John Locke

“ 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. ”

“ 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. ”

“ 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 ”

“ 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. ”

“ 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. ”

“ 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 ”

“ 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 ”

“ 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 ”

“ 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 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 ”

“ 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 ”

“ 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 ”