By Bryan Caplan
The usual touchstone of whether what someone asserts is mere persuasion
or at least a subjective conviction, i.e., firm belief, is betting.
Often someone pronounces his propositions with such confident and
inflexible defiance that he seems to have entirely laid aside all
concern for error. A bet disconcerts him. Sometimes he reveals that he
is persuaded enough for one ducat but not for ten. For he would happily
bet one, but at ten he suddenly becomes aware of what he had not
previously noticed, namely that it is quite possible that he has erred.
– Critique of Pure Reason, (A824/B852)