Chapter 3 Answer Key to Select Chapter Exercises

Exercise 3.1
1. An inductive argument is an argument intended to provide probable, not conclusive, support for its conclusion.
3. Deductive arguments are truth-preserving, as it is not possible for the premises in a deductive argument to be true, while the conclusion is false.
6. No; an inductive argument is intended to provide only probable support for its conclusion.
7. A strong inductive argument succeeds in providing probable—but not conclusive—logical support for its conclusion. A deductively valid argument guarantees the truth of its conclusion, as long as its premises are also true.
10. Yes; yes

Exercise 3.2
3. Step 1: Conclusion: You must be obsessed with bitcoin.
Premises: You’re a finance major. All finance majors are obsessed with bitcoin.
Step 2: Deductively valid.
Step 3: Does not apply.
Step 4: Does not apply.
4. Step 1: Conclusion: Good sense is of all things in the world the most equally distributed.
Premises: Everybody thinks himself so abundantly provided with it, that even those most difficult to please in all other matters do not commonly desire more of it than they already possess.
Step 2: Not deductively valid.
Step 3: Not inductively strong.
Step 4: Inductively weak.
7. Step 1: Conclusion: All loyal animals are good guard animals.
Premises: All dogs are loyal. All dogs are good guard animals.
Step 2: Not deductively valid.
Step 3: Not inductively strong.
Step 4: Deductively invalid.
8. Step 1: Conclusion: Some people in this neighbourhood are bigots.
Premises: Anyone who is not a bigot will agree that Chris is a good fellow. Some people in this neighbourhood think he’s not a good fellow.
Step 2: Deductively valid.
Step 3: Does not apply.
Step 4: Does not apply.
12. Step 1: Conclusion: Someone must have burglarized the place.
Premises: One dresser drawer was open, some money had been taken out of the safe, and there were strange scratches on the wall.
Step 2: Not deductively valid.
Step 3: Inductively strong.
Step 4: Does not apply.
14. Step 1: Conclusion: It is better to speak.
Premises: When we speak we are afraid our words will not be heard or welcomed. When we are silent, we are still afraid.
Step 2: Not deductively valid.
Step 3: Not inductively strong.
Step 4: Intended to be deductive.
18. Step 1: Conclusion: You have Ebola.
Premises: If you have a fever, headache, and unexplained bruising, then you have Ebola. You do have a fever, headache, and unexplained bruising.
Step 2: Deductively valid.
Step 3: Does not apply.
Step 4: Does not apply.

Exercise 3.3
1. Weak
4. Valid
6. Weak
7. Strong
10. Weak
12. Valid
13. Strong
16. Valid
17. Strong

Exercise 3.4
I.
2. Implicit premise: Anyone who prays every day must be devoutly religious.
4. Implicit premise: If the RCMP doesn’t have a very serious focus on stopping terrorism, then a major terrorist attack will happen in this country.
6. Implicit premise: Anyone who is a very strong student is almost certain to get an A in critical thinking.
8. Implicit premise: Any Western government that doesn’t have the resources to cover the whole world should limit its activities to the Western Hemisphere.
II.
1. There was no one else around.
4. Professor Niemi is a very good speaker who connects easily with an audience.
8. Li Fong is a student at the University of Northern Saskatchewan.
10. The typical Canadian loves hockey.

Exercise 3.5
2. Valid; disjunctive syllogism
3. Valid; modus ponens
4. Invalid; denying the antecedent
8. Invalid; denying the antecedent
12. Valid; hypothetical syllogism

Exercise 3.6
1. MP: If Bob and Doug are more than fifteen minutes late, we will need to start without them.
They are late.
Therefore, we need to start without them.
MT: If Bob and Doug are more than fifteen minutes late, we will need to start without them.
We won’t need to start without them.
Therefore, they are not late.
3. MP: If China adopts North American patterns of consumption, then the environment is doomed.
China is adopting North American patterns of consumption.
Thus, the environment is doomed.
MT: If China adopts North American patterns of consumption, then the environment is doomed.
But the environment is not doomed.
Therefore, it’s not the case that China is adopting North American patterns of consumption.
6. MP: If people love Tim Horton’s coffee, there will be long line-ups at every Tim Horton’s every morning.
People love Tim Horton’s coffee.
There will be long line-ups at every Tim Horton’s every morning.
MT: If people love Tim Horton’s coffee, there will be long line-ups at every Tim Horton’s every morning.
There aren’t long line-ups at every Tim Horton’s every morning.
People don’t love Tim Horton’s coffee.
7. MP: If you want to see a really good movie, check out that new one starring Steven Yeun.
You want to see a really good movie.
Therefore, you should check out that new movie starring Steven Yeun.
MT: If you want to see a really good movie, check out that new one starring Steven Yeun.
You aren’t going to the new movie starring Steven Yeun.
Therefore, you don’t want to see a really good movie.

Exercise 3.8
2. (1) Gamino is interested in entrepreneurship. (2) Gamino likes reading books about famous business leaders. (3) Therefore, Gamino should major in business.

A diagram of two squares labelled 1 and 2, and a circle labelled 3. Two separate arrows point from the squares to the circle.

5. (1) If it had rained last night, the streets would be wet. (2) And the streets are wet. (3) Therefore, it rained last night. (4) And that means it was impossible to do any stargazing last night.

Two squares labeled 1 and 2 are underlined and have an arrow that points to a square with a circle labeled 3. The square with a circle has an arrow that points to a circle labeled 4.

6. (1) If the experiment had succeeded, there would have been a massive explosion. (2) And there was such an explosion. (3) So we have a success. (4) If we have a success, we will win the Nobel Prize. (5) Therefore, we will win the Nobel Prize.

Two squares labeled 1 and 2 are underlined and have an arrow that points to a square with a circle labeled 3. The square with a circle is underlined with a square labeled 4. This has an arrow that points to a circle labeled 5.

Exercise 3.9
2. (1) The Dean of Arts must be incompetent. (2) Because the state of things around here suggests that he’s either incompetent or lazy. (3) He’s not lazy, though, because (4) he seems to be very good at finding ways to increase his own reputation.

A square labeled 4 has an arrow that points to a square with a circle labeled 3. The square with a circle is underlined with a square labeled 2. This has an arrow that points to a circle labeled 1.

3. (1) If an individual in a coma is still a person, then giving him a drug to kill him is murder. (2) Such an individual is in fact a person. (3) Therefore, giving him the drug is murder.

Two underlined squares labeled 1 and two are underlined with an arrow that points to a circle labeled 3.

8. (1) Grow accustomed to the belief that death is nothing to us, (2) since every good and evil lie in sensation. (3) However, death is the deprivation of sensation. (4) Therefore…death is nothing to us.

Two squares labeled 2 and 3 are underlined with an arrow pointing to a circle labeled 4.

9. (1) A cause-and-effect relationship is drawn [by those opposed to pornography] between men viewing pornography and men attacking women, especially in the form of rape. (2) But studies and experts disagree as to whether any relationship exists between pornography and violence, between images and behaviour. (3) Even the pro-censorship Meese Commission Report admitted that the data connecting pornography to violence was unreliable. Implied: (4) Therefore, the alleged cause-and-effect relationship should be doubted.

A diagram of two squares labelled 2 and 3, and a circle labelled 4. Two separate arrows point from the squares to the circle.

12. (1) Richard is a Registered Nurse, and (2) most Registered Nurses are very knowledgeable. Therefore, (3) Richard is probably very knowledgeable. (4) Richard probably studied very hard at school, because (5) most people who are very knowledgeable have studied very hard.

Two squares labeled 1 and 2 are underlined and have an arrow that points to a square with a circle labeled 3. The square with a circle labeled 3 is underlined with a square labeled 5. This has an arrow that points to a circle labeled 4.

15. (1) It’s very easy to tell whether bread is freshly baked or not. (2) The aroma is unmistakable, and (3) the inside will be soft and moist. (4) Baker’s Bakery says that their bread is freshly baked in their store everyday, (5) but they must be lying. (6) There is no aroma, and (7) the bread is hard and dry. (8) I also saw a delivery guy from the local grocery store carrying bread into the bakery.

A diagram of three arrows points to a circle labelled 5. The first arrow comes from two squares labelled 2 and 6, The two squares are underlined. The second arrow comes from two squares labelled 3 and 7. The two squares are underlined. The third arrow comes from a square labelled 8.

(Note: a more complicated diagram using more of the elements requires filling in some missing pieces.)
16. (1) It is clear that archaeologists have not yet come to terms with dowsing [the alleged ability to detect underground water or treasure by paranormal means]. (2) Where it has been the subject of tests, the tests have been so poorly designed and executed that no conclusion whatsoever could have been drawn from them. (3) The fact that such tests are usually carried out only by researchers with a prior positive view of dowsing means that the conclusions will likely also be positive. (4) The normal processes of peer review and scholarly discussion have also failed to uncover the lack of properly controlled test conditions in such studies as those of Bailey et al. and Locock, causing a generation of students and general readers, in the United Kingdom, at least, to remain under the impression that the reality of archaeological dowsing had been all but confirmed by science.

Three squares labeled 2, 3, and 4 have an arrow each that points to a circle labeled 1.

19. (1) Glimglom is either a Jabberwoky or a Bugaboo or a Sceadugenga. (2) But he’s not a Jabberwoky, because (3) he doesn’t have jaws that bite. (4) And he’s not a Bugaboo, (5) because he’s not covered in goo. (6) So he must be a Sceadugenga!

A diagram starts with a square labelled 3. An arrow from 3 points to a square with a circle labelled 2. A square labelled 5 has an arrow pointing to a square with a circle labelled 4. A square labeled 1 is underlined along with squares with circles labeled 2 and 4. The underlined have an arrow that points to a circle labeled 6. This further has an arrow that points to a circle labelled 6. Three squares are underlined and are labelled 7, 8, and 9. An arrow points from the three squares to 6.

22. (1) We should not reform Canada’s Senate because (2) our current system of appointing senators works just fine, and (3) all senators do lots of good work by holding committee hearings that shed light on important issues.

Two squares labeled 2 and 3 each have an arrow that points to a circle labeled 1.

Exercise 3.10
3. Conclusion: (1) Corporations must continue to be treated as persons by courts in Canada, as they are in all other developed nations.
Premises: (2) “Personhood” in the legal sense merely means being treated by the courts as having rights and responsibilities. (3) And without both legal rights and legal responsibilities, corporations would be very troubling figures within our communities. (4) After all, if corporations did not have responsibilities, they would not have to honour warranties or fix defects in the products they make. (5) That would clearly be bad for consumers. (6) And if corporations had no legal rights, their property would never be secure. (7) And if there property were never secure, it would be foolish to invest in them. (8) And if no one invested in them, they would cease to exist. (9) And if corporations ceased to exist, the would no longer produce goods and services and they would no longer provide jobs.

There are three groups of squares that are underlined. The first group has two squares labeled 2 and 3. The second group has two squares labeled 4 and 5. The third group has four squares labeled 6, 7, 8, and 9. Each group of underlined squares has an arrow that points to a circle labeled 1.

5. Conclusion: (1) [The] position is certainly untenable.
Premises: (2) The first thing that must occur to anyone studying moral subjectivism [the view that the rightness or wrongness of an action depends on the beliefs of an individual or group] seriously is that the view allows the possibility that an action can be both right and not right, or wrong and not wrong, etc. (3) This possibility exists because, as we have seen, the subjectivist claims that the moral character of an action is determined by individual subjective states; and these states can vary from person to person, even when directed toward the same action on the same occasion. (4) Hence one and the same action can evidently be determined to have—simultaneously—radically different moral characters.