the external world does really exist, and is not wholly dependent for
its existence upon our continuing to perceive it.

The argument which has led us to this conclusion is doubtless less
strong than we could wish, but it is typical of many philosophical
arguments, and it is therefore worth while to consider briefly its
general character and validity. All knowledge, we find, must be built
up upon our instinctive beliefs, and if these are rejected, nothing is
left. But among our instinctive beliefs some are much stronger than
others, while many have, by habit and association, become entangled
with other beliefs, not really instinctive, but falsely supposed to be
part of what is believed instinctively.

Philosophy should show us the hierarchy of our instinctive beliefs,
beginning with those we hold most strongly, and presenting each as
much isolated and as free from irrelevant additions as possible. It
should take care to show that, in the form in which they are finally
set forth, our instinctive beliefs do not clash, but form a harmonious
system. There can never be any reason for rejecting one instinctive
belief except that it clashes with others; thus, if they are found to
harmonize, the whole system becomes worthy of acceptance.

It is of course _possible_ that all or any of our beliefs may be
mistaken, and therefore all ought to be held with at least some slight
element of doubt. But we cannot have _reason_ to reject a belief
except on the ground of some other belief. Hence, by organizing our
instinctive beliefs and their consequences, by considering which among
them is most possible, if necessary, to modify or abandon, we can
arrive, on the basis of accepting as our sole data what we
instinctively believe, at an orderly systematic organization of our