1. Since there is an unlimited supply of coupons, Tim Morris' original argument (which is erroneous if coupons are really rare) is applicable. The 10-ounce bottles now effectively cost 40 cents and the 15-ounce bottles now effectively cost 60 cents, so you're getting the same deal either way (4 cents per ounce); hence, if your only goal is to get the best deal as measured by unit price, it doesn't matter which of the two sizes you pick!
(Note that by phrasing the question the way I did --- "Should you buy 10-ounce bottles of the shampoo or 15-ounce bottles?" --- and not mentioning the possibility that both choices might be equally good, I was in a sense committing the fallacy of limited choice!)
A more sophisticated analysis of the problem might take into account such externalities as the cost of travelling to the store to restock (but note that there's no limit on how many containers of shampoo you can buy at once; the only relevant limit is that you can use only one coupon per purchase) or the environmental impact of one's purchase (buying larger containers usually puts lets plastic into the waste-stream) or personal convenience (maybe you prefer the 15 ounce because it means changing shampoo bottles less frequently, or maybe you prefer the 10 ounce because they take up less space in your luggage when you pack), but the main thing I wanted you to demonstrate was an understanding of is the fact that the price per ounce is the same for both products when you've got an unlimited number of coupons.
Another way you could do the problem, without doing unit prices, is by seeing how much product you can buy for a large amount of money. For instance, for $6 you could buy 10 of the 15 ounce containers (since they're just 60 cents apiece with the coupons) or you could buy 15 of the 10 ounce containers (since they're just 40 cents apiece with the coupons); either way you'll be spending $6 for 160 ounces. (I chose to use $6 in this example because it's evenly divisible by both 60 cents and 40 cents, so there'll be no money left over, no matter which product you buy. If you used $5 (say) instead of $6, it wouldn't come out evenly, so you wouldn't be able to draw a clear conclusion.)
21. Premise: Following Reagan's defense buildup, the Soviet Union began the process of democratization that ultimately led to its breakup. Conclusion: Reagan is responsible for the changes that led to the demise of the Soviet Union. Analysis: Without historical substantiation, this is a false cause fallacy.
22. Premise: The Golden Rule is basic to every system of ethics in every culture. Conclusion: The Golden Rule is a sound ethical principle. Analysis: This is circular reasoning or diversion. No independent reason for the ethical soundness of the Golden Rule is given. Also, it is an appeal to popularity.
23. Premise: The mother has used drugs in the past. Conclusion: The decision on the custody case depends on the mother's present drug use. Analysis: Limited choice.
24. Premise: Everyone I know is voting for the Governor. Conclusion: You should vote for the Governor. Analysis: This is an appeal to popularity.
25. Premise: Mom smoked when she was my age. Conclusion: I won't heed her advice to stop smoking. Analysis: This is a personal attack.
26. Premise: Most of the great mathematicians in history have been men. Conclusion: Men must be better at mathematics than women. Analysis: This is a hasty generalization: a fact about the comparatively small number of great mathematicians over the ages is used to draw a conclusion about all men and women. Also, this is an example of false cause: factors other than men and women's natural abilities are at play here (such as bias in the historical record, the different amount of encouragement given to women, etc.)
27. Premise: No one has ever proved that telepathy doesn't exist. Conclusion: I believe in telepathy. Analysis: This is an appeal to ignorance: an absence of proof for one conclusion (telepathy does not exist) does not prove the opposite conclusion (telepathy does exist).
28. Premise: My two best teachers were both women. Conclusion: Women make better teachers than men. Analysis: This is hasty generalization.
29. Premise: Senator Smith is one of the biggest recipients of campaign contributions from the National Rifle Association. Conclusion: Senator Smith's bill cannot help the cause of gun control. Analysis: This is a case of personal attack: the fact that the Senator gets campaign funds from the NRA does not necessarily mean that he or she will only introduce bills that are to the NRA's liking. (One could also argue that it's a kind of "guilt by association," implying that on the one hand, there exist politicians who have received funds from the NRA, some of whom have gone on to support the NRA's position, and on the other, that Sen. Smith is one of these politicians. In this sense it's an implicit example of hasty generalization.)
30. Premise: Violent crime by youth has risen in virtual lockstep with increased violence on television. Conclusion: Television violence leads to real violence. Analysis: This is false cause or limited choice.
31. Premise: The percentage of the population over 18 that smokes has decreased from 40% to about 20%. The percentage of overweight people has increased from 25% to 35%. Conclusion: Quitting smoking leads to overeating. Analysis: This is false cause: just because there are now more overweight people and fewer smokers does not prove that quitting smoking causes overeating.
32. Premise: Boys score higher than girls on standardized mathematics tests. Girls score higher on verbal tests than boys. Conclusion: Boys have a greater aptitude for mathematics than girls. Girls are better at verbal skills. Analysis: This is limited choice and hasty generalization.
33. Premise: My little boy loves dolls and my little girl loves trucks. Conclusion: There's no truth to the claim that boys are more interested in mechanical toys while girls prefer maternal toys. Analysis: This is hasty generalization.
34. Premise: Goldwater's policies will lead to the annihilation of children we love. Conclusion: Vote for Johnson. Analysis: This is an appeal to emotion. (In the context of the 1964 presidential election, this was not a false choice, since when the ad appeared, the only two candidates with a chance of winning were Johnson and Goldwater.)
35. Premise: Bush favors repealing the estate tax, which falls most heavily on the rich. Conclusion: Bush wants to widen the disparity between the rich and the poor; vote for Gore. Analysis: This is a straw man argument.
36. Premise: Gore claims his regulatory changes will reduce the threat of global warming. Conclusion: Gore believes that government is the solution to all our problems; vote for Bush. Analysis: This is a straw man argument. (You could also call it a diversion, since Bush has changed from talking about the environment to talking about general issues of governance.)
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