PHI 102 - Critical Thinking
Review Exercises on Chapters 15-18
Part I: Analyze each of the inductive arguments below. Identify the purported cause, the purported effect, as well as the method used to support the conclusion: agreement, difference, joint method, method of concomitant variations, or residues.
1. I think this wool sweater is giving me a rash, because I haven't changed body soap or clothing detergent, and nothing else could be causing me this problem.
2. Research shows that the A-1 Security Gadget increases safety levels at airports. We tested the device at four major airports, and in each case the number of concealed weapons detected increased over past months.
3. Last fall's class was a perfect indicator of the effect of studying on one's class performance: the students who studied very little got D's, those
who studied a bit more got C's, and those who studied regularly got B's and A's.
4. Rayblocker sunblock lotion is superior. We tested it on Kevin , Mary, Alicia, and Joe, putting Rayblocker on one arm and the leading brand on the other. They all went swimming for hours, and in each case the arms with Rayblocker were fine, while those with the leading brand were fried to a crisp.
5. The increased planting of trees in our cities must be contributing to the rapid rise of urban smog, for the levels of smog actually observed cannot be accounted for by industrial, residential, and automotive emissions alone.
6. In some cases, all a movie needs is stellar special effects to be a box-office hit. The Red Mission had good casting but a horrible plot, while The Star Destroyer had poor casting but an intricate plot. But both had great special effects and were smash hits.
7. Jiffy Squid fries are the best, and you know what the secret is? While the recipe, the potatoes, and everything else is the same as at Burger Thing, the fries at Jiffy Squid are cooked in oil that has been through the crankcase of a '57 Desoto. The result - mmm-mmm fries!
Part II. Identify the type of statistical information contained in each of the statements below (total, ratio, frequency, mean, etc). Then determine whether or not the statement automatically supports the conclusion that follows it in brackets. If not, briefly explain why not.
8. UNLV has grown over 6% a year over the last decade, while enrollment at UNR has grown only 2% a year. [The total increase in students at UNLV is larger than the total increase of students at UNR.]
9. UNLV is devoting a significantly higher percentage of its budget to financial aid next year. [There will be a higher percentage of students receiving financial aid next year.]
10. UNR students receive, on average, higher financial aid packages than UNLV students. [UNLV students, on average, pay more in tuition than UNR students.]
11. Southern Nevada generates 68% of the state revenue, yet receives back only 52% of the state's higher education budget. [Southern Nevada receives too little higher education funding.]
12. In Dr Smith's class the average score was 82 out of a 100, while in Dr. Johnson's class the average was 70 out of 100. [More students in Dr. Smith's class received a score of 80 or higher than in Dr. Johnson's.]
13. UNLV has greatly increased its financial aid funding this year. [The average financial aid package increased this year.]
Part III. Analyze the statistical inferences below as instances of Mill's methods. First identify whether the study is observational or controlled, the independent and dependent variables, and the type of statistic (frequency or average) used to measure the effect; then, determine whether the method of difference or the method of concomitant variations is being used.
14. The key to weight loss is raising your metabolism, and the "Gut-blaster 2000" will help you do just that! We tracked over 100 people who recently began using the "Gut-blaster 2000," and their average metabolism increased by 15 percent after just one month of regular usage!
15. The greater the amount of chemical A2640 that we add to the serum, the faster laboratory rats are able to heal minor flesh wounds. We tested this additive on over 100 rats with minor flesh wounds. When a 2 percent concentration of A2640 was used, the wounds healed 25 percent faster than without the additive at all. When a 4 percent concentration was used, the wounds healed an amazinf 73 percent faster. Since no harmful side effects were detected, this test demonstrates A2640 is a helpful healing agent.
16. The new "Smoke-Out" nicotine patch helps to make it easier to quit smoking than do the competitors. A group of one-hundred long-time smokers used the "Smoke-Out" brand patch, while another group of one-hundred long-time smokers used a leading brand. Over 90 percent of the users of the "Smoke-Out" patch claimed that quitting was "not difficult," while only 15 percent of the users of the leading brand made the same claim.
17. A recent study was conducted on a group of 1000 individuals to see the effect of swimming on cholesterol levels. The study tracked the cholesterol levels over a period of one year, and those people who began to swim twice a week saw their cholesterol levels drop by 25 percent. Those who swam once a week had a drop of 10 percent. Those who did not swim at all either had constant cholesterol levels or slight increases in cholesterol levels. It seems clear that swimming regularly helps to reduce cholesterol levels.
18. A new protein additive for animal feed was tested over the course of one year on over 1000 chickens. Average egg output increased by 28 percent when the protein was used compared to when it was not.
19. Heavy weightlifting by baseball players might have some positive consequences, but it seems to have some negative consequences as well. In a survey of fiftytwo young and generally healthy players who have started lifting weights heavily in the past three years, the average percentage of time spent on the injured list due to joint and muscle injuries has increased by 41 percent over the prior three-year period. It seems that weightlifting is causing some players to lose their flexibility and become more injury prone.
20. Cities that enforced a 10 percent decrease in tolerated pollution from car exhaust have seen a 5 percent decrease in carbon monoxide pollution in the inner city area. Similarly, those that have enforced a 20 percent decrease in tolerated pollution have seen nearly a 12 percent decrease in carbon monoxide poisoning. It seems that decreasing the tolerated pollution from car exhaust is having a beneficial effect in the inner-city areas.
IV. In each of the following explanations, identify the explanandum and the hypothesis, and diagram the relation between them.
21. The photos are out of focus because the film is cheap, and the photographer inept.
22. The veggies are no longer fresh: they have gone past their suggested date, and have been in the refrigerator too long.
23. Their marriage didn't last long. She spent all of her time with her work and so couldn't devote enough energy the relationship, and he had an affair with her secretary.
24. I wasn't able to finish the assignment on time because I grew tired by mid-afternoon. I had been up very late last night because I was helping Sheila move into her new apartment. She had helped me move in, so I owed her.
25.
The congressional fracas ended earlier than was expected. The citizens demanded an end to the media circus, so the politicians finally came to terms.
26. The movie was a flop: the actors didn't mix well because the casting was not well-researched, and the effects were poor because the budget was too small.
V. Evaluate each of the following explanations for adequacy.
27. Meg is not as intelligent as Jamie, but that is because she doesn't have as high an IQ and as great an ability to think abstractly and reason thoroughly.
28. The smoking gun was in my hand because it had fallen off the roof overhead, and the jolt caused by my catching it forced it to go off by accident - killing poor Mr. Finnegan.
29. Employment figures have been in decline in this city since 1989. This is explained by the fact that that was the year when the city council first instituted high minimum-wage regulation.
30. He is very famous beause he has been interviewed on so many late-night talk show programs, like Letterman and Leno.
31. She ended the relationship because it was time to leave.
32. My car broke down the other day because it is getting old: it topped 80,000 miles on the odometer the other day.