FallaciesTo error in reason is human; to

analyze divine!

Logical Fallacy?• An error of reasoning.• When someone adopts a position, or tries to

persuade someone else to adopt a position, based on a bad piece of reasoning.

• The following is a collection of errors of reasoning that are

commonly used and thus named.

Pathos

Appeal to Emotion

Think ASPCA commercials...http://www.youtube.com/watch?v=Ae5_QkVtXdg

Ethos

Appeal to Credibility

“Trust me, I'm a doctor”

Logos

Appeal to Logic.

If A is B, and B is C, then A is C.

Man is Mortal

Socrates is a Man

Therefore, Socrates is Mortal.

Taxonomy of Fallacies

• Warning! Some fallacies are difficult to place in any category; others belong in two or three.

Ad Hominem• Ad Hominem arguments attack a person’s

character rather than that person’s reasoning.

• Example: Why should we think a candidate who recently divorced will keep his campaign promises?

Appeal to Force:

• The writer threatens the audience, explicitly or implicitly, with negative consequences if the claim is not believed.

• Example: If you do not believe in God, you will go to hell.

Appeal to Pity• The writer begs for the

approval of the claim; the audience may agree because they feel sorry for the arguer.

• I cannot get a job because the public education system failed me; I have to steal to survive. It is society's fault, not mine.

Appeal to Authority• The writer cites authorities to

show the validity of the claim, but the authority is not an expert in the field, the authority's view is taken out of context, or other experts of that field disagree with the authority quoted.

• I think that businesses should not have to limit the amount of pollutants they release into the atmosphere because Rush Limbaugh says that there is no real evidence for industrial pollutants causing the Greenhouse Effect.

Post hoc ergo propter hoc• Post hoc ergo propter hoc, Latin for "after this,

therefore because of this", is a logical fallacy that states, "Since that event followed this one, that event must have been caused by this one.“

• More and more young people are attending high schools and colleges today than ever before. Yet there is more juvenile delinquency and more alienation among the young. This makes it clear that these young people are being corrupted by their education.

https://www.youtube.com/watch?v=vRJUvFG8gbE

Appeal to the Popular orBandwagon

• The writer bases the argument on the belief that if an idea is held by a large group of people, it is true.

• Millions of people are Marxists, so Marxist economic and political theories are correct.

Appeal to Tradition

• The writer relies on traditional wisdom to support the argument. This is a logical pitfall because the argument does not consider that new ideas could apply.

• People have believed that fish is "brain food" for decades, so I don't believe the FDA when they claim that eating fish does not enhance the intellect.

Begging the Question orCircular Argument

• The writer defends the claim by using the conclusion as one of the premises to support the conclusion. Basically assuming the thing to be true that you are trying to prove.

• Example: His lies are evident from the untruthful nature of his statements.

False Delimma

• The writer only presents some of the alternatives for solving a problem when more possibilities exist because the writer assumes that the list of alternatives created is exhaustive.

• In the United States, one can vote for either Democrats or Republicans.

Guilt by Association orPoisoning the Well

• Guilt by Association/Poisoning the Well calls someone’s character into question by examining the character of that person’s associates.

• Example: Sara’s friend Amy robbed a bank; therefore, Sara is a delinquent. OrDon’t listen to him because he’s a loser.

Red Herrings

• Writers use misleading or unrelated evidence to support a conclusion.

• Example: That painting is worthless because I don’t recognize the artist. Or I know I forgot to deposit the check into the bank yesterday. But, nothing I do pleases you.

Slippery Slope• Writers arguments

suggest that one thing will lead to another, oftentimes with disastrous results.

• Example: If you get a B in high school, you won’t get into the college of your choice, and therefore will never have a meaningful career.