Debate #15 · 1690 / 1710–1713

Berkeley vs Locke on Material Substance

Whether there is anything to matter beyond its perceived qualities

Metaphysics, epistemology

Venue: Locke, *Essay Concerning Human Understanding* (1690); Berkeley, *Principles of Human Knowledge* (1710) and *Three Dialogues* (1713).

Berkeley's immaterialist response to Lockean material substance: "esse est percipi."

Locke's *Essay* (1690) defended a representational realism: external material substances cause our ideas; primary qualities (extension, motion) resemble features of bodies, secondary qualities (colour, sound, taste) do not. The underlying material substratum is "something we know not what." Berkeley's *Principles* (1710) attacked this last move: a material substance independent of all perception is both unverifiable and incoherent. To be is to be perceived (*esse est percipi*); the world of ordinary objects consists of ideas in minds, held together by being perceived by God when no finite mind perceives them. The debate (asymmetric — Locke died 1704) defines the British empiricist trajectory: Locke's representationalism collapses under its own pressure into Berkeley's idealism, which Hume then collapses further into skeptical phenomenalism.

Historical Context

Berkeley was 25 when *Principles* appeared; Locke had been dead six years. The *Three Dialogues* (1713) reformulated the position more accessibly. Berkeley's subsequent career as Bishop of Cloyne demonstrated that immaterialism was compatible with serious Christian practice.

Compare this debate

Parties

John Locke

Representational realist

External material substances cause our ideas; primary qualities really inhere in bodies, secondary qualities are powers in bodies to produce ideas in us. The material substratum is unknowable in detail but real.

Key arguments

Distinction between primary and secondary qualities; primary qualities (extension, shape, motion) resemble features of bodies.
Causal account of perception: ideas are caused by external things acting on our sensory apparatus.
Material substratum: "something I know not what" supports the qualities, though its nature is opaque to us.
Empirical method: knowledge is built from experience via reflection, not from innate ideas or speculative metaphysics.

Allied schools

Empiricism Realism Naturalism

George Berkeley

Idealist; immaterialist

*Esse est percipi*: to exist is to be perceived (or to perceive). There is no material substratum behind our ideas; ordinary objects are bundles of ideas held in existence by being perceived, ultimately by God.

Key arguments

Primary/secondary distinction collapses: arguments showing colour to be mind-dependent apply equally to extension and shape.
Material substratum is incoherent: an entity defined by being unobservable in principle is a contradiction in terms.
Ideas exist only in minds; positing matter as their cause violates parsimony and intelligibility.
God's perception underwrites the persistence and order of the world when no finite mind perceives — a positive theological theme of the position.

Allied schools

Idealism Phenomenalism Empiricism

Dimensions Engaged

◉

Matter

Matter · Ontological Status: substantival material substratum vs minds-and-ideas-only.

◎

Observer

Observer · Knowledge Extent: are ideas representations of things beyond them, or the entire furniture of reality?

Verdict in retrospect

Berkeley's critique of the Lockean material substratum was largely accepted; his positive idealism less so. Hume developed the negative side (no material substance, no spiritual substance either) without the theological backstop. Modern analytic phenomenalism (Russell, Ayer) and contemporary "mind-only" positions (panpsychism, idealist revivals) all descend from Berkeley's arguments; the broader philosophical mainstream rejected his positive metaphysics while acknowledging the force of his negative critique.

Related Debates

Sharing parties or aligned schools.

Related Experiments

Experiments that share dimensions and/or aligned schools with this debate.

Newton's Prism Experiment

1672 · 2 shared dims · 4 shared schools

The Double-Slit Experiment

1801 / 1927 · 2 shared dims · 2 shared schools

Schrödinger's Cat

1935 · 2 shared dims · 2 shared schools

Brain in a Vat

1981 · 2 shared dims · 2 shared schools

The Stern–Gerlach Experiment

1922 · 2 shared dims · 2 shared schools

The Millikan Oil-Drop Experiment

1909 · 1 shared dim · 4 shared schools

Other Personas Aligned With This Debate

Ranked by declared-influence weight in the schools either party is allied with. The named parties themselves are excluded — they're already listed above.

Charles Darwin

1809–1882 · 60% in naturalism

Sigmund Freud

1856–1939 · 55% in naturalism

David Hume

1711–1776 · 50% in empiricism

John Stuart Mill

1806–1873 · 35% in phenomenalism

Robert Hooke

1635–1703 · 35% in empiricism

Hippocrates of Cos

c. 460–370 BCE · 50% in naturalism