Errors in reasoning that lead to wrong conclusions Logical Fallacies Errors in reasoning that lead to wrong conclusions

Oversimplification Supplying neat and easy explanations for large and complicated phenomena. Examples: No wonder drug abuse is out of control. Look at how the courts have hobbled police officers. Oversimplified solutions are also popular All these teenage kids that get in trouble with the law–why, they ought to put them in work camps. That would straighten them out!

Hasty generalization Leaping to a generalization from inadequate or faulty evidence. The most familiar hasty generalization is the stereotype. Examples: Men aren’t sensitive enough to be day-care providers. I’m never asking out a redhead again. I’ve gone out with three redheads, and each one had a fiery temper.

Either/or reasoning Assuming that a reality may be divided into only two parts or extremes, or that a problem has only 2 possible solutions A form of extreme oversimplification Examples: What’s to be done about the trade imbalance with Asia? Either we ban all Asian imports, or American industry will collapse. My contribution to the Red Cross won’t solve the problem of world hunger, so it won’t do any good. I won’t bother to make a contribution at all!

Popular Appeal / Bandwagon The argument relies on widespread acceptance, not logic. Example You can’t get uptight about copyright infringement. Everyone owns illegally burned CDs and illegally copied music.

Argument ad hominem From Latin, “to the man” Attacking a person’s views by attacking his/her character Examples: Mayor Burns is divorced and estranged from his family. How can we listen to his pleas for a city nursing home? Bill: "I believe that abortion is morally wrong." Dave: "Of course you would say that, you're a priest. The arguments you gave don't count. Like I said, you're a priest, so you have to say that abortion is wrong. Further, you are just a lackey to the Pope, so I can't believe what you say."

Circular Reasoning Arguing in a circle Never offers evidence “Dogs are a menace to people because they are dangerous” Simply repeats what they already said; if they are a menace, they are naturally dangerous I am in college because that is the right thing to do. Going to college is the right thing to do because it is expected.

Begging the question When a proposition which requires proof is assumed without proof Example: Abortion is the unjustified killing of a human being and as such is murder. Murder is illegal. So abortion should be illegal. (Assumes that abortion is murder.) We know God exists because we can see the perfect order of His Creation, an order which demonstrates supernatural intelligence in its design. (Assumes that a creator exists)

Post hoc, ergo propter hoc From the Latin, “after this, therefore because of this;” Post hoc for short Because B follows A, B will be caused by A Ever since the city suspended height restrictions on skyscrapers, the city budget has been balanced He went to the store to buy shoes; therefore, the house burned down.

Appeal to Ignorance The argument mistakes lack of evidence for evidence to the contrary. In effect, the argument says, "No one knows it is true. Therefore it is false.“ Examples "There is no proof that hand gun legislation will reduce crime. We can only conclude that outlawing handguns would be a futile gesture.“ "Why do elephants paint their toenails red? To hide in strawberry patches. Have you ever seen an elephant in a strawberry patch? That proves that it works!“ Of course God exists. No one has ever proven that he doesn’t.

False Analogy The claim of persuasive likeness when no significant likeness exists Just because they are comparable in some respects, they are comparable to others as well Example: Employees are like nails. Just as nails must be hit in the head in order to make them work, so must employees. I know we’ve only dated for two months, but I feel confident about asking Becky to marry me. After all, you don’t have to eat a whole cake to know that the cake is good.

Slippery Slope Series of steps or gradations and no reason is given as to how the steps progress. This "argument" has the following form: Event A has occurred (or will or might occur). Therefore, event Z will inevitably happen. Especially clear in cases in which there is a significant number of steps between events. "We have to stop the tuition increase! The next thing you know, they'll be charging $40,000 a semester!" "You can never give anyone a break. If you do, they'll walk all over you."

Hypothesis contrary to the fact A claim about what would have been true if the stated fact were not true "In this country citizens are permitted to own guns. Therefore, if guns were outlawed, citizens would be unable to protect themselves and there would be an uncontrollable crime wave.“ If Survivor had never been filmed, reality TV would never have come into being.

Ad misericordiam Appealing to sympathy No real argument Example: If you don’t give me this job, I will die!

Undistributed Middle Not all the instances of things that are C are also instances of things that are A or of B. A is a C. B is a C. Therefore A is a B. Examples: Most Arabs are Muslims and all the 9/11 hijackers were also Muslims. Therefore most Arabs are hijackers. My 5-year-old enjoys watching television, and teenagers also enjoy watching television. Therefore my 5-year-old is a teenager.