Classical Western Philosophy III: The British Empiricists (Locke, Berkeley, Hume)

The empiricists start from the claim that all our ideas come from experience, and follow it where it leads. Locke refutes innate ideas, classifies ideas, keeps a material substratum he cannot describe and distinguishes primary from secondary qualities. Berkeley removes the distinction and the substratum and concludes that to be is to be perceived. Hume reduces ideas to copies of impressions, splits knowledge into relations of ideas and matters of fact, and finds no rational basis for causation, induction, the external world or the self. This chapter follows the syllabus items for each in that order. The syllabus prints "solipcism" under Berkeley; the word is solipsism, the view that only oneself and one's own ideas can be known to exist.

1. Locke: against innate ideas, the classification of ideas, substance and qualities

John Locke's Essay Concerning Human Understanding (1689) opens (Book I) by refuting innate ideas and principles. There is no universal assent even to "whatever is, is"; children and those with severe intellectual disability show no awareness of such principles; and even if there were universal assent, it could be explained by other means, so it would not prove innateness. To say a principle is in the mind but unperceived is, for Locke, close to contradiction. The mind begins as "white paper, void of all characters", and experience writes on it through two channels: sensation (of external objects) and reflection (the mind's perception of its own operations).

  • Ideas and their classification: simple ideas are received passively (the coldness of ice, the idea of thinking); complex ideas are made by the mind combining, comparing and abstracting. Complex ideas are of modes (simple, as a dozen; mixed, as beauty or theft), substances (as gold or a man) and relations.
  • Theory of substance: we find qualities regularly going together and suppose a substratum in which they subsist, but our idea of it is only of "something, I know not what", a support of qualities. Substance is presupposed, not perceived.
  • Primary and secondary qualities: primary qualities (solidity, extension, figure, motion or rest, number) are inseparable from body and our ideas of them resemble them; secondary qualities (colours, sounds, tastes, smells) are only powers in bodies, arising from the primary qualities of their insensible parts, to produce ideas that do not resemble anything in the bodies. Locke also names a third sort, powers to change other bodies, as fire's power to melt wax.

Knowledge, for Locke, is "the perception of the connexion and agreement, or disagreement and repugnancy, of any of our ideas" (Book IV), under four heads: identity or diversity, relation, co-existence, and real existence. It comes in three grades: intuitive knowledge, immediate and most certain, as of my own existence; demonstrative knowledge, reached through intervening ideas, as of God's existence and mathematical truths; and sensitive knowledge, the least certain, of the particular existence of external things. Because we perceive ideas and infer objects that cause them, Locke is called a representative realist.

2. Berkeley: immaterialism and esse est percipi

George Berkeley (1685–1753; A Treatise concerning the Principles of Human Knowledge, 1710; Three Dialogues between Hylas and Philonous, 1713) turned Locke's premises against Locke's conclusions. First, the primary–secondary distinction collapses: the arguments that show colour to be relative to the perceiver (it varies with the light and the eye) show the same for size and shape, and we cannot even conceive extension or motion without some colour or other sensible quality. So primary qualities, too, exist only in the mind.

  • Critique of abstract ideas (Introduction to the Principles): Locke thought we could frame the general idea of a triangle that is "neither oblique nor rectangle, equilateral, equicrural nor scalenon, but all and none of these at once". Berkeley says no such idea can be formed; a general idea is a particular idea made to stand for others of the same sort. Matter, as an unperceived substratum, is exactly such an impossible abstraction.
  • Esse est percipi (to be is to be perceived) for sensible things, and esse est percipere (to be is to perceive) for spirits. A cherry is nothing but the collection of sensible ideas, its redness, softness, taste; an unperceived cherry is a contradiction. This is immaterialism: there is no material substance, only spirits and their ideas.
  • God and self: ideas of sense, unlike ideas of imagination, are involuntary, vivid and orderly, so they must be caused by another spirit, God, whose regular way of producing them we call the laws of nature. God's perception also keeps things in existence when no finite mind perceives them. The self is an active spirit, known not by an idea (ideas are passive) but by a "notion".
🎯 The problem of solipsism
If all I directly know are my own ideas, what entitles me to believe in other minds, or in God? This is the problem the syllabus lists as "solipcism". Berkeley's answer is that I infer God as the cause of the involuntary ideas I cannot produce myself, and other finite spirits from the ideas of their bodies and actions, by analogy with myself. Critics reply that the same inference could restore matter as the cause of my ideas, which Berkeley denies because an unthinking substance cannot cause anything.

3. Hume: impressions and ideas, relations of ideas and matters of fact

David Hume (1711–1776; A Treatise of Human Nature, 1739–40; An Enquiry concerning Human Understanding, 1748) divides all perceptions into impressions, which are lively and forceful (sensations, passions), and ideas, which are their fainter copies. The copy principle says every simple idea is derived from a corresponding simple impression, which gives Hume a test for meaning: if a supposed idea cannot be traced to an impression, it is empty. He notes one exception, the "missing shade of blue", a shade one has never seen but can imagine between two that one has. Ideas are linked by three principles of association: resemblance, contiguity in time or place, and cause and effect.

Hume's fork
PointRelations of ideasMatters of fact
ExamplesGeometry, algebra, arithmetic"The sun will rise tomorrow"
How knownBy thought alone, a prioriBy experience, a posteriori
DenialSelf-contradictoryConceivable and consistent
CertaintyDemonstrativeProbable at best
ℹ️ The fork and metaphysics
The Enquiry ends with Hume's rejection of metaphysics: take any volume of school metaphysics and ask whether it contains abstract reasoning concerning quantity or number, or experimental reasoning concerning matter of fact; if neither, "commit it then to the flames: for it can contain nothing but sophistry and illusion". The logical positivists of Unit 6 revived this test in the verification principle.

4. Hume: causality, induction, the external world, the self, scepticism and the passions

  • Causality: when one billiard ball strikes another we observe priority, contiguity and constant conjunction, but no necessary connection. The idea of necessity comes from an internal impression: the felt determination of the mind, formed by custom or habit, to pass from the cause to the usual effect. A cause is "an object followed by another, and where all the objects similar to the first are followed by objects similar to the second".
  • Induction: all inference from observed to unobserved cases assumes that the future will resemble the past (the uniformity of nature). This cannot be demonstrated, since its denial is not contradictory, and cannot be shown by experience without arguing in a circle. So inductive belief rests on custom, not reason; this is the problem of induction.
  • The external world: neither the senses nor reason justify belief in the continued and distinct existence of bodies; it is produced by the imagination, prompted by the constancy and coherence of our impressions.
  • The self and personal identity: "when I enter most intimately into what I call myself, I always stumble on some particular perception or other" and never catch myself without a perception. The self is "nothing but a bundle or collection of different perceptions", and personal identity is a fiction of the imagination, which confuses a smooth succession of related perceptions with one unchanging thing.
  • Scepticism: Hume rejects the excessive (Pyrrhonian) scepticism that nature makes impossible to live by, and recommends a mitigated or academic scepticism that confines enquiry to common life and experience.
  • Reason and the passions: "Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them" (Treatise 2.3.3). Reason alone cannot move us to act; it only informs us of facts and relations, and the ends of action are set by the passions.
⚠️ Hume is not denying that causes exist
Hume's claim is about the origin of the idea of necessary connection and about the justification of causal inference, not that nothing causes anything. He himself analyses causes and gives "rules by which to judge of causes and effects". An option saying "Hume held that there are no causes in nature" overstates him.

Key takeaways

  • Locke: no innate ideas (no universal assent; children lack them); white paper; sensation and reflection; simple and complex ideas (modes, substances, relations); substance as "something, I know not what".
  • Locke: primary qualities (solidity, extension, figure, motion, number) resemble their ideas, secondary do not; knowledge as agreement or disagreement of ideas, in three grades: intuitive, demonstrative, sensitive.
  • Berkeley: primary qualities are as mind-dependent as secondary; no abstract ideas; esse est percipi; no matter; God causes our ideas of sense and sustains unperceived things; the self known by a notion; the problem of solipsism.
  • Hume: impressions and ideas; copy principle; resemblance, contiguity and causation as association; relations of ideas against matters of fact; "commit it then to the flames".
  • Hume: necessary connection from custom; the problem of induction; the external world from imagination; the self a bundle of perceptions; mitigated scepticism; reason the slave of the passions.

Practice questions (10)

Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.

  1. "Esse est percipi" (to be is to be perceived) is the doctrine of:

    1. Berkeley
    2. Hume
    3. Leibniz
    4. Locke
    Show answer

    Answer: A — Berkeley

    Berkeley applies esse est percipi to sensible things and esse est percipere to spirits. Locke kept a material substratum, Hume reduced the self to a bundle of perceptions, and Leibniz posited monads.

  2. According to Locke, our knowledge of God's existence is:

    1. Sensitive
    2. Intuitive
    3. Demonstrative
    4. Innate
    Show answer

    Answer: C — Demonstrative

    Locke gives three degrees: intuitive (of my own existence), demonstrative (of God's existence and mathematical truths) and sensitive (of external things). He rejects innate knowledge altogether.

  3. Hume held that the idea of necessary connection between cause and effect is derived from:

    1. The mind's felt determination, formed by custom, to pass from one to the other
    2. A direct impression of power in the objects
    3. An innate category of the understanding
    4. A demonstration from the principle of sufficient reason
    Show answer

    Answer: A — The mind's felt determination, formed by custom, to pass from one to the other

    We observe no power in objects, only constant conjunction; the idea of necessity is copied from an internal impression, the habitual transition of the mind. A category of the understanding is Kant's answer, and sufficient reason is Leibniz's principle.

  4. Which thinker called the self "nothing but a bundle or collection of different perceptions"?

    1. Locke
    2. Berkeley
    3. Descartes
    4. Hume
    Show answer

    Answer: D — Hume

    Hume's bundle theory is in Treatise 1.4.6. Berkeley kept the self as an active spirit known by a notion, Locke tied personal identity to consciousness and memory, and Descartes made the self a thinking substance.

  5. Berkeley rejects Locke's distinction between primary and secondary qualities chiefly because:

    1. Both kinds of quality are innate ideas
    2. Primary qualities are as perceiver-relative as secondary ones, and cannot be conceived apart from them
    3. Secondary qualities really exist in bodies, as primary ones do
    4. Only primary qualities are known by reason
    Show answer

    Answer: B — Primary qualities are as perceiver-relative as secondary ones, and cannot be conceived apart from them

    Berkeley argues that size and shape vary with the perceiver just as colour does, and that we cannot conceive extension without some sensible quality; so all qualities are ideas in the mind. He does not put secondary qualities in bodies, and he denies innate ideas.

  6. Assertion (A): Hume holds that inductive inference cannot be justified by reason. Reason (R): The principle that the future will resemble the past can be neither demonstrated nor established by experience without circularity. Choose the correct option.

    1. Both A and R are true, and R is the correct explanation of A
    2. Both A and R are true, but R is not the correct explanation of A
    3. A is true, but R is false
    4. A is false, but R is true
    Show answer

    Answer: A — Both A and R are true, and R is the correct explanation of A

    Both are true and R explains A. Every inductive inference presupposes the uniformity of nature; its denial is not contradictory, so it is not demonstrable, and any appeal to past success would itself be an induction.

  7. Assertion (A): Locke calls substance "something, I know not what". Reason (R): Locke holds that we have a clear innate idea of substance. Choose the correct option.

    1. Both A and R are true, and R is the correct explanation of A
    2. Both A and R are true, but R is not the correct explanation of A
    3. A is true, but R is false
    4. A is false, but R is true
    Show answer

    Answer: C — A is true, but R is false

    A is true: our idea of substance is only of a supposed support of qualities. R is false: Locke denies innate ideas, and the whole point is that our idea of substance is obscure, not clear.

  8. Which of the following are primary qualities for Locke? Select all that apply.

    1. Figure
    2. Number
    3. Colour
    4. Solidity
    Show answer

    Answer: A — Figure; B — Number; D — Solidity

    Locke's primary qualities are solidity, extension, figure, motion or rest, and number. Colour is a secondary quality, a power in bodies to produce an idea that does not resemble anything in them.

  9. Which of the following statements about Hume's "relations of ideas" are correct? Select all that apply.

    1. Geometry and arithmetic belong to them
    2. They include "the sun will rise tomorrow"
    3. Their denial implies a contradiction
    4. They are discoverable by thought alone
    Show answer

    Answer: A — Geometry and arithmetic belong to them; C — Their denial implies a contradiction; D — They are discoverable by thought alone

    Relations of ideas are known a priori, their denial is contradictory, and they include mathematics. "The sun will rise tomorrow" is Hume's own example of a matter of fact, whose denial is perfectly conceivable.

  10. How many principles of the association of ideas does Hume name? Type the number.

    Numerical answer — type the value.

    Show answer

    Answer: 3

    Three: resemblance, contiguity in time or place, and cause and effect (Enquiry, section 3).