CHAPTER VI.

Of universal Propositions, their Truth and Certainty.

The prevailing custom of using sounds for ideas, even when men think and reason within their own breasts, makes the consideration of words and propositions so necessary a part of the treatise of knowlege, that it is very hard to speak intelligibly of the one, without explaining the other. And since general truths, which with reason are most sought after, can never be well made known, and are seldom apprehended, but as conceived and expressed in words; it is not out of our way, in the examination of our own knowlege, to inquire into the truth and certainty of universal knowlege.

But it must be observed, that certainty is twofold, certainty of truth, and certainty of knowlege. Certainty of truth is, when words are so put together in propositions, as exactly to express the agreement or disagreement of the ideas they stand for, as really it is. Certainty of knowlege, is to perceive the agreement or disagreement of ideas as expressed in any propositions. This we usually call knowing, or being certain of the truth of any proposition.

Now because we cannot be certain of the truth of any general proposition, unless we know the precise bounds and extent of the species its terms stand for; it is necessary we should know the essence of each species, which is that which constitutes and bounds it. This in all simple ideas and modes is not hard to do: for in these the real and nominal essence being the same, there can be no doubt how far the species extends, or what things are comprehended under each term: which it is evident are all that have an exact conformity with the ideas it stands for, and no other. But in substances wherein a real essence, distinct from the nominal, is supposed to constitute and bound the

species, the extent of the general word is very uncertain; because, not knowing this real essence, we cannot know what is, or is not of that species, and consequently what may, or may not with certainty be affirmed of it.

Hence we may see that the names of substances, when made to stand for species, supposed to be constituted by real essences, which we know not, are not capable of conveying certainty to the understanding. Of the truth of general propositions made up of such terms we cannot be sure. For how can we be sure that this or that quality is in gold, for instance, when we know not what is, or is not gold; that is, what has, or has not the real essence of gold, whereof we have no idea at all.

On the other side, the names of substances, when made use of for the complex ideas men have in their minds; though they carry a clear and determinate signification with them, will not yet serve us to make many universal propositions, of whose truth we can be certain because the simple ideas, out of which the complex are combined, carry not with them any discoverable connexion of repugnancy, but with a very few other ideas.

For instance, All gold is fixed, is a proposition we cannot be certain of, how universally soever it be believed for if we take the term gold to stand for a real essence, it is evident we know not what particular substances are of that species, and so cannot with certainty affirm any thing universally of gold. But if we make the term gold stand for a species, determined by its nominal essence, be its complex idea what it will; for instance, a body yellow, fusible, malleable, and very heavy; no quality can with certainty be denied or affirmed universally of it, but what has a discoverable connexion, or inconsistency with that nominal essence. Fixedness, for instance, having no necessary connexion that we can discover

with any simple idea that makes the complex one, or with the whole combination together; it is impossible that we should certainly know the truth of this proposition, All gold is fixed. But is not this an universal certain proposition, All gold is malleable? I answer, it is so, if malleableness be a part of the complex idea the word gold stands for: but then here is nothing affirmed of gold, but that, that sound stands for an idea, in which malleableness is contained. And such a sort of truth and certainty it is, to say a centaur is four-footed.

I imagine amongst all the secondary qualities of substances, and the powers relating to them, there cannot any two be named, whose necessary coexistence or repugnance to coexist can be certainly known, unless in those of the same sense, which necessarily exclude one another. Thus by the color we cannot certainly know what smell, taste, &c. any body is of.

It is no wonder then that certainty is to be found but in very few general propositions concerning substances: our knowlege of their qualities and properties goes very seldom farther than our senses reach, or inform us. Inquisitive and observing men may, by strength of judgment, penetrate farther; and on probabilities taken from wary observations and hints well laid together, often guess right at what experience has not yet discovered to them: but this is but guessing still; it amounts only to opinion, and has not that certainty which is requisite to knowlege.

To conclude: General propositions, of what kind soever, are then only capable of certainty, when the terms used in them stand for such ideas, whose agreement or disagreement, as there expressed, is capable to be discovered by us and we are then certain of their truth or falsehood, when we perceive the ideas they 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 knowlege goes not beyond particulars.

CHAPTER VII.

Of Maxims.

There are a sort of propositions, which, under the name of maxims and axioms, have passed for principles of science; and, because they are self-evident, have been supposed innate. But if those, who would persuade us that there are innate principles, had considered, separately, the parts out of which those propositions are made, they would not, perhaps, have been so forward to believe they were innate : since, if the ideas, which made up those truths, were not, it was impossible that the propositions, made up of them, should be innate, or our knowlege of them be born with us. For if the ideas be not innate, there was a time when the mind was without those principles; and then, they will not be innate, but be derived from some other original. It is impossible for the same thing to be, and not to be, is certainly (if there be any such) an innate principle. But the names impossibility and identity stand for two ideas, so far from being innate, or born with us, that I think it requires great care and attention to form them right in our understanding. They are so far from being brought into the world with us, so remote from the thoughts of infancy and childhood, that I believe, on examination, it will be found that many grown men want them.

It may be worth while likewise to inquire into the reason of the evidence of these maxims, and examine how far they influence our other knowlege. Know

lege being but the perception of the agreement or disagreement of ideas, where that agreement or disagreement is perceived immediately by itself, without the intervention or help of any other ideas, there our knowlege is self-evident: which being so, not only maxims, but an infinite number of other propositions partake equally with them in this self-evidence. For,

In respect of identity and diversity, we may have as many self-evident propositions as we have distinct ideas. It is the first act of the mind, 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; so that all affirmations, or negations concerning them, are made without any possibility of doubt or uncertainty; and must necessarily be assented to as soon as understood: that is, as soon as we have in our minds the ideas clear and distinct, which the terms in the proposition stand for. Thus, A circle is a circle, Blue is not red, are as selfevident propositions, as those general ones, What is is, and It is impossible for the same thing to be and not to be; nor can the consideration of these axioms add any thing to the evidence, or certainty of our knowlege of them.

As to the agreement or disagreement of coexistence, the mind has an immediate perception of this but in very few. And therefore, in this sort we have very little intuitive knowlege; though, in some few propositions we have. Two bodies cannot be in the same place, I think is a self-evident proposition; the idea of fitting a place equal to the contents of its superficies being annexed to our idea of body.

As to the relations of modes, mathematicians have framed many axioms concerning that one relation of equality, as Equals taken from equals, the remainder