8

1908 Oct 28
Logic
13

"is P" and "is not P" (or other than any every P) are both true only of
Nothing, and not of any definite subject. Earlier writers confounded
this principle with the following. By the Principle of Excluded Middle
(or of excluded third,) is always meant the principle that a no pair of
mutually contradictory predicates are both false of any individual
subject. (Of course, to say that the twelve disciples of Jesus were all apostles or were not apostles are both false.) I believe the name was first given by Wolf: Baron Johann
Christian Wolf, the systematizer of Leibnizianism.

In agreement with many logicians, but departing from the usage of grammarians in two respects. In the first place I mean by the Subject (capitalized)
of an assertion or question, not the name or equivalent of a name, but or description so called by the grammarians, but that which is named, described, or
referred to, to which the predicate relates. In the second place, the grammarians usually limit the term to the subject nominative,