A System of Logic: Ratiocinative and Inductive, 7th Edition, Vol. I
John Stuart Mill · en
At first sight this division has the air of an absurdity; a solemn
distinction of things into one and more than one; as if we were to
divide horses into single horses and teams of horses. And it is true
that what is called a complex proposition is often not a proposition at
all, but several propositions, held together by a conjunction. Such, for
example, is this: Cæsar is dead, and Brutus is alive: or even this,
Cæsar is dead, _but_ Brutus is alive. There are here two distinct
assertions; and we might as well call a street a complex house, as
these two propositions a complex proposition. It is true that the
syncategorematic words _and_ and _but_ have a meaning; but that meaning
is so far from making the two propositions one, that it adds a third
proposition to them. All particles are abbreviations, and generally
abbreviations of propositions; a kind of short-hand, whereby something
which, to be expressed fully, would have required a proposition or a
series of propositions, is suggested to the mind at once. Thus the
words, Cæsar is dead and Brutus is alive, are equivalent to these: Cæsar
is dead; Brutus is alive; it is desired that the two preceding
propositions should be thought of together. If the words were, Cæsar is
dead _but_ Brutus is alive, the sense would be equivalent to the same
three propositions together with a fourth; "between the two preceding
propositions there exists a contrast:" viz. either between the two facts
themselves, or between the feelings with which it is desired that they
should be regarded.
In the instances cited the two propositions are kept visibly distinct,
each subject having its separate predicate, and each predicate its
separate subject. For brevity, however, and to avoid repetition, the
propositions are often blended together: as in this, "Peter and James
preached at Jerusalem and in Galilee," which contains four propositions:
Peter preached at Jerusalem, Peter preached in Galilee, James preached
at Jerusalem, James preached in Galilee.