Source of Doubt.
1. The doubt comes from misleading representations of the relativity of knowledge. Unquestionably there is a sense in which our knowledge may justly be said to be "relative." It is not absolute, unconditioned or unlimited. We can know only as we have facilities for knowing, and under the conditions and aspects in which objects are presented to them. We are restricted to the modes and degrees of our given capacities. There are probably many realities about us of which we can know nothing. We have no organs for their perception. Even the things that we do know reach off into transcendent relations. Philosophy has long confessed the relative character of our knowledge. Even the percepts of sense-experience, say for instance, of sight or hearing, when analyzed in physical science are found to be, in their objective cause or material conditions, somewhat different from the simple report of the organ of sense—color being the subjective sensation of light-rays on the retina of the eye, and sound the effect of vibrations of the atmosphere upon the sensorium. But in recent times various theories have represented our knowing faculties as largely untrustworthy and their data as invalid in spheres where their functions appear most certain and explicit. Locke gave basis for a movement in this direction by teaching that the immediate objects of the mind are not things, but "ideas." Berkeley's idealism repudiated the sufficiency of sense-perception to prove the objective existence of the material world. Hume questioned the substantial existence of both matter and mind. In the view of Kant human knowledge reaches only to "phenomena," the appearance of things, while the things as they are "in themselves" can not be known. The mind projects and imposes its own subjective forms of thought upon the universe. Sir Wm. Hamilton, Dean Mansel, J. S. Mill, Alexander Bain and Herbert Spencer have developed theories, variously modified but agreeing in this, that even our necessary forms of rational perception are not to be held as standing for more than relative truth, i. e. subjective impressions in our minds in the presence of environment. Doubt is cast upon the point whether what is true to our necessary or actual thought is also really true for the objective world.
The teaching will be best understood by several quotations. Sir Wm. Hamilton, though a natural realist, influenced by the speculations of Kant, while acknowledging an underlying reality for phenomena, taught that we can never know them except "under modifications determined by our own faculties."[33]
J. S. Mill, going further, says: "Our knowledge of objects, and even our fancies about objects, consist in nothing but the sensations they excite, or which we imagine them exciting in ourselves.... This knowledge is merely phenomenal.... The object is known to us only in one special relation, namely, as that which produces, or is capable of producing certain impressions on our senses; and all that we really know is these impressions."[34]
Herbert Spencer asserts the relativity of all knowledge, and says: "Clearly as we seem to know it, our apparent knowledge proves on examination to be utterly irreconcilable with itself. Ultimate religious ideas and ultimate scientific ideas, alike turn out to be merely symbols of the actual, not cognitions of it."[35]
Plainly these theories do not make our knowledge a genuine apprehension of reality, but merely internal and unreliable mental states. It is only a subjective phenomenon. We cannot know that it stands for the real truth of things. Rather, we are told, it does not. It is but an effect within the mind, determined, it may be, by things without, but modified, if not created, by the constitution and action of the mind itself. The receiving mind, like the receiving lens, determines the shape and color of the apprehended phenomenon. If there be any reality behind it and correspondent to it, we can never assure ourselves of it. The theory thoroughly discredits the trustworthiness of our faculties, both of sense-perception and of reason. They do not report the things of the world as they really are, but merely as they affect us. Our necessary conceptions, such as time, space, beauty, cause, moral law, cannot be proved to be anything else than phenomena within us. The conclusion is well stated in the language of Mr. Grote in his explanation of the views of the Greek sophists: "As things appear to me, so they are to me; as they appear to you, so they are to you."[36] It is altogether a subjective matter. We can have only a relative morality—not conformed to an objective and universal standard, but to the particular impressions we find within us.
Evidently this doctrine of relativity lands us in universal intellectual skepticism. It gives us agnosticism. Nothing is sure in a single department of knowledge. If our minds are forever presenting to us internal "forms of thought" that stand not really for the "forms of being" in the real world, if they are actually creating or painting for us what we seem to perceive and what appear to be realities objective to our faculties and existing independently of them, there is no possibility of reaching truth of any kind. But in the domain of morals this theory would prove peculiarly destructive. If the qualities of right and wrong be not in very truth real, if they be not verities of conduct in the constituted relations of human life, if the ideas answer not to a true distinction set before us for our recognition and conformity, then virtue is a dream, obligation an illusion, and conscience a fraud.
Over against this false we must place the true conception of the relativity of knowledge. We must hold, as the spontaneous sense of mankind and the best sustained psychology and philosophy of the centuries affirm, that our cognitive powers are genuine faculties for discerning the truth of things, that, while not infallible nor unlimited, they give us substantially correct knowledge, as far as it goes, of the realities of the natural and moral world in which we are placed. These powers of intelligence are not set to act delusively and imprison us in phantasmagoria or a factitious system false to that which actually exists. The correct theory, the only one that is really rational and can be lived out, must ever be that, as far as we have faculties to know at all and use them loyally, we know what is and because it is. The true reason of our knowing is the real existence of knowable realities.[37] Instead of knowing only appearances, we know the very things that appear—not perfectly, or without possibility of mistake, but yet truly. The end of knowledge is not to give us a phantasmagorical world for endless illusion, but the actual world, with its divine constitution and movement, in which we are to live, and with whose facts and laws, physical and moral, we are to harmonize our lives.
2. The false conception of the relativity of knowledge being thus set aside, and the psychological law, that the correlate of knowing is reality, being recognized, we are prepared to see the truth on the point of inquiry in this chapter, as follows:
Objective Reality.