Categorical Proposition

The general character of categorical proposition is a predicate is “simply” affirmed or denied of a subject. By simply means without implying any necessary condition between the terms of the proposition. For example: “The Earth is a planet” this is a simple proposition and there is no implication such as if or then statements.

The general character of categorical proposition may be represented by the formula.

S is p and s is not p. Where s stands for any subject and p stands for relevant predicate. The quality of categorical proposition can be two types; affirmative and negative. The earth is a planet, where all the terms are affirmative and the planet is not flat, here the proposition is negative.

The difference between affirmation and negation is called a difference of quality. Say S and P there are three different possibilities.

1.      One may affirm P of S, then the result will be S is P

2.      One may deny P of S, then the result will be negative, S is not P

3.      Lastly, one may not know whether P should be affirmed or denied of S, then it is not a proposition.

According to A. Wolf the quality of categorical propositions may be divided into 3 classes.

Singular: The earth is a planet

General: All planets move in elliptic orbits. No planets are fixed.

Particular: Some stars are self-luminous.

But sometimes, a proposition remains singular when the subject is made consists not a single object, but of a group of objects as long as they treated as a same group. For example: The British Museum Library consists of several million books and pamphlets. This is a singular proposition because everything indicates a single subject here, or a group of collection.

Kinds of categorical proposition

From the law of thoughts we know, the same predicate cannot be both affirmed or denied of the same subject. S must be either P or not be P.

By differencing the quality and quantity of categorical proposition we get four kinds of categorical propositions.

Universal affirmative, particular affirmative, universal negative, particular negative.

There are four such propositional form.

A E I O

•          A =    S a P      =          Every  S is P.                           

•          E =       S  e  P  =      No S is P.                     

•          I =    S i P     =      some s is P

•          O=    S  o P    =    Some S is not P

	Subject (S)          Predicate (P)
A=   S a P.  universal  affirmative            All men are mortal	Distributed        undistributed
E=S e P.  Universal  negative             No man is immortal	Distributed              distributed
I= s i p.  particular affirmative           some students are intelligent	Undistributed          undistributed
O= S o P   Particular negative           some men are not educated	Undistributed          Distributed

So, if SaP is true then SiP must be true.