Chapter 11 Answer Key to Select Chapter Exercises

Exercise 11.1
2. Causal reasoning is treated as part of inductive logic.
3. No. The argument could still be logically weak. An argument with a true conclusion for example might have premises that are entirely irrelevant and that therefore provide no logical support for that conclusion.
6. When you see novel health claims being published in the news, you should ask yourself:
- Does the story report a range of views?
- Are the opinions cited actual expert opinions?
- Does the reporter look at the overall body of evidence?
- Is the reporter experienced at reporting on health?
- Is the media outlet a credible one?
7. When engaging in criminal trials, the totality of evidence at hand constitutes the phenomenon to be explained.
10. Subjectivism about ethics is tempting because it is good to adopt a respectful attitude toward other people and to take their views on ethical matters seriously.
12. A descriptive claim is about how the world is; an ethical claim is about how it should be.

Exercise 11.2
2. Reject it. Cycling is widely regarded as a good form of exercise, and is in fact recommended as being less hard on one’s knees than many other forms of exercise, such as running.
4. Accept it, but not on the basis of Dr Fabro’s non-expert opinion. The claim is supported by a huge amount of data and scientific opinion.
6. Proportion belief to evidence. Eyewitnesses are notoriously unreliable; plane ticket evidence probably should make us doubt this claim.
8. Proportion belief to evidence. This might be true, but the defendant’s own father’s word is a very weak reason to believe the claim, since a parent is likely to proclaim his or her child’s innocence, regardless.
12. Proportion belief to evidence. Ethics professors may not be moral authorities, but they do tend to know which arguments have been raised, and which have survived scrutiny. This statement is worthy of fairly strong acceptance.

Exercise 11.3
3. Appeal to emotion
6. Post hoc
9. Denying the antecedent

Exercise 11.4
3. S = Falsehoods
P = Things that do great harm
M = Lies

A Venn diagram of 3 circles labeled M, S, and P that intersect. The line between S and the section of overlap between M and P is denoted with an X. the line between P and the section of overlap between M and S is denoted with an X.

Invalid.
6. S = People who are you
P = People who must avoid lying
M = Moral persons

A Venn diagram of 3 circles labeled M, S, and P that intersect. Sections M; overlap between M and S; S; and the overlap between S and P are shaded.

Valid.
The first premise is ambiguous. “Moral person” might mean “morally good person,” in which case we don’t have enough information. This might also mean “moral agent,” in which case it is acceptable (since anyone who is capable of being addressed in syllogistic terms is likely to be a moral agent). The second premise is mostly acceptable, though, of course, most people believe that there are exceptions to that rule.