In matters of social policy, where large bodies of men have to carry out a single design, uniformity must be attained by persuasion or compromise. But such matters relate only to physical well-being, into which philosophical truth can hardly be said to enter.
This relative and, in the widest sense, utilitarian view of intellectual truth applies both to quantity and quality of ideas. We should not learn what we do not sentimentally require. That is waste of power. Useless knowledge is folly, said both Plato and Aristotle. To mistake knowledge to be the pursuit of man is to confuse the means with the end, says the author of the Bhagavad Gita.
The quality of our ideas must not be good beyond our necessities. If they are, we shall suffer by acting on them. They will land us in circumstances for which our nature is not fully prepared.
If there were an abstract or standard truth, it would be good for every species of being, and no doubt the thoughts of a man are nearer to it than the thoughts of a horse. Therefore a horse ought to be improved by receiving a human intellect. But if we could insinuate into a horse's mind the knowledge possessed by an educated man, we should spoil what may have been a good horse and produce a monstrous and horrible man. So is it with ourselves. If we could receive knowledge far in advance of our requirements or out of relation to them, it would drive us mad or be itself madness. Our constitution and necessities determine what we can know and what we ought to know. Not all possible knowledge is good, and what is good for some may be useless or bad for others. Schopenhauer says well[3]: 'The faculty of Knowing ... has only arisen for the purpose of self-preservation, and therefore stands in a precise relation, admitting of countless gradations, to the requirements of each animal species.'
VI—REALISM
If our interests were single and uniform, one consistent scheme of intellectual knowledge would suffice. We need never be in fundamental contradiction with ourselves. Every advance in knowledge would illustrate and confirm what we had already learned.
But we are not of this simple constitution. We are first and essentially minds, we are next and temporarily embodied minds, and in each of these characters we have distinct and, to a great extent, conflicting interests. Hence we have to acquire different species of knowledge and admit different standards of truth. The ideas that serve the interests of the embodied man are false to the same man considered apart from his embodiment, and contrariwise—false, in the sense of being useless and perhaps misleading.
Hence the existence of Common-sense for the embodied interests, and Philosophy for the purely mental interests. Science is common knowledge carried to its utmost perfection, but not partaking in the least of the philosophical character.
Realism is the notion of perception that is acquired with our common knowledge. It is seldom explicitly defined or defended, for in order to this a comparison with philosophic theories would have to be made, and the defects of realism would be apparent. The realistic view is so named by philosophers to distinguish it from their own views.