A System of Logic: Ratiocinative and Inductive, 7th Edition, Vol. I — John Stuart Mill — John Shaqi
A System of Logic: Ratiocinative and Inductive, 7th Edition, Vol. I
John Stuart Mill · en
be no ground for making the assumption in that case which does not exist
in every other; and to deny the assumption as a general truth, is to
deny the right of making it in the particular instance.
There are, undoubtedly, the most ample reasons for stating both the
principles and the theorems in their general form, and these will be
explained presently, so far as explanation is requisite. But, that
unpractised learners, even in making use of one theorem to demonstrate
another, reason rather from particular to particular than from the
general proposition, is manifest from the difficulty they find in
applying a theorem to a case in which the configuration of the diagram
is extremely unlike that of the diagram by which the original theorem
was demonstrated. A difficulty which, except in cases of unusual mental
power, long practice can alone remove, and removes chiefly by rendering
us familiar with all the configurations consistent with the general
conditions of the theorem.
§ 4. From the considerations now adduced, the following conclusions seem
to be established. All inference is from particulars to particulars:
General propositions are merely registers of such inferences already
made, and short formulæ for making more: The major premise of a
syllogism, consequently, is a formula of this description: and the
conclusion is not an inference drawn _from_ the formula, but an
inference drawn _according_ to the formula: the real logical antecedent,
or premise, being the particular facts from which the general
proposition was collected by induction. Those facts, and the individual
instances which supplied them, may have been forgotten: but a record
remains, not indeed descriptive of the facts themselves, but showing how
those cases may be distinguished, respecting which the facts, when
known, were considered to warrant a given inference. According to the
indications of this record we draw our conclusion; which is, to all
intents and purposes, a conclusion from the forgotten facts. For this
it is essential that we should read the record correctly: and the rules
of the syllogism are a set of precautions to ensure our doing so.