Classification of Proposition

1. Classification of Propositions – There are four kinds of categorical propositions:

1. those that assert that the whole subject class included in the predicate class;
2. those that assert that the whole subject class is excluded from the predicate class;
3. those that assert that part of the subject class is included in the predicate; and,
4. those that assert that part of the subject class is excluded from the predicate class.

A	Universal-Affirmative	All S are P	All politicians are honorable men.
E	Universal-Negative	All S are not P	All politicians are not honorable men.
I	Particular-Affirmative	Some S are P	Some politicians are honorable men.
O	Particular-Negative	Some S are not P	Some politicians are not honorable men.

Form A	All S are P asserts that the predicate is affirmed of all members of S, the subject category.
Form E	No S are P asserts that the predicate is denied of all members of S.
Form I	Some S are P asserts that there is at least one member of S and the predicate is affirmed of it.
Form O	Some S are not P asserts that there is at least one of S and the predicate is denied of it.

All S are P	Every member of the S class is a member of the P class; that is, the S class is included in the P class.
No S are P	No member of the S class is a member of the P class; that is, the S class is excluded from the P class.
Some S are P	At least one member of the S class is a member of the P class.
Some S are not P	At least one member of the S class is not a member of the P class.