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Of the idea
and effects, 'twill be to little purpose to prove, that an SECT. efficacy is necessary in all operations. We do not understand our own meaning in talking so, but ignorantly confound ideas which are entirely distinct from each other. I am, indeed, ready to allow, that there may connexion. be several qualities, both in material and immaterial objects, with which we are utterly unacquainted; and if we please to call these power or efficacy, 'twill be of little consequence to the world. But when, instead of meaning these unknown qualities, we make the terms of power and efficacy signify something, of which we have a clear idea, and which is incompatible with those objects to which we apply it, obscurity and error begin then to take place, and we are led astray by a false philosophy. This is the case when we transfer the determination of the thought to external objects, and suppose any real intelligible connexion betwixt them; that being a quality which can only belong to the mind that considers them.
As to what may be said, that the operations of nature are independent of our thought and reasoning, I allow it; and accordingly have observed, that objects bear to each other the relations of contiguity and succession; that like objects may be observed, in several instances, to have like relations; and that all this is independent of, and antecedent to, the operations of the understanding. But if we go any farther, and ascribe a power or necessary connexion to these objects, this is what we can never observe in them, but must draw the idea of it from what we feel internally in contemplating them. And this I carry so far, that I am ready to convert my present reasoning into an instance of it, by a subtility which it will not be difficult to comprehend.
When any object is presented to us, it immediately
conveys to the mind a lively idea of that object which Of is usually found to attend it; and this determination knowledge
and of the mind forms the necessary connexion of these probability,
objects. But when we change the point of view from the objects to the perceptions, in that case the impression is to be considered as the cause, and the lively idea as the effect; and their necessary connexion is that new determination, which we feel to pass from the idea of the one to that of the other. The uniting principle among our internal perceptions is as unintelligible as that among external objects, and is not known to us any other way than by experience. Now, the nature and effects of experience have been already sufficiently examined and explained. It never gives us any insight into the internal structure or operating principle of objects, but only accustoms the mind to pass from one to another.
'Tis now time to collect all the different parts of this reasoning, and, by joining them together, form an exact definition of the relation of cause and effect, which makes the subject of the present inquiry. This order would not have been excusable, of first examining our inference from the relation before we had explained the relation itself, had it been possible to proceed in a different method. But as the nature of the relation depends so much on that of the inference, we have been obliged to advance in this seemingly preposterous manner, and make use of terms before we were able exactly to define them, or fix their meaning. We shall now correct this fault by giving a precise definition of cause and effect.
There may two definitions be given of this relation, which are only different by their presenting a differ
Of the idea
ent view of the same object, and making us consider it SECT. either as a philosophical or as a natural relation ; ei
XIV. ther as a comparison of two ideas, or as an association betwixt them. We may define a cause to be “ An object precedent and contiguous to another, and where necessary all the objects resembling the former are placed in like relations of precedency and contiguity to those objects that resemble the latter. If this definition be esteemed defective, because drawn from objects foreign to the cause, we may substitute this other definition in its place, viz. “ A cause is an object precedent and contiguous to another, and so united with it that the idea of the one determines the mind to form the idea of the other, and the impression of the one to form a more lively idea of the other.” Should this definition also be rejected for the same reason, I know no other remedy, than that the persons who express this delicacy should substitute a juster definition in its place. But, for my part, I must own my incapacity for such an undertaking. When I examine, with the utmost accuracy, those objects which are commonly denominated causes and effects, I find, in considering a single instance, that the one object is precedent and contiguous to the other; and in enlarging my view to consider several instances, I find only that like objects are constantly placed in like relations of succession and contiguity. Again, when I consider the influence of this constant conjunction, I perceive that such a relation can never be an object of reasoning, and can never operate upon the mind but by means of custom, which determines the imagination to make a transition from the idea of one object to that of its usual attendant, and from the impression of one to a more lively idea of the other. However extraordinary these sentiments
may appear, I think it fruitless to trouble myself with
any farther inquiry or reasoning upon the subject, but Of knowledge
shall repose myself on them as on established maxims. and
'Twill only be proper, before we leave this subject, probability.
to draw some corollaries from it, by which we may remove several prejudices and popular errors that have very much prevailed in philosophy. First, we may learn, from the foregoing doctrine, that all causes are of the same kind, and that, in particular, there is no foundation for that distinction which we sometimes make betwixt efficient causes, and causes sine qua non; or betwixt efficient causes, and formal, and material, and exemplary, and final causes. For as our idea of efficiency is derived from the constant conjunction of two objects, wherever this is observed, the cause is efficient; and where it is not, there can never be a cause of any kind. For the same reason we must reject the distinction betwixt cause and occasion, when supposed to signify any thing essentially different from each other. If constant conjunction be implied in what we call occasion, 'tis a real cause; if not, 'tis no relation at all, and cannot give rise to any argument or reasoning
Secondly, the same course of reasoning will make us conclude, that there is but one kind of necessity, as there is but one kind of cause, and that the common distinction betwixt moral and physical necessity is without any foundation in nature.
This clearly appears from the precedent explication of necessity. "Tis the constant conjunction of objects, along with the determination of the mind, which constitutes a physical necessity: and the removal of these is the same thing with chance. As objects must either be conjoined or not, and as the mind must either be determined or
Of the idea
not to pass from one object to another, 'tis impos. SECT. :
XIV. sible to admit of any medium betwixt chance and an absolute necessity. In weakening this conjunction and determination you do not change the nature of the necessity; since even in the operation of bodies, these necessary have different degrees of constancy and force, without producing a different species of that relation.
The distinction, which we often make betwixt power and the exercise of it, is equally without foundation.
Thirdly, we may now be able fully to overcome all that repugnance, which 'tis so natural for us to entertain against the foregoing reasoning, by which we endeavoured to prove, that the necessity of a cause to every beginning of existence is not founded on any arguments either demonstratiye or intuitive. Such an opinion will not appear strange after the foregoing definitions. If we define a cause to be an object precedent and contiguous to another, and where all the objects resembling the former are placed in a like relation of priority and contiguity to those objects that resemble the latter ; we may easily conceive that there is no absolute nor metaphysical necessity, that every beginning of existence should be attended with such an object. If we define a cause to be, an object precedent and contiguous to another, and so united with it in the imagination, that the idea of the one determines the mind to form the idea of the other, and the impression of the one to form a more lively idea of the other ; we shall make still less difficulty of assenting to this opinion. Such an influence on the mind is in itself perfectly extraordinary and incomprehensible; nor can we be certain of its reality, but from experience and observation.
I shall add as a fourth corollary, that we can never have reason to believe that any object exists, of which