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only corporeal substances, whose operations seem to lie more level to our understandings: for as to the operations of spirits, both their thinking and moving of bodies, we at first sight find ourselves at a loss; though perhaps, when we have applied our thoughts a little nearer to the consideration of bodies, and their operations, and examined how far our notions, even in these, reach, with any clearness, beyond sensible matter of fact, we shall be bound to confess, that even in these too our discoveries amount to very little beyond perfect ignorance and incapacity. Whilst our § ^' This is evident, the abstract corn- ideas of sub- plex ideas of substances, for which their stances con- general names stand, not comprehending tain not their real constitutions,can afford us very constitu- little universal certainty. Because our tions, we ideas of them are not made up of that, can make on which those qualities we observe in
but few ge- them, and would inform ourselves about, neralcertain ■■ j , , , . , ,, ,
propositions "o depend, or with which they have any concerning certain connexion: v. g. let the ideas to
them, which we give the name man be, as it
commonly is, a body of the ordinary shape, with sense, voluntary motion, and reason joined to it. This being the abstract idea, and consequently the essence of our species man, we can make but very few general certain
propositions concerning man, standing for such an idea. Because not knowing the real constitution on which sensation, power of motion, and reasoning, with that peculiar shape, depend, and whereby they are united
together. in the same subject, there are very few other qualities with which we can perceive them to have a necessary connexion: and therefore we cannot with certainty affirm, that all men sleep by intervals; that no man can be nourished by wood or stones; that all men will be poisoned by hemlock: because these ideas have no connexion or repugnancy with this our nominal essence of man, with this abstract idea that name stands for. We must, in these and the like, appeal to trial in particular subjects, which can reach but a little way. We must content ourselves with probability in the rest; but can have no general certainty, whilst our specific idea of man contains not that real constitution, which is the root, wherein all his inseparable qualities are united, and from whence they flow. Whilst our idea, the word man stands for, is only an imperfect collection of some sensible qualities and powers in him, there is no discernible connexion or repugnance between our specific idea and the operation of either the parts of hemlock or stones upon his constitution. There are animals that safely eat hemlock, and others that are nourished by wood and stones: but as long as we want ideas of those real constitutions of different sorts of animals, whereon these and the like qualities and powers depend, we must not hope to reach certainty in universal propositions concerning them. Those few ideas only, which have a discernible connexion with our nominal essence, or any part of it, can afford us such propositions. But these are so few, and of so little moment, that we may justly look on our certain general knowledge of substances as almost none at all.
§ 16. To conclude; general propositions, wherein of what kind soever, are then only capable lies the geof certainty, when the terms used in them neral cerstand for such ideas, whose agreement or tainty ?* disagreement, as there expressed, is ca- ^on^°S1" pable to be discovered by us. And we are then certain of their truth or falsehood, when we perceive the ideas the terms stand for to agree or not agree, according as they are affirmed or denied one of another. Whence we may take notice, that general certainty is never to be found but in our ideas. Whenever we go to seek it elsewhere in experiment, or observations without us, our knowledge goes not beyond particulars. It is the contemplation of our own abstract ideas that alone is able to afford us general knowledge.
CHAPTER VII. Of Maxims.
They are § 1. There are a sort of propositions,
self-evident. which under the name of maxims and axioms have passed for principles of science; and because they are self-evident, have been supposed innate, although nobody (that I know) ever went about to show the reason and foundation of their clearness or cogency. It may however be worth while to inquire into the reason of their evidence, and see whether it be peculiar to them alone, and also examine how far they influence and govern our other knowledge.
Wherein § 2. Knowledge, as has been shown,
that self- consists in the perception of the agreeevidence ment or disagreement of ideas: now where consists. ^aj. agreement or disagreement is per
ceived immediately by itself, without the intervention or help of any other, there our knowledge is selfevident. This will appear to be so to any one, who will but consider any of those propositions, which, without any proof, he assents to at first.sight: for in all of them he will find, that the reason of his assent is from that agreement or disagreement, which the mind, by an immediate comparing them, finds in those ideas answering the affirmation or negation in the proposition.
Self-evi- § &' ^n^s Demg so, m tne next place
dence not let us consider, whether this self-evidence peculiar to be peculiar only to those propositions received which commonly pass under the name of maxims, and have the dignity of axioms allowed them. And here it is plain, that several other truths, not allowed to be axioms, partake equally with them in this self-evidence. This we shall see, if we go over these several sorts of agreement or disagreement of ideas, which I have above-mentioned, viz. identity, relation, co-existence, and real existence; which will discover to us, that not only those few propositions, which have had the credit of maxims, are self-evident, but a great many, even almost an infinite number of other propositions are such. § 4. For, first, the immediate perception j As to of the agreement or disagreement of iden- identity and tity, being founded in the mind's having diversity, all distinct ideas, this affords us as many self- propositions evident propositions as we have distinct sel6f-evhient ideas. Every one, that has any knowledge at all, has, as the foundation of it, various and distinct ideas: and it is the first act of the mind (without which it can never be capable of any knowledge) to know every one of its ideas by itself, and distinguish it from others. Every one finds in himself, that he knows the ideas he has; that he knows also when any one is in his understanding, and what it is; and that when more than one are there, he knows them distinctly and unconfusedly one from another. Which always being so (it being impossible but that he should perceive what he perceives) he can never be in doubt when any idea is in his mind, that it is there, and is that idea it is; and that two distinct ideas, when they are in his mind, are there, and are not one and the same idea. So that all such affirmations and negations are made without any possibility of doubt, uncertainty, or hesitation, and must necessarily be assented to as soon as understood; that is, as soon as we have in our minds determined ideas, which the terms in the proposition stand for. And therefore whenever the mind with attention considers any proposition, so as to perceive the two ideas signified by the terms, and affirmed or denied one of the other, to be the same or different; it is presently and infallibly certain of the truth of such a proposition, and this equally, whether these propositions be in terms standing for more general ideas, or such as are
less so, v.g. whether the general idea of being be affirmed of itself, as in this proposition, whatsoever is, is; or a more particular idea be affirmed of itself, as a man is a man; or, whatsoever is white is white; or whether the idea of being in general be denied of not being, which is the only (if I may so call it) idea different from it, as in this other proposition, it is impossible for the same thing to be, and not to be; or any idea of any particular being be denied of another different from it, as, a man is not a horse; red is not blue. The difference of the ideas, as soon as the terms are understood, makes the truth of the proposition presently visible, and that with an equal certainty and easiness in the less as well as the more general propositions, and all for the same reason, viz. because the mind perceives, in any ideas that it has, the same idea to be the same with itself; and two different ideas to be different, and not the same. And this it is equally certain of, whether these ideas be more or less general, abstract, and comprehensive. It is not therefore alone to these two general propositions, whatsoever is, is; and it is impossible for the same thing to be, and not to be; that this sort of selfevidence belongs by any peculiar right. The perception of being, or not being, belongs no more to these vague ideas, signified by the terms whatsoever and thing, than it does to any other ideas. These two general maxims, amounting to no more in short but this, that the same is the same, and same is not different, are truths known in more particular instances, as well as in those general maxims, and known also in particular instances, before these general maxims are ever thought on, and draw all their force from the discernment of the mind employed about particular ideas. There is nothing more visible than that the mind, without the help of any proof, or reflection on either of these general propositions,perceives so clearly, and knows so certainly, that the idea of white is the