But here, perhaps, it may be demanded, how it happens, even upon my hypothesis, that these arguments above-explained produce not a total suspense of judgment, and after what manner the mind ever retains a degree of assurance in any subject? For as these new probabilities, which by their repetition perpetually diminish the original evidence, are founded on the very same principles, whether of thought or sensation, as the primary judgment, it may seem unavoidable, that in either case they must equally subvert it, and by the opposition, either of contrary thoughts or sensations, reduce the mind to a total uncertainty. I suppose, there is some question proposed to me, and that after revolving over the impressions of my memory and senses, and carrying my thoughts from them to such objects, as are commonly conjoined with them, I feel a stronger and more forcible conception on the one side, than on the other. This strong conception forms my first decision. I suppose, that afterwards I examine my judgment itself, and observing from experience, that it is sometimes just and sometimes erroneous, I consider it as regulated by contrary principles or causes, of which some lead to truth, and some to error; and in ballancing these contrary causes, I diminish by a new probability the assurance of my first decision.

This new probability is liable to the same diminution as the foregoing, and so on, IN INFINITUM. It is therefore demanded, how it happens, that even after all we retain a degree of belief, which is sufficient for our purpose, either in philosophy or common life.

I answer, that after the first and second decision; as the action of the mind becomes forced and unnatural, and the ideas faint and obscure; though the principles of judgment, and the ballancing of opposite causes be the same as at the very beginning; yet their influence on the imagination, and the vigour they add to, or diminish from the thought, is by no means equal. Where the mind reaches not its objects with easiness and facility, the same principles have not the same effect as in a more natural conception of the ideas; nor does the imagination feel a sensation, which holds any proportion with that which arises from its common judgments and opinions. The attention is on the stretch: The posture of the mind is uneasy; and the spirits being diverted from their natural course, are not governed in their movements by the same laws, at least not to the same degree, as when they flow in their usual channel.

If we desire similar instances, it will not be very difficult to find them. The present subject of metaphysics will supply us abundantly. The same argument, which would have been esteemed convincing in a reasoning concerning history or politics, has little or no influence in these abstruser subjects, even though it be perfectly comprehended; and that because there is required a study and an effort of thought, in order to its being comprehended: And this effort of thought disturbs the operation of our sentiments, on which the belief depends. The case is the same in other subjects. The straining of the imagination always hinders the regular flowing of the passions and sentiments.

A tragic poet, that would represent his heroes as very ingenious and witty in their misfortunes, would never touch the passions. As the emotions of the soul prevent any subtile reasoning and reflection, so these latter actions of the mind are equally prejudicial to the former. The mind, as well as the body, seems to be endowed with a certain precise degree of force and activity, which it never employs in one action, but at the expense of all the rest. This is more evidently true, where the actions are of quite different natures; since in that case the force of the mind is not only diverted, but even the disposition changed, so as to render us incapable of a sudden transition from one action to the other, and still more of performing both at once. No wonder, then, the conviction, which arises from a subtile reasoning, diminishes in proportion to the efforts, which the imagination makes to enter into the reasoning, and to conceive it in all its parts.

Belief, being a lively conception, can never be entire, where it is not founded on something natural and easy.

This I take to be the true state of the question, and cannot approve of that expeditious way, which some take with the sceptics, to reject at once all their arguments without enquiry or examination. If the sceptical reasonings be strong, say they, it is a proof, that reason may have some force and authority: if weak, they can never be sufficient to invalidate all the conclusions of our understanding. This argument is not just; because the sceptical reasonings, were it possible for them to exist, and were they not destroyed by their subtility, would be successively both strong and weak, according to the successive dispositions of the mind. Reason first appears in possession of the throne, prescribing laws, and imposing maxims, with an absolute sway and authority. Her enemy, therefore, is obliged to take shelter under her protection, and by making use of rational arguments to prove the fallaciousness and imbecility of reason, produces, in a manner, a patent under her and and seal.

This patent has at first an authority, proportioned to the present and immediate authority of reason, from which it is derived. But as it is supposed to be contradictory to reason, it gradually diminishes the force of that governing power and its own at the same time; till at last they both vanish away into nothing, by a regulax and just diminution. The sceptical and dogmatical reasons are of the same kind, though contrary in their operation and tendency; so that where the latter is strong, it has an enemy of equal force in the former to encounter; and as their forces were at first equal, they still continue so, as long as either of them subsists; nor does one of them lose any force in the contest, without taking as much from its antagonist. It is happy, therefore, that nature breaks the force of all sceptical arguments in time, and keeps them from having any considerable influence on the understanding. Were we to trust entirely to their self-destruction, that can never take place, until they have first subverted all conviction, and have totally destroyed human reason.

Thus the sceptic still continues to reason and believe, even though he asserts, that he cannot defend his reason by reason; and by the same rule he must assent to the principle concerning the existence of body, though he cannot pretend by any arguments of philosophy to maintain its veracity. Nature has not left this to his choice, and has doubtless, esteemed it an affair of too great importance to be trusted to our uncertain reasonings and speculations. We may well ask, What causes induce us to believe in the existence of body? but it is in vain to ask, Whether there be body or not? That is a point, which we must take for granted in all our reasonings.

The subject, then, of our present enquiry is concerning the causes which induce us to believe in the existence of body: And my reasonings on this head I shall begin with a distinction, which at first sight may seem superfluous, but which will contribute very much to the perfect understanding of what follows. We ought to examine apart those two questions, which are commonly confounded together, viz. Why we attribute a continued existence to objects, even when they are not present to the senses; and why we suppose them to have an existence DISTINCT from the mind and perception. Under this last head I comprehend their situation as well as relations, their external position as well as the independence of their existence and operation. These two questions concerning the continued and distinct existence of body are intimately connected together.

For if the objects of our senses continue to exist, even when they are not perceived, their existence is of course independent of and distinct from the perception: and vice versa, if their existence be independent of the perception and distinct from it, they must continue to exist, even though they be not perceived. But though the decision of the one question decides the other; yet that we may the more easily discover the principles of human nature, from whence the decision arises, we shall carry along with us this distinction, and shall consider, whether it be the senses, reason, or the imagination, that produces the opinion of a continued or of a distinct existence. These are the only questions, that are intelligible on the present subject. For as to the notion of external existence, when taken for something specially different from our perceptions,[1] we have already shewn its absurdity.

[1] Part. II. Sect. 6.

To begin with the SENSES, it is evident these faculties are incapable of giving rise to the notion of the continued existence of their objects, after they no longer appear to the senses. For that is a contradiction in terms, and suppose that the senses continue to operate, even after they have ceased all manner of operation. These faculties, therefore, if they have any influence in the present case, must produce the opinion of a distinct, not of a continued existence; and in order to that, must present their impressions either as images and representations, or as these very distinct and external existences.

That our senses offer not their impressions as the images of something distinct, or independent, and external, is evident; because they convey to us nothing but a single perception, and never give us the least intimation of any thing beyond. A single perception can never produce the idea of a double existence, but by some inference either of the reason or imagination. When the mind looks farther than what immediately appears to it, its conclusions can never be put to the account of the senses; and it certainly looks farther, when from a single perception it infers a double existence, and supposes the relations of resemblance and causation betwixt them.

If our senses, therefore, suggest any idea of distinct existences, they must convey the impressions as those very existences, by a kind of fallacy and illusion. Upon this bead we may observe, that all sensations are felt by the mind, such as they really are, and that when we doubt, whether they present themselves as distinct objects, or as mere impressions, the difficulty is not concerning their nature, but concerning their relations and situation. Now if the senses presented our impressions as external to, and independent of ourselves, both the objects and ourselves must be obvious to our senses, otherwise they could not be compared by these faculties. The difficulty, then, is how fax we are ourselves the objects of our senses.

It is certain there is no question in philosophy more abstruse than that concerning identity, and the nature of the uniting principle, which constitutes a person. So far from being able by our senses merely to determine this question, we must have recourse to the most profound metaphysics to give a satisfactory answer to it; and in common life it is evident these ideas of self and person are never very fixed nor determinate. It is absurd, therefore, to imagine the senses can ever distinguish betwixt ourselves and external objects.