An introductory text-book of logic - Mellone, Sydney - Rare Books at ...

OPPOSITION OF PROPOSITIONS. 71
The proposition E expresses the fact that the class
denoted by the subject is altogether outside the class
denoted by the predicate. Thus,
"no metals are
compounds," means that all the class "metals" is out
side of the class "compounds." The proposition is
fully represented by the following diagram :
Fig. 3-
Hence this proposition does tell us something about
the whole of the predicate as well as the whole of the
subject : if S is wholly outside of P, P must be wholly
outside of S.
The proposition I tells us that some at least of the
class S is included in the class P. There are two
principal cases of its possible meaning. (a)
metals are brittle," means that part of the class "metals"
is included in the class
cludes also other things
diagram is
"
" Some
brittle things," but this in
Fig. 4.
than metals. Hence the
Here part of S coincides with part of P. (I))
Europeans
" Some
"
are Frenchmen means that part of the ckiss