An Essay Concerning Human Understanding

Overview

The Essay is seven hundred and twenty pages in four books, published in 1689 and revised four times in Locke’s lifetime. He says it began about twenty years earlier, when five or six friends meeting in his rooms got stuck on a question, probably about morality and revealed religion, and it occurred to him that they were going about it the wrong way, and that before settling such questions it would be as well to examine what our understandings are fitted to deal with.

That is the whole programme. Locke calls himself an under-labourer, clearing rubbish out of the path of the master builders, by whom he means Newton, Boyle and Sydenham. The Essay is meant to establish what the instrument can do before it is used.

It is long, repetitive, and written in a plain conversational style that is easy to read and hard to summarise, because Locke advances by accumulation rather than by argument. Almost nobody reads the whole thing. Book II is the substance, Book III is more interesting than its reputation, and Book I can be read quickly.

A caution about the word idea. Locke uses it for anything whatever that the mind is immediately aware of: a colour, a pain, a memory, a concept. It does not mean a thought in the modern sense, and getting that wrong will make Book II incomprehensible.

The argument

Book I: against innate ideas. Locke opens by demolishing the view that the mind arrives stocked with certain principles. His arguments are largely empirical: if such principles were innate, everyone would assent to them, and children, idiots and whole nations plainly do not. If it is said they are known once reason develops, then either reason discovers them, in which case they are not innate, or the claim is vacuous. He extends the attack to moral principles, pointing out the variety of practices among peoples, some of them monstrous, and to the idea of God.

Locke’s motive is stated bluntly: the doctrine of innate principles has been a convenient instrument for people who want their own opinions accepted without examination.

Book II: ideas. The positive account, and the heart of the book. The mind begins as white paper, and all its materials come from two fountains. Sensation gives us what the senses report. Reflection gives us what we notice of the mind’s own operations, perceiving, thinking, doubting, willing. Everything else the mind does is compounding, comparing and abstracting on that material, and Locke’s method is to take any idea and demand its pedigree.

The famous distinction of the book is between primary and secondary qualities. Solidity, extension, figure, motion and number are in the object and our ideas of them resemble them. Colour, sound, taste and smell are powers in the object to produce sensations in us, and the ideas do not resemble anything in the thing itself. Berkeley later argued the distinction cannot be maintained.

Then substance, where Locke is candidly uncomfortable. We find qualities going constantly together and suppose something underlying them in which they inhere, and of that something we have no idea at all; he calls it a supposed I know not what, and the phrase caused him trouble for the rest of his life.

Chapter 27, on identity, was added to the second edition and has outlived most of the book. Locke separates the identity of a mass of matter, of a living organism, of a man and of a person, and argues that personal identity consists in consciousness, in how far it can be extended backwards. Hence the prince and the cobbler. Hence also the difficulty, raised at once by Thomas Reid, of the officer who remembers being flogged as a boy and the general who remembers being the officer but not the boy.

Book II also treats space, duration, number, infinity, power and the will, pleasure and pain, and the association of ideas, a chapter added late which gave the eighteenth century one of its main psychological tools.

Book III: words. Locke’s claim is that a great deal of intellectual life is fouled by language, and that many disputes would dissolve if the parties stated what they meant. Words are signs of ideas in the speaker’s mind, not of things, and the connection is arbitrary and learned. General terms do not name general things; they name abstract ideas we have made by leaving out particulars.

From this he argues that the essences we talk about are nominal, our own abstract ideas, and that real essence, the actual internal constitution of a thing, is unknown to us. We have no grounds for confidence that our classifications cut nature where it divides.

Book IV: knowledge. Knowledge is defined narrowly, as the perception of agreement or disagreement between ideas, and on that definition we have very little of it. We know our own existence intuitively, God’s demonstratively, and the existence of other things only through sensation, which Locke admits is a weaker kind of assurance but insists is adequate.

Most of what we live by is therefore not knowledge but judgement, probability and faith. Locke is comfortable with this. Our candle shines bright enough for our purposes, and complaining that we cannot know everything is a child’s objection. He ends with a treatment of faith and reason that gives reason the final say over what claims to be revelation, and with an attack on enthusiasm, meaning the conviction of private inspiration, which he regards as a way of dressing up wanting something as being told it.

How to read it

Read the Epistle to the Reader, then Book II chapters 1 to 9, then Book II chapter 27, then Book IV chapters 1 to 4 and the chapters on faith and enthusiasm. That is the argument.

Use an abridgement unless you have a reason not to. Winkler’s Hackett selection is standard and keeps what matters.

Watch the word idea, and watch where Locke’s confidence runs out. He is unusually willing to say that he does not know, and the passages on substance and on real essence are more interesting for their discomfort than for their conclusions.

Read Berkeley and then Hume afterwards, in that order. Each takes Locke’s premises and removes something he wanted to keep, Berkeley the material substance, Hume the self, and the sequence is the clearest demonstration in philosophy of a research programme running to its conclusion.

The common misreading is blank slate in the strong modern sense. Locke denies innate ideas and content, not innate faculties or tendencies; the mind in his account has substantial powers of its own, and it is the furniture that has to come from outside.

Questions it raises

• If all materials come from experience, where do mathematics and logic come from?
• Primary qualities are said to resemble our ideas of them and secondary ones not. How could that difference ever be checked from inside experience?
• Personal identity is consciousness extended backwards. What happens to the person in dreamless sleep, in amnesia, or under a false memory?
• We know only nominal essences and never real ones. Does that leave natural science describing our classifications rather than nature?
• Locke defines knowledge so narrowly that almost nothing counts, and is unbothered. Is the equanimity earned?
• He makes reason the judge of what can count as revelation. Can that position be held by a believer, and did Locke hold it consistently?