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VI.

Of the inference

to

course; and having found, that after the discovery of SECT. the constant conjunction of any objects, we always draw an inference from one object to another, we shall now examine the nature of that inference, and of from the

Per

impression the transition from the impression to the idea.

the idea. haps 'twill appear in the end, that the necessary connexion depends on the inference, instead of the inference's depending on the necessary connexion.

Since it appears, that the transition from an impression present to the memory or senses to the idea of an object, which we call cause or effect, is founded on past experience, and on our remembrance of their constant conjunction, the next question is, whether experience produces the idea by means of the understanding or imagination; whether we are determined by reason to make the transition, or by a certain association and relation of perceptions. If reason determined us, it would proceed upon that principle, that instances, of which we have had no experience, must resemble those of which we have had experience, and that the course of nature continues always uniformly the same, In order, therefore, to clear up this matter, let us consider all the arguments upon which such a proposition may be supposed to be founded; and as these must be derived either from knowledge or probability, let us cast our eye on each of these degrees of evidence, and see whether they afford any just conclusion of this nature.

Our foregoing method of reasoning will easily convince us, that there can be no demonstrative arguments to prove, that those instances of which we have had no experience resemble those of which we have had experience. We can at least conceive a change in the course of nature; which sufficiently proves that such a

III.

PART change is not absolutely impossible. To form a clear

idea of any thing is an undeniable argument for its possibility, and is alone a refutation of any pretended

Of

knowledge demonstration against it.

probability

Probability, as it discovers not the relations of ideas, considered as such, but only those of objects, must in some respects be founded on the impressions of our memory and senses, and in some respects on our ideas. Were there no mixture of any impression in our probable reasonings, the conclusion would be entirely chimerical: and were there no mixture of ideas, the action of the mind, in observing the relation, would, properly speaking, be sensation, not reasoning. 'Tis therefore necessary, that in all probable reasonings there be something present to the mind, either seen or remembered; and that from this we infer something connected with it, which is not seen nor remembered.

The only connexion or relation of objects, which can lead us beyond the immediate impressions of our memory and senses, is that of cause and effect; and that because 'tis the only one, on which we can found a just inference from one object to another. The idea of cause and effect is derived from experience, which informs us, that such particular objects, in all past instances, have been constantly conjoined with each other : and as an object similar to one of these is supposed to be immediately present in its impression, we thence presume on the existence of one similar to its usual attendant. According to this account of things, which is, I think, in every point unquestionable, probability is founded on the presumption of a resemblance betwixt those objects of which we have had experience, and those of which we have had none; and

VI.

Of the

to the idea.

therefore 'tis impossible this presumption can arise from SECT. probability. The same principle cannot be both the cause and effect of another; and this is, perhaps, the

inference only proposition concerning that relation, which is from the either intuitively or demonstratively certain.

impresssion Should any one think to elude this argument; and without determining whether our reasoning on this subject be derived from demonstration or probability, pretend that all conclusions from causes and effects are built on solid reasoning: I can only desire that this reasoning may be produced, in order to be exposed to our examination. It may perhaps be said, that after experience of the constant conjunction of certain objects, we reason in the following manner. Such an object is always found to produce another. 'Tis impossible it could have this effect, if it was not endowed with a power of production. The power necessarily implies the effect; and therefore there is a just founda- . tion for drawing a conclusion from the existence of one object to that of its usual attendant. duction implies a power : the power implies a new production: and the new production is what we infer from the power and the past production.

'Twere easy for me to show the weakness of this reasoning, were I willing to make use of those observations I have already made, that the idea of production is the same with that of causation, and that no existence certainly and demonstratively implies a power in any other object; or were it proper .to anticipate what I shall have occasion to remark afterwards concerning the idea we form of power and efficacy. But as such a method of proceeding may seem either to weaken my system, by resting one part of it on another, or to breed a confusion in my reasoning, I shall

The past pro

III.

Of

PART endeavour to maintain my present assertion without any

such assistance.

It shall therefore be allowed for a moment, that the knowledge

and production of one object by another in any one instance probability.

implies a power; and that this power is connected with its effect. But it having been already proved, that the power lies not in the sensible qualities of the cause; and there being nothing but the sensible qualities present to us; I ask, why in other instances you presume that the same power still exists, merely upon the appearance of these qualities? Your appeal to past experience decides nothing in the present case; and at the utmost can only prove, that that very object, which produced any other, was at that very instant endowed with such a power; but can never prove, that the same power must continue in the same object or collection of sensible qualities ; much less, that a like power is always conjoined with like sensible qualities. Should it be said, that we have experience, that the same power continues united with the same object, and that like objects are endowed with like powers, I would renew my question, why from this experience we form any conclusion beyond those past instances, of which we have had experience? If you answer this question in the same manner as the preceding, your answer gives still occasion to a new question of the same kind, even in infinitum ; which clearly proves, that the foregoing reasoning had no just foundation.

Thus, not only our reason fails us in the discovery of the ultimate connexion of causes and effects, but even after experience has informed us of their constant conjunction, 'tis impossible for us to satisfy ourselves by our reason, why we should extend that experience beyond those particular instances which have fallen

SECT.

VI.

to

under our observation. We suppose, but are never able to prove, that there must be a resemblance betwixt those objects, of which we have had experience, of the and those which lie beyond the reach of our discovery. from the

kimpression We have already taken notice of certain relations,

the idea. which make us pass from one object to another, even though there be no reason to determine us to that transition; and this we may establish for a general rule, that wherever the mind constantly and uniformly makes a transition without any reason, it is influenced by these relations. Now, this is exactly the present case. Reason can never show us the connexion of one object with another, though aided by experience, and the observation of their constant conjunction in all past instances. When the mind therefore passes from the idea or impression of one object to the idea or belief of another, it is not determined by reason, but by certain principles, which associate together the ideas of these objects, and unite them in the imagination. Had ideas no more union in the fancy, than objects seem to have to the understanding, we could never draw any inference from causes to effects, nor repose belief in any matter of fact. The inference therefore depends sole

! ly on the union of ideas.

The principles of union among ideas, I have reduced to three general ones, and have asserted, that the idea or impression of any object naturally introduces the idea of any other object, that is resembling, contiguous to, or connected with it. These principles I allow to be neither the infallible nor the sole causes of an union among ideas. . They are not the infallible causes. For one may fix his attention during some time on any one object without looking farther. They are not the sole causes. For the thought has evident

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