Logical Fallacies

Logical Fallacies

A Logical Fallacy is… A mistake in reasoning.

Types of Logical Fallacies

Ad HominemFalse CausalityRed HerringOvergeneralizationBandwagon Effect

Ad Hominem

Using a personal attack to disprove an argument.

Types: name calling; irrelevant character issue; guilt by association; false analogy.

Example: You can't tell me I should quit smoking. You've never done cancer research, so what would you know about it?

False Causality

Because one thing follows another, it has caused the other

The cause identified is only part of the entire cause

Example: The only reason that Katy missed school was because she is hanging out with the wrong crowd.

Red Herring

Reasons have little relevance to the argument at hand.

Desperate arguers often try to change the ground of the argument by changing the subject.

Example: Winthrop should pave the lot behind Dinkins. Besides, I can never find a parking space on campus anyway

Overgeneralization

The argument draws a conclusion from a sample that is too small and is made up of too few cases

Example: In both of the murder mysteries I have read, the District Attorney was the culprit. All mystery writers like to make lawyers out to be villains."

Bandwagon Effect

The main argument is that everyone is doing it and everyone should join.

Example: Fifty million Elvis fans can’t be wrong, I have to buy the CD!

Which Fallacy is being used?

1. "Affirmative action proponents accuse me of opposing equal opportunity in the work force. I think my positions on military expenditures, education and public health speak for themselves."

2. "Despite the women's movement in the ‘70s, women still do not receive equal pay for equal work. Obviously, all such attempts to change the status quo are doomed to failure."

Which Fallacy is it?

"Since Harvard, Stanford, and Berkeley have all added a multicultural component to their graduations requirements, Notre Dame should get with the program.

Traditional historians appeal to the public's feeling of nationalism just as the Nazis did.“

We must have a poltergeist in the house. When the dog ran under the table the vase just seemed to jump off the shelf all by itself.