# An Essay Concerning Human Understanding/Book IV/Chapter VIII

1. Some propositions bring no increase to our knowledge. Whether the maxims treated of in the foregoing chapter be of that use to real knowledge as is generally supposed, I leave to be considered. This, I think, may confidently be affirmed, That there are universal propositions, which, though they be certainly true, yet they add no light to our understanding ; bring no increase to our knowledge. Such are –
2. As identical propositions. First, All purely identical propositions. These obviously and at first blush appear to contain no instruction in them ; for when we affirm the said term of itself, whether it be barely verbal, or whether it contains any clear and real idea, it shows us nothing but what we must certainly know before, whether such a proposition be either made by, or proposed to us. Indeed, that most general one, what is, is, may serve sometimes to show a man the absurdity he is guilty of, when, by circumlocution or equivocal terms, he would in particular instances deny the same thing of itself ; because nobody will so openly bid defiance to common sense, as to affirm visible and direct contradictions in plain words ; or, if he does, a man is excused if he breaks off any further discourse with him. But yet I think I may say, that neither that received maxim, nor any other identical proposition, teaches us anything ; and though in such kind of propositions this great and magnified maxim, boasted to be the foundation of demonstration, may be and often is made use of to confirm them, yet all it proves amounts to no more than this, That the same word may with great certainty be affirmed of itself, without any doubt of the truth of any such proposition ; and let me add, also, without any real knowledge.
3. Examples. For, at this rate, any very ignorant person, who can but make a proposition, and knows what he means when he says ay or no, may make a million of propositions of whose truth he may be infallibly certain, and yet not know one thing in the world thereby ; v.g. « what is a soul, is a soul, » ; or, « a soul is a soul » ; « a spirit is a spirit » ; « a fetiche is a fetiche, » &c. These all being equivalent to this proposition, viz. what is, is ; i.e. what hath existence, hath existence ; or, who hath a soul, hath a soul. What is this more than trifling with words ? It is but like a monkey shifting his oyster from one hand to the other : and had he but words, might no doubt have said, « Oyster in right hand is subject, and oyster in left hand is predicate » : and so might have made a self-evident proposition of oyster, i.e. oyster is oyster ; and yet, with all this, not have been one whit the wiser or more knowing : and that way of handling the matter would much at once have satisfied the monkey’s hunger, or a man’s understanding, and they would have improved in knowledge and bulk together.
How identical propositions are trifling.
I know there are some who, because identical propositions are self-evident, show a great concern for them, and think they do great service to philosophy by crying them up ; as if in them was contained all knowledge, and the understanding were led into all truth by them only. I grant as forwardly as any one, that they are all true and self-evident. I grant further, that the foundation of all our knowledge lies in the faculty we have of perceiving the same idea to be the same, and of discerning it from those that are different ; as I have shown in the foregoing chapter. But how that vindicates the making use of identical propositions, for the improvement of knowledge, from the imputation of trifling, I do not see. Let any one repeat, as often as he pleases, that « the will is the will, » or lay what stress on it he thinks fit ; of what use is this, and an infinite the like propositions, for the enlarging our knowledge ? Let a man abound, as much as the plenty of words which he has will permit, in such propositions as these : « a law is a law, » and « obligation is obligation » ; « right is right, » and « wrong is wrong » : – will these and the like ever help him to an acquaintance with ethics, or instruct him or others in the knowledge of morality ? Those who know not, nor perhaps ever will know, what is right and what is wrong, nor the measures of them, can with as much assurance make, and infallibly know, the truth of these and all such propositions, as he that is best instructed in morality can do. But what advance do such propositions give in the knowledge of anything necessary or useful for their conduct ?
He would be thought to do little less than trifle, who, for the enlightening the understanding in any part of knowledge, should be busy with identical propositions and insist on such maxims as these : « substance is substance, » and « body is body » ; « a vacuum is a vacuum, » and « a vortex is a vortex » ; « a centaur is a centaur, » and « a chimera is a chimera, » &c. For these and all such are equally true, equally certain, and equally self-evident. But yet they cannot but be counted trifling, when made use of as principles of instruction, and stress laid on them as helps to knowledge ; since they teach nothing but what every one who is capable of discourse knows without being told, viz. that the same term is the same term, and the same idea the same idea. And upon this account it was that I formerly did, and do still think, the offering and inculcating such propositions, in order to give the understanding any new light, or inlet into the knowledge of things, no better than trifling.
Instruction lies in something very different ; and he that would enlarge his own or another’s mind to truths he does not yet know, must find out intermediate ideas, and then lay them in such order one by another, that the understanding may see the agreement or disagreement of those in question. Propositions that do this are instructive ; but they are far from such as affirm the same term of itself ; which is no way to advance one’s self or others in any sort of knowledge. It no more helps to that than it would help any one in his learning to read, to have such propositions as these inculcated to him – « An A is an A, » and « a B is a B » ; which a man may know as well as any schoolmaster, and yet never be able to read a word as long as he lives. Nor do these, or any such identical propositions help him one jot forwards in the skill of reading, let him make what use of them he can.
If those who blame my calling them trifling propositions had but read and been at the pains to understand what I have above writ in very plain English, they could not but have seen that by identical propositions I mean only such wherein the same term, importing the same idea, is affirmed of itself : which I take to be the proper signification of identical propositions ; and concerning all such, I think I may continue safely to say, that to propose them as instructive is no better than trifling. For no one who has the use of reason can miss them, where it is necessary they should be taken notice of ; nor doubt of their truth when he does take notice of them.
But if men will call propositions identical, wherein the same term is not affirmed of itself, whether they speak more properly than I, others must judge ; this is certain, all that they say of propositions that are not identical in my sense, concerns not me nor what I have said ; all that I have said relating to those propositions wherein the same term is affirmed of itself. And I would fain see an instance wherein any such can be made use of, to the advantage and improvement of any one’s knowledge. Instances of other kinds, whatever use may be made of them, concern not me, as not being such as I call identical.
4. Secondly, propositions in which a part of any complex idea is predicated of the whole. Another sort of trifling propositions is, when a part of the complex idea is predicated of the name of the whole ; a part of the definition of the word defined. Such are all propositions wherein the genus is predicated of the species, or more comprehensive of less comprehensive terms. For what information, what knowledge, carries this proposition in it, viz. « Lead is a metal » to a man who knows the complex idea the name lead stands for ? All the simple ideas that go to the complex one signified by the term metal, being nothing but what he before comprehended and signified by the name lead. Indeed, to a man that knows the signification of the word metal, and not of the word lead, it is a shorter way to explain the signification of the word lead, by saying it is a metal, which at once expresses several of its simple ideas, than to enumerate them one by one, telling him it is a body very heavy, fusible, and malleable.
5. As part of the definition of the term defined. Alike trifling it is to predicate any other part of the definition of the term defined, or to affirm any one of the simple ideas of a complex one of the name of the whole complex idea ; as, « All gold is fusible. » For fusibility being one of the simple ideas that goes to the making up the complex one the sound gold stands for, what can it be but playing with sounds, to affirm that of the name gold, which is comprehended in its received signification ? It would be thought little better than ridiculous to affirm gravely, as a truth of moment, that gold is yellow ; and I see not how it is any jot more material to say it is fusible, unless that quality be left out of the complex idea, of which the sound gold is the mark in ordinary speech. What instruction can it carry with it, to tell one that which he hath been told already, or he is supposed to know before ? For I am supposed to know the signification of the word another uses to me, or else he is to tell me. And if I know that the name gold stands for this complex idea of body, yellow, heavy, fusible, malleable, it will not much instruct me to put it solemnly afterwards in a proposition, and gravely say, all gold is fusible. Such propositions can only serve to show the disingenuity of one who will go from the definition of his own terms, by reminding him sometimes of it ; but carry no knowledge with them, but of the signification of words, however certain they be.
6. Instance, man and palfrey. « Every man is an animal, or living body, » is as certain a proposition as can be ; but no more conducing to the knowledge of things than to say, a palfrey is an ambling horse, or a neighing, ambling animal, both being only about the signification of words, and make me know but this – That body, sense, and motion, or power of sensation and moving, are three of those ideas that I always comprehend and signify by the word man : and where they are not to be found together, the name man belongs not to that thing : and so of the other – That body, sense, and a certain way of going, with a certain kind of voice, are some of those ideas which I always comprehend and signify by the word palfrey ; and when they are not to be found together, the name palfrey belongs not to that thing. It is just the same, and to the same purpose, when any term standing for any one or more of the simple ideas, that altogether make up that complex idea which is called man, is affirmed of the term man : – v.g. suppose a Roman signified by the word homo all these distinct ideas united in one subject, corporietas, sensibilitas, potentia se movendi rationalitas, risibilitas ; he might, no doubt, with great certainty, universally affirm one, more, or all of these together of the word homo, but did no more than say that the word homo, in his country, comprehended in its signification all these ideas. Much like a romance knight, who by the word palfrey signified these ideas : – body of a certain figure, four-legged, with sense, motion, ambling, neighing, white, used to have a woman on his back – might with the same certainty universally affirm also any or all of these of the word palfrey : but did thereby teach no more, but that the word palfrey, in his or romance language, stood for all these, and was not to be applied to anything where any of these was wanting. But he that shall tell me, that in whatever thing sense, motion, reason, and laughter, were united, that thing had actually a notion of God, or would be cast into a sleep by opium, made indeed an instructive proposition : because neither having the notion of God, nor being cast into sleep by opium, being contained in the idea signified by the word man, we are by such propositions taught something more than barely what the word man stands for : and therefore the knowledge contained in it is more than verbal.
7. For this teaches but the signification of words. Before a man makes any proposition, he is supposed to understand the terms he uses in it, or else he talks like a parrot, only making a noise by imitation, and framing certain sounds, which he has learnt of others ; but not as a rational creature, using them for signs of ideas which he has in his mind. The hearer also is supposed to understand the terms as the speaker uses them, or else he talks jargon, and makes an unintelligible noise. And therefore he trifles with words who makes such a proposition, which, when it is made, contains no more than one of the terms does, and which a man was supposed to know before : v.g. a triangle hath three sides, or saffron is yellow. And this is no further tolerable than where a man goes to explain his terms to one who is supposed or declares himself not to understand him ; and then it teaches only the signification of that word, and the use of that sign.
8. But adds no real knowledge. We can know then the truth of two sorts of propositions with perfect certainty. The one is, of those trifling propositions which have a certainty in them, but it is only a verbal certainty, but not instructive. And, secondly, we can know the truth, and so may be certain in propositions, which affirm something of another, which is a necessary consequence of its precise complex idea, but not contained in it : as that the external angle of all triangles is bigger than either of the opposite internal angles. Which relation of the outward angle to either of the opposite internal angles, making no part of the complex idea signified by the name triangle, this is a real truth, and conveys with it instructive real knowledge.
9. General propositions concerning substances are often trifling. We having little or no knowledge of what combinations there be of simple ideas existing together in substances, but by our senses, we cannot make any universal certain propositions concerning them, any further than our nominal essences lead us. Which being to a very few and inconsiderable truths, in respect of those which depend on their real constitutions, the general propositions that are made about substances, if they are certain, are for the most part but trifling ; and if they are instructive, are uncertain, and such as we can have no knowledge of their real truth, how much soever constant observation and analogy may assist our judgment in guessing. Hence it comes to pass, that one may often meet with very clear and coherent discourses, that amount yet to nothing. For it is plain that names of substantial beings, as well as others, as far as they have relative significations affixed to them, may, with great truth, be joined negatively and affirmatively in propositions, as their relative definitions make them fit to be so joined ; and propositions consisting of such terms, may, with the same clearness, be deduced one from another, as those that convey the most real truths : and all this without any knowledge of the nature or reality of things existing without us. By this method one may make demonstrations and undoubted propositions in words, and yet thereby advance not one jot in the knowledge of the truth of things : v.g. he that having learnt these following words, with their ordinary mutual relative acceptations annexed to them : v.g. substance, man, animal, form, soul, vegetative, sensitive, rational, may make several undoubted propositions about the soul, without knowing at all what the soul really is : and of this sort, a man may find an infinite number of propositions, reasonings, and conclusions, in books of metaphysics, school-divinity, and some sort of natural philosophy : and, after all, know as little of God, spirits, or bodies, as he did before he set out.
10. And why. He that hath liberty to define, i.e. to determine the signification of his names of substances (as certainly every one does in effect, who makes them stand for his own ideas), and makes their significations at a venture, taking them from his own or other men’s fancies, and not from an examination or inquiry into the nature of things themselves ; may with little trouble demonstrate them one of another, according to those several respects and mutual relations he has given them one to another ; wherein, however things agree or disagree in their own nature, he needs mind nothing but his own notions, with the names he hath bestowed upon them : but thereby no more increases in his own knowledge than he does his riches, who, taking a bag of counters, calls one in a certain place a pound, another in another place a shilling, and a third in a third place a penny ; and so proceeding, may undoubtedly reckon right, and cast up a great sum, according to his counters so placed, and standing for more or less as he pleases, without being one jot the richer, or without even knowing how much a pound, shilling, or penny is, but only that one is contained in the other twenty times, and contains the other twelve : which a man may also do in the signification of words, by making them, in respect of one another, more or less, or equally comprehensive.
11. Thirdly, using words variously is trifling with them. Though yet concerning most words used in discourses, equally argumentative and controversial, there is this more to be complained of, which is the worst sort of trifling, and which sets us yet further from the certainty of knowledge we hope to attain by them, or find in them ; viz. that most writers are so far from instructing us in the nature and knowledge of things, that they use their words loosely and uncertainly, and do not, by using them constantly and steadily in the same significations, make plain and clear deductions of words one from another, and make their discourses coherent and clear, (how little soever they were instructive) ; which were not difficult to do, did they not find it convenient to shelter their ignorance or obstinacy under the obscurity and perplexedness of their terms : to which, perhaps, inadvertency and ill custom do in many men much contribute.
12. Marks of verbal propositions. To conclude. Barely verbal propositions may be known by these following marks :
Predication in abstract.
First, All propositions wherein two abstract terms are affirmed one of another, are barely about the signification of sounds. For since no abstract idea can be the same with any other but itself, when its abstract name is affirmed of any other term, it can signify no more but this, that it may, or ought to be called by that name ; or that these two names signify the same idea. Thus, should any one say that parsimony is frugality, that gratitude is justice, that this or that action is or is not temperate : however specious these and the like propositions may at first sight seem, yet when we come to press them, and examine nicely what they contain, we shall find that it all amounts to nothing but the signification of those terms.
13. A part of the definition predicated of any term. Secondly, All propositions wherein a part of the complex idea which any term stands for is predicated of that term, are only verbal : v.g. to say that gold is a metal, or heavy. And thus all propositions wherein more comprehensive words, called genera, are affirmed of subordinate or less comprehensive, called species, or individuals, are barely verbal.
When by these two rules we have examined the propositions that make up the discourses we ordinarily meet with, both in and out of books, we shall perhaps find that a greater part of them than is usually suspected are purely about the signification of words, and contain nothing in them but the use and application of these signs.
This I think I may lay down for an infallible rule, That, wherever the distinct idea any word stands for is not known and considered, and something not contained in the idea is not affirmed or denied of it, there our thoughts stick wholly in sounds, and are able to attain no real truth or falsehood. This, perhaps, if well heeded, might save us a great deal of useless amusement and dispute ; and very much shorten our trouble and wandering in the search of real and true knowledge.