Transcript File
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.