Logical FallaciesErrors in judgment and faulty reasoning

Oversimplification

Press here for results. What results???

Drastically simple solution to what is clearly a complex problem: We have a balance-of-trade deficit because foreigners make better products than we do.

Hasty generalization

Yes, those are bran flakes. Yum!

In inductive reasoning, a generalization that is based on too little evidence or on evidence that is not representative: My grandparents eat bran flakes for breakfast, just as most older folks do.

Post hoc, ergo propter hoc “After this, therefore

because of this.” Confusing chance or

coincidence with causation.

The fact that one event comes after another does not necessarily mean that the first event caused the second: I went to the hockey game last night. The next thing I knew I had a cold.

Begging the question

“Active euthanasia is morally acceptable. It is a decent, ethical thing to help another human being escape suffering through death.”

Premise: It is a decent, ethical thing to help another human being escape suffering through death.Conclusion: Active euthanasia is morally acceptable.

Assuming in a premise something that needs to be proven: Lying is wrong because people should always tell the

truth.

False analogy

Clone = Cure

Making a misleading analogy between logically unconnected ideas: If we can clone mammals, we should be able to find a cure for cancer.

Either/or thinking

Love job!!! Hate job!!!

Seeing only two alternatives when there may in fact be other possibilities: Either you love your job, or you hate it.

Non sequitur

Very sincere? Expert?

“It does not follow.” An inference or

conclusion that is not clearly related to the established premises or evidence: She is very sincere. She must know what she’s talking about.

Slippery Slope (a type of non sequitur)

Experiment? Protect?

The speaker argues that, once the first step is undertaken, a second or third step will inevitably follow, much like the way one step on a slippery incline will cause a person to fall and slide all the way to the bottom.

“Animal experimentation reduces our respect for life. If we don’t respect life, we are likely to be more and more tolerant of violent acts like war and murder. Soon our society will become a battlefield in which everyone constantly fears for their lives. It will be the end of civilization. To prevent this terrible consequence, we should make animal experimentation illegal right now.”

LOADED LANGUAGE Using words with

strongly negative or positive connotations.

Example: “The doctor’s horse-and-buggy attitudes tyrannize mothers.”

BANDWAGON APPEAL

Monkey see, monkey do.

Urging readers to adopt a course of action because “everyone is doing it”.

“Every other high school in the county has a soccer team; we need one, too.”

CIRCULAR REASONING

Change the law Should be amended

Supporting a point by merely stating it in other words.

Example: “The law should be amended because it needs changing.”

Ad hominem

“Andrea Dworkin has written several books arguing that pornography harms women. But Dworkin is just ugly and bitter, so why should we listen to her?”

What??? Ugly and bitter, so what?

In an ad hominem argument, the arguer attacks his or her opponent instead of the opponent’s argument.

Red Herring

Helping people get along doesn’t necessarily make it more fair

No evidence as to why a curve would be fair.

Partway through an argument, the arguer goes off on a tangent, raising a side issue that distracts the audience from what’s really at stake. Often, the arguer never returns to the original issue.

“Grading this exam on a curve would be the most fair thing to do. After all, classes go more smoothly when the students and the professor are getting along well.”

Straw Man Argument: A subtype of the red herring

Weak opponent created= Straw man

In the straw man fallacy, the arguer sets up a weak version of the opponent’s position and tries to score points by knocking it down. But just as being able to knock down a straw man (like a scarecrow) isn’t very impressive. Includes any lame attempt to "prove" an argument by overstating, exaggerating, or over-simplifying the arguments of the opposing side.

The opponent argues, "Tennessee should increase funding to unemployed single mothers during the first year after childbirth because they need sufficient money to provide medical care for their newborn children." The second speaker retorts, "My opponent believes that some parasites who don't work should get a free ride from the tax money of hard-working honest citizens. I'll show you why he's wrong . . ."

Just a few of the many

The End for now. . .

Logical Fallacies