Formal Fallacies - Errors in the form or structure of an argument. Also known as logical fallacies because they each reach an invalid conclusion from the premise. Almost always being a syllogistic fallacy.

1. Rule One

A valid affirmative (A/I) conclusion cannot be reached if at least one of its premises is negative (E/O).

  • "A" statements are universal affirmative ~ All S are P
  • "E" statements are universal negative ~ No S are P
  • "I" statements are particular affirmative ~ Some S are P
  • "O" statements are particular negative ~ Some S aren't P

If E/O X A/I or X E/O A/I then it will not work

2. Rule Two

A valid conclusion cannot be reached if both of its premises are negative

  • No people under 35 years old are presidential candidates, no presidential candidates are children, some people under 35 are children

In this example both premises are negative.

3. Rule Three

A valid syllogism cannot be constructed with more than three terms.

  • Major Term- predicate of the conclusion and is produced in the major premise.
  • Minor Term- Subject of the conclusion and is introduced in the minor premise.
  • Middle Term- A term that exists in both the major and minor premises but not the conclusion.

e.g., people who donate to charities are good,
Jarvis does not donate to charities,
Jarvis is bad.
(blurred the lines between good and bad)

  • Nothing is better than a long nap, a short nap is better than nothing, a short nap is better than a long nap.

In this example there are two uses for the word "nothing".

4. Rule Four

If the major term is distributed in the conclusion, it must also be distributed in the major premise.

  • All dogs are mammals (A/I), No cats are dogs (X), No cats are mammals (E/I).

The Laws of Distribution

Distributed - Terms that refer to all members of a class
Undistributed - Terms that refer to less than all members of a class.
Proposition Subject Predicate
A Distributed Undistributed
E Distributed Distributed
I Undistributed Undistributed
O Undistributed Distributed

1. All cats are mammals ~ A
2. No cats are dogs ~ E
3. Some cats are tabbies ~ I
4. Some cats are not tabbies ~ O

5. Rule Five

If the major term is distributed in the conclusion, it must also be distributed in the minor premise.
1. All cats are felines
2. All cats are mammals
3. All mammals are felines

6. Rule Six

A valid negative conclusion cannot be reached if both of its premises are affirmative.

7. Rule Seven

The middle term must be distributed in at least one premise.

8. Rule Eight

A particular conclusion from universal premises cannot be valid if no members of a referenced class exit.

Begging The Question

  • Latin Name; petitio pincilii (assuming the initial point)
  • Logical Fallacy- the writer and or speaker assumes the statement is true.
  • Begging the Question- using a premise to support itself.

e.g., Why is it important for everyone to have a voice?

  • Assuming the truth of conclusion of an argument in the premise on order for the conclusion to follow.

Premise & Conclusion

Premise = Conclusion
Reasoning from the premises to the conclusion brings you back to where you started.
P= premise C= conclusion
P -> C -> P = P=C
P/C = P/C
e.g., Killing people is wrong so the death penalty is wrong.
e.g., To assume something you have no right to assume.

Informal Fallacy Examples

*Cherry Picking - When one chooses information by applying said information to their argument in order to persuade the audience, ignoring uncomfortable results, only choosing the ones that go with your claim. It is a result of confirmation bias
*Naturalistic Fallacy - What is naturally occurring in life ought to be morally right.
*Strawman Argument - When someone misrepresents or misidentifies their opponents view, intentionally or accidental.
*Bandwagon Fallacy - Appeals to popularity, based on "majority rule," argument is based on following the popular stream of things
*Fallacy of many questions/ Loaded question - A question that forces respondent to accept a controversial premise
*Hasty Generalization - Conclusion based on a small sample rather than looking at statistics that are much more useful
*Fallacy of the mean- Finding the compromise/middle ground of an argument.

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