Logical FallaciesAKA “How NOT to Win an Argument”

Logical fallacies

• Adapted from Technical Communication, 8th edition, Markel

Ad hominem

Ad hominem, also called “argument against the speaker”

Argument against the writer, not the writer’s argument

Argument from ignorance

A claim is true because it has never been proven false, or false because it has never been proven true

Appeal to pity

An argument based on emotion, not on reason

Argument from authority

An argument that a claim is valid because the person making the claim is an expert

Circular argument

AKA “begging the question”

An argument that assumes what it is attempting to prove is already true

Either-or argument

An argument that poses only two possible alternatives when there may be more alternatives

Ad populum

AKA “bandwagon argument”

An argument that a claim is valid because many people think it is or act as if it is

Hasty generalization

AKA “inadequate sampling”

An argument that draws a conclusion based on an insufficient number of cases

Post hoc reasoning

From post hoc, ergo propter hoc

Assuming event A causes event B because event A precedes event B

Oversimplifying

AKA “slippery slope”

An argument that omits important information in establishing a causal link

Red herring

A false clue or a way to mislead your reader about your true intentions; a distraction

Straw man

To present a simplified version of an opponent’s viewpoint to make his or her viewpoint easier to attack

Spot the Error

We shouldn’t sell the Ridgeway division. It’s been a part of our company for over 40 years! I would be sad to see it go.

Spot the Error

Nobody has ever proven that global warming is occurring. Therefore, global warming is a myth.

Spot the Error

According to Dr. Smith, global warming is a fact. Therefore, it must exist.

Spot the Error

http://www.youtube.com/watch?v=0ewWFWQwlTs

Spot the Error

Why do I believe in God? Because the Bible tells me God exists. Why do I believe the Bible? Because God’s disciples wrote the Bible, of course!

Spot the Error

If we don’t start selling our products online, we’ll certainly go out of business.

Spot the Error

• http://www.southparkstudios.com/clips/151029/

Spot the Error

Of course Matthew is in favor of buying more computers for the office—he is crazy about computers.

Spot the Error

I believe smoking in teens is detrimental to their health. Over 20 studies have shown that teen smokers are likely to become lifelong smokers. Therefore, I believe we should all stop smoking and instead chew bubblegum. I own a candy store, and I would be happy to sell everyone bubblegum at a discounted rate.

Spot the Error

Spot the Error

John Doe is opposed to euthanizing homeless animals in animal shelters. Obviously, Joe is saying that he wants the world to be overrun by homeless cats and dogs. Eventually, he wants cats and dogs to take over the planet and destroy mankind. I oppose Joe’s argument that animals are more important than humans for these reasons…

Spot the Error

Our four major competitors have started selling products online. Obviously, we should, too.

http://apenglish3period8.wikispaces.com/logical+fallacies

Spot the Error

The new Gull is an unreliable car. Two of my friends own Gulls, and they both have problems with their vehicles.

Spot the Error

Mississippi should pass the new highway safety law. The other 49 states have already passed it; therefore, it’s a good idea for our state.

Spot the Error

There must be something wrong with the new circuit breaker in the office. Ever since it was installed, the air conditioner has been working improperly.

Spot the Error

http://www.theonion.com/content/video/new_live_poll_allows_pundits_to

Spot the Error

To achieve world peace, we all need to wear “I FAVOR WORLD PEACE” buttons on our clothes. That should fix the problem.

Spot the Error