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Essay Concerning Human Understanding Book Ii Summary

Not to be confused with An Enquiry Concerning Human Understanding.

Title page of the first edition

AuthorJohn Locke

Publication date

(dated 1690)

An Essay Concerning Human Understanding is a work by John Locke concerning the foundation of human knowledge and understanding. It first appeared in 1689 (although dated 1690) with the printed title An Essay Concerning Humane Understanding. He describes the mind at birth as a blank slate (tabula rasa, although he did not use those actual words) filled later through experience. The essay was one of the principal sources of empiricism in modern philosophy, and influenced many enlightenment philosophers, such as David Hume and George Berkeley.

Book I of the Essay is Locke's attempt to refute the rationalist notion of innate ideas. Book II sets out Locke's theory of ideas, including his distinction between passively acquired simple ideas, such as "red," "sweet," "round," etc., and actively built complex ideas, such as numbers, causes and effects, abstract ideas, ideas of substances, identity, and diversity. Locke also distinguishes between the truly existing primary qualities of bodies, like shape, motion and the arrangement of minute particles, and the secondary qualities that are "powers to produce various sensations in us"[1] such as "red" and "sweet." These secondary qualities, Locke claims, are dependent on the primary qualities. He also offers a theory of personal identity, offering a largely psychological criterion. Book III is concerned with language, and Book IV with knowledge, including intuition, mathematics, moral philosophy, natural philosophy ("science"), faith, and opinion.

Book I[edit]

The main thesis is that there are "No Innate Principles", by this reasoning:

If we will attentively consider new born children, we shall have little reason to think that they bring many ideas into the world with them

and that "by degrees afterward, ideas come into their minds."[2] Book I of the Essay is devoted to an attack on nativism or the doctrine of innate ideas. Locke allowed that some ideas are in the mind from an early age, but argued that such ideas are furnished by the senses starting in the womb: for instance, differences between colours or tastes. If we have a universal understanding of a concept like sweetness, it is not because this is an innate idea, but because we are all exposed to sweet tastes at an early age.[3]

One of Locke's fundamental arguments against innate ideas is the very fact that there is no truth to which all people attest. He took the time to argue against a number of propositions that rationalists offer as universally accepted truth, for instance the principle of identity, pointing out that at the very least children and idiots are often unaware of these propositions.[4]

Book II[edit]

Whereas Book I is intended to reject the doctrine of innate ideas proposed by Descartes and the rationalists, Book II explains that every idea is derived from experience either by sensation – direct sensory information – or reflection – "the perception of the operations of our own mind within us, as it is employed about the ideas it has got".

Furthermore, Book II is also a systematic argument for the existence of an intelligent being: "Thus, from the consideration of ourselves, and what we infallibly find in our own constitutions, our reason leads us to the knowledge of this certain and evident truth, that there is an eternal, most powerful, and most knowing being; which whether any one will please to call God, it matters not!"

Book III[edit]

Book 3 focuses on words. Locke connects words to the ideas they signify, claiming that man is unique in being able to frame sounds into distinct words and to signify ideas by those words, and then that these words are built into language.

Chapter ten in this book focuses on "Abuse of Words." Here, Locke criticizes metaphysicians for making up new words that have no clear meaning. He also criticizes the use of words which are not linked to clear ideas, and to those who change the criteria or meaning underlying a term.

Thus he uses a discussion of language to demonstrate sloppy thinking. Locke followed the Port-Royal Logique (1662)[5] in numbering among the abuses of language those that he calls "affected obscurity" in chapter 10. Locke complains that such obscurity is caused by, for example, philosophers who, to confuse their readers, invoke old terms and give them unexpected meanings or who construct new terms without clearly defining their intent. Writers may also invent such obfuscation to make themselves appear more educated or their ideas more complicated and nuanced or erudite than they actually are.

Book IV[edit]

This book focuses on knowledge in general – that it can be thought of as the sum of ideas and perceptions. Locke discusses the limit of human knowledge, and whether knowledge can be said to be accurate or truthful.

Thus there is a distinction between what an individual might claim to "know", as part of a system of knowledge, and whether or not that claimed knowledge is actual. For example, Locke writes at the beginning of Chap. IV (Of the Reality of Knowledge): "I doubt not my Reader by this Time may be apt to think that I have been all this while only building a Castle in the Air; and be ready to say to me, To what purpose all of this stir? Knowledge, say you, is only the Perception of the Agreement or Disagreement of our own Ideas: but who knows what those Ideas may be? ... But of what use is all this fine Knowledge of Man's own Imaginations, to a Man that enquires after the reality of things? It matters now that Mens Fancies are, 'tis the Knowledge of Things that is only to be priz'd; 'tis this alone gives a Value to our Reasonings, and Preference to one Man's Knowledge over another's, that is of Things as they really are, and of Dreams and Fancies."

In the last chapter of the book, Locke introduces the major classification of sciences into physics, semiotics, and ethics.

Reaction, response, and influence[edit]

Many of Locke's views were sharply criticized by rationalists and empiricists alike. In 1704 the rationalist Gottfried Leibniz wrote a response to Locke's work in the form of a chapter-by-chapter rebuttal, the Nouveaux essais sur l'entendement humain ("New Essays on Human Understanding"). Leibniz was critical of a number of Locke's views in the Essay, including his rejection of innate ideas, his skepticism about species classification, and the possibility that matter might think, among other things. Leibniz thought that Locke's commitment to ideas of reflection in the Essay ultimately made him incapable of escaping the nativist position or being consistent in his empiricist doctrines of the mind's passivity. The empiricist George Berkeley was equally critical of Locke's views in the Essay. Berkeley's most notable criticisms of Locke were first published in A Treatise Concerning the Principles of Human Knowledge. Berkeley held that Locke's conception of abstract ideas was incoherent and led to severe contradictions. He also argued that Locke's conception of material substance was unintelligible, a view which he also later advanced in the Three Dialogues Between Hylas and Philonous. At the same time, Locke's work provided crucial groundwork for future empiricists such as David Hume. John Wynne published An Abridgment of Mr. Locke's Essay concerning the Human Understanding, with Locke's approval, in 1696. Louisa Capper wrote An Abridgment of Locke's Essay concerning the Human Understanding, published in 1811.

See also[edit]



  • Locke, John. An Essay Concerning Humane Understanding. 1st ed. 1 vols. London: Thomas Bassett, 1690.
  • Locke, John. An Essay Concerning Human Understanding. Edited by Alexander Campbell Fraser. 2 vols. Oxford: Clarendon Press, 1894.
  • Locke, John. Works, Vol 1. London: Taylor, 1722.
  • Clapp, James Gordon. "John Locke." Encyclopedia of Philosophy. New York: Macmillan, 1967.
  • Uzgalis, William. "John Locke." Stanford Encyclopedia of Philosophy. Retrieved on 22 July 2007.
  • Ayers, Michael. Locke: Epistemology and Ontology. 2 vols. London: Routledge, 1991.
  • Bennett, Jonathan. Locke, Berkeley, Hume: Central Themes. Oxford: Oxford University Press, 1971.
  • Bizzell, Patricia, and Bruce Herzberg, eds. The Rhetorical Tradition. 2nd ed. Boston: Bedford/St. Martin's, 2001.
  • Chappell, Vere, ed. The Cambridge Companion to Locke. Cambridge: Cambridge University Press, 1994.
  • Fox, Christopher. Locke and the Scriblerians. Berkeley: University of California Press, 1988.
  • Jolley, Nicholas. Locke: His Philosophical Thought. Oxford: Oxford University Press, 1999.
  • Lowe, E.J. Locke on Human Understanding. London: Routledge, 1995.
  • Yolton, John. John Locke and the Way of Ideas. Oxford: Oxford University Press, 1956.
  • Yolton, John. John Locke and the Compass of Human Understanding. Cambridge: Cambridge University Press, 1970.

External links[edit]

  1. ^Essay, II, viii, 10
  2. ^Essay, I, iii, 2.
  3. ^Essay, I, ii, 15.
  4. ^Essay, I, iv, 3.
  5. ^Arnauld, Antoine; Nicole, Pierre (1662). La logique ou l'Art de penser. Paris: Jean Guignart, Charles Savreux, & Jean de Lavnay. . See part 1, chapter 13, Observations importantes touchant la définition des noms.


In asking where we get our idea of substances, Locke finds himself in one of the stickier sections of the Essay. He gives us the following picture of the origin of our ideas of substances: As we go through the world we carve up the dense sensory array into discrete objects, noticing which qualities regularly seem to cluster together. For instance, we see softness, blackness, a certain small size, a certain catlike shape moving all together throughout our experience, and we assume that all of these qualities make up a single object. However, he claims, this cluster of our ideas of observable qualities cannot in itself form the idea of a substance. We must also add to this an idea of whatever it is that these properties belong to; we do not simply believe that these properties exist out in the world, but rather that they are properties of something. That something, he argues, corresponds to our idea of substance in general or substratum. It is helpful to think of a substratum as an invisible pincushion, with all of the observable qualities that belong to it being the pins. The substratum itself is unobservable (and, hence, because of Locke's empiricism, unknowable) because it cannot itself have observable qualities; it is the thing in which observable qualities inhere. Anything we can observe or describe is a property rather than the substratum itself. Our idea of the substratum, therefore, is necessarily very obscure and confused. All we really know about the substratum is that it is supposed to support the observable properties of a substance. Beyond that, we have no hint and no hope of getting a hint. Locke is very eager to point out that the case is equally bleak for both mental and physical substances. Contrary to what most people believe, he argues, we do not know bodies any better than we know the mind. In both cases, we can only know the observable qualities. When it comes to what the properties belong to, we are completely in the dark in both cases. When he is being particularly careful. he remembers to point out that, really, since all we know are observable properties, there is no basis for even claiming that there are two different types of substance in the world. For the most part, however, he talks as if dualism were true (that is, as if mind and body were two distinct kinds of substances). In addition to treating the logico-linguistic problem of substances (i.e. What is metaphysically responsible for supporting properties? How can we make sense of the way we speak about them?), Locke also briefly touches on the scientific problem of substances: What is causally responsible for properties? The cause of properties, he claims, is the constitution of objects, their hidden microstructures. He treats this idea in greater depth in Book III.


Locke's discussion of substratum is probably one of the most confusing sections of the Essay, in large part because he himself is so obviously torn on the topic. In several instances, Locke uses language that would suggest he does not really believe substrata exist, that our idea of substratum refers to nothing and thus is meaningless. For instance, at I.iv.18 he says that we "signify nothing by the word "substance," but only an uncertain supposition of we know not what." At II.xxiii.18 he calls it a "promiscuous use of a doubtful term." Perhaps most provocatively, at II.xxiii.2 he compares the idea of a substratum to the explanatory tool of an Indian philosopher who, "saying that the world was supported by a great elephant, was asked what the elephant rested on, to which his answer was a great tortoise. Being again pressed to know what gave support to the broad-backed tortoise, he replied, something he knew not what." This mocking analogy seems to suggest that Locke considers "substratum" an entirely empty word, referring to nothing but our own limit of understanding. At the same time, Locke retains the idea in his picture. Given that one of his primary aims in the Essay is to encourage us to banish terms with no real meaning--terms that are supposed to refer to something in the world but do not or that have no clear ideas associated with them--his retention of this term is puzzling. Clearly, as suspicious as he was of the idea, he felt that it was necessary, though whether it is necessary only as a conceptual tool to make sense of our experience (as it would seem from the quotes above) or as something that must exist to make sense of the natural world itself (which he seems to suggest throughout the rest of the discussion) is really not clear. There are at least four reasons why Locke felt that it was crucial to include the notion of substratum in his account. First, he felt that the idea was needed in order to make sense of our language. If someone asks what a ladybug is, the answer would take the following form: "It is a thing that is black and red, with such and such a size and shape, that eats such and such..." There are qualities out in the world that correspond to the predicates in this sentence (even if the correspondence is not one of resemblance), so, Locke feels, there must also be something corresponding to the subject, the "thing." Not everyone in the history of philosophy felt this way. Some people, such as David Hume, felt that "thing" was just a peculiarity of how language works, a linguistic hanger on which we can hang qualities. In the world, however, there are only the qualities. When we say a thing that "is..." we do not really mean there is a thing that has these qualities, but simply that these qualities are the identity of the substance in question. This view is called the "bundle theory" of substances, because it regards substances as mere collections of observable properties. There are good reasons, though, why Locke did not want to go in this direction. This theory raises tremendous problems for itself. The biggest problem is the question of persistence through change. If a school bus just is a collection of yellow color, an oblong shape, powers of motion etc., what happens if I paint the school bus green, or if it breaks down and loses its powers of motion? If we have a new bundle of qualities, does that mean we have a new substance? The bundle theorist needs to come up with a good explanation of how the substance remains the same when the bundle changes. Persistence through change on Locke's view, however, is easy to account for, which is the second reason why he felt he needed to keep the notion of substratum. The substratum persists through any change. The substance, therefore, remains the same substance through changes in properties. A third reason Locke felt compelled to accept the notion of substratum was to explain what unifies co-occurring ideas, making them into a single thing, distinct from any other thing. The substratum, Locke claims at II.xxiii.1 and 37, helps elucidate this unity. It is not entirely clear, though, how the substratum is supposed to do this. Lastly, the substratum provides Locke with a way to account for the notion of support. The very idea of a quality involves dependence, being a quality of something. So what are qualities dependant on, what do they exist in? The answer, of course, is the substratum.

It is these considerations that push Locke to reluctantly embrace a notion that he himself admits may well be utterly meaningless.

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