LESSON #9

Fallacies of Presumption, Ambiguity and Grammatical Analogy

Reading Assignment: 3.4 (pp. 155-172)

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15. Begging the question This is an example of circular reasoning. Usually there is a questionably true premise that says the same thing as the conclusion but in a different way. Sometimes this questionable premise is merely inferred instead of being actually stated in the argument. The arguer is hoping you won't notice this.

16. Complex question - (not actually an argument in itself but an argument is implied.) A question is posed as a single question but it really has several parts to it, e. g., have you stopped beating your dog? You find yourself between a rock and a hard place in trying to answer this question with a "yes" or a "no."

17. False dichotomy - An either/or is presented that ignores other alternatives. Usually one side is obviously undesirable and the arguer is hoping you will agree to the other choice. But there are actually more than two choices.

18. Suppressed evidence - this is the name for an argument that intentionally ignores other strong evidence that would undermine or change the conclusion.

19. Equivocation --a pun--The same word or phrase is used (either explicitly or implicitly) in two different senses. You should be able to identify the offending word or phrase.

20. Amphiboly - An illogical conclusion is drawn, based upon a grammatical ambiguity, i.e. an ambivalently formed sentence or phrase.

21. Composition - The arguer tries to transfer attributes from the parts to the whole where the attributes aren't relevant.

22. Division - arguer tries to illicitly transfer attributes from the whole to the parts.

Logic Coach Assignment: 3.4 I all, III 1-30

Assignment 1: (10 points each)

From the eight fallacies listed above, (or no fallacy) identify the fallacies in the following arguments. If you are unsure of your answer, explain your reasoning.

1. The Grateful Dead were the greatest rock group in the world. This must have been true or thousands of Deadheads wouldn't have devoted their lives to following them. You can believe the Deadheads because they have a more highly developed sensibility than average people, and they aren't co-opted by capitalist society. This is obvious, otherwise they wouldn't have been following the Dead.

2. Good steaks are rare these days. So don't order yours well done.

3. I was having trouble breathing and my doctor prescribed some medicine to stop it. I refuse to take it because I don't want to stop breathing.

4. Molecules are in constant random motion. The Statue of Liberty is composed of molecules. Therefore, the Statue of Liberty is in constant random motion.

5. I don't know why people still bring up the subject of Hiroshima. We dropped a bomb and it destroyed some buildings and killed some people. But that's to be expected in a war.

 

ASSIGNMENT 2: (10 points each)

From all fallacies learned in this chapter, identify the fallacies in the following arguments: (again, "no fallacy" is an option, and you may want to explain your answer)

          1. Secretary to Boss: I believe it's time I deserved a raise. After all, I've been very careful about  not
             "accidentally"  mentioning  that man you have lunch with every day.

2. Congressman Jones denies that he is a liberal, so he must be a conservative.

3. Spain is 99 percent Catholic. Alfonso Rodriquez is a Spaniard. Therefore, Alfonso Rodriguez is 99 percent Catholic.

4. The federal government should save New York from defaulting on its bond obligations because New York deserves such aid.

5. When did you stop cheating on your girlfriend?

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