The I proposition, such as “Some men are wise,” concerns itself with only a part of the subject and only a part of the predicate, consequently neither subject nor predicate is distributed. This relation is verified by the representation, [Fig. 3].

In the O proposition the subject is undistributed, while the predicate is distributed. For example, in the proposition, “Some men are not wise,” “some men” would indicate that only a part of the logical subject is under consideration. But the predicate is distributed because “some men” is denied of the whole of the predicate,“wise.” This may become clear by studying [Fig. 4]. Here all of the shaded part which stands for the subject, “some men,” is excluded from the whole of the “wise” circle. But all of the shaded part is only a part of the entire “men” circle, consequently the subject which the shaded part represents (some men) is undistributed. The predicate, “wise,” however, is distributed, as the subject is excluded from every part of it. It is well to remember that not, when used with the copula, distributes the predicate which follows it.

If the student is to succeed in testing the value of arguments, he must ever have “at the tip of his tongue” his knowledge of the distribution of the terms of the four logical propositions. With this in view the following schemes are offered:

I.
SubjectPredicate
Adistributedundistributed
Edistributeddistributed
Iundistributedundistributed
Oundistributeddistributed
II.
Adistributedundistributed
Oundistributeddistributed
Edistributeddistributed
Iundistributedundistributed
III.
AAll S is P
ENo S is P
ISome S is P
OSome S is not P

Referring to scheme II it may be observed that A and O contradict each other; i. e., where A is distributed O is undistributed and vice versa. A similar relation exists between E and I.

In scheme III the underline under the symbol indicates the term which is distributed.

IV. As a fourth scheme a “key word” might be adopted. Any of these three might be used: (1) saepeo, or (2) asebinop, or (3) uaesneop. The significance of “saepeo” is this: “s” stands for subject distributed, “p” for predicate distributed, “a” “e” “o” for the logical propositions where any distribution occurs. Putting the letters together gives this: subject distributed of propositions A and E, predicate distributed of propositions E and O.

Similarly, “asebinop” stands for this: “as,” a distributes its subject; “eb” e distributes both; “in,” i distributes neither; “op,” o distributes the predicate.

In the coined word “uaesneop” appear six letters which compose “saepeo,” and the letters have the same significance. The two additional letters, u and n, stand for universal and negative. The interpretation of the entire word, therefore, is this: “uaes,” the universals a and e distribute their subjects; neop, the negatives e and o distribute their predicates.

It seems to me that the last word is the most helpful as it emphasizes the two facts which are the most used; namely, (1) Only the universals distribute their subjects; (2) Only the negatives distribute their predicates.