xovevonporn. See Shaftsbury's Essay on the freedom of wit and humour, part 3. sect. 1. Note, 2. It denotes that experience and knowledge of life which is acquired by living in society. Thus Horace seems to use it, lib. 1. satir. 3. lin. 66. And thus Quintilian speaking of the advantages of a public education; "Sensum ipsum qui communis dicitur, ubi discet, cum se a congressu, "qui non hominibus solum, sed mutis quoque animalibus naturalis est, segregarit;" lib. 1. cap. 2. 3. It seems to signify that instinctive persuasion of truth which arises from intuitive evidence, and is the foundation of all reasoning: 66 66 Corpus enim per se communis deliquat esse Lucretius, lib. 1 ver. 423. |