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
An hypothetical proposition is not, like the pretended complex
propositions which we previously considered, a mere aggregation of
simple propositions. The simple propositions which form part of the
words in which it is couched, form no part of the assertion which it
conveys. When we say, If the Koran comes from God, Mahomet is the
prophet of God, we do not intend to affirm either that the Koran does
come from God, or that Mahomet is really his prophet. Neither of these
simple propositions may be true, and yet the truth of the hypothetical
proposition may be indisputable. What is asserted is not the truth of
either of the propositions, but the inferribility of the one from the
other. What, then, is the subject, and what the predicate of the
hypothetical proposition? "The Koran" is not the subject of it, nor is
"Mahomet:" for nothing is affirmed or denied either of the Koran or of
Mahomet. The real subject of the predication is the entire proposition,
"Mahomet is the prophet of God;" and the affirmation is, that this is a
legitimate inference from the proposition, "The Koran comes from God."
The subject and predicate, therefore, of an hypothetical proposition are
names of propositions. The subject is some one proposition. The
predicate is a general relative name applicable to propositions; of this
form--"an inference from so and so." A fresh instance is here afforded
of the remark, that particles are abbreviations; since "_If_ A is B, C
is D," is found to be an abbreviation of the following: "The proposition
C is D, is a legitimate inference from the proposition A is B."