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

1. Our knowledge being short, we want something else. The understanding faculties being given to man, not barely for speculation, but also for the conduct of his life, man would be at a great loss if he had nothing to direct him but what has the certainty of true knowledge. For that being very short and scanty, as we have seen, he would be often utterly in the dark, and in most of the actions of his life, perfectly at a stand, had he nothing to guide him in the absence of clear and certain knowledge. He that will not eat till he has demonstration that it will nourish him ; he that will not stir till he infallibly knows the business he goes about will succeed, will have little else to do but to sit still and perish.
2. What use to be made of this twilight state. Therefore, as God has set some things in broad daylight ; as he has given us some certain knowledge, though limited to a few things in comparison, probably as a taste of what intellectual creatures are capable of to excite in us a desire and endeavour after a better state : so, in the greatest part of our concernments, he has afforded us only the twilight, as I may so say, of probability ; suitable, I presume, to that state of mediocrity and probationership he has been pleased to place us in here ; wherein, to check our over-confidence and presumption, we might, by every day’s experience, be made sensible of our short-sightedness and liableness to error ; the sense whereof might be a constant admonition to us, to spend the days of this our pilgrimage with industry and care, in the search and following of that way which might lead us to a state of greater perfection. It being highly rational to think, even were revelation silent in the case, that, as men employ those talents God has given them here, they shall accordingly receive their rewards at the close of the day, when their sun shall set and night shall put an end to their labours.
3. Judgment, or assent to probability, supplies our want of knowledge. The faculty which God has given man to supply the want of clear and certain knowledge, in cases where that cannot be had, is judgment : whereby the mind takes its ideas to agree or disagree ; or, which is the same, any proposition to be true or false, without perceiving a demonstrative evidence in the proofs. The mind sometimes exercises this judgment out of necessity, where demonstrative proofs and certain knowledge are not to be had ; and sometimes out of laziness, unskilfulness, or haste, even where demonstrative and certain proofs are to be had. Men often stay not warily to examine the agreement or disagreement of two ideas which they are desirous or concerned to know ; but, either incapable of such attention as is requisite in a long train of gradations, or impatient of delay, lightly cast their eyes on, or wholly pass by the proofs ; and so, without making out the demonstration, determine of the agreement or disagreement of two ideas, as it were by a view of them as they are at a distance, and take it to be the one or the other, as seems most likely to them upon such a loose survey. This faculty of the mind, when it is exercised immediately about things, is called judgment ; when about truths delivered in words, is most commonly called assent or dissent : which being the most usual way, wherein the mind has occasion to employ this faculty, I shall, under these terms, treat of it, as least liable in our language to equivocation.
4. Judgement is the presuming things to be so, without perceiving it. Thus the mind has two faculties conversant about truth and falsehood : –
First, Knowledge, whereby it certainly perceives, and is undoubtedly satisfied of the agreement or disagreement of any ideas.
Secondly, Judgment, which is the putting ideas together, or separating them from one another in the mind, when their certain agreement or disagreement is not perceived, but presumed to be so ; which is, as the word imports, taken to be so before it certainly appears. And if it so unites or separates them as in reality things are, it is right judgment.