Locke's Essay on the Human Understanding

Review of:
An Essay concerning Human Understanding (by John Locke)

It may reasonably be doubted whether any writer on philosophical subjects ever produced such a broad, solid effect on the minds of the English people as Locke. Nor do we think that his influence has been or will be much diminished, although no one has ever produced a more vigorous reaction against his teaching. Read the Essay on the Human Understanding, and you will be continually under the impression that you are reading the commonplaces of all contemporary literature reduced to a philosophical shape. Read the Essay on Civil Government or the Letters on Toleration, and the same reflection continually presents itself—this is the doctrine which I have heard all my life, on which people all round me are continually acting, and against which more aspiring forms of philosophy are only protests which have not as yet succeeded, and do not seem likely to succeed, in reaching the minds of the great body of people who think about philosophy.

There is, indeed, no one of the great departments of life in which Locke has not exercised, and does not to this day exercise, a degree of influence which is perhaps, in itself, the strongest evidence supplied by the history of modern speculation, of the practical importance of philosophical inquiries. Hardly any writer, too, has been made the subject of so much comment of the controversial kind. Reid, Dugald Stewart, Sir William Hamilton, De Maistre, M. Victor Cousin and many others — almost every one, in a word, who has believed in any of the various forms of idealism which have succeeded each other for the last century or more in England, Germany, and France — has criticised Locke, with more or less dissent, and more or less justice to his great qualities.

He has, indeed, been made the centre of so extensive a literature that a man who forms his opinion of him from reading his books for himself can hardly fail to be conscious of a certain presumption. It seems too coarse and blunt a way of making acquaintance with books about which so much has been said. Still it is difficult not to feel that the question which the Count in the Soirées de St. Petersburg asks of his interlocutor, before they go into the subject of Locke, 'l'avez vous lu?' might be not altogether superfluous with respect to many of his modern critics, for the Essay on the Human Understanding is one of those books which has been so thoroughly assimilated by that part of the world which cares in the most cursory manner for speculative subjects, that large numbers of people naturally suppose themselves to have read it, when in point of fact they never have.

I will, therefore, give a very short account of the arrangement and sequence of its parts, before making a few observations on some points connected with it. One of the most ingenious and striking criticisms ever made upon it is the one which was made by Home Tooke in the Diversions of Purley. He speaks of the essay as 'a grammatical treatise, or a treatise on words or on language,' and describes its title as 'a lucky mistake' which attracted readers who would not have cared to read it, if it had been called, as it should have been, a Grammatical Essay.

Like most vigorous paradoxes, this has a good deal of truth in it, though it is very far from being entirely true. The book may fairly be said to consist mainly of an inquiry into the meaning of those words which are most usually employed in philosophical speculations, followed up by an inquiry into the general theory of language, and the states of mind which different kinds of language refer to, such as knowledge, doubt, and assent in its various degrees. It is not, as its title would imply, an essay on the thinking faculty itself; and the difficulty which has been found in understanding certain parts of it has arisen principally from the circumstance that it does not contain, as is the case with several other works which may properly be compared with it—Hobbes's Leviathan, for instance, and Tucker's Light of Nature — any attempt to describe clearly the faculties of the mind itself. So far at least as they are the subject of inquiry at all, they are spoken of, not as they are in themselves, but as they are displayed in their operation upon particular subjects and collections of thoughts. We are told, for instance, of the manner in which the mind compares and compounds together, or in which it separates from each other, particular ideas, but no separate names are assigned to the faculties by which it performs these operations.

The whole book would have been wonderfully cleared up, and the true relation of its author to other philosophers would have been set in a much clearer light than that in which it stands at present, if it had contained a chapter on the Imagination, another on the Memory, another on the Judgment, considered as functions or operations of the mind itself, in the place of the 9th, 10th, and 11th chapters of the Second Book, on Perception, Retention, and Discerning, each of which is regarded, not as it is felt by the mind, but in its effects upon particular thoughts.

The obscurity and confusion which, as all Locke's critics have observed, is introduced into the whole work by the indefinite and inconsistent manner in which he uses the word 'idea' might have been almost entirely avoided if he had given a clear account of his view of the province of the imagination, and had said plainly whether he recognised any other 'immediate object of the mind in thinking' (this is his own definition of 'ideas' in his answer to Stillingfleet) than mental pictures.

Whoever reads his book carefully will find that much might be said on both sides of this question. In almost innumerable instances he uses the word as if it were synonymous with 'mental picture.' He says, for instance, 'The ideas of our youth often die before us. The pictures drawn in our minds are laid in fading colours.' So 'the idea of the particular colour of gold is not to be got by any description of it, but only by the frequent exercise of the eyes about it.' But elsewhere he says, 'There is an eternal, most powerful, most knowing Being, which whether any one will please to call God it matters not. The thing is evident, and from this idea, duly considered, will easily be deduced all those other attributes which we ought to ascribe to this Eternal Being.'

The contrast between the two senses in which the word idea is used in these passages is only one out of a very large number which might be taken, and the want of a definite psychology which this indicates may perhaps be considered as the principal defect of a book which ought never to be mentioned without admiration.

It must, however, be observed, on the other hand, that this defect gives Locke's work wider connections than it would otherwise have had with the different schools of philosophy. There are certain parts of it which almost connect him with the idealism of which he was the great opponent. It is difficult, for instance, to make much of his chapter 'Of our Knowledge of the Existence of a God' (Book IV. ch. x.), without resorting to propositions which it is very hard indeed to derive from mere experience. The whole argument proceeds on the proposition that 'man knows by an intuitive certainty that bare nothing can no more produce any real being than it can be equal to two right angles.' That nothing producing something is an unmeaning collection of sounds is most true; but to infer, from the fact that a particular set of sounds raises no picture in the mind, the fact that the same sort of being must have existed from all eternity—a word which does not raise a more distinct image than the word nothing— is to leave altogether the ground of sensation, imagination, and experience.

Passing from the deficiencies of the essay to its contents, it is impossible to praise too highly the wonderful labour, fertility of mind, and shrewdness of observation which it displays. It was the work of about nineteen years, having been begun about 1670, and published for the first time in 1689, when Locke was fifty-seven years of age. Its purpose is happily expressed in the first page, as being 'to inquire into the original certainty and extent of human knowledge, together with the grounds and degrees of belief, opinion, and assent.' It may be convenient to say a word or two as to its present scope, well known as it is.

The First Book, 'Of Innate Notions,' refutes the doctrine that certain notions are innate.
The Second Book, 'Of Ideas,' classifies and analyses ideas which must be understood, in this place, in the large sense of all the objects of the mind in thinking —in other words, our thoughts on all subjects.
The Third Book, 'Of Words'—which is usually, and we think with justice, regarded as the most remarkable part of the whole essay—is an examination of language considered as the instrument of thought.
The Fourth Book, 'Of Knowledge and Opinion,' describes the result ultimately reached by our thinking, whether in the shape of knowledge, or in that of opinion or belief.

The positive part of the book thus tells us what we think about, what thinking means, what instruments we use for the purpose of thinking, and what is the result of the operation. To make the plan complete, as we have already observed, there ought to be a description of the thinking subject itself, and an account of the degree to which, and the manner in which, it may be made its own object. The second sentence of the book directly recognises and proposes this design, but, as we have tried to show, it is very imperfectly carried out.

Leaving this, however, we will say a few words on the topics handled in each of the four books. The First Book, which attacks the doctrine of innate notions, is one to which, in the present state of speculation, it is difficult to do. justice. To understand its value, we ought to have a degree of knowledge, which it would not be worth the while of any competent person to acquire, of what in Locke's time was still to some degree regarded as the orthodox philosophy of the schools.

Notwithstanding the shocks which scholasticism had received ever since the revival of learning, a great deal of its spirit still survived all over Europe in the latter half of the seventeenth century. All the great writers of that century—Chillingworth, Jeremy Taylor, Bossuet, Bayle, to mention a few out of many instances—wrote with a sort of half-respectful, half-contemptuous reference to it, as if it was a sort of learning of which learned men ought not to be ignorant, but which at the same time they ought to be able to dispense with, and leave on one side. On the other hand, the great thinkers of the age, and especially Descartes and Hobbes, vehemently attacked it, from their different points of view; so that it is known to ordinary readers of the present day principally by the attacks made upon it, or by the half-contemptuous use of it by writers who were rather proud to know something about it, though they felt that its day was past.

The First Book of Locke's essay is obviously levelled at the views entertained by men bred up in these doctrines. What it proves beyond all possibility of doubt, as it seems to us, is that the minds of men are not furnished from their birth with a certain number of cut-and-dried propositions of incontrovertible truth, which are the foundations of all their general knowledge. It is difficult to understand how any one ever can have believed, or have seriously supposed himself to believe, that children come into the world observing 'Whatever is is,' and 'It is impossible for a thing to be and not to be.'

On another ground Locke's arguments do not appear to touch, or even to be aimed at, the more recent forms of the doctrine of innate ideas, such, for instance, as the doctrine that the mind does not derive from experience the form which experience— that is, sensation—receives when submitted to its action; in other words, that the mind is naturally furnished with the means of classifying the impressions which sensation supplies to it, so that, when a number of different impressions are brought before it, it recognises them as different, when the same impression is brought before it more than once it recognises it as the same, and so on. Whether such views as these are true or false is another question, but they are not the sort of 'innate notions' against which Locke's arguments were directed; and it is by no means certain that they might not be brought under the head of 'ideas of reflection' which he gives as one class of our ideas.

This brings us to the subject of his Second Book, which deals with the origin and classification of our thoughts. All our ideas—taking the word in its most extended term—he ranges under the two heads of ideas of sensation and ideas of reflection. His language in his book, as we have already observed, appears to imply that ideas of all sorts are in the nature of mental pictures. 'Let us suppose,' he says, 'the mind to be white paper, void of all characters, without any ideas; how comes it to be furnished? Whence comes it by that vast store which the busy and boundless fancy of man has painted on it with an almost endless variety? To this I answer in one word, from Experience.' Under the head of Experience, however, Locke distinctly includes experience of the operations of our own minds, 'which operations, when the soul comes to reflect on and consider, do furnish the understanding with another set of ideas which could not be had from things without, and such are perception, thinking, doubting, etc' The perception of their operations, 'though it be not sense, is very like it, and might properly enough be called "internal sense."'

These are the ideas of reflection, and between ideas of reflection as understood by Locke, and the doctrine of innate ideas as stated by modern advocates of that opinion, there appears to us to be less difference than is perhaps usually supposed to exist. If it is admitted on the one hand that if the mind were destitute of experience it would never have any knowledge at all either of itself, or of the external world, and if it is conceded, on the other, that external experience sets at work certain internal faculties, of the nature and operations of which men are as directly conscious as they are of different colours, or of the pains and pleasures of the senses, the question whether experience is the only source of knowledge, and whether ideas are or are not innate, becomes a matter rather of propriety of language than of fact.

The analysis of the different forms of thought, of which the rest of the Second Book is made up, is, like all such analyses, rather dry. The reduction of solidity, duration, power, and the like, to cases of sensation or reflection is an indispensable part of the task which Locke and other writers on the same subject propose to themselves, yet it is the least interesting part of their work.

Some, however, of Locke's chapters may be noticed in passing, because of their close connection with other works. His chapter on 'The Idea of Power' (Book II. cxxi.), which includes his theory of free will and the foundations of morals, is almost identical with Hobbes's view of the same subject. It is, indeed, singular that he should travel over exactly the same portion without quoting or referring to him, though he falls into almost the same expressions at times. Hobbes and Locke both insist on the incongruity of the ideas of will and freedom. Where a man can do what he likes, he is free to do what he likes; but whether he shall like this or that, is a question with which his will is in no way concerned. The liking—the wish to do this or that—is the will, and this wish or will is free when it is able to gratify itself. To ask whether it calls itself into existence is to talk nonsense.

The chapter on 'Cause and Effect' (xxvi.) naturally suggests Hume's more celebrated speculation on the same subject. Locke dismisses the matter in a single paragraph. We observe, he says, that several qualities and substances begin to exist, and that they 'receive this their existence from the due application and operation of some other being.' 'That which produces any simple or complex idea we denote by the general word "cause," and that which is produced "effect."' It must be owned that this 'producing' and 'receiving their existence' are very vague phrases, and Locke does not seem to have been aware of the difficulty of attaching to them any other signification than that of invariable sequence and antecedence.

The chapters on ' Our Complex Ideas of Substance' (xxiii.), and on 'Distinct and Confused Ideas' (xxix.), are the introduction to Berkeley, as the chapter last mentioned is the introduction to Hume. When, indeed, we read Locke with a knowledge of Berkeley, it is difficult to see how Locke failed to hold part at all events of Berkeley's most characteristic doctrines, if indeed he did not hold them. Can anybody, e.g., be more Berkeleyan than this: 'The substance wood, which is a certain collection of simple ideas so called, by the application of fire is turned into another substance called "ashes"—i.e. another complex idea consisting of a collection of simple ideas quite different from that complex idea which we call wood.' Substance, indeed, as explained by Locke, is—to use a significant bull—as unsubstantial a thing as Berkeley himself could wish, for he appears to regard it as an obscure imperfect hypothesis, which we frame because we cannot do without it, but which does not represent any existing fact. All that Berkeley adds to this is, that we can do perfectly well without a word which adds nothing to our knowledge, and is not even an instructive admission of ignorance.

The Third Book classifies words, the instruments of thought, as the Second classifies the thoughts themselves. Hallam, Lord Macaulay, and Mr. Mill rival each other in their praise of this part of the work; and it is, indeed, a complete and admirable vindication and exemplification of the fundamental doctrine of the school of which Locke is certainly the greatest master. It might be shortly expressed by saying, that to be the masters, and not the slaves, of language, is the condition of all real knowledge; that all words whatever are signs and names of our own apprehensions of things, and not independent truths annexed to certain things, independently of the human will, and capable of instructing us as to matters of fact, when duly studied. This is worked out at length, by Locke, in eleven chapters of which it is impossible to get any notion except by careful study.

We may observe, however, that any one who wishes to see how much great men may have in common where no suspicion of plagiarism can exist, ought to compare these chapters with the chapter on 'Speech' (Pt. I. ch. iv.) in Hobbes's Leviathan, and with the scattered references to the same subject which are to be found in other parts of that extraordinary work. The difference between the two is the difference between the seed and the plant. Hobbes gives the principles of the subject with a piercing subtlety and vigorous mother wit, which are not exactly the characteristic qualities of Locke; but Locke works out the whole question from beginning to end with a patient, comprehensive, laborious sagacity which is past all praise, and has raised an imperishable monument to his honour.

The last Book, 'Of Knowledge and Opinion,' pleases us less than the rest of the essay. The forte of Locke's mind was comprehensiveness and sagacity, but he was not, we think, equally happy in precision, or in that sort of subtlety which goes along with precision. With all his study of language, he is at times imposed upon by words, as in the case of cause and effect and substance; and the turn of mind, whatever it was, that led him away from psychology produced a good deal of obscurity in parts of his works. He defines knowledge, for instance, as 'the perception of the connection and agreement, or disagreement and repugnancy, of any of our ideas'; and, as we have already noticed, he uses 'idea,' in this Fourth Book, not in the sense of mental image or picture in which he had generally used it before, but in some other sense the nature of which does not very clearly appear.

Moreover, it is not very easy to understand clearly part of what he says as to the agreement of ideas. Agreement, he tells us, may be of four kinds, and may consist either in identity and diversity, or in relations of various kinds, as equality, or in coexistence, or in 'actual real existence.' It is not easy to understand what he means by 'actual real existence,' or indeed what was his notion of 'reality.'

The whole of this book, which is the crown and conclusion of the work, looks out, so to speak, into a region which Locke did not explore, and is, if we may venture to criticise so great a man, not altogether consistent with the general turn of the earlier books. It assumes throughout a whole set of truths, the derivation of which from sensation or reflection is not clearly made out. His account, for instance, of reasoning and demonstration continually suggests the criticism that he is trying to leap off his own shadow, by professing to find in sensation and reflection more than they do or can contain.

There are also several chapters in which he appears to fall repeatedly into the error of which he was the most eager and thoroughgoing antagonist, that of arguing from sounds to facts. Such is his chapter (Book IV. ch. x.) 'Of our Knowledge of the Existence of a God,' throughout the whole of which he appears to argue from the incapacity of the human mind to conceive this or that to the existence of such and such states of fact. To deduce, from the maxim ex nihilo nihil fit, that there must always have been a Being of some sort, and that that Being must have been cogitative, and must have contained in itself from the first all the perfections that could ever exist afterwards; and further to assert that this Being could not be material and so forth, is in reality to manufacture knowledge out of ignorance, thinly disguised by words which are almost unmeaning.

Locke's theology, and his theories about the nature of the soul, form a sort of parenthesis in his system which by no means harmonises with the rest of it. After his excursion into the region of a priori speculation in chap, x., he returns in chap. xi. to our knowledge of the existence of other things than God and ourselves, and here he immediately reverts to his natural tone. 'The knowledge of the existence of any other thing we can have only by sensation, for there being no necessary connection of real existence with any idea a man hath in his memory, nor of any other existence but that of God with the existence of any other being, no particular man can know the existence of any other being, but only when by actual operation upon him it makes itself perceived by him. For the having the idea of anything in our mind no more proves the existence of that thing than the picture of a man evidences his being in the world, or the visions of a dream make thereby a true history.' Many points of the rest of the book are admirable. For instance, the whole doctrine of the degrees of assent, and of the means by which assent is produced, and especially his estimate of the nature and use of the syllogism, are out of all comparison superior to anything else written on such topics in his own days, or till very long afterwards.

We cannot affect to give within any moderate compass more than the barest sketch of the ground-plan of a work like this; yet the very slightness of the sketch may give it a certain interest, as a few pencil-strokes will sometimes give a notion of a face more easy to take in and remember than an elaborate picture.

Saturday Review, December 29, 1866.