inciples of logic.

It would seem, also, though this is more disputable, that there are some
self-evident ethical principles, such as 'we ought to pursue what is
good'.

It should be observed that, in all cases of general principles,
particular instances, dealing with familiar things, are more evident
than the general principle. For example, the law of contradiction states
that nothing can both have a certain property and not have it. This is
evident as soon as it is understood, but it is not so evident as that a
particular rose which we see cannot be both red and not red. (It is of
course possible that parts of the rose may be red and parts not red, or
that the rose may be of a shade of pink which we hardly know whether to
call red or not; but in the former case it is plain that the rose as a
whole is not red, while in the latter case the answer is theoretically
definite as soon as we have decided on a precise definition of 'red'.)
It is usually through particular instances that we come to be able to
see the general principle. Only those who are practised in dealing with
abstractions can readily grasp a general principle without the help of
instances.

In addition to general principles, the other kind of self-evident truths
are those immediately derived from sensation. We will call such truths
'truths of perception', and the judgements expressing them we will
call 'judgements of perception'. But here a certain amount of care
is required in getting at the precise nature of the truths that are
self-evident. The actual sense-data are neither true nor false. A
particular patch of colour which I see, for example, simply exists: it
is not the sort of thing that is true or false. It is true that there is
such a patch, true that it has a certain shape and degree of brightness,
true that it is surrounded by certain other colours. But the patch
itself, like everything else in the world of sense, is of a radically
different kind from the things that are true or false, and therefore
cannot properly be said to be _true_. Thus whatever self-evident truths
may be obtained from our senses must be different from the sense-data
from which they are obtained.

It would seem that there are two kinds of self-evident truths of
perception, though perhaps in the last analysis the two kinds may
coalesce. First, there is the kind which simply asserts the _existence_
of the sense-datum, without in any way analysing it. We see a patch
of red,