Logical Fallacies in Persuasion

When Good Use of Appeals Goes Wrong

Attacking a Person

Attack Ad Hominem

Attack Ad HominemWhen someone uses attack ad hominem, they are attacking

a person instead of the person’s argument or actions.Attack ad hominem is used frequently with political

campaign ads, so be looking for it when you watch television!

For example, if a candidate says, “You shouldn’t believe ________ because he is a bad person,” is an example of attack ad hominem. The candidate is not criticizing an argument and he has no basis or evidence for his claim.

Noticing Ad Hominem

Whether you agree with this ad or not is not the point. Notice that the original ad does not give a basis for

the argument whatsoever.

It’s just a fancy way of saying because B

comes after A, A caused B.

False Causality

False CausalitySometimes, things cause other things to happen.

That’s why we study cause and effect in language arts. However, sometimes two events are merely coincidental, so one cannot be blamed for the other.

For example, let’s say I gave a pop quiz one day in class. During the pop quiz, two students get a physical fight. Saying that I caused the fight is false causality, even if the students were both stressed already because of the quiz.

False Causality

Common sense usually helps us see straight through ads that use

false causality.

Doesn’t it seem fishy to you when

an ad jumps around from topic to topic?

Red Herring

Red HerringRed herring is when someone goes completely off on a

tangent in the middle of his argument.The point of red herring is to distract the audience

from what’s really at stake.Oftentimes, the speaker never goes back to the

original issue.

Red Herring

What does that silly duck standing on one leg have to do with the

flying spaghetti monster?

Because everyone loves them.

Overgeneralization

OvergeneralizationThink of stereotypes: that is an overgeneralization.This is when someone makes an assumption about an

entire group based on one inadequate sample.All teachers are mean. • Well, that’s not necessarily true. One based that

opinion on the small sample of teachers to which he has been exposed.

Overgeneral-ization

Of course all horses are cats…

Because everyone’s doing it

Bandwagon Effect

Bandwagon EffectThis is definitely use of pathos, as it is the tendency

that advertisers have to make the audience believe they want something by showing that everyone has it.

Ads that use bandwagon attempt to appeal to a person’s innate desire to “fit in.”

Bandwagon Effect

For what do you think this is advertising?

Find the logical fallacy…

People who believe in UFOs

are either crazy or stupid.

Which logical fallacy does this example

represent?

Find the logical fallacy…

I took EZ-No-Cold, and two days later, my cold disappeared.

Which logical fallacy does this example

represent?

Find the logical fallacy…

Jim comes home over an hour late. Sally

says, “I was worried. Why are

you late? Why didn’t you call?” Jim replies, “Have you seen the weather

lately?”Which logical fallacy does this example

represent?

Find the logical fallacy…

Tina bought a used camera while she

was up in Portland, and got a great deal. Portland

must be a good place to buy used

cameras.Which logical fallacy does this example

represent?

Find the logical fallacy…

“But officer, I don’t deserve a ticket; everyone

goes this speed. If I went any slower,

I wouldn’t be going with the

stream of traffic.”Which logical fallacy does this example

represent?