Summary
Categorical Proposition: A proposition that relates two classes (or
categories). Standard-form categorical propositions occur in four forms and
are identified by letter names:
A: All are .
E: No are .
I: Some are .
O: Some are not .
Every standard

Categorical Syllogisms
Standard Form, Mood, and Figure
Categorical Syllogisms
Immediate inferences of the kind we've looked at involve inference from one categorical statement to an e
the statements form a simple argument one that consists of a conclusion

Categorical Propositions
Quality, Quantity, and Distribution
Quantity, quality, distribution and categorical form
Each categorical statement in logic asserts that there is a relationship between one category and another.
of inclusion or exclusion. In effe

Categorical Propositions
Venn Diagrams and the Modern Square of Opposition
The hypothetical viewpoint
Until now we've assumed that the class of things referred to by the subject term of each categorical statement contains at lea
called the "Aristotelian v

Categorical Propositions
Conversion, Obversion, and Contraposition
Conversion, Obversion and Contraposition
The inferences discussed so far have been concerned only with statements that contain identical subjects a
also make an inference from a categorica

Categorical Propositions
Venn Diagrams and the Traditional Standpoint
Venn Diagrams and the Traditional Standpoint
As we've already seen, the Aristotelian standpoint differs from the Boolean in how it inter
(A and E) statements. The Aristotelian standpoin

Categorical Propositions
The Traditional Square of Opposition
In the previous section, we looked at Venn diagrams used to illustrate the logical relations between the subject and predicate
different subjects and predicates, whether through conversion, obv

Categorical Propositions
The Components of Categorical Propositions
Categorical Propositions
In talking about informal fallacies, we were looking at defects in both deductive and inductive arguments. W
arguments. Remember that a deductive argument is one

Venn Diagrams and the Modern
Square of Opposition
Preview
Think of a football game. At kickoff time, all the members of one team are at one end of the field, and all the
members of the other team are at the other end. This idea of assigning distinct spati

Categorical Syllogisms
Venn Diagrams
The Venn-Diagram Test for Validity
The Venn diagrams we studied earlier in connection with categorical statements illustrate the relations bet
overlapping circles. In a categorical syllogism, the statements contain a t