Elements of the philosophy of the human mind. By Dugald Stewart. Rev. and abridged, with critical and explanatory notes, for the use of colleges and schools. By Francis Bowen ...

488 REASONING AND DEDUCTIVE EVIDENCE.
lDifference between the logical and the popular meaning of the
word porobability. - In our anticipations of astronomical phenomena, as well as in those which we form concerning the result
of any familiar experiment in physics, philosophers are accustomed to speak of the event as only probable, although our confidence in its happening is not less complete than if it rested on
the basis of mathematical demonstration. The word probable,
therefore, when thus used, does not imply any defciency in the
proof, but only marks the particular nature of that proof, as contradistinguished from another species of evidence. It is opposed,
not to what is certain, but to what admits of being demonstrated
after the manner of mathematicians. This differs widely from
the meaning annexed to the same word in popular discourse:
according to which, whatever event is said to be probable, is understood to be expected with some degree of doubt. "As certain as death "" as certain as the rising of the sun "-are
proverbial modes of expression in all countries; and they are
both of them, borrowed from events which, in philosophical language, are only probable or contingent. In like manner, the
existence of the city of Pekin, and the reality of Caesar's assassination, which the philosopher classes with probabilities, because
they rest solely upon the evidence of testimony, are universally
classed with certainties by the rest of mankind; and in any
case but the statement of a logical theory, the application to
such truths of the word probable, would be justly regarded as
an impropriety of speech. This difference between the technical meaning of the word probability, as employed by logicians,
sand the notion usually attached to it in the business of life,
together with the erroneous theories concerning the nature of
demonstration, which I have already endeavored to refute,have led many authors of the highest name, in some of the
most important arguments which can employ human reason, to
overlook that irresistible evidence which was placed before their
eyes, in search of another mode of proof altogether unattainable in moral inquiries, and which, if it could be attained, would
not be less li-able to the cavils of skeptics.