predicated of the same thing in the same relation; but are not
Contradictories, since, in a given case, neither may be predicable: if a
flower is blue in a certain part, it cannot in the same part be red; but
it may be neither blue nor red, but yellow; though it is certainly
either blue or not-blue. All co-ordinate terms are formal Contraries;
but if, in fact, a series of co-ordinates comprises only two (as
male-female), they are empirical Contradictories; since each includes
all that area of the _suppositio_ which the other excludes.

The extremes of a series of co-ordinate terms are Opposites; as, in a
list of colours, white and black, the most strongly contrasted, are said
to be opposites, or as among moods of feeling, rapture and misery are
opposites. But this distinction is of slight logical importance.
Imperfect Positive and Negative couples, like 'happy and unhappy,' which
(as we have seen) are not contradictories, are often called Opposites.

The members of any series of Contraries are all included by any one of
them and its contradictory, as all colours come under 'red' and
'not-red,' all moods of feeling under 'happy' and 'not-happy.'




CHAPTER V

THE CLASSIFICATION OF PROPOSITIONS


§ 1. Logicians classify Propositions according to Quantity, Quality,
Relation and Modality.