A System of Logic, Ratiocinative and Inductive (Vol. 1 of 2)
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 all 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.”