Front Page Titles (by Subject) CHAP. XXXII.: Of true and false Ideas. - The Works, vol. 1 An Essay concerning Human Understanding Part 1
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CHAP. XXXII.: Of true and false Ideas. - John Locke, The Works, vol. 1 An Essay concerning Human Understanding Part 1 
The Works of John Locke in Nine Volumes, (London: Rivington, 1824 12th ed.). Vol. 1.
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Of true and false Ideas.
Truth and falsehood properly belong to propositions.
§ 1. Though truth and falsehood belong, in propriety of speech, only to propositions; yet ideas are oftentimes termed true or false (as what words are there, that are not used with great latitude, and with some deviation from their strict and proper significations?) Though, I think, that when ideas themselves are termed true or false, there is still some secret or tacit proposition, which is the foundation of that denomination: as we shall see, if we examine the particular occasions wherein they come to be called true or false. In all which, we shall find some kind of affirmation or negation, which is the reason of that denomination. For our ideas, being nothing but bare appearances or perceptions in our minds, cannot properly and simply in themselves be said to be true or false, no more than a single name of any thing can be said to be true or false.
Metaphysical truth contains a tacit proposition.
§ 2. Indeed both ideas and words may be said to be true in a metaphysical sense of the word truth, as all other things, that any way exist, are said to be true; i. e. really to be such as they exist. Though in things called true, even in that sense, there is perhaps a secret reference to our ideas, looked upon as the standards of that truth, which amounts to a mental proposition, though it be usually not taken notice of.
No idea, as an appearance in the mind, true or false.
§ 3. But it is not in that metaphysical sense of truth which we inquire here, when we examine whether our ideas are capable of being true or false; but in the more ordinary acceptation of those words: and so I say, that the ideas in our minds being only so many perceptions, or appearances there, none of them are false: the idea of a centaur having no more falsehood in it, when it appears in our minds, than the name centaur has falsehood in it, when it is pronounced by our mouths, or written on paper. For truth or falsehood lying always in some affirmation, or negation, mental or verbal, our ideas are not capable, any of them, of being false, till the mind passes some judgment on them; that is, affirms or denies something of them.
Ideas referred to any thing may be true or false.
§ 4. Whenever the mind refers any of its ideas to any thing extraneous to them, they are then capable to be called true or false. Because the mind in such a reference makes a tacit supposition of their conformity to that thing: which supposition, as it happens to be true or false, so the ideas themselves come to be denominated. The most usual cases wherein this happens, are these following:
Other men’s ideas, real existence, and supposed real essences, are what men usually refer their ideas to.
§ 5. First, when the mind supposes any idea it has conformable to that in other men’s minds, called by the same common name; v. g. when the mind intends or judges its ideas of justice, temperance, religion, to be the same with what other men give those names to.
Secondly, when the mind supposes any idea it has in itself to be conformable to some real existence. Thus the two ideas, of a man and a centaur, supposed to be the ideas of real substances, are the one true, and the other false; the one having a conformity to what has really existed, the other not.
Thirdly, when the mind refers any of its ideas to that real constitution and essence of any thing, whereon all its properties depend: and thus the greatest part, if not all our ideas of substances, are false.
The cause of such references.
§ 6. These suppositions the mind is very apt tacitly to make concerning its own ideas. But yet, if we will examine it, we shall find it is chiefly, if not only, concerning its abstract complex ideas. For the natural tendency of the mind being towards knowledge; and finding that if it should proceed by and dwell upon only particular things, its progress would be very slow, and its work endless; therefore to shorten its way to knowledge, and make each perception more comprehensive; the first thing it does, as the foundation of the easier enlarging its knowledge, either by contemplation of the things themselves that it would know, or conference with others about them, is to bind them into bundles, and rank them so into sorts, that what knowledge it gets of any of them, it may thereby with assurance extend to all of that sort; and so advance by larger steps in that, which is its great business, knowledge. This, as I have elsewhere shown, is the reason why we collect things under comprehensive ideas, with names annexed to them, into genera and species, i. e. into kinds and sorts.
§ 7. If therefore we will warily attend to the motions of the mind, and observe what course it usually takes in its way to knowledge; we shall, I think, find that the mind having got an idea, which it thinks it may have use of, either in contemplation or discourse, the first thing it does is to abstract it, and then get a name to it; and so lay it up in its store-house, the memory, as containing the essence of a sort of things, of which that name is always to be the mark. Hence it is that we may often observe, that when any one sees a new thing of a kind that he knows not, he presently asks what it is, meaning by that inquiry nothing but the name. As if the name carried with it the knowledge of the species, or the essence of it; whereof it is indeed used as the mark, and is generally supposed annexed to it.
Cause of such references.
§ 8. But this abstract idea being something in the mind between the thing that exists, and the name that is given to it; it is in our ideas, that both the rightness of our knowledge, and the propriety or intelligibleness of our speaking, consists. And hence it is, that men are so forward to suppose, that the abstract ideas they have in their minds are such as agree to the things existing without them, to which they are referred; and are the same also, to which the names they give them do by the use and propriety of that language belong. For without this double conformity of their ideas, they find they should both think amiss of things in themselves, and talk of them unintelligibly to others.
Simple ideas may be false in reference to others of the same name, but are least liable to be so.
§ 9. First then, I say, that when the truth of our ideas is judged of, by the conformity they have to the ideas which other men have, and commonly signify by the same name, they may be any of them false. But yet simple ideas are least of all liable to be so mistaken; because a man by his senses, and every day’s observation, may easily satisfy himself what the simple ideas are, which their several names that are in common use stand for; they being but few in number, and such as if he doubts or mistakes in, he may easily rectify by the objects they are to be found in. Therefore it is seldom, that any one mistakes in his names of simple ideas; or applies the name red to the idea green; or the name sweet to the idea bitter: much less are men apt to confound the names of ideas belonging to different senses; and call a colour by the name of a taste, &c. whereby it is evident, that the simple ideas they call by any name, are commonly the same that others have and mean when they use the same names.
Ideas of mixed modes most liable to be false in this sense.
§ 10. Complex ideas are much more liable to be false in this respect: and the complex ideas of mixed modes, much more than those of substances: because in substances (especially those which the common and unborrowed names of any language are applied to) some remarkable sensible qualities, serving ordinarily to distinguish one sort from another, easily preserve those, who take any care in the use of their words, from applying them to sorts of substances, to which they do not at all belong. But in mixed modes we are much more uncertain; it being not so easy to determine of several actions, whether they are to be called justice or cruelty, liberality or prodigality. And so in referring our ideas to those of other men, called by the same names, ours may be false; and the idea in our minds, which we express by the word justice, may perhaps be that which ought to have another name.
Or at least to be thought false.
§ 11. But whether or no our ideas of mixed modes are more liable than any sort to be different from those of other men, which are marked by the same names; this at least is certain, that this sort of falsehood is much more familiarly attributed to our ideas of mixed modes, than to any other. When a man is thought to have a false idea of justice, or gratitude, or glory, it is for no other reason, but that his agrees not with the ideas which each of those names are the signs of in other men.
§ 12. The reason whereof seems to me to be this, that the abstract ideas of mixed modes, being men’s voluntary combinations of such a precise collection of simple ideas; and so the essence of each species being made by men alone, whereof we have no other sensible standard existing any where, but the name itself, or the definition of that name: we have nothing else to refer these our ideas of mixed modes to, as a standard to which we would conform them, but the ideas of those who are thought to use those names in their most proper significations; and so as our ideas conform or differ from them, they pass for true or false. And thus much concerning the truth and falsehood of our ideas, in reference to their names.
As referred to real existences, none of our ideas can be false, but those of substances.
§ 13. Secondly, as to the truth and falsehood of our ideas, in reference to the real existence of things; when that is made the standard of their truth, none of them can be termed false, but only our complex ideas of substances.
First, simple ideas in this sense not false, and why.
§ 14. First, our simple ideas being barely such perceptions as God has fitted us to receive, and given power to external objects to produce in us by established laws and ways, suitable to his wisdom and goodness, though incomprehensible to us, their truth consists in nothing else but in such appearances as are produced in us, and must be suitable to those powers he has placed in external objects, or else they could not be produced in us: and thus answering those powers, they are what they should be, true ideas. Nor do they become liable to any imputation of falsehood, if the mind (as in most men I believe it does) judges these ideas to be in the things themselves. For God, in his wisdom, having set them as marks of distinction in things, whereby we may be able to discern one thing from another, and so choose any of them for our uses, as we have occasion; it alters not the nature of our simple idea, whether we think that the idea of blue be in the violet itself, or in our mind only; and only the power of producing it by the texture of its parts, reflecting the particles of light after a certain manner, to be in the violet itself. For that texture in the object, by a regular and constant operation, producing the same idea of blue in us, it serves us to distinguish, by our eyes, that from any other thing, whether that distinguishing mark, as it is really in the violet, be only a peculiar texture of parts, or else that very colour, the idea whereof (which is in us) is the exact resemblance. And it is equally from that appearance to be denominated blue, whether it be that real colour, or only a peculiar texture in it, that causes in us that idea: since the name blue notes properly nothing but that mark of distinction that is in a violet, discernible only by our eyes, whatever it consists in: that being beyond our capacities distinctly to know, and perhaps would be of less use to us, if we had faculties to discern.
Though one man’s idea of blue should be different from another’s.
§ 15. Neither would it carry any imputation of falsehood to our simple ideas, if by the different structure of our organs it were so ordered, that the same object should produce in several men’s minds different ideas at the same time: v. g. if the idea that a violet produced in one man’s mind by his eyes were the same that a marygold produced in another man’s, and vice versa. For since this could never be known, because one man’s mind could not pass into another man’s body, to perceive what appearances were produced by those organs; neither the ideas hereby, nor the names would be at all confounded, or any falsehood be in either. For all things that had the texture of a violet, producing constantly the idea that he called blue; and those which had the texture of a marygold, producing constantly the idea which he as constantly called yellow; whatever those appearances were in his mind, he would be able as regularly to distinguish things for his use by those appearances, and understand and signify those distinctions marked by the names blue and yellow, as if the appearances, or ideas in his mind, received from those two flowers, were exactly the same with the ideas in other men’s minds. I am nevertheless very apt to think, that the sensible ideas produced by any object in different men’s minds, are most commonly very near and undiscernibly alike. For which opinion, I think, there might be many reasons offered: but that being besides my present business, I shall not trouble my reader with them: but only mind him, that the contrary supposition, if it could be proved, is of little use, either for the improvement of our knowledge, or conveniency of life; and so we need not trouble ourselves to examine it.
First, simple ideas in this sense not false, and why.
§ 16. From what has been said concerning our simple ideas, I think it evident, that our simple ideas can none of them be false in respect of things existing without us. For the truth of these appearances, or perceptions in our minds, consisting, as has been said, only in their being answerable to the powers in external objects to produce by our senses such appearances in us; and each of them being in the mind, such as it is, suitable to the power that produced it, and which alone it represents; it cannot upon that account, or as referred to such a pattern, be false. Blue and yellow, bitter or sweet, can never be false ideas: these perceptions in the mind are just such as they are there, answering the powers appointed by God to produce them; and so are truly what they are, and are intended to be. Indeed the names may be misapplied: but that in this respect makes no falsehood in the ideas; as if a man ignorant in the English tongue should call purple scarlet.
Secondly, modes not false.
§ 17. Secondly, neither can our complex ideas of modes, in reference to the essence of any thing really existing, be false. Because whatever complex idea I have of any mode, it hath no reference to any pattern existing, and made by nature: it is not supposed to contain in it any other ideas than what it hath; nor to represent any thing but such a complication of ideas as it does. Thus when I have the idea of such an action of a man, who forbears to afford himself such meat, drink, and clothing, and other conveniencies of life, as his riches and estate will be sufficient to supply, and his station requires, I have no false idea; but such an one as represents an action, either as I find or imagine it; and so is capable of neither truth or falsehood. But when I give the name frugality or virtue to this action, then it may be called a false idea, if thereby it be supposed to agree with that idea, to which, in propriety of speech, the name of frugality doth belong: or to be conformable to that law, which is the standard of virtue and vice.
Thirdly, ideas of substances when false.
§ 18. Thirdly, our complex ideas of substances, being all referred to patterns in things themselves, may be false. That they are all false, when looked upon as the representations of the unknown essences of things, is so evident that there needs nothing to be said of it. I shall therefore pass over that chimerical supposition, and consider them as collections of simple ideas in the mind taken from combinations of simple ideas existing together constantly in things, of which patterns they are the supposed copies: and in this reference of them to the existence of things, they are false ideas. 1. When they put together simple ideas, which in the real existence of things have no union; as when to the shape and size that exist together in a horse is joined, in the same complex idea, the power of barking like a dog: which three ideas, however put together into one in the mind, were never united in nature; and this therefore may be called a false idea of a horse. 2. Ideas of substances are, in this respect, also false, when from any collection of simple ideas that do always exist together, there is separated, by a direct negation, any other simple idea which is constantly joined with them. Thus, if to extension, solidity, fusibility, the peculiar weightiness, and yellow colour of gold, any one join in his thoughts the negation of a greater degree of fixedness than is in lead or copper, he may be said to have a false complex idea, as well as when he joins to those other simple ones the idea of a perfect absolute fixedness. For either way, the complex idea of gold being made up of such simple ones as have no union in nature, may be termed false. But if we leave out of this his complex idea, that of fixedness quite, without either actually joining to, or separating of it from the rest in his mind, it is, I think, to be looked on as an inadequate and imperfect idea, rather than a false one; since though it contains not all the simple ideas that are united in nature, yet it puts none together but what do really exist together.
Truth or falsehood always supposes affirmation or negation.
§ 19. Though in compliance with the ordinary way of speaking I have showed in what sense, and upon what ground our ideas may be sometimes called true or false; yet if we will look a little nearer into the matter, in all cases where any idea is called true or false, it is from some judgment that the mind makes, or is supposed to make, that is true or false. For truth or falsehood, being never without some affirmation or negation, express or tacit, it is not to be found but where signs are joined and separated according to the agreement or disagreement of the things they stand for. The signs we chiefly use are either ideas or words, wherewith we make either mental or verbal propositions. Truth lies in so joining or separating these representatives, as the things they stand for do in themselves agree or disagree; and falsehood in the contrary, as shall be more fully shown hereafter.
Ideas in themselves neither true nor false.
§ 20. Any idea then which we have in our minds, whether conformable or not to the existence of things, or to any idea in the minds of other men, cannot properly for this alone be called false. For these representations, if they have nothing in them but what is really existing in things without, cannot be thought false, being exact representations of something: nor yet, if they have any thing in them differing from the reality of things, can they properly be said to be false representations, or ideas of things they do not represent. But the mistake and falsehood is,
Butare false, 1. When judged agreeable to another man’s idea, without being so.
§ 21. First, when the mind having any idea, it judges and concludes in the same that is in other men’s minds, signified by the same name; or that it is conformable to the ordinary received signification or definition of that word, when indeed it is not; which is the most usual mistake in mixed modes, though other ideas also are liable to it.
2. When judged to agree to real existence, when they do not.
§ 22. Secondly, when it having a complex idea made up of such a collection of simple ones as nature never puts together, it judges it to agree to a species of creatures really existing; as when it joins the weight of tin to the colour, fusibility, and fixedness of gold.
3. When judged adequate, without being so.
§ 23. Thirdly, when, in its complex idea it has united a certain number of simple ideas that do really exist together in some sort of creatures, but has also left out others as much inseparable, it judges this to be a perfect complete idea of a sort of things which really it is not; v. g. having joined the ideas of substance, yellow, malleable, most heavy, and fusible, it takes that complex idea to be the complete idea of gold, when yet its peculiar fixedness and solubility in aqua regia are as inseparable from those other ideas or qualities of that body, as they are from one another.
4. When judged to represent the real essence.
§ 24. Fourthly, the mistake is yet greater, when I judge, that this complex idea contains in it the real essence of any body existing, when at least it contains but some few of those properties which flow from its real essence and constitution. I say, only some few of those properties; for those properties consisting mostly in the active and passive powers it has, in reference to other things, all that are vulgarly known of any one body of which the complex idea of that kind of things is usually made, are but a very few, in comparison of what a man, that has several ways tried and examined it, knows of that one sort of things: and all that the most expert man knows are but a few, in comparison of what are really in that body, and depend on its internal or essential constitution. The essence of a triangle lies in a very little compass, consists in a very few ideas: three lines including a space make up that essence: but the properties that flow from this essence are more than can be easily known or enumerated. So I imagine it is in substances, their real essences lie in a little compass, though the properties flowing from that internal constitution are endless.
Ideas, when false.
§ 25. To conclude, a man having no notion of any thing without him, but by the idea he has of it in his mind (which idea he has a power to call by what name he pleases) he may indeed make an idea neither answering the reason of things, nor agreeing to the idea commonly signified by other people’s words; but cannot make a wrong or false idea of a thing, which is no otherwise known to him but by the idea he has of it: v. g. when I frame an idea of the legs, arms, and body of a man, and join to this a horse’s head and neck, I do not make a false idea of any thing; because it represents nothing without me. But when I call it a man or Tartar, and imagine it to represent some real being without me, or to be the same idea that others call by the same name; in either of these cases I may err. And upon this account it is, that it comes to be termed a false idea; though indeed the falsehood lies not in the idea, but in that tacit mental proposition, wherein a conformity and resemblance is attributed to it, which it has not. But yet, if having framed such an idea in my mind, without thinking either that existence, or the name man or Tartar, belongs to it, I will call it man or Tartar, I may be justly thought fantastical in the naming, but not erroneous in my judgment; nor the idea any way false.
More properly to be called right or wrong.
§ 26. Upon the whole matter, I think, that our ideas, as they are considered by the mind, either in reference to the proper signification of their names, or in reference to the reality of things, may very fitly be called right or wrong ideas, according as they agree or disagree to those patterns to which they are referred. But if any one had rather call them true or false, it is fit he use a liberty, which every one has, to call things by those names he thinks best; though, in propriety of speech, truth or falsehood will, I think, scarce agree to them, but as they, some way or other, virtually contain in them some mental proposition. The ideas that are in a man’s mind, simply considered, cannot be wrong, unless complex ones, wherein inconsistent parts are jumbled together. All other ideas are in themselves right, and the knowledge about them right and true knowledge: but when we come to refer them to any thing, as to their patterns and archetypes, then they are capable of being wrong, as far as they disagree with such archetypes.