The Cambridge Companion to Locke's 'Essay Concerning Human Understanding'

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First published in 1689, John Locke's Essay Concerning Human Understanding is widely recognised as among the greatest works in the history of Western philosophy. The Essay puts forward a systematic empiricist theory of mind, detailing how all ideas and knowledge arise from sense experience. Locke was trained in mechanical philosophy and he crafted his account to be consistent with the best natural science of his day. The Essay was highly influential and its rendering of empiricism would become the standard for subsequent theorists. This Companion volume includes fifteen new essays from leading scholars. Covering the major themes of Locke's work, they explain his views while situating the ideas in the historical context of Locke's day and often clarifying their relationship to ongoing work in philosophy. Pitched to advanced undergraduates and graduate students, it is ideal for use in courses on early modern philosophy, British empiricism and John Locke.
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Editorial Reviews

From the Publisher
'This is not only an immensely valuable and stimulating collection of essays, but also a beautifully edited and produced one, with an elegant and readable typeface, no typographical errors, and a very extensive bibliography. All Locke specialists should possess a copy and all teachers of Locke should include it on their students' reading lists.' Locke Studies
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Product Details

  • ISBN-13: 9780521834339
  • Publisher: Cambridge University Press
  • Publication date: 3/28/2007
  • Series: Cambridge Companions to Philosophy Series
  • Edition description: First Edition
  • Pages: 502
  • Product dimensions: 5.98 (w) x 8.98 (h) x 1.38 (d)

Meet the Author

Lex Newman is associate professor of philosophy at the University of Utah.
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The Cambridge Companion to
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The Essay is first published in December of 1689 by a fifty-seven-year-old John Locke (1632–1704). (That same year Locke publishes the Two Treatises of Government and the Letter Concerning Toleration.) The philosophical themes of the Essay are the product of years of thought, as many as twenty in some cases. Locke continues working on the Essay in the decade following its initial publication. He produces three updates – a second edition in 1694, a third in 1695, and a fourth in 1700. He oversees a translation into French. And he writes three public responses to objections from Edward Stillingfleet, the bishop of Worcester, one of which is a book-length work in its own right. The result of Locke’s efforts is an undisputed philosophical masterpiece. The systematic empiricism he develops would become the standard for subsequent theorists. The importance of some of the positions developed in the Essay continues to the present day.

The Essay is the product of more than simply the tireless efforts of a gifted philosophical mind. The seventeenth century is a period of significant intellectual development in Europe– developments to which the philosophical themes of the Essay are responsive. In the opening essay of the present volume (Chapter 1), “The Intellectual Setting and Aims of the Essay,” G. A. J. Rogers details the historical factors influencing Locke.

Consistent with the title of the Essay, Locke refers to “the Subject of this Treatise” as being “the UNDERSTANDING” (E: 6). The Introduction states his “Purpose” as being “to enquire into the Original, Certainty, and Extent of humane Knowledge; together, with the Grounds and Degrees of Belief, Opinion, and Assent” (E I.i.2: 43). The express concern with epistemology is reflected a few lines later in Locke’s overview of his method:

First, I shall enquire into the Original of those Ideas, Notions, or whatever else you please to call them, which a Man observes, and is conscious to himself he has in his Mind; and the ways whereby the Understanding comes to be furnished with them.
Secondly, I shall endeavour to shew, what Knowledge the Understanding hath by those Ideas; and the Certainty, Evidence, and Extent of it.
Thirdly, I shall make some Enquiry into the Nature and Grounds of Faith, or Opinion: whereby I mean that Assent, which we give to any Proposition as true, of whose Truth yet we have no certain Knowledge: And here we shall have Occasion to examine the Reasons and Degrees of Assent. (E I.i.3: 44)

In the course of his inquiry, Locke explores topics that today are studied under such headings as action theory, epistemology, ethics, metaphysics, philosophy of language, philosophy of mind, philosophy of science, physics, and psychology, among others.

The Essay unfolds in accord with the threefold order just outlined, but with a rather different emphasis than is suggested by Locke’s remarks. The topics Locke lists under “First” occupy the majority of attention and are distributed over the first three books of the Essay. The topics under “Secondly” and “Thirdly” are combined in the fourth and final book. The titles of the four books are as follows:

I.Of Innate Notions
II.Of Ideas
III.Of Words
IV.Of Knowledge and Opinion

Books I and II are in some sense a two-part investigation into the origin of mental content. Book I gives a negative account, addressing the kinds of views Locke rejects. Book II gives Locke’s positive account – a detailed empiricist account. “Let us then suppose the Mind to be, as we say, white Paper, void of all Characters, without any Ideas; How comes it to be furnished?” (E II.i.2: 104) The bulk of Locke’s answer unfolds over the course of Book II, the longest book of the Essay. The present volume includes seven essays on topics connected with these first two books of the Essay.

The first such essay concerns Locke’s rejection of nativism. Book I makes a series of attacks on nativism, arguing that our knowledge does not arise from “innate Principles,” or from notions “as it were stamped upon the Mind of Man” (E I.ii.1: 48). Unclear is whom Locke targets with these attacks, or how he understands their accounts. In “Locke’s Polemic Against Nativism” (Chapter 2), Samuel C. Rickless attempts to clear up the confusion, along with clarifying both the structure of Locke’s anti-innatist arguments and their success.

Locke holds that sense experience provides the building blocks of mental content – what he calls simple ideas. From these simple ideas the mind constructs complex ideas. At both levels of ideas, Locke makes further taxonomic divisions. The result is an elaborate taxonomy of ideas that helps define the organization of topics in Book II. In “The Taxonomy of Ideas in Locke’s Essay” (Chapter 3), Martha Brandt Bolton clarifies this classification scheme, while addressing interpretative problems associated with the major divisions.

The theory has it that simple ideas of external sense are our window to the world. A corpuscularian understanding of body has implications for how the qualities of bodies help produce such ideas in the mind. What emerges is a famous distinction between two kinds of qualities. In “Locke’s Distinctions Between Primary and Secondary Qualities” (Chapter 4), Michael Jacovides explains Locke’s account while arguing that it is much richer than has been appreciated – Locke is in fact drawing several overlapping distinctions.

The longest chapter of the Essay concerns the idea of power. Ideas of power figure in numerous aspects of Locke’s philosophy, including the centerpiece of the chapter – his treatment of human freedom. In “Power in Locke’s Essay” (Chapter 5), Vere Chappell sorts out Locke’s views on power – clarifying its widespread role in his philosophy, and defending a compatibilist interpretation of Locke’s views on human freedom.

Appeals to substance have a distinguished philosophical history. The notion purports to get at what it is to be a thing in the most basic sense. Recent interpretations have tended to have Locke disavowing the traditional notion of substance. In “Locke on Substance” (Chapter 6), Edwin McCann carefully examines four influential such interpretations, concluding that an interpretation attributing to Locke a traditional conception of substance emerges as superior.

Related to our conceiving the world in terms of individual substances is that we have ideas of identity over time – ideas, for example, of a mature oak tree as being the same organism as some earlier tree that looked quite different, or of our own selves as being the same persons that performed actions years earlier. In “Locke on Ideas of Identity and Diversity” (Chapter 7), Gideon Yaffe explains Locke’s account, focusing especially on his famous treatment of personal identity.

In significant respects, ideas take center stage throughout the Essay. Yet Locke scholarship is divided about how he understands the nature of ideas – whether he regards ideas as representational entities, and, if so, what this means. At stake is whether the mind directly perceives the world, or is instead trapped behind a veil of its own ideas. In “Locke on Ideas and Representation” (Chapter 8), Thomas M. Lennon clarifies the contours of the debate, while arguing that Locke does not regard ideas as imposing a barrier between mind and world.

Book III develops further the theory of ideas, notably in connection with general ideas and essences. In addition, Book III presents Locke’s influential theory of language. The present volume includes two essays on Book III topics.

Experience leads us to classify objects into such kinds as trees, horses, gold, and so on. We tend to assume that the world naturally divides into such kinds – indeed, that the essences of the kinds are just as we conceive them. Locke rejects these assumptions. He distinguishes real and nominal essences, arguing that we classify external objects based on nominal essences. In “Locke on Essences and Classification” (Chapter 9), Margaret Atherton works through the texts and issues, developing an interpretation of Locke’s account.

The traditional view of Locke’s philosophy of language is that it presents a theory of linguistic meaning. Recent commentators have questioned this traditional account, arguing that it does not accurately portray Locke’s understanding of the signification relation between words and ideas. In “Language, Meaning, and Mind in Locke’s Essay” (Chapter 10), Michael Losonsky challenges these recent commentators and defends the traditional account.

Locke’s theories of ideas and language having been expounded, Book IV turns to his theory of knowledge. Locke distinguishes two main sorts of propositional cognition: knowledge, wherein the mind has certainty; judgment, wherein it achieves only probability. Book IV presents separate accounts of knowledge and judgment, while treating a number of related issues. The present volume includes five essays on Book IV topics.

The opening lines of Book IV state that “Knowledge is only conversant” with ideas, because ideas are the only immediate objects the mind “does or can contemplate” (E IV.i.1: 525). Thus restricted to ideas, Locke defines knowledge as the perception of the agreement or disagreement of two ideas – a definition that has generated considerable scholarly debate. In “Locke on Knowledge” (Chapter 11), I defend an interpretation of Locke’s account of knowledge that takes his controversial definition at face value.

In the course of developing the themes of Book IV, Locke makes claims bearing on his own ontological commitments. It has seemed to many readers that his claims are inconsistent – that they reveal tension in his views about the epistemic status of corpuscularianism, and further tension in his views about the nature of mind. In “Locke’s Ontology” (Chapter 12), Lisa Downing examines the claimed tensions and argues that they can be resolved.

Locke maintains that inquiries into morality are those to which our natural faculties are “most suited,” concluding that “Morality is the proper Science, and Business of Mankind of general” (E IV.xii.11: 646). Locke’s claims about the nature of moral ideas and moral knowledge raise many questions. In “The Moral Epistemology of Locke’s Essay” (Chapter 13), Catherine Wilson sorts through these various claims in an effort to clarify the account.

Locke generally reserves the language of judgment for contexts of probability, thus distinguishing it from knowledge. Since on his view strict knowledge is quite limited in scope, it emerges that judgment plays an extensive role in his broader philosophical system. In “Locke on Judgment” (Chapter 14), David Owen presents a general interpretation of Locke’s theory of judgment, arguing, among other things, that the contributions of the intellect and the will in Locke’s account make it importantly different from Descartes’s well-known account.

Having explained knowledge and judgment, Locke discusses two further grounds of assent – divine revelation, and religious enthusiasm. That these further grounds of assent are bases of religious conviction raises questions about the balancing of faith and natural reason. In “Locke on Faith and Reason” (Chapter 15), Nicholas Jolley discusses Locke’s overall philosophy of religion, his treatment of faith and reason, and his treatment of enthusiasm.

Locke’s Essay covers far more topics of interest than are discussed here. That his Essay presents powerful and influential philosophical ideas in an uncommonly systematic fashion renders it a philosophical gold mine for both students and scholars. As the essays in the present volume collectively exhibit, Locke scholarship is alive and well. A host of interpretive issues continue to be debated, and much of the diversity of interpretive positions in the field is represented in these pages. That these interpretive debates do, in many cases, track ongoing philosophical debates attests to the ongoing relevance of Locke’s philosophy. The philosophical world still has much to learn from the Essay.


1     The intellectual setting

and aims of the essay

The Essay Concerning Human Understanding, though dated 1690, was published in late 1689, when its author was fifty-seven. It had been completed in Holland, where Locke had fled in 1683. It had a much longer gestation than this suggests, however. When it was published it was the product of a mature philosophical mind that had been reflecting on the issues that it considers for nearly twenty years. Locke tells us in the “Epistle to the Reader” something of its origin and history. He writes that five or six friends:

Meeting at my chamber, and discoursing on a subject very remote from this [i.e., human understanding], found themselves quickly at a stand, by the Difficulties that rose on every side. After we had a while puzzled our selves, without coming any nearer a Resolution of those Doubts which perplexed us, it came in to my Thoughts, that we took a wrong course; and that, before we set our selves upon Enquiries of that Nature, it was necessary to examine our own Abilities, and see, what Objects our Understandings were, or were not fitted to deal with. This I proposed to the Company, who all readily assented; and thereupon it was agreed, that this should be our first Enquiry. Some hasty and undigested Thoughts, on a Subject I had never before considered, which I set down against our next Meeting, gave the first entrance into this Discourse, which having been thus by Chance, was continued by Intreaty; written by incoherent parcels, and after long intervals of neglect, resum’d again, as my Humour or Occasions permitted; and at last, in a retirement, where an Attendance on my Health gave me leisure, it was brought into that order, thou now seest it. (E: 7)

We can now fill out this story in much detail, and some of that detail is directly relevant to understanding Locke’s purposes in writing the book. To begin with, it is known that the subject matter of the discussion in which Locke and his friends were originally engaged was “morality and revealed religion.”1 The meeting itself took place in the winter, probably February, of 1671 and in Exeter House in the Strand, the London home of Lord Ashley, later first earl of Shaftesbury, situated where the Strand Palace Hotel now stands. Whether that first document that Locke prepared for the meeting is still in existence is not certain. What we have now are two early drafts of the Essay, both probably written in 1671 (though even this is not absolutely certain), known as Drafts A and B.2 But in Locke’s voluminous manuscripts there are many other references to material relevant to the background and production of the Essay through its five early editions. Further, in order to understand those drafts, and therefore the published book, we have to look to Locke’s intellectual background as a philosopher, educated in the traditions of the more puritan strands of the Church of England, and as somebody who had entered deeply into studies in medicine, chemistry, and at least some other branches of natural philosophy before he began to write works of philosophy as now understood. And this was against a background in which Locke had taken his Oxford first degree and was thus familiar with the main tenets of Scholastic philosophy, and in the immediately following years had become familiar with and influenced by the new philosophy emanating from France, of which that of Descartes was by far the most important.

Locke had been a student and tutor at Christ Church, Oxford, the largest and most important college in the university, from the time that he graduated in 1656 until he moved to London to join Shaftesbury’s household eleven years later in 1667, where he was to be based until 1675. Shaftesbury had by then become the leading Whig politician in the country, and much of his time was spent on government business. During those eight years Locke often worked as Shaftesbury’s personal assistant in dealing with matters of politics and government. He was also responsible for finding Shaftesbury’s son a wife and, in due course, for the education of the son produced from that marriage, the future third earl of Shaftesbury. He also, as secretary of presentations, became a civil servant and was responsible for dealing with ecclesiastical matters that came under Shaftesbury’s control as lord chancellor, the highest political appointment in the land. When possible, Locke was also engaged in medical practice with Thomas Sydenham, probably the greatest physician of the age. In 1668, he became a Fellow of the recently established Royal Society, attending its meetings when he was able and renewing contacts from his days with the Oxford Philosophical Society, of which the two most distinguished were Robert Boyle and Robert Hooke, but which also included many others, such as Christopher Wren, remembered as the architect of St Paul’s Cathedral; the civil servant Samuel Pepys; Richard Lower, the physician; Sir Kenelm Digby; John Wilkins, who had been one of the moving forces behind the new science in Oxford and who later became Bishop of Chester; Nehemiah Grew, the botanist; and many other distinguished and not-so-distinguished men of science.

Perhaps enough has been said to indicate that Locke was far from being a standard academic philosopher in the modern sense. Indeed, as we shall see, the modern subject known as philosophy was in many respects to be created by his Essay. Although he had spent years teaching logic, rhetoric, and moral philosophy in Oxford, Locke’s great intellectual passions in his earlier years were medicine and chemistry. It is of major significance for understanding his philosophy that in these disciplines he was actively engaged in research with the two outstanding figures in the respective fields, Thomas Sydenham and Robert Boyle.

The Royal Society was an institution that claimed to be putting into practice the plans for the increase in knowledge of the natural world that had been advocated by Francis Bacon at the beginning of the century. Supporters of the Baconian vision had been active in both Oxford and London during the period of the Commonwealth following the English Civil War and the execution of King Charles I in 1649, the year Locke had entered Christ Church. At the heart of Bacon’s programme was the aspiration to increase people’s knowledge of the natural world and to use that knowledge for practical benefit. Leading proponents of that movement in Oxford included Robert Boyle, an aristocrat of independent means, and John Wilkins, master of Wadham College and married to the sister of the man who was effectively the country’s ruler, Oliver Cromwell. Locke attended the chemistry classes that Boyle introduced in Oxford and began research on respiration and on human blood with Boyle. In 1660, at the Restoration of the monarchy, many of the Oxford group moved back to London, and it was this group, together with physicians and other men interested in natural philosophy, who were responsible for creating the new society. With royal patronage, it immediately achieved a status that would otherwise not have been available to it and soon provided a forum for the international exchange of information about a wide range of natural phenomena based on observation and experiment, in the way Bacon had advocated. Locke began to attend its weekly meetings in 1668, on his election to the Society, along with his medical work with Thomas Sydenham and his many commitments to Shaftesbury.

We shall look more closely at the connections between Locke and the Baconian movement associated with the Royal Society later. But let us now return to Locke and his studies in Oxford prior to his arrival in London. These fall into two very clear sections. As an undergraduate, Locke had to follow the reading prescribed for him by his tutor, but beginning in 1656 he could and did read much more widely and combined his reading with practical enquiries, especially in chemistry and medicine. The undergraduate course required him to advance further his mastery of Latin, mainly through rigorous and frequent exercises; logic, which was, of course, that of Aristotle’s syllogistic; mathematics and astronomy, including Euclid and contemporary works of astronomy based on the heliocentric theory; and the classical texts of Greece and Rome.3

It is particularly interesting that in all such enquiries, there is little or no evidence that Locke would have encountered major works of what today would have been called the classics in philosophy. No doubt he would have been familiar with the major works of Aristotle, but perhaps not with those of Plato. Certainly he would not have encountered as a matter of course any of the major philosophers of the Middle Ages. Of Latin authors, only Cicero and Seneca would have been certainties. And by Locke’s day none of the works of early modern philosophers such as Bacon, Descartes, Hobbes, and Gassendi would have been included as texts.

© Cambridge University Press
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Table of Contents

Introduction Lex Newman; 1. The intellectual setting and aims of the Essay G. A. J. Rogers; 2. Locke's polemic against nativism Samuel C. Rickless; 3. The taxonomy of ideas in Locke's Essay Martha Brandt Bolton; 4. Locke's distinctions between primary and secondary qualities Michael Jacovides; 5. Power in Locke's Essay Vere Chappell; 6. Locke on substance Edwin McCann; 7. Locke on ideas of identity and diversity Gideon Yaffe; 8. Locke on ideas and representation Thomas M. Lennon; 9. Locke on essences and classification Margaret Atherton; 10. Language, meaning, and mind in Locke's Essay Michael Losonsky; 11. Locke on knowledge Lex Newman; 12. Locke's ontology Lisa Downing; 13. The moral epistemology of Locke's Essay Catherine Wilson; 14. Locke on judgment David Owen; 15. Locke on faith and reason Nicholas Jolley.
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