Clear and distinct ideas are terms which, though familiar and frequent in men’s mouths, I have reason to think every one who uses does not perfectly understand.  And possibly ’tis but here and there one who gives himself the trouble to consider them so far as to know what he himself or others precisely mean by them.  I have therefore in most places chose to put determinate or determined, instead of clear and distinct, as more likely to direct men’s thoughts to my meaning in this matter.  By those denominations, I mean some object in the mind, and consequently determined, i. e. such as it is there seen and perceived to be.  This, I think, may fitly be called a determinate or determined idea, when such as it is at any time objectively in the mind, and so determined there, it is annexed, and without variation determined, to a name or articulate sound, which is to be steadily the sign of that very same object of the mind, or determinate idea.

To explain this a little more particularly.  By determinate, when applied to a simple idea, I mean that simple appearance which the mind has in its view, or perceives in itself, when that idea is said to be in it:  by determined, when applied to a complex idea, I mean such an one as consists of a determinate number of certain simple or less complex ideas, joined in such a proportion and situation as the mind has before its view, and sees in itself, when that idea is present in it, or should be present in it, when a man gives a name to it.  I say should be, because it is not every one, nor perhaps any one, who is so careful of his language as to use no word till he views in his mind the precise determined idea which he resolves to make it the sign of.  The want of this is the cause of no small obscurity and confusion in men’s thoughts and discourses.

I know there are not words enough in any language to answer all the variety of ideas that enter into men’s discourses and reasonings.  But this hinders not but that when any one uses any term, he may have in his mind a determined idea, which he makes it the sign of, and to which he should keep it steadily annexed during that present discourse.  Where he does not, or cannot do this, he in vain pretends to clear or distinct ideas:  it is plain his are not so; and therefore there can be expected nothing but obscurity and confusion, where such terms are made use of which have not such a precise determination.

Upon this ground I have thought determined ideas a way of speaking less liable to mistakes, than clear and distinct:  and where men have got such determined ideas of all that they reason, inquire, or argue about, they will find a great part of their doubts and disputes at an end; the greatest part of the questions and controversies that perplex mankind depending on the doubtful and uncertain use of words, or (which is the same) indetermined ideas, which they are made to stand