George Berkeley (1685-1753), Irish philosopher and clergyman, generally regarded as the founder of the modern school of idealism. Berkeley held that matter cannot be conceived to exist independent of the mind; the phenomena of sense can be explained only by supposing a deity that continually evokes perception of them in the human mind.

Born in County Kilkenny, Ireland, on March 12, 1685, Berkeley studied at Trinity College, Dublin, where he became a Fellow in 1707. In 1710 he published The Principles of Human Knowledge. When it failed to convince people of his theory, he published a more popular version, The Three Dialogues Between Hylas and Philonous, in 1713. Both statements of his philosophy were regarded as foolish by his contemporaries. Meanwhile, Berkeley had been ordained a deacon in the Anglican Church of Ireland and became increasingly prominent as a churchman. In 1728 he moved to America to attempt to found a missionary college in Bermuda. Although he abandoned his plan in 1732, he had a great effect on higher education while in America, assisting in the development of Yale and Columbia universities and a number of other schools. In 1734 he was made Bishop of Cloyne, remaining in this position until his retirement. He died on January 14, 1753.

Berkeley’s philosophical theory was developed as an answer to the scepticism and atheism that he felt to be implicit in contemporary philosophy, influenced as it was by John Locke’s “way of ideas”. Locke had distinguished between the ideas of which people are immediately aware in perception, and the physical objects that are the causes of those ideas. Berkeley argued that, since all that human beings can ever be aware of are ideas (of sight, sound, touch, etc.), any belief in material objects distinct from these ideas (but causing them) is empty speculation, unjustifiable and meaningless. To close the gap that has opened between ideas and physical objects, it must be recognized that, for objects such as tables and trees, being consists in being perceived (“esse est percipi”). They do not exist outside of the mind. The difference then, between a real table and a hallucinatory table lies in the orderliness, arrangement, and regularity of the ideas that go together to constitute the real one, but not the other.

Minds, unlike objects such as trees and tables, are active. Their being consists in perceiving, in having ideas. Of the ideas present to the minds, some lie within a person’s control (they can be conjured up), while others arise regardless of the will (sights and sounds force themselves on the consciousness). Berkeley argued that those ideas that arise regardless of the will must depend upon some other will, namely the will of God. Thus, what are taken to be material objects that exist beyond the mind are ideas in the infinite mind of God.

The relation between the ideas in God’s mind and the corresponding ideas in human minds creates difficulties for Berkeley’s philosophy. There cannot, it seems, be one idea, shared between God and people, since God’s ideas are so much fuller—unless, that is, people are prepared to admit that there are many things about their own ideas of which they are unaware. If, on the other hand, the ideas in God’s mind are different from those in people’s minds, the gap that existed in Locke’s philosophy—namely that between ideas in consciousness and the physical things that cause them—threatens to re-emerge as a gap between the ideas in consciousness and the ideas in God’s mind that also give cause to them. Thus, Berkeley’s theory falls into the same trap as that of Locke.

There is also a problem for Berkeley in explaining how it is possible to talk of minds at all, especially since he tends to explain the grasping of meanings as the having of appropriate ideas. Berkeley was aware of the difficulty, but argued that since minds are active and ideas are passive, an (accurate) idea of the mind cannot be formed. He maintained that it is possible to speak meaningfully of minds by forming the appropriate “notion”, yet he explains very little about the nature of notions, other than the fact that they are not ideas.

Berkeley’s philosophical system produced few followers, despite his claim that it was in accordance with common sense. Nevertheless, his criticisms of arguments for an external world separate from ideas were forceful and have influenced philosophers ever since.