nowledge of truths
is infected with some degree of doubt, and a theory which ignored this
fact would be plainly wrong. Something may be done, however, to mitigate
the difficulties of the question.

Our theory of truth, to begin with, supplies the possibility of
distinguishing certain truths as _self-evident_ in a sense which ensures
infallibility. When a belief is true, we said, there is a corresponding
fact, in which the several objects of the belief form a single complex.
The belief is said to constitute _knowledge_ of this fact, provided
it fulfils those further somewhat vague conditions which we have been
considering in the present chapter. But in regard to any fact, besides
the knowledge constituted by belief, we may also have the kind of
knowledge constituted by _perception_ (taking this word in its widest
possible sense). For example, if you know the hour of the sunset,
you can at that hour know the fact that the sun is setting: this is
knowledge of the fact by way of knowledge of _truths_; but you can also,
if the weather is fine, look to the west and actually see the setting
sun: you then know the same fact by the way of knowledge of _things_.

Thus in regard to any complex fact, there are, theoretically, two ways
in which it may be known: (1) by means of a judgement, in which its
several parts are judged to be related as they are in fact related; (2)
by means of _acquaintance_ with the complex fact itself, which may (in a
large sense) be called perception, though it is by no means confined to
objects of the senses. Now it will be observed that the second way of
knowing a complex fact, the way of acquaintance, is only possible when
there really is such a fact, while the first way, like all judgement,
is liable to error. The second way gives us the complex whole, and is
therefore only possible when its parts do actually have that relation
which makes them combine to form such a complex. The first way, on the
contrary, gives us the parts and the relation severally, and demands
only the reality of the parts and the relation: the relation may not
relate those parts in that way, and yet the judgement may occur.

It will be remembered that at the end of Chapter XI we suggested that
there might be two kinds of self-evidence, one giving an absolute
guarantee of truth, the other only a partial guarantee. These two kinds
can now be distinguished.

We may say that a truth is self-evident, in the first and most absolute