Philosophia Christi: The External World
In an age of rampant Atheistic Materialism, when most are accustomed to accept implicitly the testimony of the senses, it is almost impossible to accept the suggestion that sense impressions don't accurately represent external qualities and objects. Yet the question of just how far subjective states correspond to objective reality-how far our faculties can be trusted in the search after truth-is obviously of primary importance. Doubtless we've all watched a sunset with its gorgeous manifestation and changing panorama of color. Most of us have also admired a landscape in which nature seemed almost ethereal, or listened to the sound of a rainstorm, or to the roar of waves as they beat against a rock-bound coast. Should science analyze the colors into mere particles, explain away the roar of the ocean as nothing more than wave lengths of air, etc., the objective world becomes a drab and uninspiring place pretty quickly. The scientific knowledge gained won't compensate for the loss of the beauty or power we sensed in nature. The attitude of students of philosophy in regard to the objective value of sense impressions can be classified as the threefold the attitude of the Skeptic, the Idealist, and the Realist. First, the contention of the skeptic is the idea that objective knowledge is impossible, that between states of consciousness and their external causes there may not be the remotest resemblance, that it is impossible to bridge the gulf which separates the subjective from the objective (if in truth the latter has any existence), that under the circumstances doubt is the truest wisdom. An examination, however, of this position demonstrates inconsistency and indeed contradiction. The assertion "doubt is the truest wisdom " is put forward either as:
a) a sure principle, or
b) as a doubtful one, or
c) as neither certain nor doubtful.
If the first supposition is taken, it is clear that a positive and certain principle is laid down in direct contradiction to the fundamental tenet that "nothing is certain," and in the second and third hypotheses the element of doubt is fatal to the value of the statements. The expression of an opinion on the part of the skeptic involves at least three contradictions:
1) he assumes as certain his own existence;
2) he accepts the truth of the principle of contradiction in as much as this principle underlies every statement; and
3) he draws a distinction between knowledge and ignorance, between certainty and doubt.
As a result, Skepticism stands self condemned.
Idealism is a modified form of skepticism. Idealists admit the certainty of states of consciousness. Monistic Idealists recognize the unity of the subject which experiences the states of consciousness in contradistinction to the "pluristic idealism" of Hume and others who held that the succession of conscious states are so many separate experiences without an underlying unity of subject. Monistic Idealism is subdivided according as the percipient subject is believed to be the individual "ego" (subjective monistic idealism); whereas if the percipient subject is a world mind (universal consciousness, of which the individual mind forms but a manifestation) another form of idealism emerges, Objective Monistic Idealism, of which Fichte, Hegel and Schelling were the chief supporters.
Perhaps the most striking example of an idealistic system logically developed is that of Kant. He attributes to the human mind three main cognitive faculties: perception, understanding, and reason. Each of these faculties contains forms of thought by the application of which to the materials given in the senses knowledge in the scientific sense is produced. Perception has two forms: time and space. Understanding has twelve categories under four general heads: quantity, quality, relation, modality; and reason seeking after unity places before itself ideals in which the phenomena of consciousness, of the outer world and of possible existence are summed up. Hence the ideals of the soul, of the universe, and of God. And these ideals are not objects of actual and positive knowledge, but regulative principles which guide reason in its search after highest truth.
I want to point out two objections to Idealism. First it misapprehends the true meaning of knowledge. The mere succession of mental phenomena can never furnish materials for scientific knowledge, unless the mind can grasp the causal relations which bind them together. The discovery of the planet Neptune is a case in point. Leverrier and Adams both noted irregularities in the orbit described by Uranus which led them finally to postulate the existence of another planet. Here was a suggestion, the truth of which depended upon the reality of. the force of attraction, the respective positions of the planets and other objective considerations. And though Neptune had never been recognized as belonging to our solar system and was invisible to the naked eye, the astronomer relying upon the objective truth of physical principles was able to indicate the portion of the cosmos where the new planet would be seen, if suitable optical means were employed. Physical science and Idealism are simply not compatible.
The second objection is equally strong: every form of Idealism questions the truth of the information derived from the perceptive faculties, and thus logically leads to Skepticism. Some students of philosophy take up a position midway between Idealism and Natural Realism. They're sometimes known as Critical Realists. Their system rests upon a fundamental principle which is as follows: states of consciousness are primarily known, and from them by aid of the principle of causality, the inference to the objectivity of the external world is made. But the question arises how can the truth of the law of causality be known unless we are assured of the real existence of cause and effect which our sensitive faculties perceive? The intuitive principle of causality is recognized by the intellect from the materials furnished by sense perceptions; so that to invoke the aid of causality in order to establish the objectivity of sense perceptions is the logical fallacy known as "petitio principii," or in more familiar language the fallacy of "begging the question". But even if the truth of the principle of causality is granted, the only inference which can be made is that there is an external cause of sensitive cognition, but of the nature of the cause nothing is known. Critical Realism is thus seen to be practically identical with the phenomenalism of Kant mentioned above.
It is also helpful to examine the chief principles of Natural Realism, the most fundamental and important of which asserts that we have an immediate perception of the outward world, that sense impressions are not directly perceived but determine the sense to the immediate perception of the outward object. This is the complementary truth overlooked by Idealists that attacks their conclusions. No matter how logical their reasoning may be, if it sets out from faulty premises, the error will be more abundant in accordance with the efficiency of the logical process.