10.RI08 I can analyze and evaluate specific claims in a text to determine if the reasoning is valid and the evidence fully supports the claim

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 Even though it's only the first day, I can tell this is going to be a boring course. In this example, the author is basing his evaluation of the entire course on only the first day, which is notoriously boring and full of housekeeping tasks for most courses. To make a fair and reasonable evaluation the author must attend not one but several classes, and possibly even examine the textbook, talk to the professor, or talk to others who have previously finished the course in order to have sufficient evidence to base a conclusion on.

False Causality (Post Hoc) The assumption that because one event follows another, the first is the cause of the second. 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.

Self-Contradiction When the argument is self-contradictory and cannot possible be true. I don’t care what you believe as long as you don’t harm others. The arguer must always care if the person believes something that will harm others or not.

*Circular Reasoning An argument in which the writer, instead of applying evidence simply restates the point in other language. Students should not be allowed to park in lots now reserved for faculty because those lots should be for faculty only.

Ad Hominem (Argument against the Person ) An attack on the character of the person rather than his/her argument. Senator Jones was a conscientious objector during the Vietnam War, so his proposal to limit military spending has no merit.

“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.

Ad Populum (Bandwagon Appeal) A claim that an idea should be accepted because a large number of people favor it or believe it to be true. Everyone knows that smoking marijuana is physically addictive and psychologically harmful.

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.

Slippery Slope This is a conclusion based on the premise that if A happens, then eventually through a series of small steps, through B, C,..., X, Y, Z will happen, too, basically equating A and Z. So, if we don't want Z to occur, A must not be allowed to occur either. If we ban Hummers because they are bad for the environment eventually the government will ban all cars, so we should not ban Hummers.

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/LessonPlanDetails.aspx?myId=7. Hacker, D. (1999). A Writer’s Reference, 4th 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.