Chapter 4 Answer Key to Select Chapter Exercises

Exercise 4.1
1. The large collection of very well-supported beliefs that we all rely on to inform our actions and choices.
3. No, not always. But we should doubt any claim that conflicts with our background information, and we should assign a low probability to any claim that conflicts with a great deal of our background information.
5. Any two of: education and training; experience; reputation; and accomplishments.
7. When the experts disagree about a claim, we have good reason to doubt it.
11. We often suspect bias when an expert is being paid by special-interest groups or companies to render an opinion, when the expert expresses very strong belief in a claim even though there is no evidence to support it, or when the expert stands to gain financially from the actions or policies that he or she supports.
13. Any two: Impairment, expectation, or innumeracy
15. Possible answer: People may deny the evidence, ignore it, or reinterpret it.
16. The tendency to seek out or use only confirming evidence.
19. If we’re in the habit of basing our judgments on evidence that’s merely psychologically available, we will frequently commit the error known as hasty generalization—drawing a conclusion about a whole group based on an inadequate sample of the group.
22. Advertisers may: try to get you to identify with attractive individuals or groups; use catchy slogans; make misleading comparisons; use weasel words to make a claim that is technically true but superficially misleading.

Exercise 4.2
2. Reject; the claim conflicts with background information about the origins of the virus.
5. Proportion belief to the evidence; it is well-known that many Canadians carry high levels of credit card debt, though there is debate over whether it is dangerously high. Additional statistical information should be sought.
7. Proportion belief to the evidence; the claim is probably true at least in part, though the scope of the sharing may be exaggerated. It is widely known that many governments have sought out and used additional legal powers to allow them to gather information.
8. Reject; McPhail would likely have to have been at least in her 30s when elected, which means she would have had to be born around 1890 (which indeed she was). So to have died last year, she would have had to be over 130 years old, which would beat the world record for longevity by quite a lot.
12. Accept; in general, such reports from Health Canada are very reliable.
16. Reject; the claim is very likely to be false (Canada has a mediocre history at the Olympic games overall, and has generally done better in the winter, not summer, Olympics).
18. Proportion belief to the evidence; depending on how “viable” is defined, the claim seems more likely to be false than true (because some modern democracies do, in fact, seem viable).
19. Accept; likely to be true (both products serve the same purpose, and so are substitutable to some extent, and people generally respond to price changes).