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Informal Fallacies: Example Test

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  INFORMAL FALLACY TEST

Directions: Do not write on the pages of this test. Please indicate the two best answers to the fallacies, in each of the following passages, on the ANSWER SHEET enclosed with this test.


1. Old man Brown claims that he saw a flying saucer in his farm, but he never got beyond the fourth grade in school and can hardly read or write. He is completely ignorant of what scientists have written on the subject, so his report cannot possibly be true.

Ad hominem
--Brown's education is irrelevant to his ability to observe.

2. My client is an integral part of this community. If he is sent to prison not only will this city suffer but also he will be most missed by his family. You surely cannot find it in your hearts to reach any other verdict than "not guilty."

Ad misericordiam--
The pity being invoked for the client is not relevant to his guilt or innocence.

3. You ought to try to study harder in school this year, Samuel, because it will spare your parents the embarrassment of a letter from the instructor telling them you're slipping.

Ad baculum
--The reasons for Samuel to study should be independent of the threat to inform his parents.

4. You will back up my story and tell the committee I am reasoning logically; because if you don't I will do everything in my power to see that you are fired.

Ad baculum
--The threat of being fired, presumably, is not logically relevant to the purported story.

5. I believe in the Bible because it is the written word of God through his prophets. Obviously, God would not lie to his prophets. After all, the Bible says so.

Petitio principii
--The premiss and final conclusion are equivalent statements.

6. Congress shouldn't bother to consult major universities about educational appropriations. As members of educational establishment, they will naturally want as much money for education as they think they can get.

Ad hominem
--Reasons should be evaluated on their own merits not the character of the persons issuing them.

7. In recent studies researchers have show that women have more accurate intuition than men do. The reason cited is that men's intuition is more often mistaken.

Petitio principii
--The premiss and conclusion are equivalent propositions.

8. I can see that you are in the market for a new car. We're having a sale on Pintos this month. Do you want to pay cash or do you want the installment plan?

Complex question: Buying a Pinto is being presupposed.

9. John has really worked hard on his term project, and he will really be depressed if he does not make an A. For these reasons, you just have to give him an A on his project.

Ad misericordiam
--John's feelings are not logically relevant to the quality of his project.

10. What is right is what is morally obligatory. What is morally obligatory is what you should do. Of course, you should do something because it is the right thing to do.

Petitio principii
--A premiss and conclusion in this argument chain are logically the same.

11. I can see that the efficiency with which the Tornado Home Vacuum System works and the marvelous way in which it saves on toil and drudgery in the home impresses you. Therefore, shall I charge it to your account or do you want to pay cash?

Complex question: Buying the Vacuum System is being presupposed.

12. If we wish to determine which of a person's motives determine his actions, we need only examine which of the alternative courses of action he chooses to perform. Therefore, a person's motives are determined by the actions he chooses to perform.

Petitio principii
--the conclusion is being presupposed in the premiss.

13. A prosecutor states to the jury: "You cannot let this man go free because our society is not safe with him at large. Who knows who his next victim will be?"

Complex question--The prosecutor is not warranted in presupposing without proof that the defendant is guilty.

14. It should be no surprise to you that if a Democrat is elected in the next presidential election that we will have one of the worst recessions in years. Recessions always seem to be created by Democratic administrations.

False cause--No causal mechanism is shown for the relation between events.

15. As I walked to the library from the Learning Center not one person spoke to me. Lander University is not as friendly as I was led to believe.

Converse accident--A generalization is reached from one incident; here, there is a lack of sufficient evidence for the conclusion.

16. How can we save our country from the bureaucratic dictatorship, the corruption, and the creeping socialism of the present administration? Only one way vote Independent.

Complex question: The presupposition of this question might not be generally granted.

17. I don't care what your arguments are; you are using Mickey Mouse tactics. The arguments you give are simply tacky.

Ad hominem
--Character attacks and name calling are irrelevant to the cogency of the arguments.

18. Officer, please excuse my going over the speed limit, but my mother is ill and I'm being audited by the IRS, and I don't know how I can meet all my bills.

Ad misericordiam
--The pity being invoked is irrelevant to the question of whether or not the man was speeding.

19. Why haven't you been studying, as you should? You would feel a lot better if you would take you school work more seriously.

Complex question--The locutor is assuming without proof that you have not been studying.

20. Those who say that extra-sensory perception is not reliable are mistaken. The police, Hollywood stars, and politicians have all relied on it.

Ad populum
--Simply because many persons believe something does not make the belief true. On might argue here, as well, the fallacy of ad verecundiam occurs since these persons are not authorities in the field being mentioned.

21. But Doctor, surely your advice that I should not drink coffee is not sound advice since you yourself often drink coffee.

Ad hominem
(tu quoque)--The attack on the Doctor's habits are irrelevant to the recommendation to the patient.

22. The late Ely Culbertson, one of the world's outstanding bridge players, once declared that the United Nations as presently constituted has serious defects. He must be right because I don't think the opinion of a man of his caliber should be taken lightly.

Ad verecundiam
--The authority is being quoted outside of his field of expertise.

23. The General Assembly of the United Nations keeps voting for radical issues. Therefore, the U. S. will be forced to reduce its financial contribution to the U. N. unless there is a demonstrated change soon.

Ad baculum
--The arguments are being side-stepped by the threat to withdraw money.

24. During the Gulf war many Americans made immense profits. That is an indisputable fact. Therefore, there can be no doubt that American business interests instigated the war.

False cause--Simply because two events occur, one cannot assume that one caused the other without further evidence.

25. No mathematician has ever been able to demonstrate the truth of the variants of the Goldberg conjecture, so they cannot all be true.

Ad ignorantiam--From the fact that there is no proof, no conclusion can be drawn.

26. Everyone says that a logic course is easier than a math course, so it must be.

Ad populum
--Common belief could be mistaken.  Even so, it is arguable that popular opinion is the proper way to determine the degree of difficulty of a course. The better answer would be "No Fallacy."

27. Unless you back up my story and tell the committee I am reasoning logically, I'll do everything in my power to see that you are fired.

Ad baculum
--The threat of force here is irrelevant to the truth of the story.

28. The best students make the best grades. Therefore, getting high grades will undoubtedly cause you to be a better student.

False cause--Notice why this fallacy is not petitio principii.  The awarding of high grades quite possibly would make one a worse student.

29. Everyone believes that men write the best novels; therefore, there is little doubt that they do so.

Ad populum--Even if one were to assume the truth of the premiss, popular opinion is not what determines the quality of novels.

30. Since the Bible says, "Thou shall not kill," it would be wrong to exterminate the termites in City Hall.

Accident--The reasoning goes from a general principle to an atypical application of the rule not meant to be subsumed under the rule.

31. But Mom I don't see why I have to wear socks; Einstein never did wear socks.

Ad verecundiam
--Einstein's field of expertise does not extend to the wearing of socks. 

32. I once knew a philosophy student who went crazy and another one who was not that well balanced. You can see what the study of philosophy did to them.

False cause--No causal mechanism is being proposed for the connection of these events.

33. A great many charges of graft and corruption have been brought against Senator Anderson over the past several years, and he has had numerous opportunities to refute them, but he has never done so. Therefore, I think, the evidence indicates he is not to be trusted.

Ad ignorantiam--
From the fact that there is no proof, no conclusion can be drawn.

34. The present U.S. administration has not yet developed an energy policy. Nonetheless, almost every other developed nation in the world has an energy policy, except us. Therefore, the United States should have a unified energy policy.

Ad populum
--The popularity of a practice or a belief is insufficient to establish its truth.

35. The welfare program is totally unnecessary. Why, I know a guy who runs a very lucrative illegal gambling operation and drives his new Cadillac down every week to collect his welfare check.

Converse accident--One case is insufficient to establish a generalization.

36. It was his fault, Officer. You can tell by the kind of car I'm driving and by my clothes that I am a good citizen and would not lie. Look at the rattletrap he is driving, and look at how he is dressed. You can't believe anything that a dirty, longhaired hippie like that might tell you. Search his car; he probably has pot in it.

Ad hominem
--The attack on the character is not relevant to the truth or falsity of the charges.

37. General Jed M. Lamgetter believes that it is absolutely essential to our future security that we immediately upgrading our computing systems to Linux from Microsoft NT. But his arguments are hardly deserving of careful consideration, for in a couple of weeks General Lamgetter will retire from the Army and become CEO and be given large stock options in Red Hat, one of the main Linux producers.

Ad hominem-
-General Lamgetter's circumstances should not be logically relevant to the truth or falsity of his assertions.

38. The real reason you favor the draft is that you're too old to be drafted.

Ad hominem--The personal attack is taken rather than looking for the reasons supporting the positions.

39. Richard Nixon: "Mr. Sparkman and Mr. Stevenson should come before the American people, as I have and make a complete financial statement as to their financial history, and if they don't, it will be an admission that they have something to hide.

Ad ignorantiam
--No conclusion can be drawn from the lack of evidence.

40. Stanford produces the best graduates in the United States. Therefore, any every Ph.D. from Stanford is better than any other Ph.D. in the country.

Division--The quality of the whole does not necessarily extend to the parts.

41. Water extinguishes fire. Oxygen is part of water. Therefore, oxygen will extinguish fire.

Division--The parts of a whole do not necessarily have the same qualities.

42. Priests take a vow of poverty. The Church is a corporate body composed of priests. Therefore, the Church should not own property.
Composition--The parts do not necessarily have to have the same characteristics as the whole.

43. Since the average life-span of an individual in developing countries is thirty years, the leaders in those countries grow old before they have time to learn the rudiments of good government.

Division--The average life-span does not apply distributively to the individuals cited.

44. As the convener of the ninth annual Women's Freedom Movement, let me remind you once again that women have been discriminated against for centuries, and they have suffered as second-rate people for centuries. I, for one, refuse to submit to this discrimination and second-rate treatment any longer.

Division--The speaker has not lived for centuries.

45. I ought always to do what is right. I have a right to say what I think. Therefore, I ought always to say what I think.

Equivocation--The word "right" is being used in two different senses.

46. As a result of a poll of 28 adults interviewed on Main Street in Greenwood, S.C. on Friday night, we can conclude that all people in Greenwood prefer going downtown to watching TV.

Converse accident--The samples collected are atypical of the population of the city mentioned.

47. According to the law, a man is innocent until proved guilty. So Mr. Ratskeller must be innocent of the charge of bribery, since he has not yet been proved guilty. Therefore, since Mr. Mafia is innocent, it would be wrong to convict him.

Equivocation--Two different senses are being used: legal and actual innocence.

48. Although you have said you will give me no more of your time, I'll not ask for any more of your time; I'll just ask for the amount of time you have already given once more.

Amphiboly--The loose combination of words leads to two different interpretations for the phrase "more of your time."

49. A description of a candidate who is woefully inept: "I most enthusiastically recommend this candidate with no qualifications whatsoever."

Amphiboly--Is the candidate qualified or not?

50. Nothing would be better than a high score on this test, but a poor grade would be better than nothing, so conclude that a bad grade would be better than a high score.  

Equivocation--Two different senses of "nothing" are being used in the argument.

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