An Essay Concerning Humane Understanding, Volume 2: MDCXC, Based on the 2nd Edition, Books 3 and 4
John Locke · en
Probability wanting that intuitive evidence which, infallibly determines
the understanding and produces certain knowledge, the mind, if it WILL
PROCEED RATIONALLY, ought to examine all the grounds of probability, and
see how they make more or less for or against any proposition, before
it assents to or dissents from it; and, upon a due balancing the whole,
reject or receive it, with a more or less firm assent, proportionably to
the preponderancy of the greater grounds of probability on one side or
the other. For example:--
If I myself see a man walk on the ice, it is past probability; it is
knowledge. But if another tells me he saw a man in England, in the midst
of a sharp winter, walk upon water hardened with cold, this has so great
conformity with what is usually observed to happen, that I am disposed
by the natures of the thing itself to assent to it; unless some manifest
suspicion attend the relation of that matter of fact. But if the same
thing be told to one born between the tropics, who never saw nor
heard of any such thing before, there the whole probability relies on
testimony: and as the relators are more in number, and of more credit,
and have no interest to speak contrary to the truth, so that matter
of fact is like to find more or less belief. Though to a man whose
experience has always been quite contrary, and who has never heard of
anything like it, the most untainted credit of a witness will scarce
be able to find belief. As it happened to a Dutch ambassador, who
entertaining the king of Siam with the particularities of Holland, which
he was inquisitive after, amongst other things told him, that the water
in his country would sometimes, in cold weather, be so hard, that men
walked upon it, and that it would bear an elephant, if he were there. To
which the king replied, HITHERTO _I_ HAVE BELIEVED THE STRANGE THINGS
YOU HAVE TOLD ME, BECAUSE _I_ LOOK UPON YOU AS A SOBER FAIR MAN, BUT NOW
_I_ AM SURE YOU LIE.
6. Probable arguments capable of great Variety.