A System of Logic: Ratiocinative and Inductive, 7th Edition, Vol. I
John Stuart Mill · en
Archbishop Whately has contended that syllogizing, or reasoning from
generals to particulars, is not, agreeably to the vulgar idea, a
peculiar _mode_ of reasoning, but the philosophical analysis of _the_
mode in which all men reason, and must do so if they reason at all. With
the deference due to so high an authority, I cannot help thinking that
the vulgar notion is, in this case, the more correct. If, from our
experience of John, Thomas, &c., who once were living, but are now dead,
we are entitled to conclude that all human beings are mortal, we might
surely without any logical inconsequence have concluded at once from
those instances, that the Duke of Wellington is mortal. The mortality of
John, Thomas, and company is, after all, the whole evidence we have for
the mortality of the Duke of Wellington. Not one iota is added to the
proof by interpolating a general proposition. Since the individual cases
are all the evidence we can possess, evidence which no logical form into
which we choose to throw it can make greater than it is; and since that
evidence is either sufficient in itself, or, if insufficient for the one
purpose, cannot be sufficient for the other; I am unable to see why we
should be forbidden to take the shortest cut from these sufficient
premises to the conclusion, and constrained to travel the "high priori
road," by the arbitrary fiat of logicians. I cannot perceive why it
should be impossible to journey from one place to another unless we
"march up a hill, and then march down again." It may be the safest road,
and there may be a resting-place at the top of the hill, affording a
commanding view of the surrounding country; but for the mere purpose of
arriving at our journey's end, our taking that road is perfectly
optional; it is a question of time, trouble, and danger.