Front Page Titles (by Subject) V.—: OF CERTAIN LAWS OF BELIEF, INSEPARABLY CONNECTED WITH THE EXERCISE OF CONSCIOUSNESS, MEMORY, PERCEPTION, AND REASONING - Selections from the Scottish Philosophy of Common Sense
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V.—: OF CERTAIN LAWS OF BELIEF, INSEPARABLY CONNECTED WITH THE EXERCISE OF CONSCIOUSNESS, MEMORY, PERCEPTION, AND REASONING - Thomas Reid, Selections from the Scottish Philosophy of Common Sense 
Selections from the Scottish Philosophy of Common Sense, edited, with an introduction by G.A. Johnston (Chicago: Open Court, 1915).
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OF CERTAIN LAWS OF BELIEF, INSEPARABLY CONNECTED WITH THE EXERCISE OF CONSCIOUSNESS, MEMORY, PERCEPTION, AND REASONING
1. It is by the immediate evidence of consciousness that we are assured of the present existence of our various sensations, whether pleasant or painful; of all our affections, passions, hopes, fears, desires, and volitions. It is thus, too, we are assured of the present existence of those thoughts which, during our waking hours, are continually passing through the mind, and of all the different effects which they produce in furnishing employment to our intellectual faculties.
According to the common doctrine of our best philosophers, it is by the evidence of consciousness we are assured that we ourselves exist. The proposition, however, when thus stated, is not accurately true; for our own existence (as I have elsewhere observed) is not a direct or immediate object of consciousness, in the strict and logical meaning of that term. We are conscious of sensation, thought, desire, volition; but we are not conscious of the existence of Mind itself; nor would it be possible for us to arrive at the knowledge of it, (supposing us to be created in the full possession of all the intellectual capacities which belong to human nature), if no impression were ever to be made on our external senses. The moment that, in consequence of such an impression, a sensation is excited, we learn two facts at once,—the existence of the sensation, and our own existence as sentient beings;—in other words, the very first exercise of consciousness necessarily implies a belief, not only of the present existence of what is felt, but of the present existence of that which feels and thinks: or (to employ plainer language) the present existence of that being which I denote by the words I and myself. Of these facts, however, it is the former alone of which we can properly be said to be conscious, agreeably to the rigorous interpretation of the expression. A conviction of the latter, although it seems to be so inseparable from the exercise of consciousness that it can scarcely be considered as posterior to it in the order of time, is yet (if I may be allowed to make use of a scholastic distinction) posterior to it in the order of nature; not only as it supposes consciousness to be already awakened by some sensation, or some other mental affection; but as it is evidently rather a judgment accompanying the exercise of that power, than one of its immediate intimations concerning its appropriate class of internal phenomena. It appears to me, therefore, more correct to call the belief of our own existence a concomitant or accessory of the exercise of consciousness, than to say, that our existence is a fact falling under the immediate cognizance of consciousness, like the existence of the various agreeable or painful sensations which external objects excite in our minds.
2. That we cannot, without a very blameable latitude in the use of words, be said to be conscious of our personal identity, is a proposition still more indisputable; inasmuch as the very idea of personal identity involves the idea of time, and consequently presupposes the exercise not only of consciousness, but of memory. The belief connected with this idea is implied in every thought and every action of the mind, and may be justly regarded as one of the simplest and most essential elements of the understanding. Indeed, it is impossible to conceive either an intellectual or an active being to exist without it. It is, however, extremely worthy of remark, with respect to this belief that, universal as it is among our species, nobody but a metaphysician ever thinks of expressing it in words, or of reducing into the shape of a proposition the truth to which it relates. To the rest of mankind, it forms not an object of knowledge; but a condition or supposition, necessarily and unconsciously involved in the exercise of all their faculties. On a part of our constitution, which is obviously one of the last or primordial elements at which it is possible to arrive in analyzing our intellectual operations, it is plainly unphilosophical to suppose that any new light can be thrown by metaphysical discussion. All that can be done with propriety, in such cases, is to state the fact.
And here, I cannot help taking notice of the absurd and inconsistent attempts which some ingenious men have made, to explain the gradual process by which they suppose the mind to be led to the knowledge of its own existence, and of that continued identity which our constitution leads us to ascribe to it. How (it has been asked) does a child come to form the very abstract and metaphysical idea expressed by the pronoun I or moi? In answer to this question, I have only to observe, that when we set about the explanation of a phenomenon, we must proceed on the supposition that it is possible to resolve it into some more general law or laws with which we are already acquainted. But, in the case before us, how can this be expected, by those who consider that all our knowledge of mind is derived from the exercise of reflection; and that every act of this power implies a conviction of our own existence as reflecting and intelligent beings? Every theory, therefore, which pretends to account for this conviction, must necessarily involve that sort of paralogism which logicians call a petitio principii; inasmuch as it must resolve the thing to be explained into some law or laws, the evidence of which rests ultimately on the assumption in question. From this assumption, which is necessarily implied in the joint exercise of consciousness and memory, the philosophy of the human mind, if we mean to study it analytically, must of necessity set out; and the very attempt to dig deeper for its foundation, betrays a total ignorance of the logical rules, according to which alone it can ever be prosecuted with any hopes of success.
It was, I believe, first marked by M. Prévost of Geneva, (and the remark, obvious as it may appear, reflects much honour on his acuteness and sagacity), that the inquiries concerning the mind, founded on the hypothesis of the animated statue—inquiries which both Bonnet and Condillac professed to carry on analytically—were in truth altogether synthetical. To this criticism it may be added, that their inquiries, in so far as they had for their object to explain the origin of our belief of our own existence, and of our personal identity, assumed, as the principles of their synthesis, facts at once less certain and less familiar than the problem which they were employed to resolve.
Nor is it to the metaphysician only that the ideas of identity and of personality are familiar. Where is the individual who has not experienced their powerful influence over his imagination, while he was employed in reflecting on the train of events which have filled up the past history of his life; and on that internal world, the phenomena of which have been exposed to his own inspection alone? On such an occasion, even the wonders of external nature seem comparatively insignificant; and one is tempted, (with a celebrated French writer), in contemplating the spectacle of the universe, to adopt the words of the Doge of Genoa, when he visited Versailles—“Ce qui m’étonne le plus ici, c’est de m’y voir.”1
3. The belief which all men entertain of the existence of the material world, (I mean their belief of its existence independently of that of percipient beings,) and their expectation of the continued uniformity of the laws of nature, belong to the same class of ultimate or elemental laws of thought, with those which have been just mentioned. The truths which form their objects are of an order so radically different from what are commonly called truths, in the popular acceptation of that word, that it might perhaps be useful for logicians to distinguish them by some appropriate appellation, such, for example, as that of metaphysical or transcendental truths. They are not principles or data (as will afterwards appear) from which any consequence can be deduced; but form a part of those original stamina of human reason, which are equally essential to all the pursuits of science, and to all the active concerns of life.
4. I shall only take notice farther, under this head, of the confidence which we must necessarily repose in the evidence of memory, (and, I may add, in the continuance of our personal identity,) when we are employed in carrying on any process of deduction or argumentation,—in following out, for instance, the steps of a long mathematical demonstration. In yielding our assent to the conclusion to which such a demonstration leads, we evidently trust to the fidelity with which our memory has connected the different links of the chain together. The reference which is often made, in the course of a demonstration, to propositions formerly proved, places the same remark in a light still stronger; and shews plainly that, in this branch of knowledge, which is justly considered as the most certain of any, the authority of the same laws of belief which are recognised in the ordinary pursuits of life is tacitly acknowledged. Deny the evidence of memory as a ground of certain knowledge, and you destroy the foundations of mathematical science as completely as if you were to deny the truth of the axioms assumed by Euclid.
The foregoing examples sufficiently illustrate the nature of that class of truths which I have called Fundamental Laws of Human Belief, or Primary Elements of Human Reason. A variety of others, not less important, might be added to the list;1 but these I shall not at present stop to enumerate, as my chief object, in introducing the subject here, was to explain the common relation in which they all stand to deductive evidence. In this point of view, two analogies, or rather coincidences, between the truths which we have been last considering, and the mathematical axioms which were treated of formerly, immediately present themselves to our notice.
1. From neither of these classes of truths can any direct inference be drawn for the farther enlargement of our knowledge. This remark has been already shewn to hold universally with respect to the axioms of geometry, and it applies equally to what I have called Fundamental Laws of Human Belief. From such propositions as these—I exist; I am the same person to-day that I was yesterday; the material world has an existence independent of my mind; the general laws of nature will continue, in future, to operate uniformly as in time past—no inference can be deduced, any more than from the intuitive truths prefixed to the Elements of Euclid. Abstracted from other data, they are perfectly barren in themselves; nor can any possible combination of them help the mind forward one single step in its progress. It is for this reason that, instead of calling them, with some other writers, first principles, I have distinguished them by the title of fundamental laws of belief; the former word seeming to me to denote, according to common usage, some fact, or some supposition, from which a series of consequences may be deduced.
If the account now given of these laws of belief be just, the great argument which has been commonly urged in support of their authority, and which manifestly confounds them with what are properly called principles of reasoning, is not at all applicable to the subject; or at least does not rest the point in dispute upon its right foundation. If there were no first principles, (it has been said,) or in other words, if a reason could be given for everything, no process of deduction could possibly be brought to a conclusion. The remark is indisputably true; but it only proves (what no logician of the present times will venture to deny) that the mathematician could not demonstrate a single theorem, unless he were first allowed to lay down his definitions; nor the natural philosopher explain or account for a single phenomenon, unless he were allowed to assume, as acknowledged facts, certain general laws of nature. What inference does this afford in favour of that particular class of truths to which the preceding observations relate, and against which the ingenuity of modern sceptics has been more particularly directed? If I be not deceived, these truths are still more intimately connected with the operations of the reasoning faculty than has been generally imagined; not as the principles (ἀρχαί) from which our reasonings set out, and on which they ultimately depend, but as the necessary conditions on which every step of the deduction tacitly proceeds; or rather (if I may use the expression) as essential elements which enter into the composition of reason itself.
2. In this last remark I have anticipated, in some measure, what I had to state with respect to the second coincidence alluded to, between mathematical axioms, and the other propositions which I have comprehended under the general title of fundamental laws of human belief. As the truth of axioms is virtually presupposed or implied in the successive steps of every demonstration, so, in every step of our reasonings concerning the order of Nature, we proceed on the supposition, that the laws by which it is regulated will continue uniform as in time past; and that the material universe has an existence independent of our perceptions. I need scarcely add, that in all our reasonings whatever, whether they relate to necessary or to contingent truths, our own personal identity, and the evidence of memory, are virtually taken for granted. These different truths all agree in this, that they are essentially involved in the exercise of our rational powers; although, in themselves, they furnish no principles or data by which the sphere of our knowledge can, by any ingenuity, be enlarged. They agree farther in being tacitly acknowledged by all men, learned or ignorant, without any formal enunciation in words, or even any conscious exercise of reflection. It is only at that period of our intellectual progress when scientific arrangements and metaphysical refinements begin to be introduced, that they become objects of attention to the mind, and assume the form of propositions.
In consequence of these two analogies or coincidences, I should have been inclined to comprehend, under the general title of axioms, all the truths which have been hitherto under our review, if the common usage of our language had not, in a great measure, appropriated that appellation to the axioms of mathematics; and if the view of the subject which I have taken, did not render it necessary for me to direct the attention of my readers to the wide diversity between the branches of knowledge to which they are respectively subservient.
I was anxious also to prevent these truths from being all identified, in point of logical importance, under the same name. The fact is, that the one class (in consequence of the relation in which they stand to the demonstrative conclusions of geometry) are comparatively of so little moment, that the formal enumeration of them was a matter of choice rather than of necessity; whereas the other class have unfortunately been raised, by the sceptical controversies of modern times, to a conspicuous rank in the philosophy of the human mind. I have thought it more advisable, therefore, to bestow on the latter an appropriate title of their own; without, however, going so far as to reject altogether the phraseology of those who have annexed to the word axiom a more enlarged meaning than that which I have usually given to it. Little inconvenience, indeed, can arise from this latitude in the use of the term; provided only it be always confined to those ultimate laws of belief, which, although they form the first elements of human reason, cannot with propriety be ranked among the principles from which any of our scientific conclusions are deduced.
Corresponding to the extension which some late writers have given to axioms, is that of the province which they have assigned to intuition; a term which has been applied, by Dr Beattie and others, not only to the power by which we perceive the truth of the axioms of geometry, but to that by which we recognise the authority of the fundamental laws of belief, when we hear them enunciated in language. My only objection to this use of the word is, that it is a departure from common practice; according to which, if I be not mistaken, the proper objects of intuition are propositions analogous to the axioms prefixed to Euclid’s Elements. In some other respects, this innovation might perhaps be regarded as an improvement on the very limited and imperfect vocabulary of which we are able to avail ourselves in our present discussions.1
To the class of truths which I have here called laws of belief, or elements of reason, the title of principles of common sense was long ago given by Father Buffier, whose language and doctrine concerning them bears a very striking resemblance to those of some of our later Scottish logicians. This, at least, strikes me as the meaning which these writers in general annex to the phrase, although all of them have frequently employed it with a far greater degree of latitude. When thus limited in its acceptation, it is obviously liable, in point of scientific accuracy, to two very strong objections, both of which have been already sufficiently illustrated. The first is, that it applies the appellation of principles to laws of belief from which no inference can be deduced; the second, that it refers the origin of these laws to Common Sense. Nor is this phraseology more agreeable to popular use than to logical precision. If we were to suppose an individual, whose conduct betrayed a disbelief of his own existence, or of his own identity, or of the reality of surrounding objects, it would by no means amount to an adequate description of his condition to say, that he was destitute of common sense. We should at once pronounce him to be destitute of reason, and would no longer consider him as a fit subject of discipline or of punishment. The former expression, indeed, would only imply that he was apt to fall into absurdities and improprieties in the common concerns of life. To denominate, therefore, such laws of belief as we have now been considering, constituent elements of human reason, while it seems quite unexceptionable in point of technical distinctness, cannot be justly censured as the slightest deviation from our habitual forms of speech. On the same grounds, it may be fairly questioned, whether the word reason would not, on some occasions, be the best substitute which our language affords for intuition, in that enlarged acceptation which has been given to it of late. If not quite so definite and precise as might be wished, it would be at least employed in one of those significations in which it is already familiar to every ear; whereas the meaning of intuition, when used for the same purpose, is stretched very far beyond its ordinary limits. And in cases of this sort, where we have to choose between two terms, neither of which is altogether unexceptionable, it will be found much safer to trust to the context for restricting in the reader’s mind what is too general, than for enlarging what use has accustomed us to interpret in a sense too narrow.
I must add, too, in opposition to the high authorities of Dr Johnson and Dr Beattie, that for many years past, reason has been very seldom used by philosophical writers, or, indeed, by correct writers of any description, as synonymous with the power of reasoning. To appeal to the light of humanreason from the reasonings of the schools, is surely an expression to which no good objection can be made, on the score either of vagueness or of novelty. Nor has the etymological affinity between these two words the slightest tendency to throw any obscurity on the foregoing expression. On the contrary, this affinity may be of use in some of our future arguments, by keeping constantly in view the close and inseparable connexion which will be afterwards shown to exist between the two different intellectual operations which are thus brought into immediate contrast.1
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[1 ]D’Alembert, Apologie de l’Étude.
[1 ]Such, for example, as our belief of the existence of efficient causes; our belief of the existence of other intelligent beings besides ourselves, etc., etc.
[1 ]According to Locke, we have the knowledge of our own existence by intuition; of the existence of God by demonstration; and of other things by sensation—Book iv. chap. ix. § 2.
[1 ]“Elements of the Philosophy of the Human Mind,” (Works, vol. iii. pp. 40-51).