John Locke

“ 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. ”

“ 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 he leave out of this his complex idea that of fixedness quite, without either actually joining to or separating 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. ”

“ 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 conveniences 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 nor falsehood. ”

“ 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. ”

“ Though one man’s idea of blue should be different from another’s. 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 marigold 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 ”

“ 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. ”

“ 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. ”

“ Ideas and words may be said to be true, inasmuch as they really are ideas and words. 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 ”

“ 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 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. ”

“ 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. ”

“ As referred to real existence, none of our ideas can be false but those of substances. 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. ”

“ 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 : mush 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, when called false. To conclude, a man having no notion of anything 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 ”

“ 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 or separated, according to the agreement or disagreement of the things they stand for. The signs we chiefly use are either ideas or words ”