1. As part of his work for NASA, Dr. Murdock was asked to find out what percentage of people in the continental united States saw Haley’s Comet when it was last visible. He randomly selected three major cities, Seattle, Cleveland, and Boston, and polled 1000 randomly selected people from these cities. He finds that fewer than 5% of the people he interviewed saw the comet, so he concludes that fewer than 5% of people in the continental United States saw the comet. Discuss whether Murdock is using a generalization or an analogy, name the sample and the target, and discuss whether there are any fallacies present in the argument (if so, why; if not, why not?).
2. In 1935, in order to get newspapers to subscribe to his weekly polls, George Gallup promised he would predict the winner of the 1936 presidential election. He actually guaranteed the newspapers that were subscribing to his poll that if he was wrong, he would refund all their money. And that was just part of the bet. Gallup also guaranteed that he would predict the percentages more accurately than the leading poll of the day, conducted by the Literary Digest magazine. The Literary Digest poll had picked the winner in every presidential election since 1916. The Digest poll was conducted on a vast scale. A staff of several thousand workers stuffed ballots into envelopes, in some years as many as 20 million of them. The ballots were mailed to names polled from automobile registration lists and telephone directories. The assumption was that the more people you interview, of course you’re going to get closer to the truth. But the method George Gallup relied on was called quota sampling. The idea was to canvass groups of people who were representative of the electorate. Gallup sent out hundreds of interviewers across the country, each of whom was given quotas for different types of respondents; so many middle-class urban women, so many lower-class rural men, and so on. Gallup’s team conducted some 3,000 interviews, but nowhere near the 10 million polled that year by the Literary Digest. Who is going to correctly predict the winner of the 1936 presidential election, the Literary Digest or George Gallup? Explain your answer by discussing the methodology of each pollster, and by using the terminology provided to you in chapter 10.
3. As Bob is driving on an exit off the freeway, he comes to a stop light and sees a homeless man asking people for spare change. “See, he’s a perfect example of why we shouldn’t be giving welfare benefits to the homeless,” Bob mutters to his wife. “He’s too lazy to get a job, but he’s healthy enough to beg people for their hard-earned money all day long.” What are the sample and the target in Bob’s argument? Are there any inductive fallacies present in Bob’s reasoning? If so, explain why. If not, explain why not.
4. The National Rifle Association’s website conducted a poll of gun owners in America, asking whether the respondents are opposed to gun-control laws. 2000 American gun-owning NRA members went online and responded to the poll. The poll result shows that 80% of them are opposed to gun-control laws. The group concludes that most people in America are opposed to gun-control laws. For this passage, determine whether the argument is an analogical argument or a generalization (explain your answer), and explain which inductive fallacies, if any, are present in the argument.
5. What is the definition of a “randomly chosen sample” (according to the definition discussed in your text), and what is the goal of randomly choosing a sample?
6. What is the definition of a self-selected sample (according to the textbook or instructor), and what is the problem with using a self-selected sample as the basis of an inductive argument?
7. Explain the relationship between error margin and sample size (assuming the confidence level remains the same), why the concept of error margin is necessary in an inductive argument, and how error margin is applied to the target population. You may want to use an example to help explain your answer.
8. Dad is making a “Hunter’s Stew”. The stew includes chunks of beef, potato, carrot and barley in a thick broth full of many hearty spices. As the stew is simmering in a pot on the stove, Son walks into the kitchen and says, “Let’s see if this stew tastes any good!” Son gets a big spoon and begins to dip his spoon into the top of the pot. Before Son has a chance to get the spoonful of stew, Dad yells, “Mix the stew up before you taste it!” For this passage, name the intended sample, the intended target, the property in question, and explain why Son should stir the stew before he tastes it.
9. When Haley’s Comet hovered over Jerusalem in 66 CE, the historian Josephus prophesied it meant the destruction of the city. Jerusalem fell four years later during a failed uprising against Roman occupiers, thus confirming the power of the comet. Is this argument subject to any causal fallacies discussed in the PowerPoint presentation for chapter 11? Explain your answer.
10. Jack is hired by a company to see if a new product not yet on the market, Topocal, will cause hair to grow on the heads of bald men. He recruits one thousand bald men, and randomly divides them into two groups: Five hundred men in group A rub Topocal on their heads everyday, and five hundred men in group B rub water from an unmarked bottle on their heads (a placebo) everyday. After six months, Jack finds that there has been hair growth in 7% of group A, and 2% of group B. a) What is the control group? What is the experimental group? b) What is “D” in this case? c) What type of study is this (controlled cause to effect, non-controlled cause to effect, or non-controlled effect to cause)? Explain your answer briefly. d) Are the results of this study statistically significant (use the table in chapter 11 to find the answer to this question)? e) What is the target population to which we hope to apply the results of this study?
11. For the last ten years, unemployment has increased in January and retail sales have gone down in February. Clearly, the decrease in retail sales is caused by the increase in unemployment. Is this argument subject to any of the following causal fallacies: post hoc ergo propter hoc, reverse causation, ignoring an underlying cause? Explain your answer.
12. Determine whether the following statement is an example of Method of Difference Reasoning or Method of Agreement Reasoning (and briefly explain your answer). Fund-raising director for a public radio station: “I know that our music director hates it when we play classical music. But go back and look at our most successful fund drives; every big day has been a day heavily loaded with classical music.”
13. Determine whether the following statement is an example of Method of Difference Reasoning or Method of Agreement Reasoning (and briefly explain your answer). “I had a lot of noise on my car stereo when the engine was running, until I thought maybe that the way to fix the problem is to install a 4MH choke coil in the hot wire from the battery to the stereo. I did it, and it cured the problem.”
14 Determine whether the following statement is an example of Method of Difference Reasoning or Method of Agreement Reasoning (and briefly explain your answer). Sharon has observed that her teacher sometimes seems to be in a bad mood. “Well,” she thinks, “it seems to happen when people haven’t done their assignments. That must be it.”
15. Jack hears on the evening news that several scientific studies have demonstrated that taking acetaminophen causes liver damage. Jack immediately runs to his medicine cabinet and throws away all his painkillers that contain acetaminophen, and he recommends to his friends and family that they do the same. Jack now believes that acetaminophen will cause liver damage in him and his loved ones. Discuss whether Jack’s reaction is justified (is Jack correctly interpreting the claim that “acetaminophen causes liver damage?”). Be sure to use the concepts in chapter 11 to help explain your answer. You should discuss the nature of general causal claims.
16. Determine whether this is an inductive generalization, or an analogical argument. Identify the sample and target, if this is a generalization, or the analogues, if this is an analogical argument. Identify the property in question, and discuss which, if any, fallacy exists in the passage:
Remark made while driving on the Pennsylvania Turnpike: “We’ve seen nine cars with license plates from west of the Mississippi today, and six of them have been from Texas. Texans must travel more than other people.”
17.Six months ago, several of Molly’s friends joined the Trimtime Fitness Center. Each of them participated in Trimtime’s weight-reduction and fitness regimen. All reported substantial weight reduction, and all are visibly slimmer. Molly is convinced. She joins Trimtime and enrolls in the same program, hoping and expecting to see the same results. She is especially delighted to learn that Trimtime had adjusted its program to make it even more effective in a shorter period of time. Discuss whether this is an analogical argument or an inductive generalization, and discuss the strength or weakness of the argument, using the appropriate terminology from chapter 10.
18. Bill: “If you don’t believe in God, you’re much more likely to commit suicide. You can tell that by looking at places like Sweden and Norway where there’s a higher percentage of atheists than the norm and their per capita suicide rate is higher, too. ”
What causal fallacy from among the following choices is Bill making (reverse causation, ignoring an underlying cause, post hoc ergo propter hoc, cum hoc ergo propter hoc, ignoring statistical regression)? Discuss your answer.
