This document defines and provides examples of different types of formal fallacies: 1) Formal fallacies are mistakes in the form of a deductive argument that make the argument invalid. They include four terms, undistributed middle, illicit major/minor terms, exclusive premises, and drawing an affirmative conclusion from a negative premise. 2) Four terms fallacy occurs when a syllogism contains more than three terms. Undistributed middle fallacy is when the middle term is not distributed in at least one premise. Illicit major/minor is when a term is distributed in the conclusion but not the relevant premise. 3) Exclusive premises fallacy involves two negative premises. Drawing an affirmative

2. Fallacy:
“Any error or mistake in reasoning is called
Fallacy”.
The pattern of mistakes that appear in deductive
argument of a certain specifiable form, it is a
mistake in form of argument it is called Formal
Fallacies.
Formal Fallacy:

3. Four Terms
Undistributed Middle
Illicit Major & Illicit Minor
Exclusive Premises
Drawing an Affirmative Conclusion
from a negative premise.
Existential Fallacy
Formal
Fallacy

4. Four Terms:
“Avalid form of categorical syllogism must contain
exactly the three terms, each of which is used in
the same sense throughout the argument”.
Example:
All are
is a
Therefore, 6th September is fruit.

5. Undistributed middle:
“In a valid standard form of categorical
syllogism, the middle term(M) must be
distributed in at least one premise”.
Example:
All Russians were .
All anarchists were .
Therefore, all anarchists were Russians.

6. Illicit process of Major & Minor
term:
“A valid standard form of categorical
syllogism, if either term is distributed in
conclusion then it must be distributed in the
premise”.Illicit Major:
All dogs are
No cats are dogs
Therefore, No cats are .
Illicit Minor:
All mobiles are electronic device
All mobiles are
Therefore, all are electronic device.

7. Exclusive Premise:
“No standard form categorical syllogism
having two negative premise is valid”.
Example:
Therefore, some magicians are not
astrologers.

8. Drawing an affirmative conclusions from a
negative premise:
“If either premise of a valid standard form
categorical syllogism is negative, the
conclusion must be negative”.
Example:
Some artists are poets
Therefore, some artists are
managers.

9. Existential Fallacy:
“No valid standard form categorical
syllogism with a particular conclusion
can have universal premise”.
Example:
All household pets are domestic animals
No unicorn are domestic animals
.