LETTER XIX.

THEORIES OF PERCEPTION CONTINUED. -KANT.

AFTER having followed me through an examination of the doctrines of Hobbes, Locke, Berkeley, Hume, D'Alembert, and Stewart on the perception of external objects, I fear you will scarcely have patience to encounter a repetition of the scrutiny directed to the analogous doctrines of Kant.

It is, however, of some importance, I think, to take his mode of presenting the question into consideration, and to put a succinct exposure of its fallacies on record. At the same time, if you feel weary of these vain speculations raised about a very simple matter, you will not lose much by skipping over the whole of the present Letter and the one immediately following, as they will contain little but a renewed examination of assumptions and assertions already disposed of, under a different form.

For the sake of perspicuity as well as to relieve the close attention required by these abstruse questions, I purpose to notice, first, Kant's negative doctrine (if I may so term it) respecting the nature of our perception or knowledge of external things; and, secondly, his positive doctrine respecting the action of our minds upon them.

In pursuance of this plan, I will devote the present Letter to his doctrine respecting our knowledge of the external world.

Following after Locke, he maintains in various forms of expression, but with more thoroughness and consistency than the English philosopher, that we have, in reality, no knowledge of external things.

Sometimes he tells us that we perceive only phenomena, not things in themselves; or, as he himself expresses it, "that all our intuition is nothing but the representation of phenomenon ;" "that the things which we envisage [perceive through the senses] are not that in themselves for which we take them." Again he affirms, "We know nothing but our manner of perceiving them;" "what the objects would be in themselves would still never be known by the clearest cognition of their phenomenon, which alone is given to us.' He proceeds to say, that "by our sensibility [i. e. through our organs of sense], we are not acquainted merely obscurely, but not at all, with the quality of things in themselves; and so soon as we remove our subjective quality [i. e. the percipient faculty or mind], the represented object, together with the properties which the sensible intuition attributed to it, is not to be met with anywhere; neither can it be met with, since this very subjective quality determines the form of the object as phenomenon."

* Critick of Pure Reason, p. 47.

*

Here he describes in various phrases the process of perception, or rather non-perception, through the organs of sense; but in all of them there are inconsistency and confusion of thought on the very surface.

He speaks of things as existing, yet tells us that we are incapable of perceiving or knowing them: we know only their phenomena, and they are not that in themselves for which we take them. But (to repeat an argument I have already used), if we are acquainted only with phenomena, how can we speak without self-contradiction of anything else? How can we find out that objects which we cannot know have any existence at all? How can we tell that what we perceive are only phenomena, and not real things, when, to distinguish between phenomena and real things, we must perceive not only the former, but the latter, which, we are told in the same breath, we are incapable of doing? Thus, if you say with Kant, that you perceive only phenomena, you subject yourself to the reply that it is impossible for you to tell that they are not realities, since you have nothing to compare them with; and as it is not worth while contending about a name, you may as well call them realities at

once.

To the assertion that the things which we perceive are not in themselves what we take them to be-in other words, that the realities are unlike their phenomena, which is only the same doc

trine in different phrase-a similar argument applies.

You can tell whether two things are alike or unlike only by perceiving them both, or having a knowledge of both. If you confess that you know nothing at all of one, you are plainly not in a condition to pronounce whether it is like or unlike the other: if you are not acquainted with the original, you cannot judge of the resemblance or want of resemblance in the copy.

Another strange position in the preceding passage is, that "we know nothing but our manner of perceiving objects," which, if not inconsistent with his other assertions, is at least equally self-contradictory. Knowing our manner of perceiving objects implies that we do perceive them, otherwise we assuredly could not know the manner of it. Mark, too, the assertion that, as soon as we remove our subjective quality, the represented object with its properties, is not and cannot be met with anywhere. Met with? By whom? "Meeting with " is the act of a percipient being, and, consequently, the assertion implies that, if we turn away from the object, it straightway becomes imperceptible not only to ourselves, but to any "subjective quality" that might go in search of it. On this theory every object would be created afresh in every act of perception, which is carrying the matter farther even than it was carried by Berkeley, who being put to a strait by the suppo

sition that an idea would be annihilated when it ceased to be perceived by your mind or mine, adroitly took refuge in the allegation that this by no means followed, since it might be perceived by some other mind.

It is worth while to advert more particularly to the proposition often reiterated by Kant, that we cannot know things in themselves a proposition extensively accepted by modern philosophers.

This is, in my view, a perfectly unmeaning assertion. We cannot form the slightest conception of knowing external things, except as we do know them, i. e. through the organs of sense. Do you demur at this? Then be so good as to tell me the precise signification of knowing things in themselves; give me a specimen of that sort of knowledge we have not; and point out how you have gained so curious a piece of transcendental information.

No one manifestly is entitled to deny that our knowledge is of things in themselves, unless he not only possesses the sort of knowledge which he denies to others, and has found on comparison that we the rest of the human race-have only a knowledge of things as they are not in themselves, but actually produces it for our examination. Till that is done, assertions about knowing things in themselves must be regarded as utterly without meaning.

Hobbes, whose doctrine, as we have seen, agrees