for which no reason can be given is an
unreasonable belief. In the main, this view is just. Almost all our
common beliefs are either inferred, or capable of being inferred, from
other beliefs which may be regarded as giving the reason for them. As a
rule, the reason has been forgotten, or has even never been consciously
present to our minds. Few of us ever ask ourselves, for example, what
reason there is to suppose the food we are just going to eat will not
turn out to be poison. Yet we feel, when challenged, that a perfectly
good reason could be found, even if we are not ready with it at the
moment. And in this belief we are usually justified.

But let us imagine some insistent Socrates, who, whatever reason we
give him, continues to demand a reason for the reason. We must sooner
or later, and probably before very long, be driven to a point where we
cannot find any further reason, and where it becomes almost certain that
no further reason is even theoretically discoverable. Starting with the
common beliefs of daily life, we can be driven back from point to point,
until we come to some general principle, or some instance of a general
principle, which seems luminously evident, and is not itself capable
of being deduced from anything more evident. In most questions of
daily life, such as whether our food is likely to be nourishing and not
poisonous, we shall be driven back to the inductive principle, which we
discussed in Chapter VI. But beyond that, there seems to be no further
regress. The principle itself is constantly used in our reasoning,
sometimes consciously, sometimes unconsciously; but there is no
reasoning which, starting from some simpler self-evident principle,
leads us to the principle of induction as its conclusion. And the same
holds for other logical principles. Their truth is evident to us, and we
employ them in constructing demonstrations; but they themselves, or at
least some of them, are incapable of demonstration.

Self-evidence, however, is not confined to those among general
principles which are incapable of proof. When a certain number of
logical principles have been admitted, the rest can be deduced from
them; but the propositions deduced are often just as self-evident as
those that were assumed without proof. All arithmetic, moreover, can
be deduced from the general principles of logic, yet the simple
propositions of arithmetic, such as 'two and two are four', are just as
self-evident as the pr