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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 'tis 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 inquiry, 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.[Pg 246] 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 specifically different from our perceptions, we have already shown its absurdity.[1]
To begin with the senses,'tis 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 supposes 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 head 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 far we are ourselves the objects of our senses.
'Tis 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 'tis evident these ideas of self[Pg 248] and person are never very fixed nor determinate. 'Tis absurd therefore to imagine the senses can ever distinguish betwixt ourselves and external objects.
Add to this, that every impression, external and internal, passions, affections, sensations, pains and pleasures, are originally on the same footing; and that whatever other differences we may observe among them, they appear, all of them, in their true colours, as impressions or perceptions. And indeed, if we consider the matter aright, 'tis scarce possible it should be otherwise; nor is it conceivable that our senses should be more capable of deceiving us in the situation and relations, than in the nature of our impressions. For since all actions and sensations of the mind are known to us by consciousness, they must necessarily appear in every particular what they are, and be what they appear. Every thing that enters the mind, being in reality as the perception, 'tis impossible any thing should to feeling appear different. This were to suppose, that even where we are most intimately conscious, we might be mistaken.
But not to lose time in examining, whether 'tis possible for our senses to deceive us, and represent our perceptions as distinct from ourselves, that is, as external to and independent of us; let us consider whether they really do so, and whether this error proceeds from an immediate sensation, or from some other causes.
To begin with the question concerning external existence, it may perhaps be said, that setting aside the metaphysical question of the identity of a thinking substance, our own body evidently belongs to us; and as several impressions appear exterior to the body, we suppose them also exterior to ourselves. The paper, on which I write at present, is beyond my hand. The[Pg 249] table is beyond the paper. The walls of the chamber beyond the table. And in casting my eye towards the window, I perceive a great extent of fields and buildings beyond my chamber. From all this it may be inferred, that no other faculty is required, beside the senses, to convince us of the external existence of body. But to prevent this inference, we need only weigh the three following considerations. First, that, properly speaking, 'tis not our body we perceive, when we regard our limbs and members, but certain impressions, which enter by the senses; so that the ascribing a real and corporeal existence to these impressions, or to their objects, is an act of the mind as difficult to explain as that which we examine at present. Secondly, sounds, and tastes, and smells, though commonly regarded by the mind as continued independent qualities, appear not to have any existence in extension, and consequently cannot appear to the senses as situated externally to the body. The reason why we ascribe a place to them, shall be considered afterwards.[2] Thirdly, even our sight informs us not of distance or outness (so to speak) immediately and without a certain reasoning and experience, as is acknowledged by the most rational philosophers.
