(2) Universal Negative (E).

(3) Particular Affirmative (I).

(4) Particular Negative (O).

261. This is an exhaustive classification of propositions, and any
proposition, no matter what its form may be, must fall under one or
other of these four heads. For every proposition must be either
universal or particular, in the sense that the subject must either be
known to be used in its whole extent or not; and any proposition,
whether universal or particular, must be either affirmative or
negative, for by denying modality to the copula we have excluded
everything intermediate between downright assertion and denial. This
classification therefore may be regarded as a Procrustes' bed, into
which every proposition is bound to fit at its proper peril.

262. These four kinds of propositions are represented respectively
by the symbols A, E, I, O.

263. The vowels A and I, which denote the two affirmatives, occur in
the Latin words 'affirmo' and 'aio;' E and O, which denote the two
negatives, occur in the Latin word 'nego.'



_Extensive and Intensive Propositions._