IDEALISM (IDEA, ante), as the term is generally used, is that scheme of philosophy which, carried to its legitimate results as was done by bishop Berkeley, regards all external phenomena as having no existence apart from a thinking subject. Descartes and his followers taught that nature has given to the mind various simple ideas, with the capacity also of compounding, separating, associating, and comparing them. The ten dency of this theory is towards skepticism concerning everything except the .existence of ideas. If they be the only objects of thought. and have no existence except when the mind is conscious of them, then no object of thought can have a continued and per manent existence. Bishop Berkeley, evading this consequence in regard to the exist ence of mind and spirit, asserted it concerning the material world. Ele maintained that there is no such thing as matter in the universe; that sun and moon, earth and sea, our own bodies and those of our friends, being only ideas in the minds of those who think of them, have no existence when not objects of thought; and that the universe may be reduced to two categories—minds, and ideas in the arid. To this conclusion philoso phers before him had led the way, Descartes taught that the existence of objects of sense is not selfetrident, but must be proved by ailgainent. Others tried ID find arguments that would prove it, but without entire success; all their reasoning being. in the opinion of many, sufficient only to show that the existence of external things was probable but not certain. Nalebranche rested the question on the authority of ievela• Lion; but to this the reply was that revelation itself eau come to men only through their senses. Berkeley thought that if his theory were admitted many difficulties would be solved, many intricate points made plain, and skepticism brought to an end. But the actual result of his system was very different. By seeming to throw distrust on the evidence of the senses and to take away the grounds of a belief which is both natural and universal, its tendency was to shake men's faith in the primary truths which are the basis of their knowledge and the guides of their conduct. Beginning where Berkeley began, Hume went much further, and left hardly one article of human faith unassailed. He denied the reality not only of the object perceived, but of the mind perceiving; and reduced all thinking existence to a succession of rapidly fleeting ideas, each one being known only at the instant of its manifestation to consciousness, and then fading away.
He maintained that men do not know that any one thing depends on any other in the relation of an effect to its cause; and the conclusion at which his reasoning aimed was not the mere negation of this or that positive belief, but universal distrust of the human faculties as a means for the acquisition of knowledge. They contradict each other, lie said, and leave nothing certain except that nothing can be known as certain.
Idealism has indeed its interwoven truth, but it is a truth misapprehended and per verted. There are impressions, inferences, and imaginations, mingling, naturally or inadvertently, lawfully or unlawfully, with all genuine knowledge. These the ideal philosophy confounds, instead of distinguishing them in theory as common sense does in practice. As a system its radical vice is that while it admits the reality of certain objects, as mind and spirit, it inconsistently maintains that certain other things, as those of the material universe, which the mind just as intuitively knows to be real, are not real. It commonly begins by declaring that external objects have no such reality as men generally suppose them to have; advancing, from this point, to the denial that they have any reality at all, it still makes pretensions to a realism founded, not on the external phenomenon, but on the internal idea. From this refuge also logical necessity drives it away and forces it to assert that self is not as it seems, or that it exists only as it is felt, or when it is felt, and that men cannot know whether there be objects before them or not, or whether there be an eye or a mind to perceive them. There is no way or avoiding blank skepticism except by standing up for the trustworthiness of all the original intuitions of the human mind and affirming that there is a reality whenever those intuitions, taken comprehensively, actually declare that there is. If the mind can trust the faculties God has given it, it does perceive matter objectively; that is, some thing extended and solid is the immediate object of touch and sight; and this something is not in itself an idea, but matter.