Idealism

Idealism, theory of reality and of knowledge that attributes a key role to the mind in the constitution of the world as it is experienced. Different versions and applications of idealism are discernible in the history of philosophy. In its most radical and commonly rejected form it is equivalent to solipsism, the view that reality is nothing but the activity of one’s own mind and that nothing really exists or can be known to exist but one’s own mind and its thoughts. The idealist, however, usually gives full recognition to the external, or natural, world, avoiding any claim that it can be reduced to the mere process of thinking. The mind, on the other hand, is active and, indeed, is able to produce and sustain modes of being that would not otherwise exist, such as law, religion, art, and mathematics. Furthermore, the way that natural objects exist in human experience is affected by the activity of the mind, and attention to this influence is essential if inquiries concerning the world are to be scientific.

Plato, a distant precursor of idealism, postulated the existence of a realm of ideas or “forms” that are imperfectly reflected in the varied objects of common experience. He maintained that these ideal forms are not only more clearly intelligible but also more real than the transient and essentially illusory objects themselves.

The 18th-century Irish philosopher and clergyman George Berkeley speculated that all aspects of everything of which one is conscious are actually reducible to the ideas present in the mind. The observer does not conjure external objects into existence, however; the true ideas of these are caused in the human mind directly by God. The 18th-century German philosopher Immanuel Kant greatly refined idealism through his critical inquiry into the limits of possible knowledge. Kant held that all that can be known of things is the way in which they appear in experience; there is no way of knowing what they are substantially in themselves. He also held, however, that the fundamental principles of science are essentially grounded in the constitution of the mind rather than being derived from the external world.

The 19th-century German philosopher G. W. F. Hegel regarded as invalid Kant’s theory concerning the inescapable human ignorance of what things are in themselves, arguing instead for the ultimate intelligibility of all existence. Hegel also maintained that the highest achievements of the human spirit (culture, science, religion, and the state) are not the result of naturally determined processes in the mind, but are conceived and sustained by the activity of free, reflective intellect. Further strains of idealistic thought can be found in the works of the 19th-century Germans J. G. Fichte and F. W. J. Schelling, the 19th-century British philosopher F. H. Bradley, the 19th-century Americans C. S. Peirce and Josiah Royce, and the 20th-century Italian Benedetto Croce.