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Sect. II. Of deductive evidence.

mind, with all their modifications, operations, and effects. By the first, we must acknowledge, when applied to things, and combined with the discoveries of the second, our researches into nature in a certain line are facilitated, the understanding is enlightened, and many of the arts, both elegant and useful, are improved and perfected. Without the aid of the second, society must not only suffer, but perish. Human nature itself could not subsist. This organ of Rnowledge, which extends its influence to every precinct of philosophy, and governs in most, serves also to regulate all the ordinary, but indispensable concernments of life. To these it is admirably adapted, notwithstanding its inferiority in respect of dignity, accuracy, and perspicuity. For it is principally to the acquisitions procured by experience, that we owe the use of language, and the knowledge of almost every thing that makes the soul of a man differ from that of a new-born infant. On the other hand, there is no despot so absolute, as not be liable to a check on some side or other, and that the prerogatives of demonstration are not so very considerable, as on a cursory view one is apt to imagine; that this, as well as every other operation of the intellect, must partake in the weakness incident to all our mental faculties, and inseparable from our nature, I shall afterwards take an opportunity particulary to evince,

PART II...The nature and origin of Experience.

I should now consider the principal tribes compre,

Part II. The nature and origin of experience.

hended under the general name of moral evidence: but, that every difficulty may be removed, which might retard our progress in the proposed discussion, it will be necessary, in the first place, to explore more accurately those sources in our nature, which give being to experience, and, consequently, to all those attainments, moral and intellectual, that are derived from it. These sources are two, sense and memory. The senses, both external and internal, are the original inlets of perception. They inform the mind of the facts which, in the present instant, are situated within the sphere of their activity, and no sooner discharge their office in any particular instance, than the articles of information exhibited by them, are devolved on the memory. Remembrance instantly succeeds sensation, insomuch that the memory becomes the sole repository of the knowledge received from sense; knowledge which, without this repository, would be as instantaneously lost as it is gotten, and could be of no service to the mind. Our sensations would be no better than the fleeting pictures of a moving object on a camera obscura, which leave not the least vestige behind them. Memory, therefore, is the original voucher extant, of those past realities for which we had once the evidence of sense. Her ideas are, as it were, the prints that have been left by sensible impressions. But, from these two faculties, considered in themselves, there results to us the knowledge only of individual facts, and only of such facts as either heretofore have come, or, at present, do come, under the notice of our senses.

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Sect. II. Of deductive evidence.

Now, in order to render this knowledge useful to us, in discovering the nature of things, and in regulating our conduct, a further process of the mind is necessary, which deserves to be carefully attended to, and may be thus illustrated. I have observed a stone fall to the ground when nothing intervened to impede its motion. This single fact produces little or no effect on the mind beyond a bare remembrance. At another time, I observe the fall of a tile, at another, of an apple; and so of almost every kind of body in the like situation. Thus, my senses first, and then my memory, furnish me with numerous examples, which, though different in every other particular, are similar in this, that they present a body moving downwards till ob-, structed either by the ground, or by some intervenient object. Hence my first notion of gravitation. For, with regard to the similar circumstances of different facts, as by the repetition such circumstances are more deeply imprinted, the mind acquires a habit of retaining them, omitting those circumstances peculiar to each, wherein their differences consist. Hence, if objects of any kind in a particular manner circumstanced, are remembered to have been usually, and still more, if uniformly succeeded by certain particular consequences, the idea of the former, in the supposed circumstance introduced into the mind, immediately associates the idea of the latter; and if the object itself, so circumstanced, be presented to the senses, the mind instantly anticipates the appearance of the customary consequence. This holds also inversely. The retention and association above explained, are called Experience. The anticipation is in effect no other than

Part II. The nature and origin of experience.

a particular conclusion from that experience. Here we may remark, by the way, that though memory gives birth to experience, which results from the comparison of facts remembered, the experience or habitual association remains, when the individual facts on which it is founded are all forgotten. I know from an experience, which excludes all doubt, the power of fire in melting silver, and yet may not be able at present to recollect a particular instance in which I have seen this effect produced, or even in which I have had the fact attested by a credible witness.

SoME will perhaps object, that the account now given makes our experimental reasoning look like a sort of mechanism necessarily resulting from the very constitution of the mind. I acknowledge the justness of the remark, but do not think that it ought to be regarded as an objection. It is plain that our reasoning in this way, if you please to call it so, is very early, and precedes all reflection on our faculties, and the manner of applying them. Those who attend to the progress of human nature through its different stages, and through childhood in particular, will observe, that children make great aequisitions in knowledge from experience, long before they attain the use of speech. The beasts also, in their sphere, improve by experience, which hath in them just the same foundation of sense and memory as in us, and hath, besides, a similar influence on their actions. It is precisely in the same manner, and with the same success, that you might train a dog, or accustom a child, to expect food on

sect. II. of deductive evidence.

your calling to him in one tone of vioce, and to dread your resentment, when you use another. The brutes have evidently the rudiments of this species of ratiomality, which extends as far in them as the immediate purposes of self-preservation require, and which, whether you call it reason or instinct, they both acquire and use in the same manner as we do. That it reaches no farther in them, seems to arise from an original incapacity of classing, and (if I may use the expression) generalising their preceptions; an exercise which to us very quickly becomes familiar, and is what chiefly fits us for the use of language. Indeed, in the extent of this capacity, as much perhaps as in any thing, lies also the principal natural superiority of one man over another.

But that we may be satisfied, that to this kind of reasoning, in its earliest and simplest form, little or no reflection is necessary, let it be observed, that it is how universally admitted by opticians, that it is not purely from sight, but from sight aided by experience, that we derive our notions of the distance of visible objects from the eye. The sensation, say they, is instantaneously followed by a conclusion or judgment founded on experience. The point is determined from the different phases of the object, found, in former trials, to be connected with different distances, or from the effort that accompanies the different conformations we are obliged to give the organs of sight, in order to obtain a distinct vision of the object. Now, if this be the case, as I think hath been sufficiently

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