A System of Logic: Ratiocinative and Inductive, 7th Edition, Vol. I
John Stuart Mill · en
As all experience begins with individual cases, and proceeds from them
to generals, it might seem most conformable to the natural order of
thought that Induction should be treated of before we touch upon
Ratiocination. It will, however, be advantageous, in a science which
aims at tracing our acquired knowledge to its sources, that the inquirer
should commence with the latter rather than with the earlier stages of
the process of constructing our knowledge; and should trace derivative
truths backward to the truths from which they are deduced, and on which
they depend for their evidence, before attempting to point out the
original spring from which both ultimately take their rise. The
advantages of this order of proceeding in the present instance will
manifest themselves as we advance, in a manner superseding the necessity
of any further justification or explanation.
Of Induction, therefore, we shall say no more at present, than that it
at least is, without doubt, a process of real inference. The conclusion
in an induction embraces more than is contained in the premises. The
principle or law collected from particular instances, the general
proposition in which we embody the result of our experience, covers a
much larger extent of ground than the individual experiments which form
its basis. A principle ascertained by experience, is more than a mere
summing up of what has been specifically observed in the individual
cases which have been examined; it is a generalization grounded on those
cases, and expressive of our belief, that what we there found true is
true in an indefinite number of cases which we have not examined, and
are never likely to examine. The nature and grounds of this inference,
and the conditions necessary to make it legitimate, will be the subject
of discussion in the Third Book: but that such inference really takes
place is not susceptible of question. In every induction we proceed from
truths which we knew, to truths which we did not know; from facts
certified by observation, to facts which we have not observed, and even
to facts not capable of being now observed; future facts, for example;
but which we do not hesitate to believe on the sole evidence of the
induction itself.
Induction, then, is a real process of Reasoning or Inference. Whether,
and in what sense, as much can be said of the Syllogism, remains to be
determined by the examination into which we are about to enter.
CHAPTER II.
OF RATIOCINATION, OR SYLLOGISM.
§ 1. The analysis of the Syllogism has been so accurately and fully
performed in the common manuals of Logic, that in the present work,
which is not designed as a manual, it is sufficient to recapitulate,
_memoriæ causâ_, the leading results of that analysis, as a foundation
for the remarks to be afterwards made on the functions of the syllogism,
and the place which it holds in science.