George Berkeley

Introduction

George Berkeley is the Anglo-Irish philosopher and Anglican bishop whose subjective idealism is one of the most rigorous and most counter-intuitive positions in modern philosophy. His central doctrine — esse est percipi, to be is to be perceived — holds that material substance does not exist; there are only ideas (the contents of perception) and the minds that perceive them. The position has been continuously mischaracterized since its publication (Samuel Johnson's famous I refute it thus, kicking a stone, captures the standard misunderstanding); the actual Berkeleyan position is considerably more sophisticated.

Berkeley occupies the middle position in the canonical British empiricist trio between Locke and Hume. He accepts the empiricist starting point (all knowledge derives from experience) but pushes it in a direction Locke had not anticipated: if all we ever have are ideas in our minds, what philosophical work does positing a material substance behind those ideas actually do? Berkeley's answer is none, and material substance should be dispensed with accordingly.

Life

Berkeley was born in 1685 near Kilkenny, Ireland, to an Anglo-Irish family. He entered Trinity College, Dublin, in 1700 at age fifteen, completed his BA in 1704, was elected a fellow of Trinity in 1707, and was ordained an Anglican priest in 1710. The early Trinity years saw the rapid composition of his major philosophical works: An Essay Towards a New Theory of Vision (1709), A Treatise Concerning the Principles of Human Knowledge (1710), and Three Dialogues Between Hylas and Philonous (1713). By age twenty-eight Berkeley had published the philosophical work for which he would be remembered.

In the years following, Berkeley traveled extensively (France, Italy, North America), held various ecclesiastical and academic positions, and attempted (unsuccessfully) to establish a college in Bermuda for the education of American colonists and Native Americans. He spent nearly three years in Rhode Island (1729–1731) waiting for promised funds that never materialized; the time in America influenced his views on education and the colonies.

In 1734 Berkeley was appointed Bishop of Cloyne in southern Ireland, where he served for nearly twenty years. The later writings include Alciphron (1732), a dialogue defending Christianity against free-thinking critics, and The Analyst (1734), a critique of the foundations of the new infinitesimal calculus that pointed out genuine logical problems Newton and Leibniz had not adequately addressed. He died in Oxford in 1753 at age sixty-seven.

The problem he worked on

Berkeley inherited the empiricist framework Locke had developed in the Essay Concerning Human Understanding (1689). Locke had distinguished primary qualities (those that genuinely belong to objects: solidity, extension, figure, motion) from secondary qualities (those that exist only as the object's powers to produce ideas in us: color, sound, taste). Locke had held that primary qualities exist in material substances that produce our ideas of them.

Berkeley argued that Locke's position is unstable. The same arguments Locke gives for the subjectivity of secondary qualities apply equally to primary qualities: we never directly experience extension or motion in the object; we experience only our ideas of extension and motion. If the secondary qualities are mind-dependent, so are the primary qualities. And if all qualities of supposed material substances exist only as ideas in minds, then there is no need (and no coherent way) to posit a material substance behind the ideas. The hypothesis of material substance does no philosophical work; it should be dispensed with.

The positive doctrine that results is that reality consists of ideas (the contents of perception) and the spirits or minds that perceive them. The continuity and lawfulness of experience (the regularities of nature that physics studies) are explained not by mind-independent matter but by the perceiving activity of an infinite mind (God), who constantly perceives the ideas that constitute the natural order even when finite minds are not perceiving them.

Contributions

Subjective idealism: esse est percipi

Berkeley's central doctrine, presented in the Principles of Human Knowledge and dramatized in the Three Dialogues. To exist is to be perceived (in the case of ideas) or to perceive (in the case of spirits). There are no unperceived existences; the hypothesis of a material substance existing independently of any perception is incoherent.

The doctrine is not the absurd position it is often taken for. Berkeley is not claiming that objects cease to exist when we look away (the famous limerick problem); the continuous perception by the divine mind sustains their existence even when finite minds are not attending to them. Nor is Berkeley denying the reality of the external world in any practical sense; tables and chairs continue to be real, lawful, and shared among observers. What Berkeley is denying is the philosophical hypothesis of an unperceivable material substance lying behind the perceptible ideas.

The critique of abstract general ideas

The Introduction to the Principles attacks Locke's account of abstract general ideas. Locke had argued that we form general ideas (the idea of triangle in general, the idea of human being in general) by abstracting from the particular features of specific instances. Berkeley argues that no such abstraction is psychologically possible: when we try to form the idea of triangle in general, we always end up with a particular triangle (a particular size, shape, orientation). The idea of triangle in general that Locke posits is a philosophical fiction; what actually does the cognitive work is the use of particular ideas as representatives of others through linguistic convention.

The doctrine has had substantial influence on later nominalist and conceptualist traditions in philosophy of language.

The new theory of vision

An Essay Towards a New Theory of Vision (1709) develops a detailed empirical theory of visual perception. Berkeley argues that visual perception of distance is not direct but is the product of associative learning: we have learned to associate certain features of the visual field (apparent size, convergence of the eyes, accommodation of the lens) with the tactile and kinesthetic experiences that correspond to objects being near or far. The doctrine — that visual depth is not directly perceived but is a learned interpretation — anticipated significant portions of subsequent psychology of perception and remains a continuing reference in vision science.

The Analyst

Berkeley's late mathematical critique (The Analyst, 1734) addresses the foundations of the new infinitesimal calculus that Newton and Leibniz had developed. Berkeley argues that the concept of an infinitesimal (a quantity that is sometimes zero and sometimes non-zero, depending on the step of the calculation) is logically incoherent — the ghosts of departed quantities. The critique embarrassed mathematicians who had been using the calculus to spectacular practical effect without secure foundations; the eventual nineteenth-century reconstruction of the calculus through the theory of limits (Cauchy, Weierstrass) is partly a response to the kind of logical concern Berkeley raised.

Key works

• An Essay Towards a New Theory of Vision (1709). Detailed empirical theory of visual perception.
• A Treatise Concerning the Principles of Human Knowledge (1710). The major philosophical work; the systematic statement of subjective idealism.
• Three Dialogues Between Hylas and Philonous (1713). The same doctrine in dialogue form, designed for accessibility.
• Alciphron, or the Minute Philosopher (1732). Seven dialogues defending Christianity against free-thinking critics.
• The Analyst (1734). The critique of the foundations of the calculus.
• Siris (1744). A late work on the medicinal virtues of tar-water and on various philosophical and theological themes.

Influences and influenced

Influenced by: Locke (the foundational empiricist framework); Malebranche (the French rationalist whose occasionalism shared certain features with Berkeley's position); the Cartesian tradition through its English reception; the natural philosophy of Boyle and Newton.

Influenced: Hume (whose skeptical empiricism developed substantially in dialogue with Berkeley); Schopenhauer (who admired Berkeley's idealism and considered him a major precursor); the late-eighteenth and nineteenth-century idealist traditions; vision science through the New Theory of Vision; the contemporary nominalist tradition in philosophy of language through the critique of abstract ideas.

Reception

Berkeley's contemporary reception was substantial in Britain and Ireland but treated his idealism largely as a paradox to be refuted rather than a position to be developed. Samuel Johnson's famous (and philosophically inadequate) I refute it thus, kicking a stone in response to Boswell's mention of Berkeley, captures the standard reception. The serious philosophical engagement came from Hume, whose empiricist development took Berkeleyan moves seriously, and from the Scottish common-sense school (Reid), which opposed Berkeley but engaged him carefully.

The German reception was substantial. Kant's Critique of Pure Reason engages Berkeley by name in the Refutation of Idealism (B274–79), partly to distinguish Kant's transcendental idealism from what Kant takes to be Berkeley's subjective idealism. Schopenhauer was more sympathetic, treating Berkeley as a major predecessor.

The twentieth-century reception has been continuously active. A.A. Luce and T.E. Jessop's nine-volume edition (Nelson, 1948–1957) made the complete works available in modern form. The contemporary literature includes substantial work on Berkeley's philosophy of perception, his nominalism, his philosophy of science, and his philosophical theology.

Continuing engagement

Major recent scholarly work includes Kenneth Winkler's Berkeley: An Interpretation (1989), Jonathan Bennett's Locke, Berkeley, Hume: Central Themes (1971), Lisa Downing's substantial essays on Berkeley's philosophy of science, and the Cambridge Companion to Berkeley (Kenneth Winkler, ed., 2005). The journal Berkeley Studies documents ongoing scholarship. Active scholarly debates concern Berkeley's relation to common-sense realism, the consistency of his account of physical objects with his account of God's perception, the nature of Berkeleyan notions (his term for our cognitive access to spirits), and Berkeley's place in the history of philosophy of perception.

Further reading

• Empiricism — the tradition
• Locke — the empiricist predecessor Berkeley both extends and radicalizes
• Hume — the empiricist successor who took empiricist commitments further
• Substance — the metaphysical category Berkeley argues against (in its material form)
• Episteme — the cognitive achievement Berkeley analyzes through the empiricist framework
• Belief Systems — the structure Berkeley's analysis reshapes

The most radical British empiricist. The philosopher whose subjective idealism took the empiricist starting point to its most counter-intuitive conclusion.