# An Essay Concerning Human Understanding/Book II/Chapter XI

1. No knowledge without discernment. Another faculty we may take notice of in our minds is that of discerning and distinguishing between the several ideas it has. It is not enough to have a confused perception of something in general. Unless the mind had a distinct perception of different objects and their qualities, it would be capable of very little knowledge, though the bodies that affect us were as busy about us as they are now, and the mind were continually employed in thinking. On this faculty of distinguishing one thing from another depends the evidence and certainty of several, even very general, propositions, which have passed for innate truths ; – because men, overlooking the true cause why those propositions find universal assent, impute it wholly to native uniform impressions ; whereas it in truth depends upon this clear discerning faculty of the mind, whereby it perceives two ideas to be the same, or different. But of this more hereafter.
2. The difference of wit and judgment. How much the imperfection of accurately discriminating ideas one from another lies, either in the dulness or faults of the organs of sense ; or want of acuteness, exercise, or attention in the understanding ; or hastiness and precipitancy, natural to some tempers, I will not here examine : it suffices to take notice, that this is one of the operations that the mind may reflect on and observe in itself It is of that consequence to its other knowledge, that so far as this faculty is in itself dull, or not rightly made use of, for the distinguishing one thing from another, – so far our notions are confused, and our reason and judgment disturbed or misled. If in having our ideas in the memory ready at hand consists quickness of parts ; in this, of having them unconfused, and being able nicely to distinguish one thing from another, where there is but the least difference, consists, in a great measure, the exactness of judgment, and clearness of reason, which is to be observed in one man above another. And hence perhaps may be given some reason of that common observation, – that men who have a great deal of wit, and prompt memories, have not always the clearest judgment or deepest reason. For wit lying most in the assemblage of ideas, and putting those together with quickness and variety, wherein can be found any resemblance or congruity, thereby to make up pleasant pictures and agreeable visions in the fancy ; judgment, on the contrary, lies quite on the other side, in separating carefully, one from another, ideas wherein can be found the least difference, thereby to avoid being misled by similitude, and by affinity to take one thing for another. This is a way of proceeding quite contrary to metaphor and allusion ; wherein for the most part lies that entertainment and pleasantry of wit, which strikes so lively on the fancy, and therefore is so acceptable to all people, because its beauty appears at first sight, and there is required no labor of thought to examine what truth or reason there is in it. The mind, without looking any further, rests satisfied with the agreeableness of the picture and the gaiety of the fancy. And it is a kind of affront to go about to examine it, by the severe rules of truth and good reason ; whereby it appears that it consists in something that is not perfectly conformable to them.
3. Clearness done hinders confusion. To the well distinguishing our ideas, it chiefly contributes that they be clear and determinate. And when they are so, it will not breed any confusion or mistake about them, though the senses should (as sometimes they do) convey them from the same object differently on different occasions, and so seem to err. For, though a man in a fever should from sugar have a bitter taste, which at another time would produce a sweet one, yet the idea of bitter in that man’s mind would be as clear and distinct from the idea of sweet as if he had tasted only gall. Nor does it make any more confusion between the two ideas of sweet and bitter, that the same sort of body produces at one time one, and at another time another idea by the taste, than it makes a confusion in two ideas of white and sweet, or white and round, that the same piece of sugar produces them both in the mind at the same time. And the ideas of orange-colour and azure, that are produced in the mind by the same parcel of the infusion of lignum nephriticum, are no less distinct ideas than those of the same colours taken from two very different bodies.
4. Comparing. The Comparing them one with another, in respect of extent, degrees, time, place, or any other circumstances, is another operation of the mind about its ideas, and is that upon which depends all that large tribe of ideas comprehended under relation ; which, of how vast an extent it is, I shall have occasion to consider hereafter.
5. Brutes compare but imperfectly. How far brutes partake in this faculty, is not easy to determine. I imagine they have it not in any great degree : for, though they probably have several ideas distinct enough, yet it seems to me to be the prerogative of human understanding, when it has sufficiently distinguished any ideas, so as to perceive them to be perfectly different, and so consequently two, to cast about and consider in what circumstances they are capable to be compared. And therefore, I think, beasts compare not their ideas further than some sensible circumstances annexed to the objects themselves. The other power of comparing, which may be observed in men, belonging to general ideas, and useful only to abstract reasonings, we may probably conjecture beasts have not.
6. Compounding. The next operation we may observe in the mind about its ideas is Composition ; whereby it puts together several of those simple ones it has received from sensation and reflection, and combines them into complex ones. Under this of composition may be reckoned also that of enlarging, wherein, though the composition does not so much appear as in more complex ones, yet it is nevertheless a putting several ideas together, though of the same kind. Thus, by adding several units together, we make the idea of a dozen ; and putting together the repeated ideas of several perches, we frame that of a furlong.
7. Brutes compound but little. In this also, I suppose, brutes come far short of man. For, though they take in, and retain together, several combinations of simple ideas, as possibly the shape, smell, and voice of his master make up the complex idea a dog has of him, or rather are so many distinct marks whereby he knows him ; yet I do not think they do of themselves ever compound them and make complex ideas. And perhaps even where we think they have complex ideas, it is only one simple one that directs them in the knowledge of several things, which possibly they distinguish less by their sight than we imagine. For I have been credibly informed that a bitch will nurse, play with, and be fond of young foxes, as much as, and in place of her puppies, if you can but get them once to suck her so long that her milk may go through them. And those animals which have a numerous brood of young ones at once, appear not to have any knowledge of their number ; for though they are mightily concerned for any of their young that are taken from them whilst they are in sight or hearing, yet if one or two of them be stolen from them in their absence, or without noise, they appear not to miss them, or to have any sense that their number is lessened.
8. Naming. When children have, by repeated sensations, got ideas fixed in their memories, they begin by degrees to learn the use of signs. And when they have got the skill to apply the organs of speech to the framing of articulate sounds, they begin to make use of words, to signify their ideas to others. These verbal signs they sometimes borrow from others, and sometimes make themselves, as one may observe among the new and unusual names children often give to things in the first use of language.
9. Abstraction. The use of words then being to stand as outward marks of our internal ideas, and those ideas being taken from particular things, if every particular idea that we take in should have a distinct name, names must be endless. To prevent this, the mind makes the particular ideas received from particular objects to become general ; which is done by considering them as they are in the mind such appearances, – separate from all other existences, and the circumstances of real existence, as time, place, or any other concomitant ideas. This is called Abstraction, whereby ideas taken from particular beings become general representatives of all of the same kind ; and their names general names, applicable to whatever exists conformable to such abstract ideas. Such precise, naked appearances in the mind, without considering how, whence, or with what others they came there, the understanding lays up (with names commonly annexed to them) as the standards to rank real existences into sorts, as they agree with these patterns, and to denominate them accordingly. Thus the same colour being observed to-day in chalk or snow, which the mind yesterday received from milk, it considers that appearance alone, makes it a representative of all of that kind ; and having given it the name whiteness, it by that sound signifies the same quality wheresoever to be imagined or met with ; and thus universals, whether ideas or terms, are made.
10. Brutes abstract not. If it may be doubted whether beasts compound and enlarge their ideas that way to any degree ; this, I think, I may be positive in, – that the power of abstracting is not at all in them ; and that the having of general ideas is that which puts a perfect distinction betwixt man and brutes, and is an excellency which the faculties of brutes do by no means attain to. For it is evident we observe no footsteps in them of making use of general signs for universal ideas ; from which we have reason to imagine that they have not the faculty of abstracting, or making general ideas, since they have no use of words, or any other general signs.
11. Brutes abstract not, yet are not bare machines. Nor can it be imputed to their want of fit organs to frame articulate sounds, that they have no use or knowledge of general words ; since many of them, we find, can fashion such sounds, and pronounce words distinctly enough, but never with any such application. And, on the other side, men who, through some defect in the organs, want words, yet fail not to express their universal ideas by signs, which serve them instead of general words, a faculty which we see beasts come short in. And, therefore, I think, we may suppose, that it is in this that the species of brutes are discriminated from man : and it is that proper difference wherein they are wholly separated, and which at last widens to so vast a distance. For if they have any ideas at all, and are not bare machines, (as some would have them,) we cannot deny them to have some reason. It seems as evident to me, that they do some of them in certain instances reason, as that they have sense ; but it is only in particular ideas, just as they received them from their senses. They are the best of them tied up within those narrow bounds, and have not (as I think) the faculty to enlarge them by any kind of abstraction.
12. Idiots and madmen. How far idiots are concerned in the want or weakness of any, or all of the foregoing faculties, an exact observation of their several ways of faultering would no doubt discover. For those who either perceive but dully, or retain the ideas that come into their minds but ill, who cannot readily excite or compound them, will have little matter to think on. Those who cannot distinguish, compare, and abstract, would hardly be able to understand and make use of language, or judge or reason to any tolerable degree ; but only a little and imperfectly about things present, and very familiar to their senses. And indeed any of the forementioned faculties, if wanting, or out of order, produce suitable defects in men’s understandings and knowledge.
13. Difference between idiots and madmen. In fine, the defect in naturals seems to proceed from want of quickness, activity, and motion in the intellectual faculties, whereby they are deprived of reason ; whereas madmen, on the other side, seem to suffer by the other extreme. For they do not appear to me to have lost the faculty of reasoning, but having joined together some ideas very wrongly, they mistake them for truths ; and they err as men do that argue right from wrong principles. For, by the violence of their imaginations, having taken their fancies for realities, they make right deductions from them. Thus you shall find a distracted man fancying himself a king, with a right inference require suitable attendance, respect, and obedience : others who have thought themselves made of glass, have used the caution necessary to preserve such brittle bodies. Hence it comes to pass that a man who is very sober, and of a right understanding in all other things, may in one particular be as frantic as any in Bedlam ; if either by any sudden very strong impression, or long fixing his fancy upon one sort of thoughts, incoherent ideas have been cemented together so powerfully, as to remain united. But there are degrees of madness, as of folly ; the disorderly jumbling ideas together is in some more, and some less. In short, herein seems to lie the difference between idiots and madmen : that madmen put wrong ideas together, and so make wrong propositions, but argue and reason right from them ; but idiots make very few or no propositions, and reason scarce at all.
14. Method followed in this explication of faculties. These, I think, are the first faculties and operations of the mind, which it makes use of in understanding ; and though they are exercised about all its ideas in general, yet the instances I have hitherto given have been chiefly in simple ideas. And I have subjoined the explication of these faculties of the mind to that of simple ideas, before I come to what I have to say concerning complex ones, for these following reasons : –
First, Because several of these faculties being exercised at first principally about simple ideas, we might, by following nature in its ordinary method, trace and discover them, in their rise, progress, and gradual improvements.
Secondly, Because observing the faculties of the mind, how they operate about simple ideas, – which are usually, in most men’s minds, much more clear, precise, and distinct than complex ones, – we may the better examine and learn how the mind extracts, denominates, compares, and exercises, in its other operations about those which are complex, wherein we are much more liable to mistake.
Thirdly, Because these very operations of the mind about ideas received from sensations, are themselves, when reflected on, another set of ideas, derived from that other source of our knowledge, which I call reflection ; and therefore fit to be considered in this place after the simple ideas of sensation. Of compounding, comparing, abstracting, &c., I have but just spoken, having occasion to treat of them more at large in other places.
15. The true beginning of human knowledge. And thus I have given a short, and, I think, true history of the first beginnings of human knowledge ; – whence the mind has its first objects ; and by what steps it makes its progress to the laying in and storing up those ideas, out of which is to be framed all the knowledge it is capable of : wherein I must appeal to experience and observation whether I am in the right : the best way to come to truth being to examine things as really they are, and not to conclude they are, as we fancy of ourselves, or have been taught by others to imagine.
16. Appeal to experience. To deal truly, this is the only way that I can discover, whereby the ideas of things are brought into the understanding. If other men have either innate ideas or infused principles, they have reason to enjoy them ; and if they are sure of it, it is impossible for others to deny them the privilege that they have above their neighbours. I can speak but of what I find in myself, and is agreeable to those notions, which, if we will examine the whole course of men in their several ages, countries, and educations, seem to depend on those foundations which I have laid, and to correspond with this method in all the parts and degrees thereof.
17. Dark room. I pretend not to teach, but to inquire ; and therefore cannot but confess here again, – that external and internal sensation are the only passages I can find of knowledge to the understanding. These alone, as far as I can discover, are the windows by which light is let into this dark room. For, methinks, the understanding is not much unlike a closet wholly shut from light, with only some little openings left, to let in external visible resemblances, or ideas of things without : would the pictures coming into such a dark room but stay there, and lie so orderly as to be found upon occasion, it would very much resemble the understanding of a man, in reference to all objects of sight, and the ideas of them.
These are my guesses concerning the means whereby the understanding comes to have and retain simple ideas, and the modes of them, with some other operations about them.
I proceed now to examine some of these simple ideas and their modes a little more particularly.