No induction, however broad its basis, can confer certainty--in the
strict sense of the word. The experience of the whole human race through
innumerable years has shown that stones unsupported fall to the ground,
but that does not make it certain that any day next week unsupported
stones will not move the other way. All that it does justify is the very
strong expectation, which hitherto has been invariably verified, that
they will do just the contrary.
Only one absolute certainty is possible to man--namely, that at any
given moment the feeling which he has exists.
All other so-called certainties are beliefs of greater or less
intensity.