George Berkeley

Quick Facts

• Name: George Berkeley
• Lived: 1685-1753
• Born: near Kilkenny, Ireland
• Died: Oxford, England
• Main role: Irish philosopher and Anglican bishop
• Main tradition: early modern Empiricism
• Best known for: immaterialism, the view that ordinary sensible things are ideas perceived by minds
• Famous slogan: esse est percipi, "to be is to be perceived"

The Big Question

What do we really mean when we say a table, tree, or stone exists?

Berkeley thought philosophers had invented a useless extra thing called "matter." We see colors, feel hardness, hear sounds, and notice shapes. Then philosophers say there must also be a hidden material substance underneath those experiences. Berkeley asks: what is that hidden thing supposed to add? If no one can see it, touch it, imagine it clearly, or explain how it helps us understand the world, why believe in it?

His answer is not that chairs and apples are fake. His answer is that they are not mind-independent material objects. They are stable, public patterns of experience ordered by God.

In One Minute

Berkeley was one of the great early modern empiricists, along with John Locke and David Hume. Empiricism says knowledge must be tied to experience. Berkeley pushed that rule hard. If a word has no clear connection to experience, he treated it with suspicion.

His main view is immaterialism. Reality contains minds, which perceive and choose, and ideas, which are the things perceived. The apple on the table is not a hidden lump of matter plus appearances. It is a real object made up of perceivable features: color, shape, taste, smell, firmness, position, and so on. Those features exist when perceived by a mind. The regular order of the world is secured by God, the infinite mind that causes and sustains our sense experience.

What They Taught

Berkeley taught that the world we deal with every day is made of perceivable ideas, not matter hidden behind ideas. An idea, for Berkeley, is anything directly given in experience: a color, sound, smell, taste, pain, warmth, shape, motion, memory image, or imagined scene. Ideas are passive. They appear to a mind, but they do not choose or act.

A spirit is an active mind. A spirit perceives ideas, remembers, imagines, wills, and chooses. Human beings are finite spirits. God is the infinite spirit. Berkeley's basic map of reality is therefore simple: there are spirits and there are ideas. There is no third kind of thing called material substance.

This is why Berkeley attacks matter. In older philosophy, matter was often described as a substance that supports qualities. A red apple has redness, roundness, firmness, and sweetness, and matter is supposed to be the hidden support that owns those qualities. Berkeley says this support is never experienced. We experience the red, round, firm, sweet apple. We do not experience a bare material holder behind it.

He also rejects a common split between primary and secondary qualities. Many philosophers before him said colors, tastes, and sounds depend on the perceiver, while shape, size, motion, and number belong to the object itself. Berkeley replies that shape and size also show up only in perception. A tower looks small from far away and large up close. A coin looks round from one angle and oval from another. Motion looks different depending on where the observer stands. If color is mind-dependent because it varies with the perceiver, Berkeley thinks the same pressure applies to shape, size, and motion.

His slogan esse est percipi means "to be is to be perceived." More carefully, sensible things exist by being perceived or by being available within the God-ordered system of perception. Berkeley is not saying that each person invents the world by imagining it. Dreaming of a fire does not burn your hand. A real fire does. The difference is that real sense experience is vivid, orderly, shared with other people, and not under our private control.

God does important work in Berkeley's system. I can choose to imagine a purple mountain, but I cannot choose what I see when I open my eyes. Sense ideas arrive in a steady order I do not create. Berkeley argues that this order must come from a spirit more powerful than us. God causes the regular sequence of sense ideas we call nature. Laws of nature are the reliable patterns in those ideas.

This lets Berkeley keep ordinary talk and science. We can still say fire heats water, the heart pumps blood, and the moon is far away. Strictly speaking, Berkeley thinks God is the true active cause, while physical causes are regular signs. But in daily life and science, it is useful to track those regular signs. Science studies the stable order of experience.

Berkeley's philosophy of vision fits the same pattern. In An Essay towards a New Theory of Vision, he argues that sight does not immediately give us distance. We learn to connect visual cues with touch, movement, and bodily experience. A flat picture can look deep because sight works through learned signs.

Key Ideas With Examples

• Immaterialism: Berkeley's denial that mind-independent material substance exists. Example: the table is real, but its reality is not a hidden material core. It is the ordered set of perceivable features: hardness, color, shape, resistance, location, and use.

• Ideas: the passive contents of experience. Example: the warmth of sunlight, the red of a rose, the sting of a cut, and the memory image of a street are all ideas.

• Spirits: active perceivers and choosers. Example: you can decide to imagine a blue square, but the blue square you imagine is an idea. The "you" doing the imagining is a spirit.

• Esse est percipi: for sensible things, existing means being perceived. Example: an apple's redness, smell, taste, and firmness are all perceivable. Berkeley thinks there is no extra apple-substance hiding behind those features.

• God as the keeper of order: God explains why the world is stable when no human is looking. Example: the tree in the garden does not depend on your private attention. Its place in the shared order of experience depends on God.

• Rejection of abstract ideas: Berkeley denies that the mind has completely featureless general images. Example: when you think about triangles in general, you may picture a particular triangle and use it generally. You do not need an impossible triangle that is neither equilateral, isosceles, nor scalene.

• Attack on primary qualities: Berkeley argues that shape, size, and motion are perceived just like color and taste. Example: a stick partly in water looks bent, a coin looks oval from the side, and a building looks small from a distance. Perception changes with conditions.

• Science as pattern tracking: science does not need hidden matter. Example: a scientist can study how heat, pressure, and motion regularly appear together without claiming to perceive a material substance underneath them.

Major Works

An Essay towards a New Theory of Vision (1709) argues that distance and depth are not simply read off by the eyes. We learn visual meaning by connecting sight with touch, movement, and past experience.

A Treatise Concerning the Principles of Human Knowledge (1710) gives Berkeley's direct case for immaterialism. It attacks abstract ideas, rejects material substance, explains ideas and spirits, and argues that God orders sense experience.

Three Dialogues between Hylas and Philonous (1713) presents the same view as a debate. Hylas defends matter. Philonous, Berkeley's spokesman, argues that the sensible world is real but does not need material substance.

De Motu (1721) discusses motion and mechanics. Berkeley treats scientific terms with caution and argues that mechanics should focus on useful laws and measurements rather than pretending to reveal hidden forces as ultimate causes.

Alciphron (1732) is a dialogue against freethinkers and religious skeptics. It also matters for Berkeley's view of language: words can guide action and thought even when they do not stand for simple pictured ideas.

The Analyst (1734) criticizes the foundations of calculus as used by Newtonian mathematicians. Berkeley's point was partly religious and partly philosophical: he wanted mathematicians to be less smug about clarity when their own methods used puzzling infinitesimals.

Siris (1744) begins with tar-water, a medical remedy Berkeley promoted, and moves into reflections on nature, signs, spirit, and God. It was his bestselling book during his lifetime.

Why It Matters

Berkeley matters because he makes a simple challenge hard to ignore: if all we directly experience are colors, sounds, shapes, pressures, pains, and other ideas, what exactly is matter supposed to be?

His answer is extreme, but it exposes a real problem in theories of perception. A philosopher who believes in a mind-independent physical world has to explain how perception reaches that world and why the hidden world is not an empty add-on.

He also matters for philosophy of language. Berkeley warns that philosophical words can look meaningful after they have lost contact with experience. "Matter," "substance," and "abstract idea" are his main examples. The warning survives even among philosophers who reject his idealism.

Finally, Berkeley is important because he shows that empiricism does not automatically lead to materialism. He uses experience-first thinking to defend a religious and idealist picture of reality.

Proponents, Critics, and Opponents

Berkeley builds on Locke but turns Locke's empiricism against Locke's own belief in material substance. Locke says the mind deals with ideas from experience. Berkeley asks why we should add an unknowable material support behind those ideas.

He also responds to the problem sharpened by Rene Descartes: if the mind directly knows its own ideas, how does it know an external material world? Berkeley's answer is to deny that the external material world is needed. He is also close to Occasionalism, especially the God-centered philosophy of Nicolas Malebranche, because he makes God central to the order of nature.

David Hume inherits Berkeley's pressure on abstract terms and his suspicion of hidden metaphysical supports, but removes Berkeley's theological guarantee. In Hume, empiricism becomes more skeptical. Order in experience looks more like habit and expectation than proof of a God-governed world.

Immanuel Kant treats Berkeley as an idealist he must avoid. Kant agrees that the mind helps structure experience, but he wants ordinary objects to remain empirically real, not merely private ideas.

Common-sense critics object that Berkeley makes unperceived objects strange. Does the desk vanish when no one is in the room? Berkeley answers by appealing to God's perception and God's will to keep the world orderly. Critics also argue that he moves too quickly from regular experience to God, and that his attack on matter does not prove matter is meaningless.

Later philosophers in Analytic Philosophy return to Berkeley for debates about perception, meaning, abstraction, and whether philosophical problems come from bad uses of language.

Related Pages

• John Locke
• Rene Descartes
• Occasionalism
• Empiricism
• David Hume
• Immanuel Kant
• Analytic Philosophy