View. Nor does it conflict with this view that we learn to judge of the true distance of objects, and are often deceived in regard to it. The measurement of distance, the more or less of it, is of course a matter of experience, a thing to be learned by practice. It does not follow, however, that we may not by the eye directly, and at first, perceive an object to be external, and removed from us, in other words distant, though we may not know at first how distant. The rays of light that come to us from this external object, may give us direct perception of the object as external, as extended, and as occupying apparently a given locality in space more or less remote, while at the same time it may be left to other senses and to experience to determine how great that dis tance is. Questions as to Touch.-Passing now from the sense of sight to that of touch, we find similar questions discussed among philosophers respecting the precise information af forded by this sense. Does touch give us immediate perception of externality, extension, form, hardness, softness, etc., including the various mechanical properties of bodies? To this sense it has been common to ascribe these faculties of perception. They are so attributed by Reid, Upham, Wayland, and, I believe, by modern writers generally, with the exception of Brown and Hamilton. It may Probability of another Source of Information. be questioned, I think, whether, as regards some of these qualities at least, it is not rather the consciousness of resist ance to muscular effort, than the sense of touch, properly speaking, that is the informing source. So, for example, as to hardness; the application of an external body lightly to he hand awakens the sense of touch, but conveys no idea of hardness. Let the same object be allowed to rest with gradually increasing weight upon the hand until it becomes painful, and we get the idea of weight, gravitation, but not of the hardness or impenetrability of the object. It is only when our muscular effort to move or penetrate the external body is met and resisted by the same, that we learn the im penetrability of the opposing body. Other Perceptions attributable to the same Source. -So with regard to externality, extension, and form. When an external object, a cube, for example, or an ivory ball, is placed on the palm of the hand, sensation is awakened, but is that sensation necessarily accompanied with the percep tion of the external object as such? Does the mere tactua! sensation, in the first instance, and of itself, inform us that there is something external to ourselves, that what we feel is not a part of our own organism? We are conscious of a change in the sensation of the part affected, but are we immediately conscious that this change is produced by something external? Let there be given, however, the consciousness of resistance to our muscular movements, as when the cube or ball, for instance, prevents the effort to close the hand, or when our locomotion is impeded by the presence of some obstacle, and will not the same resistance inform us of the extension of the resisting body, and so of its form and figure? We learn whereabout in space this resistance occurs, and where it ceases. The tactual sensation would indeed very soon come to our aid in this cognition, and serve as a guiding sense, even in the absence of the former. The question is, whether this alone would, in the first in stance, give us such cognitions? Our first Ideas of Extension, how derived. We have had reference in this discussion only to the qualities of external bodies. There can be little question that our first ideas of extension are derived from our own sentient organism, the consciousness of sensations in different parts of the body, distinct from, and out of each other, thus affording the knowledge of an extended sentient organization. The idea of externality, or outness, and extension, thus acquired, the transition is easy from the perception of our own bodies as possessing these qualities, to the cognizance of the same qualities in external objects. VI.-CREDIBILITY OF OUR SENSATIONS AND PERCEPTIONS. Denied by some. There have always been those who were disposed to call in question the testimony of the senses. Such were the Eleatics and the Skeptics among the Greck philosophers, and there have not been wanting among the moderns minds of acuteness and ingenuity that have fol lowed in the same path. While admitting the phenomena of sense, the appearance of things as being so and so, they have called in question the corresponding objective reality Things appear to me to be thus and thus-such and such impressions are made on my senses that I cannot deny; but how do I know that the reality corresponds to my im. pressions, or, in fact, that there is any reality? How know we our senses to be reliable? What evidence have we that they do not habitually deceive us? Evidence demanded. – It were perhaps a sufficient answer to this question to reply, What evidence have we, or can we have, that they do deceive us? In the absence of all evidence to the contrary, is it not more reasonable to suppose that our perceptions correspond to realities, than that they are without foundation, uncaused, or caused by something not at all answering to the apparent object of perception; more reasonable to suppose that there is a real table or book answering to my perception of one, than that I have the perception while there is no such reality? It remains with those, then, who question and deny the validity of senseperception, to show reasons for such denial. And this be comes the more imperative on them, inasmuch as they contradict the common belief and universal opinion of mankind- nay, what, in spite of all their arguments, is still, by their own confession, their own practical conviction and belief. Evidence impossible. — But whence is this evidence to come? Where is it to be sought? How are we to prove that sense deceives us, except by arguments drawn from sense? And if sense is not reliable in the first instance, why re.y upon it in the second, to prove that it is not re liable? If the senses do habitually deceive us, manifestly it can never be shown that they do. And, even if this could be shown, it would be impossible to find any thing better to rely upon in their stead. We have these guides or We have these instruments of observation provided for the voyage of life. We may pronounce them worthless ud throw them into the sea, but we cannot replace them. none. Inconsistent and contradictory Testimony of Sense.But it may be replied that the testimony of sense is often inconsistent with itself, and contradictory of itself. What is sweet to one is sour and bitter to another. What seems a round tower in the distance becomes a square one as you approach; and the straight stick that you hold in your hand appears crooked when thrust into the water. There is in reality, however, no contradiction or inconsistency in the cases supposed. The change of circumstances accounts in every instance for the change of appearance. In the case of the stick, for example, the different density of the water accounts for the refraction of the rays of light that pass through it, and this accounts for the crooked appearance of the stick that is only partially submerged. So in the other cases; it is no contradiction that an object which appears round at a distance of ten miles, should appear square at the distance of so many rods- or that the taste of two persons should not agree as to the savor of a given object. Deceptions of Sense. It may be further objected that in certain states of the physical organism, sensations are experienced which seem to be of external origin, but are really produced by internal changes; and that in such cases we have the same perceptions, see the same objects, hear the same things, that we should if there were a corresponding external reality, while nevertheless there is no such reality, and it can be proved that there is none. If this may happen in some cases, why not in others, or in all? Reply.I reply, the simpl. fact, that in the case sup posed the deception can be detected and proved, shows the difference between that and ordinary perception. If the senses were not habitually reliable, we could not detect the mistake in this particular instance. If all coin were counterfeit, how could we detect a counterfeit coin? We know, moreover, how to account for the mistake in the case before us. It occurs, by the supposition, only in a certain state of he organism, that is, only in a diseased, abnormal condition of the system. The exception proves the rule. Distinction of direct and indirect Testimony. - A dis tinction is to be made, in the discussion of this subject, be tween the direct and indirect testimony of the senses, be tween that which is strictly and properly perception, and that which is only conception, judgment, inference. What I really perceive, for example, in the case of the distant tower, or the stick partially under water, is only a given appearance; I infer from that appearance that the tower is round and the stick crooked, and in that inference I am mistaken. My judgment is at fault here, and not my senses. They testified truly and correctly. They gave the real appearance, and this was all they could give, all they ever give. This has been well stated by Dr. Reid, and, long before him, the same ground was taken, in reply to the same objection, by Aristotle and also by Epicurus. - Direct Perception gives what. In regard to direct and immediate perception, the case is different. Here the testimony is positive to the existence of the object. When something resists my voluntary movement, I am conscious of that resistance, conscious of something external and resisting. I cannot. deny the fact of that consciousness. I nay, however, deny the correctness, the truthfulness of what consciousness affirms. To do this, however, is to put an end to all reasoning on the subject, for, when we give up consciousness as no longer reliable, there is nothing left to fall back upon. If any one chooses to leap from this preci pice, we can only say finis. |