An Essay Concerning Humane Understanding, Volume 2: MDCXC, Based on the 2nd Edition, Books 3 and 4
John Locke · en
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 THE 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 idea of white, and not the idea
of blue; and that the idea of white, when it is in the mind, is there,
and is not absent; [that the consideration of these axioms can add
nothing to the evidence or certainty of its knowledge.] [Just so it is
(as every one may experiment in himself) in all the ideas a man has in
his mind: he knows each to be itself, and not to be another; and to be
in his mind, and not away when it is there, with a certainty that cannot
be greater; and, therefore, the truth of no general proposition can be
known with a greater certainty, nor add anything to this.] So that,
in respect of identity, our intuitive knowledge reaches as far as our
ideas. And we are capable of making as many self-evident propositions,
as we have names for distinct ideas. And I appeal to every one's own
mind, whether this proposition, 'a circle is a circle,' be not as
self-evident a proposition as that consisting of more general terms,
'whatsoever is, is'; and again, whether this proposition, 'blue is not
red,' be not a proposition that the mind can no more doubt of, as
soon as it understands the words, than it does of that axiom, 'it is
impossible for the same thing to be and not to be?' And so of all the
like.
5. In Co-existance we have few self-evident Propositions.
II. SECONDLY, as to CO-EXISTANCE, or such a necessary connexion between
two ideas that, in the subject where one of them is supposed, there the
other must necessarily be also: of such agreement or disagreement as
this, the mind has an immediate perception but in very few of them. And
therefore in this sort we have but very little intuitive knowledge: nor
are there to be found very many propositions that are self-evident,
though some there are: v.g. the idea of filling a place equal to the
contents of its superficies, being annexed to our idea of body, I think
it is a self-evident proposition, that two bodies cannot be in the same
place.
6. III. In other Relations we may have many.