Reading Handbookpage R24

FAULTY LOGIC/REASONING

Or...What is wrong with this statement?

So, what is faulty logic?

Lets break it down.

Faulty = having faults or imperfect Logic = reason or sound judgment

Therefore, faulty logic is an imperfect or flawed reason.

Why learn this?

Learning to recognize faulty logic will help you become a more astute consumer of products and information.

#1 Type of Faulty Logic:

Circular Reasoning

DEFINITION: The writer (or speaker or ad) supports a claim with restatements of that same claim. The argument goes around and around with the reason making the same claim as the original argument.

EXAMPLE: John Upton is a wonderful writer because he writes so well.

EXPLANATION: The second half of the statement says basically the same thing as the first half.

Circular Reasoning

#2 Type of Faulty Logic: Overgeneralization

DEFINITION: The writer reaches conclusions from a limited number of facts. (Look for words such as all, every, and always.)

EXAMPLE: I loved that movie we saw last night with Brad Pitt. I am going to rent all of his movies, and I am sure Ill like all of them.

EXPLANATION: It is an imperfect judgment (or faulty logic!) to assume that you will love all Brad Pitt movies just because you loved one!

EXAMPLE: Enron was a large, corrupt company, so all large companies are corrupt.

EXPLANATION: One example of something does not make the statement true in all cases. There are large companies that are not like Enron and have perfectly honest dealings.

Overgeneralization

#3 Type of Faulty Logic:

False Cause

DEFINITION: An assumption is made that one event causes the other when in fact, it did not.

EXAMPLE: Our house was burglarized right after that new family moved in next door.

EXPLANATION: This statement attributes a false cause (new family next door) to the effect (the burglary).

False Cause

False Cause

#4 Type of Faulty Logic:

Oversimplification

DEFINITION:

This occurs when a single cause is assumed to have created a problem or an issue. In reality, the problem or issue may have been created by a number of causes.

A complex situation is explained as if it were much simpler than it is.

EXAMPLE: The cause of the Civil War was slavery.

EXPLANATION: The above statement is too simplistic. Slavery was only one of several reasons the Civil War was fought.

Oversimplification

#5 Type of Faulty Logic:

Commonly held opinion

DEFINITION:

An argument that is deemed correct just because everyone else supposedly thinks it is correct.

EXAMPLE: Everyone knows that cats make better pets than dogs.

#6 Type of Faulty Logic:

Hasty Generalization

DEFINITION:

A conclusion is drawn from too little evidence or from evidence that is biased

EXAMPLE: I got sick after eating at the pizza place, so Italian food must be bad for me.

EXAMPLE: After my son was vaccinated for chicken pox, he developed autism, so vaccinations must cause autism.

#7 Type of Faulty Logic:

Non Sequitur

(literally it does not follow

DEFINITION:

A statement that uses irrelevant proof to support a claim. A non sequitur is sometimes used to win an argument by diverting the readers attention to proof that cant be challenged

EXAMPLE: I will probably flunk the driving test. I was late for school today.

EXAMPLE: It rained today because I washed my car.

#8 Type of Faulty Logic:

Either / or fallacy

DEFINITION:

A statement that suggests there are only two choices available in a situation that really offers more than two options

EXAMPLE: Either you eat a balanced diet, or you will die before you are fifty.

EXAMPLE: You can support your country by voting for me, or you can watch it fall to pieces.

EXAMPLE: A new car may be expensive, but do you want me to drive around in the junk pile for the rest of my life?

#9 Type of Faulty Logic:

Personal attack or name-calling

(also called ad hominem,

which means against the man)

DEFINITION:

An attempt to discredit an idea by attacking the person or the group associated with it. Candidates often engage in name-calling during political campaigns.

EXAMPLE: After Sally presents an eloquent and compelling case for a more equitable taxation system, Sam asks the audience whether we should believe anything from a woman who isn't married.

#10 Type of Faulty Logic:

Evading the Issue

DEFINITION:

Refuting an objection with arguments and evidence that do not address the central issue

EXAMPLE: I know I didnt clean up my room, but that gave me more time to study and improve my grades.

Now practice what you have learned.

What type of faulty logic is the following statement?

STATEMENT: I argued with Mrs. Coulter before I turned in my homework, so I got a bad grade on my paper.

THE ANSWER: False Cause

WHY? The student suggests that because he/she argued with his English teacher prior to turning in a paper (cause), the result/effect was a bad grade.

STRATEGY: Try to identify an end result or effect. Ask yourself: Did the reason given really cause the end result?

What is the faulty reasoning

in the following statement?

STATEMENT: I hated the movie because it was the worst movie I ever saw.

THE ANSWER: Circular Reasoning

WHY? ...the worst movie I ever saw is basically the same thing as I hated the movie. Its saying the same thing.

STRATEGY: Look at the end of the sentence. Is it really similar to the beginning? Is it going around and around?

What is the faulty reasoning here?

STATEMENT: I know why you failed all your classes last semester. You dont study.

THE ANSWER: Oversimplification

WHY? There could be many reasons why a student experiences difficulty in school. Reducing the problem to one solution is oversimplifying.

STRATEGY: Look for an effect that has MANY possible causes.

What is the faulty reasoning here?

STATEMENT: You got a good grade on your essay because the teacher likes you.

THE ANSWER: False Cause

WHY? This statement attributes the effect (a good grade) to a false cause (the teacher likes you).

STRATEGY: Look at the cause and effect. Ask yourself: Is this really the cause?

What is the faulty reasoning here?

STATEMENT: Juan is an impressive speaker because he always impresses his listeners deeply.

THE ANSWER: Circular Reasoning

WHY? He impresses his listeners deeply is basically the same thing as Juan is an impressive speaker. The statement is going around in circles.

STRATEGY: Look at the sentence beginning and the sentence ending. Ask yourself: Does it go around in circles?

What is the faulty reasoning here?

STATEMENT: All teenagers are irresponsible.

THE ANSWER: Overgeneralization

WHY? All teenagers are NOT irresponsible. This statement relies on stereotypes and is an unfair conclusion based on limited observations.

STRATEGY: Look for the context cluesthe word all. Ask yourself: Are all teenagers irresponsible?

What is the faulty reasoning here?

STATEMENT: This class is awesome because we do amazing things in here.

THE ANSWER: Circular Reasoning

WHY? ...we do amazing things is very similar to This class is awesome. Again, the last half of the statement is similar to the first half; its going around and around in a circle.

STRATEGY: Look at sentence beginnings and sentence endings, the cause and effect. Are they similar?

One last flawed statement...

STATEMENT: Teenagers have bad skin because they dont wash their faces.

THE ANSWER: Oversimplification

WHY? This answer argues that there is only one reason for teenagers skin problems. In fact, there are numerous causes.

STRATEGY: Look for a cause and effect relationship. Ask yourself: Could there be more than one cause that brings about the effect? If the answer is yes, then the answer is too simple.

Identifying Faulty Reasoning

Reading Handbook, Section 5, page R25

DIRECTIONS: Number your paper 17.

Identify each logical fallacy in the Practice and Apply exercise on page R25 and explain why you identified it as such.

Every sentence is a different type of logical fallacy.

Choose from these:

false cause, evading the issue, commonly held opinion,

hasty generalization, circular reasoning, oversimplification,

non sequitur

1. Everyone agrees that running is the best form of exercise.

2. All you need is a good pair of shoes and youre ready to hit the road.

3. Ive run a mile twice this week, so I should know.

4. As a result, Ive slept better and the tone on my clarinet has improved.

5. When you run, your heart beats faster because your pulse rate increases.

6. That means that your cells get more oxygen, which is the second most common gas in the earths atmosphere. You also get to enjoy the beauty of the world around you as you build up your stamina.

7. So if you dont want to be a hopeless couch potato, get going and run for your life!