Structure of a Categorial Syllogism
-  The Mood  -

The premises and conclusion of a categorical syllogism can have any of the standard forms: A, E, I, or O. A categorical syllogism is identified, in part, by reference to this fact. We list the letters that identify the forms of the propositions in the syllogism in the following order: major premise, minor premise, conclusion. This list is called the mood of the syllogism.

Example:
The mood of the following argument is AAA:

All mammals are animals that breathe by means of lungs.
All whales are mammals.
Therefore, all whales are animals that breathe by means of lungs.


Comprehension Questions

1 What kind of proposition is an A proposition?
a) universal affirmative
b) universal negative
c) particular affirmative
d) particular negative
2 What kind of proposition is an E proposition?
a) universal affirmative
b) universal negative
c) particular affirmative
d) particular negative
3 What kind of proposition is an I proposition?
a) universal affirmative
b) universal negative
c) particular affirmative
d) particular negative
4 What kind of proposition is an O proposition?
a) universal affirmative
b) universal negative
c) particular affirmative
d) particular negative
5 The letters that identify the forms of a proposition in a categorical syllogism are arranged in what order?
a) conclusion, major premise, minor premise
b) major premise, conclusion, minor premise
c) minor premise, major premise, conclusion
d) major premise, minor premise, conclusion
6 What is the mood of the following categorical syllogism?

No horned animal is a predator
All moose are horned animals


No moose is a predator
a) AAE
b) EAE
c) AEE
d) AEO
e) none of the above
7 What is the mood of the following categorical syllogism?

No Marxist advocates private property
All conservatives advocate private property


No conservative is a Marxist
a) EAE
b) AEE
c) IOE
d) EOO
e) none of the above
8 What is the mood of the following categorical syllogism?

All mammals are animals that breathe by means of lungs
All whales are mammals


All whales are animals that breathe by means of lungs
a) III
b) EEE
c) OOO
d) AAA
9 What is the mood of the following categorical syllogism?

Some crimes against property are fraud
All frauds are felonies


Some felonies are crimes against property
a) AII
b) IAI
c) IEI
d) OEO
e) none of the above
10 What is the mood of the following categorical syllogism?

All of Shakespeare's dramas are in blank verse
Some great plays are in blank verse


Some great plays are Shakespeare's dramas
a) AAA
b) IAI
c) AII
d) AIA
e) none of the above


The Mood | The Figure
Assessment of Categorial Syllogisms by Rules

© Copyright 1998, W.W. Norton & Co.