Common Logical Fallacies Flawed Arguments Logical Fallacies Flaws

Common Logical Fallacies Flawed Arguments

Logical Fallacies… • Flaws in an argument • Often subtle • Learning to recognize these will: – Strengthen your own arguments – Help you critique other’s arguments

Hasty Generalization • A generalization based on insufficient or unrepresented evidence – Deaths from drug overdoses in Metropolis have doubled over the last three years. Therefore, more Americans than ever are dying from drug abuse. – You get a text from some other number while with a significant other; the SO assumes you’re up to no good (seeing someone else).

Non Sequitur (Does Not Follow) • A conclusion that does not follow logically from preceding statements or that is based on irrelevant data. – Mary loves children, so will make an excellent school teacher.

False Analogy • The assumption that because two things are alike in some respects, they are alike in others. – If we put humans on the moon, we should be able to find a cure for the common cold. – There’s a car that can drive itself, and we still can’t edit Tweets after we post them.

“Either… or” Fallacy • The suggestion that only two alternatives exist when in fact there are more. – Either learn how to program a computer, or you won’t be able to get a decent job after college. – If you’re not religious, then you must be an atheist.

False Causation (Faulty cause and Post Hoc Ergo Propter Hoc) • These arguments misidentify the cause of something. – Faulty Cause: A cause is attributed when there is insufficient evidence to prove it. • Ex: “I was thinking about you when the phone rang. I must be psychic. ” – Post Hoc: Assertion that an earlier event caused a later one simply because it occurred before the second. • Ex: “The computer doesn’t work now, and you were the last one on it. You broke the computer! • Since Governor Smith took office, unemployment for minorities in the state has decreased by seven percent. Governor Smith should be applauded for reducing unemployment among minorities. • Sara took an herbal remedy for her cold, and she got better. The herb cured her!

Circular Reasoning/ Begging the Question (Unsupported Assertion) • An argument in which the writer, instead of applying evidence, simply restates the point in another way. • The truth of the argument’s conclusion is assumed by its premises. • The conclusion is assumed, then used to prove itself. – Begging the Question: • Students should not be allowed to park in lots now reserved for faculty because those lots should be for faculty only. – Circular Reasoning: • • • Mary: God exists John: How do you know? Mary: The Bible says he does. John: Why should I believe the Bible? Mary: It was written by God.

Bandwagon Appeal (Argumentum ad Populum) • A claim that an idea should be accepted because a large number of other people favor it or believe it to be true. – Everyone knows that smoking marijuana is physically addictive and psychologically harmful. – Americans support the Affordable Care Act!

Argument to the Person (Ad Hominem) • An attack on the person proposing an argument rather than on her/his argument itself. – Senator Jones was a conscientious objector during the Vietnam War, so his proposal to limit military spending has no merit. – Of course you’d say we should help the poor; you’re a nice person!

Red Herring • An argument that focuses on an irrelevant issue to detract attention from the real issue. – Reporters are out to get the president, so it’s no wonder we are hearing rumors about these scandals.

Appeal to Force/Fear (Ad Baculum) Appeal to Adverse Consequences • The ad baculum fallacy is committed whenever the proponent of an argument attempts to persuade the audience to accept the conclusion by predicting (or causing) unpleasant consequences if it is not accepted. – You ought to vote for Senator Gulch, because if you don’t, I’ll burn your house down. – If we allow so and so to be elected, the government will take away all our rights and freedoms.

Appeal to Authority/Celebrity (Ad Verecundiam) • Different from an ethos appeal; but it is a fallacy in the use of ethos • The ad verecundiam fallacy consists of an appeal to irrelevant authority, that is, an ‘authority’ who is not an authority in the field of question (or at least one we have no reason to believe to be such an authority). – Oprah says that she won’t eat beef and neither should you. – Alec Baldwin feels that American foreign policy is ineffective. – Jenny Mc. Carthy says vaccinations cause Autism.

Appeal to Pity (Ad Misericordiam) • Ad Misericordiam is an appeal to accept the truth of a conclusion out of pity for the arguer or some third party. Either the arguer (or someone else) is already an object of pity, or they will become one if the conclusion is not accepted. – If I don’t get at least a B in this course my GPA will drop below 2. 0. If that happens I’ll lose my scholarship and have to quit school, so I ought to get a B in this course.

Appeal to Ignorance • One sometimes encounters arguments that some claim should be accepted because they have never been disproved. The move from ‘not disproved’ to ‘proved’ is invalid. – No one has ever shown that it is impossible that the stars rule our lives; therefore, astrology is true. – No one can prove Bigfoot doesn’t exist; therefore, he must exist!

Slippery Slope • An error in reasoning in which some event must inevitably follow from another without any reasons for the inevitability of the event in question. • In most cases, there a series of steps or gradations between the first event and the end result that have been omitted, and no explanation is given as to why the intermediary events will simply be bypassed. – Students and faculty need to speak out against the tuition increase. If they don’t, the next thing you know, they'll be charging $40, 000 a semester! – If marriage is allowed for same sex couples, what’s to stop other kinds of marriage from becoming legal? Pets? Family members? Yourself? • Note the presupposition here too

Straw Man • This fallacy is committed when a person simply ignores a person's actual argument and instead substitutes a distorted, exaggerated or misrepresented version of his or her position. In other words, you create your own “version” (the straw man) of someone else’s argument, then argue against your own version in order to prove his wrong (knock down the straw man). • You probably have committed a straw man if someone responds, “That’s not what I said. ” – Me: Minor offenders are making prison overcrowding much worse. – Opponent: Letting all minor offenders out of jail would create chaos in society!

Straw Man (cont. ) • An example: Science professor explains that evolution means species change over long periods of time in response to their environment. The disbelieving student, to prove him wrong, says, “You can’t tell me that men came from a bunch of monkeys. ” Then he proceeds to explain why apes couldn’t simply have turned into men after a while. • Notice: The arguer states his opponent's position incorrectly and then argues against that false position rather than his opponent's *actual* position. The name refers to the ease with which he defeats or knocks over this fake man or false position.

Ad populum http: //www. cafepress. com

Circular reasoning http: //www. cafepress. com

Either/Or http: //www. cafepress. com

Credits Annenberg Public Policy Center (2008). Monty Python and the Quest for the Perfect Fallacy. Retrieved 10 -1 -08 from http: //www. factchecked. org/Lesson. Plan. Details. aspx? my. Id=7. Hacker, D. (1999). A Writer’s Reference, 4 th ed. New York: Bedford/St. Martins. Mike, H. B. (1999). Language and Logic. Dubuque, Iowa: Kendall/Hunt Publishing, 1999. Wheeler, K. (2008). Logical fallacies handlist. Retrieved 10 -1 -08 from http: //web. cn. edu/kwheeler/fallacies_list. html Many thanks to Shawn Mole for providing much of the condensed research.