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WorkJohn Locke

An Essay Concerning Human Understanding

Locke's inventory of the human mind: every idea traced back to experience, and the limits of knowledge marked.

by John Locke1,120 passages held

  • English, the original language, and your language
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First published
(aged 57)
Original language
English

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Overview

Five or six friends met in Locke's rooms in London around 1671 to talk about morality and revealed religion, and the talk stalled. Locke proposed that they had begun at the wrong end: before arguing about such things, they should find out what the human mind is able to know. He expected the answer to fill one sheet of paper. It took him nearly twenty years. He wrote it in pieces between other work and finished it in exile in Holland, and it came out in London late in 1689, with 1690 on the title page. His bookseller paid £30 for the copyright. An Essay Concerning Human Understanding argues that the mind starts empty. No principle of logic, morality or religion is stamped on it at birth; every idea a person has comes from the senses or from the mind watching its own workings, and knowledge reaches only as far as those ideas can be compared with one another. Locke was writing against the university philosophers of his day and the followers of Descartes, who built on truths supposed to be inborn. On his account most of what people call knowledge is well-grounded belief, the inner constitution of things is hidden from us, and anyone who claims certainty in religion or politics owes an account of where the idea came from. The book went through four editions in his lifetime and was put into French in 1700 and into Latin in 1701. Edward Stillingfleet, Bishop of Worcester, attacked it in print in 1696 as a danger to the doctrine of the Trinity. The German philosopher Leibniz answered it chapter by chapter in a book that stayed unpublished until 1765. In 1703 the heads of the Oxford colleges agreed that their tutors should not read it with pupils.

Key concepts

What does Locke mean by an “idea”?

An idea is whatever the mind is occupied with when it thinks. Locke uses the word very broadly: the yellow someone sees, the pain they feel, the thought of an elephant and the notion of justice are all ideas. The Essay asks where each one comes from, because he holds that we know nothing about the world except by way of the ideas we have.

What is the difference between sensation and reflection?

They are the two sources of all ideas. Sensation is what the senses bring in from outside: colours, sounds, tastes, hardness. Reflection is the mind noticing its own activity, which gives it the ideas of thinking, doubting, believing and willing. Locke compares the two to windows letting light into a dark room, and holds that a mind which had neither would have nothing to think about.

What are simple and complex ideas?

A simple idea is one the mind receives whole and cannot break down or make up, such as the smell of a rose or the feeling of cold. A complex idea is built by the mind from simple ones by combining, comparing or abstracting: an army, beauty, a centaur. Locke’s test for any grand notion is to ask which simple ideas it was assembled from.

What are primary and secondary qualities?

Primary qualities belong to a body whatever anyone perceives: its solidity, shape, size, motion and number. Secondary qualities are powers a body has, through its tiny parts, to produce colours, sounds, tastes and smells in a perceiver. Locke’s example is porphyry, a stone that shows red and white in the light and no colour in the dark, though nothing in the stone has changed.

What is the difference between nominal and real essence?

The nominal essence of a thing is the set of observable qualities people have agreed a name stands for: gold is yellow, heavy, and can be hammered thin. The real essence is the hidden inner make-up that causes those qualities. Locke argues that we sort things only by the first, because the second is unknown to us, so species are drawn up by people who name them.

How does Locke distinguish knowledge from judgment?

Knowledge is certainty: the mind sees that two ideas agree or disagree, as it sees that white is not black or follows a proof step by step. Judgment is what the mind uses where it cannot see this and must go by likelihood, weighing its own experience and the testimony of others. Locke thinks most of life is governed by judgment, and that its assent comes in degrees.

Themes of the book

What this book returns to, gathered into themes and ordered by how much of the text each one occupies.

A Mind Furnished by Experience

If no truth is stamped on the mind at birth, where does everything a person thinks come from? The answer decides whether any principle of morals or religion may be excused from showing its origin.

Book I clears the ground: the maxims said to be inborn are unknown to children and to whole nations, so universal assent proves nothing. Book II builds the alternative. The mind is white paper, and two sources write on it: sensation, which brings in colours, sounds and solidity, and reflection, the mind’s notice of its own workings. Simple ideas arrive unasked and cannot be invented; complex ones are assembled from them. Locke aims this at the university philosophers and at the followers of Descartes, and its effect is levelling. A principle that nobody may question becomes a belief with a history.

  • ideas
  • innate ideas
  • perception
  • sensation
  • empiricism
  • epistemology

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The Same Person over Time

What makes someone today the same person who acted years ago: the same body, the same soul, or something else? On the answer hangs who may justly be praised, blamed or punished for a deed.

Locke separates three things usually run together: the same substance, the same man and the same person. A man is a living body of a certain shape; a person is a thinking being that can consider itself as itself in different times and places. What carries that identity is consciousness, reaching back in memory to past actions and owning them. A soul that remembered nothing of an earlier life would be no more that earlier person than a stranger is. He calls “person” a forensic term, a word for assigning actions and their merit, and he lets the hard cases of lost memory stand as real difficulties.

  • consciousness
  • memory

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Words and the Sorting of Things

Do the names for kinds of things, such as gold, horse or man, follow divisions that nature made or divisions that people made? If people made them, a great many disputes are about words and nothing else.

Book III holds that words stand for ideas in the speaker’s mind, and that a general name marks an abstract idea people have put together. Gold, for the goldsmith as for the child, is whatever fits the list of qualities each attaches to the word; Locke calls that list the nominal essence. The real essence, the inner constitution from which the qualities flow, is unknown and so cannot be what sorts things into species. Against the schools, which treated species as fixed moulds, he points to borderline births and to the shifting lists themselves. His remedy is modest: define the terms and check them against things.

  • language
  • classification
  • meaning
  • communication
  • real essence
  • substance

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How Far Knowledge Reaches

How much can a human being know for certain, and what is to be done about everything else? The answer shrinks knowledge, enlarges judgment, and asks that a belief be held no more firmly than its evidence allows.

Knowledge, in Book IV, is the perception that ideas agree or disagree, and it comes in three grades: intuition, demonstration, and the senses’ assurance that things exist outside us. That covers mathematics, our own existence and God’s, and Locke hopes a demonstrable morality. It does not cover the inner workings of bodies, so natural science remains probable opinion. For the rest of life there is judgment, working in what he calls the twilight of probability. Since nobody’s grounds are complete, people owe one another forbearance. Against those who claim private inspiration he holds that reason must judge every supposed revelation.

  • knowledge
  • certainty
  • probability
  • belief
  • evidence
  • judgment
  • reason
  • truth

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Within this work

passages held
1,120
distinct concepts
618
by passages held, corpus-wide
#54

What this book thinks together

The wheel takes this book’s leading concepts and shows how often they come up together. The wider the band between two, the more of its passages speak of both. Among them, most often together: “ideas” and “language”.
Concept co-occurrence, strongest first 8 concepts, joined by 26 pairings. 83 pairings reach beyond these concepts and are not drawn.
ConceptPaired conceptShared passages
ideaslanguage77
knowledgelanguage63
ideasknowledge51
classificationlanguage49
knowledgesubstance33
languagesubstance32
ideassubstance29
ideasperception27
classificationideas22
innate ideasknowledge21
classificationsubstance15
epistemologyknowledge13
knowledgeperception13
classificationknowledge11
perceptionsubstance11
epistemologyinnate ideas10
languageperception10
epistemologysubstance9
epistemologyideas8
ideasinnate ideas6
innate ideasperception5
epistemologyperception4
innate ideaslanguage4
epistemologylanguage3
classificationperception2
innate ideassubstance1

Works held

The author's work in order, this book marked in place. Your-language title first, the original beneath it where the two differ; side chips show which full texts are held.

  1. 1689 A Letter Concerning Toleration (Epistola de Tolerantia)

    The one statement of his case for religious freedom that Locke made briefly and to a friend. Everything else he printed on the subject defends this text against one of its critics, Jonas Proast.

     EN
  2. 1689 An Essay Concerning Human Understanding you are here EN
  3. 1689 Two Treatises of Government

    Two parts of a longer manuscript whose middle was lost before printing, as Locke's preface says. The book is his political theory, and it shares a year and a purpose with A Letter Concerning Toleration: each sets a limit on what a ruler may do.

     EN
  4. 1690 Further Letters Concerning Toleration

    A sequel in three parts to A Letter Concerning Toleration: Locke's second and third letters and the fragment of a fourth, each a reply to the Oxford chaplain Jonas Proast. The third is where he tests his case hardest.

     EN
  5. 1693 Some Thoughts Concerning Education

    Written for the household of his friend Edward Clarke and enlarged by Locke through several editions. It is his book of practical advice on raising a child, and it applies the Essay's view that the mind is formed by what it meets.

     EN
  6. 1695 The Reasonableness of Christianity

    His main work on religion, and the opening of the study of Scripture that occupied his last years. He defended it twice against John Edwards, a Cambridge Calvinist, and kept his name off all three books while he lived.

     EN
  7. 1696 Several Papers Relating to Money, Interest and Trade

    Advice written for ministers and for Parliament during the currency crisis of the 1690s, and gathered under Locke's name in 1696. The account of money behind it is sketched in the chapter on property in the Two Treatises.

     EN
  8. 1697 Letters to the Bishop of Worcester

    Locke's own commentary on the Essay, written under attack: three replies to Edward Stillingfleet, issued as separate pamphlets between 1697 and 1699, with a short answer to a second critic, Thomas Burnet, Master of the Charterhouse.

     EN
  9. 1706 Of the Conduct of the Understanding

    An unfinished draft, printed from Locke's papers two years after his death. It is the practical companion to the Essay and overlaps with his advice on education.

     EN
  10. 1706 Posthumous Works

    From the volume of unpublished papers that Locke's executors issued in 1706: a critique of Malebranche from the 1690s and a short discourse on miracles from 1702. Both extend arguments begun in the Essay.

     EN
  11. 1708 Some Familiar Letters between Mr. Locke and Several of His Friends

    Letters to the Molyneux brothers of Dublin — Locke's side of the correspondence — taken from a volume his publishers issued in 1708. It is the closest view of him at work on the later editions of the Essay.

     EN
  12. 1720 A Collection of Several Pieces

    The Carolina constitution of 1669 predates the Two Treatises by ten years or more, and the two are often set against each other. Pierre Des Maizeaux published it in 1720 together with shorter pieces left out of the collected works.

     EN
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