IM – 9 | 18
The key to making this one easy is seeing that the first premise should be translated as “All
broadcast networks are media outlets that have had a decline in television audience during
the last six years.”
7. ▲Using I = people who lift papers from the Internet
C = people who are cheating themselves
8. All G are R.
9. All C are P.
All R are P.
10. ▲D = people who dance the whole night
W = people who waste time
Exercise 9-20
Whether the answers below fit the questions will depend on the shape of the argument after the
appropriate obversions and other operations are carried out. If you modify different claims, an
invalid syllogism may break a different rule. Still, if a syllogism breaks a rule in one version, it
will break some rule in any other version. We have presumed the versions of the syllogisms
found above.
IM – 9 | 20
Some formatted drives are not drives that contain data.
Valid; breaks no rule
4. All tobacco products are substances that damage people’s health.
Some tobacco products are addictive substances.
Some addictive substances are substances that damage people’s health.
Valid; breaks no rule
8. ▲No off-road vehicles are vehicles allowed in the unimproved portion of the park.
Some off-road vehicles are not four-wheel-drive vehicles.
Some four-wheel-drive vehicles are allowed in the unimproved portion of the park.
Invalid: breaks rule 1
IM – 9 | 23
16. P = parties the police have to break up; C = campus parties; O = parties that get out of
control
17. F = fundamentalist Christians; E = evangelicals; R = revivalists
18. ▲P = plastic furniture; C = cheap-looking furniture; L = their new lawn furniture
Valid
19. I = intramural sports; O = Olympic sports; C = intercollegiate sports
20. M = moas; D = Dinornithidae; E = creatures that still exist
All M are D.
21. ▲D = people on the district tax roll; C = citizens; E = eligible voters
All D are C.
IM – 9 | 24
23. D = countries that have been living under a dictatorship; F = countries familiar with social
requirements of democracy; T = countries that will make a successful quick transition to
24. ▲C = people identical to Cobweb; L = liberals; T = officials who like to raise taxes
All C are L.
25. I = investor-held securities; R = companies that should be allowed to raise rates; P = public
utilities
26. Note: these terms are easily confused, since it’s natural to represent two of them with the
letter “C.”
27. I = things that are important to learn; U = things that are not useful; C = chemistry (things
identical with chemistry)
28. Getting students to represent this one correctly can be instructive, but it can also be a lot
like pulling teeth.
W = stockholders’ information about a company’s worth; M = information that must come
from the managers of a company; B = information that must come from the very people
who are trying to buy the stock from stockholders.
All W are M.
IM – 9 | 27
2. a
Exercise 9-25
There is a syllogism present: All homeless people wear worn-out hippie gear; the people the
witnesses saw wore worn-out hippie gear; therefore, the people the witnesses saw are homeless
people.
Exercise 9-26
First syllogism:
All instances of pornography are things that demean women’s worth and promote violence.
[Unstated: All things that demean women’s worth and promote violence are things that violate
women’s rights.]
Exercise 9-27
1. ▲L = ladybugs; A = aphid-eaters; G = good things to have in your garden
All L are A.
