Formal and Informal Fallacies

Diana does not like meat; therefore, she must be vegan.

• Informal Fallacy

• The Fallacy Fallacy

• Formal Fallacy

• Antecedent

Which of the following is an example of denying the antecedent fallacy?

• If A, then B. A is true. Therefore, B is not true.

• If A, then B. B is not true. Therefore, A is not true.

• If A, then B. A is not true. Therefore, B is not true.

• If A, then B. A is not true. Therefore, B is true.

My old friend Stan did great after college, so he must have worked hard as a student.

• Affirming the Consequent

• Denying the Consequent

• Affirming the Antecedent

• Denying the Antecedent

If today is Tuesday, then John will go to work.

Today is Tuesday.

Therefore, John will go to work.

• Modus ponens

• Modus Tollens

• Affirming the Antecedent

• Indirect Support

I will not wear my sunglasses.

Therefore, it is not bright and sunny today.

• Modus Tollens

• Modus Ponens

• Affirming the Consequent

• Denying the Antecedent

A fallacy is...

• An unintentional defect in reasoning.

• An intentional defect in reasoning.

• An unintentional or intentional defect in reasoning.

An argument with good content can still contain a formal fallacy.

• True

• False

Determine what kind of fallacy is exemplified by the following argument:

(1) Most people who buy lottery tickets won't win the lottery;

(2) Michael bought a lottery ticket;

(C) So, Michael won't win the lottery.

• Formal

• Informal

An argument with good form can still contain an informal fallacy.

• True

• False

No one has been able to prove the Loch Monster doesn't exist.

Therefore, the Loch Ness Monster must exist.

Which informal fallacy is committed in the following argument?

• Appeal to Authority

• Slippery Slope

• Appeal to Ignorance

• Red Herring