LOGIC 101: Introduction to Persuasive Methods. Errors in LOGIC (Logical Fallacies)

LOGIC 101: Introduction to Persuasive Methods

Errors in LOGIC (Logical Fallacies)

Slippery Slope

Argues that A will cause B, then C, D, E….. all the way downhill to Z!

Much of it is based on assumption.

The series of events will inevitably lead to a catastrophe conclusion

Examples of slippery slope arguments:

Kids start out using the internet to do their schoolwork, but it isn’t long before they start surfing the net and chatting with perverts wearing leather and using fake names in chat rooms. Next thing you know, they start meeting pedophiles in malls and end up dead. So, I don’t let my kids use the internet. Today its gay marriage, and tomorrow they’ll be asking to legalize polygamy. Then marriage between family members. What about to pets? After all, animals have rights too, don’t they?

One more slippery slope…

“If you give us homework, then I’m going to have to stay up late. If I do that, I’m probably going to get sick just like my little sister who has a fever of 106 and is throwing up everything. Then , I’m going to do horrible at baseball tryouts, and I’ll never make Varsity. So, I’ll have to forget the major leagues, abandon my childhood dreams, and resign myself to collecting cans for a living. But, if you want to go ahead and give us homework, I can’t stop you; you’re the teacher.”

Circular Reasoning

The argument claims to prove a conclusion

BUT

The conclusion has already been assumed as a premise

Examples of circular reasoning:

Mike was the best candidate for president, because he was totally better than any of the others.

If such actions were not illegal, then they would not be prohibited by the law.

Signals of circular reasoning:

An arguer keeps repeating a claim as if he has given evidence to support a conclusion.

This is actually a ploy to avoid giving any justification

The Bare Assertion

Definition: to close a debate with a simple declaration that it's over simply because you say so.

Example:

Son: Dad, can I have the car

tonight?

Father: Nope.

Son: Why not?

Father: Because I said so.

These phrases are bare assertions

Because I said so. That's just the way it is. That's all there is to it. Trust me.

Other Examples of Bare Assertion

Literature. The bare assertion is common in literature (The play Twelve Angry Men is loaded with fallacies. Juror #3 offers the bare assertion to another juror, number 4, when he says, "Now listen to this man (Juror #4), he knows what he's talking about.")Expository writing. Often bare assertions are given instead of evidence or support for a point. A student essay might read: "Though some people don't agree that smoking causes cancer, they are wrong and that's all there is to it."

BIAS and Persuasive techniques

Bandwagon Appeal (Impressing with large numbers)

Assumes that “if everybody’s doing it, it must be good/ right/ okay”

Examples of bandwagon appeal:

“McDonald’s Hamburgers, billions sold”

Have you seen Spiderman III? The lines at the theatre are a block long! It must be really good!

Remember: everybody does it is the opposite of thinking for yourself.

Appeal to tradition

Argues “this is how it has been done in the past” as a reason for why something should continue to be done

Of course racial segregation is best for our state. We have had racial segregation in the South for over 100 years and no one has talked about changing it in all that time. So, it has got to be good.

Appeals to False Authority

An arguer claims he/ she is knowledgeable enough in a subject to make a judgment, but actually is not. Often used in advertising

Examples of to appeals to false authority:

Actresses selling cosmeticsAn Olympic athlete selling an over-the-counter or prescription drug

Appeal to Ignorance

Arguer claims something has been proven based on a lack of evidence disproving it.

Examples of appeals to ignorance:

You can’t prove that other forms of life don’t exist in the universe. Therefore, other forms of life must exist in the universe.

Nobody has proven that Clarence has not been stealing churros from the concession stand. Therefore, Clarence must be stealing churros.

Appeal to Emotion

Attempt to manipulate an emotional response in place of a valid or compelling argument.

This sort of "reasoning" is very common in politics and it serves as the basis for a large portion of modern advertising.

Appeal to Emotion, continued

Appeals to emotion include appeals to fear, envy, hatred, pity, pride, and more.

It's important to note that sometimes a logically coherent argument may inspire emotion or have an emotional aspect, but the problem and fallacy occurs when emotion is used instead of a logical argument, or to obscure the fact that no compelling rational reason exists for one's position.

Bill goes to hear a politician speak. The politician tells the crowd about the evils of the government and the need to throw out the people who are currently in office. After hearing the speech, Bill is full of hatred for the current politicians. Because of this, he feels good about getting rid of the old politicians and accepts that it is the right thing to do because of how he feels.

The new PowerTangerine computer gives you the power you need. If you buy one, people will envy your power. They will look up to you and wish they were just like you. You will know the true joy of power. TangerinePower.

Ad hominem

An ad hominem argument is any kind of argument that criticizes an idea by pointing something out about the people who hold the idea rather than directly addressing the merits of the idea.

''Ad hominem'' is Latin for "directed toward the man (as opposed to the issue at hand)"

Kerin would be a weak school board member. She’s a ginger and, even worse, she’s a Baptist!

Senator Randolph: "These feminists are wrong about the Equal Rights Amendment. They're just a small band of braless bubbleheads.