LOGICAL FALLACIESAll of these children are wrong.

What is a logical fallacy?A logical fallacy is a potential vulnerability or weakness in an argument.

Ms. Holland’s favorite definition: a failure to make a logical connection between the claim and the evidence used to support that claim.

More, please!

• Practically speaking, the logical breakdown in most weak arguments occurs in the use of evidence, since evidence is what we use to prove arguments.

• Fallacies may be accidental, but they can also be used deliberately to manipulate or deceive, like they teach in college debate.

• Logical fallacies work against the clear, civil discourse that should be at the heart of an argument.

Fallacies of Relevance:• A RED HERRING occurs when a speaker skips to a new and irrelevant

topic in order to avoid the topic of discussion. Politicians love this.

• One type of red herring is the AD HOMINEM FALLACY. Ad hominem means “to the man.” This fallacy is the diversionary tactic of switching the argument from the issue at hand to the character of the other speaker. Another politician favorite. It’s fine to question a speaker’s character, but only if it’s relevant to the argument.

• Analogies are the most vulnerable type of evidence because they are always susceptible to the charge that the two things aren’t comparable, which results in a FAULTY ANALOGY.

Fallacies of Accuracy:• The most common example of inaccurate evidence

resulting in a fallacy is one called the straw man. A STRAW MAN FALLACY occurs when a speaker chooses a deliberately poor or oversimplified example in order to ridicule and refute an opponent’s viewpoint.

• Another fallacy that results from using inaccurate evidence is the EITHER/OR FALLACY, also called the FALSE DILEMMA. In this fallacy, the speaker presents two extreme options as the only possible choices.

Fallacies of Insufficiency:• The most common of fallacies occurs when evidence is

insufficient. We call this a HASTY GENERALIZATION, meaning that there is not enough evidence to support a particular conclusion.

• CIRCULAR REASONING involves repeating the claim as a way to provide evidence, resulting in no evidence at all.

More! More Fallacies!

• HASTY GENERALIZATION: additionally, these can come from first-hand evidence and anecdotes. Don’t do!

• POST HOC ERGO PROPTER HOC: “after which therefore because of which.” You can’t claim something was a cause just because it happened before; correlation does not equal causation.

• APPEAL TO FALSE AUTHORITY: occurs when someone who has no expertise to speak on an issue is cited as an authority.

• BANDWAGON APPEAL: occurs when evidence boils down to “everybody’s doing it, so it must be a good thing to do.”

Homework! Wheeee! Identify the logical fallacy in each of the following examples:

1. What’s the problem? All of my friends have a curfew of midnight!

2. A person who is honest will not steal, so my client, an honest person, clearly is not guilty of theft.

3. Her economic plan is impressive, but remember: this is a woman who spent six weeks in the Betty Ford Center getting treatment for alcoholism.

4. Since Mayor Perry has been in office, our city has had a balanced budget; if he were governor, the state budget would finally be balanced.

5. If we outlaw guns, only outlaws will have guns.

6. Smoking is dangerous because it is harmful to your health.

7. He was last year’s MVP, and he drives a Volvo. That must be a great car.

8. A national study of grades 6-8 showed that test scores went down last year and absenteeism was high; this generation is going to the dogs.

Kinds of evidence:

FIRSTHAND

• Personal experience

• Anecdotes

• Current events

SECONDHAND

• Historical information

• Expert opinion

• Quantitative evidence

• Literary sources

Are these children fancy enough? NO.

Choose one of the thesis statements you developed and write three paragraphs of support, using a different type of evidence in each. You will probably have to do some research if you want to use historical information, expert testimony, or quantitative data.

These should be typed or beautifully handwritten and ready at the beginning of the class on Friday, 12/11.