Phil 04 – Fall 09 Homework Four
Section 02, due Wed. Oct. 21.
Section 09, due Thur. Oct. 22.
1. Suppose you are debating the claim that cigarette smoking causes cancer. Which of the following assertions, if true, would be logically relevant support for or against that point and which would be irrelevant?
(a) If large numbers of people stop smoking, then many small tobacco farmers will have to close their farms and find some other way to make a living.
(b) Everyone has a right to smoke since this is a free country and the government has no business imposing restrictions on tobacco use.
(c) Smokers are usually heavy coffee drinkers. It may be true that cigarette smokers are more likely to develop cancer, but it’s not because they smoke, rather it is because they drink lots of coffee.
(d) My uncle Fred smoked three packs of Camels a day for fifty-three years before he died in an auto accident. An autopsy showed he didn’t have a trace of cancer in him.
Problems 2-6, determine whether deductively valid, inductively strong, or neither.
2. If the defendant’s fingerprints were on the murder weapon, then she was at the scene of the crime.
But according to the prosecutor’s own expert testimony, the defendant’s
fingerprints were not on the murder weapon.
Therefore, she was not at the scene of the crime.
3. If you had wanted to go scuba diving, then you would have brought your tank ,mask, belt and flippers.
You brought your mask and flippers, but not your tank and belt.
You must not want to go scuba diving.
4. Most days are weekdays, as opposed to weekend days.
There will be a day
when the population of the
So the day on which the
5. Either the crippled economy or the sex scandals will drive the prime minister from office. If inflation rises, then we will have a crippled economy. Inflation will not rise. Therefore, the sex scandals will drive the prime minister from office.
6. Stylish dressers are neither flashy nor dull. If someone is not flashy, then they are tasteful. Consequently, every stylish dresser is tasteful and not dull.
7. Jones reasons as follows:
Professor Zorg is a world-renowned expert on banking and finance. He has won many prestigious awards for his work in this area.
Zorg asserts that p is true (where p is in his area of expertise)
Therefore, it is reasonable for Jones to believe that p is probably true.
Jones is drawing an over-hasty conclusion. Specify two additional items of information Jones should know before he draws that conclusion.
8. If George H. W. Bush (Bush senior) said something about the first Iraq war (which happened during his presidency) and a bum in Capitol Park said quite the opposite, whom should you believe? Or should you not believe either one without more information?
9. Which of the following, if any, are examples of enumerative induction:
(a) Sixty percent
of American bachelors read Playboy.
Therefore, sixty percent of Canadian bachelors read Playboy.
(b) Sixty percent of American bachelors read Playboy.
Therefore, sixty percent of all
bachelors read Playboy.
(c) Sixty percent of all bachelors read Playboy.
Therefore, sixty percent of American bachelors read Playboy.
10. A random survey of 1000 callers to a drug hotline (where callers are given over-the-phone information and advice on drug use and abuse) over a period of one year produced the following results: 573 callers reported they were steady users of hard drugs; 220 reported they were only “recreational” (occasional) hard drug users; 92 callers reported they were not drug users; they just wanted information; and the remainder refused to answer questions about their drug use. The takers of the survey concluded that a majority of drug users – at least among those in the calling area – are steady users of hard drugs.
(a) What is the target group (or target population) of this study?
(b) What property or characteristic of that target group did they want to know?
(c) What sample of that target group did they use to arrive at their conclusion?
(d) Based on that sample, what did they conclude about the target population?
(e) This is actually a seriously flawed study. Their conclusion should not be trusted. What is wrong with it?
11. The latest virus invasion, particularly through the Microsoft Outlook program, illustrates yet another aspect of the problem of monopoly. In effect, the Windows monopoly is a computer monoculture with all the same problems of other monocultures. In agriculture one of the worries over the widespread planting of monoculture crops is their higher susceptibility to harmful insects and disease, since specialized bugs and microorganisms can rapidly increase in numbers in a monoculture crop. We might want to encourage diversity in our computer software not just for economic reasons but to avoid future catastrophic outbreaks of computer viruses. (Note: By a “monoculture crop” is meant a large farm or group of farms that plant only one specific variety of plant.)
This is obviously an argument from analogy of the form:
A’s (primary subject) are like B’s (the analogue).
B’s have property p.
Therefore, A’s probably have p.
(a) Specify clearly what A and B are in the argument, as well as property p.
(b) Describe one possible disanalogy between A and B that could weaken the argument.
12. The cost to
achieve a reduction of auto thefts and vandalism is substantial and is borne by
all New Yorkers, not just motorists.
Costly police protection, the sleep-disturbing noise of car alarms and
the preemption of limited open parking space in the city are substantial
societal burdens that are imposed by motorists who park their private property
free of charge on the public streets. In
contrast, motorists who park their cars in secure off-street garages and lots
and (indirectly) pay taxes on those sites, do not
impose those burdens. It is time for
those who park on the street to pay for the extra city services they
consume. After all, a majority of
households in
(a) Write out the conclusion in one clear sentence. Do not include any supporting premises in that sentence.
(b) Write out each of the supporting premises as separate lines.
(c) The maker of this argument is obviously assuming the truth of a general moral principle that the reader is likely to agree with. What is that principle?
13. A problem in deductive reasoning. Four women, one of whom was known to have committed a terrible crime, made the following statements when questioned by the police:
Fawn: Kitty did it.
Kitty: Robin did it.
Bunny: I didn’t do it.
Robin: Kitty lied.
If only one of these four statements is true, who was the guilty woman?
Hint: If you want to solve the problem in a systematic way, use the reduction ad absurdum method. Assume one of the women told the truth and see if that leads to a contradiction. If so, she obviously did not tell the truth, so move to the next woman and follow the same steps.