PHL 130
Fall 2015
Problem Set #3- Answer Key
Total: 56 points for completion + 44 points graded
Chp.15, Exercise II (5 pts for completion)
(1) Dismisser. Given that companies in general and tobacco companies in particular could easily
be unreliable when they are profit-driven, we could say that this argument provides an
adequate justification for its conclusion.
(2) Dismisser. This argument could be seen as providing a justification, not a very adequate one
though. It uses a lot of guarding terms, which weakens the argument and therefore the
justification for the conclusion.
(3) Denier. The argument does not provide an adequate justification. We cannot conclude that we
must not need a draft just based on the fact that members of the congress are not eligible for
it. A decision for a draft is usually more complicated than this situation.
Chp.15, Exercise III (5 pts for completion)
The following answers are my formulations. Your answers do not have to be identical to them as
long as you provide reasons for your explanation.
(9) Vanna must be the most beautiful woman in America, because she won the Miss America
contest.
- Is the cited authority in fact an authority in the appropriate area?
It depends. We could argue that Miss America has some authority with respect to
the issues related to beauty. However, we could also argue that beauty is a
phenomenon where references to authority might not really make sense since it is
conceptualized socially, culturally, and politically.
- Is this the kind of question that can now be settled by expert consensus?
Not really. When it comes to beauty, which standards experts use and how these
standards came to be standards at all are really interesting questions that challenge
the idea that we can have experts on beauty.
- Has the authority been cited correctly?
Probably yes, but in order to answer this question properly we have to know the
context of the utterance.
1 - Can the cited authority be trusted to tell the truth?
Yes, the cited authority could be trusted to tell the truth but whether we trust the
truth they tell is a different question.
- Why is an appeal to authority being made at all?
Probably because there are not a lot of authorities who we can refer to with
respect to issues related to beauty.
(10) There were 250,000 protesters at the rally, because its organizers gave that figure.
- Is the cited authority in fact an authority in the appropriate area?
Yes. However, we could also think of journalists who were following the rally as
other possible authorities in a situation like this one.
- Is this the kind of question that can now be settled by expert consensus?
Yes, it is.
- Has the authority been cited correctly?
It depends on the context where the utterance is made.
- Can the cited authority be trusted to tell the truth?
It is complicated, right? The organizer might want to tell the truth for credibility
reasons. However, at the same time, in order to make the rally look like more
effective than it was, they could round the figure up to an extent.
- Why is an appeal to authority being made at all?
Because there are only some people who can give a true estimate of how many
people might have attended to the rally.
Chp.15, Exercise IV (5 pts for completion + 6pts graded)
(6) Tradition + Popular Opinion
I would say that in order to determine whether this argument is fallacious or not, we have
to know what the author or speaker means by “something” in this case.
(7) Popular Opinion
If the jurors are not biased in an important way, we could say that the argument is not
fallacious.
2 (8) Tradition + Popular Opinion
To determine whether this argument is fallacious or not, we first need to know how many
people these polls have included and whether this overwhelming majority actually
corresponds to a real overwhelming majority. Even if that is the case, we could still take
issue with the statement that “most of the people cannot be wrong all the time” given the
history of human civilizations.
Chp.16, Exercise I (6 pts for completion)
(1) “A student of mine told me that I am her favorite professor, and I know that she is telling the
truth, because no student would lie to her favorite professor.”
P1: No student would lie to her favorite professor.
P2: A student of mine told me that I’m her favorite professor.
P3* (Implicit premise): She is not lying (or she is telling the truth) that I’m her favorite
professor.
C: She is telling the truth that I’m her favorite professor.
As written, not circular. If we consider the implicit premise, it is circular. It begs the question
in almost every context – any objection to my conclusion is an objection to my premises.
(2) “Intoxicating beverages should be banned, because they can make people drunk.”
P1: Intoxicating beverages can make people drunk.
P2* (Implicit premise): Things that make people drunk should be banned.
C: Intoxicating beverages should be banned.
As written, it is not circular. If we consider the implicit premise and if we take “things that
make people drunk” to mean “intoxicating beverages,” then it is circular. It begs the
question.
(3) “Capitalism is the only correct economic system, because without it free enterprise would be
impossible.”
3 P1: Without capitalism, free enterprise would be impossible.
P2* (Implicit premise): An economic systems can only be the correct one if it enables
free-enterprise.
C: Capitalism is the only correct economic system.
Not circular. It begs the question if you take capitalism to be free enterprise, which many do;
otherwise, it would not beg the question.
(4) “Free trade is good for the country, because it brings the country all of the advantages of an
unimpeded flow of goods.”
P1: Free trade bring the country all of the advantages of an unimpeded flow of goods.
P2* (Implicit premise): Anything which brings all of the advantages of an unimpeded
flow of goods is good for the country.
C: Free trade is good for the country.
If we interpret “anything which brings all of the advantages of an unimpeded flow of goods”
in P2 as free trade, then P2 and C mean the same thing, in which case the argument is
circular. It also begs the question.
Chp.17, Exercise I (5 pts for completion)
(7) Counterexample: You don’t even leave the house at all so nothing will happen to you: one
could say that you are being too careful.
(8) Counterexample: In a situation where you can save someone’s life without hurting anybody
else, a lie will not be necessarily wrong. Some ethicists could still argue against this though.
(9) Counterexample: If we take this sentence literally, we can always ask a doctor to treat us
whereas we are usually not willing to treat ourselves or others.
Chp.17, Exercise II (5 pts for completion)
(1) “There is life on the moon.” There are no counterexamples to this because “there is life on
the moon” is not a universal claim that you can refute with a single contrary instance.
(2) “Killing is usually wrong.” This statement is too general and guarded to refute with a
counterexample. Any counterexample where you claim “killing is right,” the statement will still
be true because of the word ‘usually’.
4 Ch. 17, Exercise IV (5 pts for completion + 6 pts graded)
(7) “Some morally wrong actions are morally permitted.”
P1: Let me assume that some morally wrong actions are morally permitted.
P2: We know that morally permitted actions are by definition not morally wrong.
3: By P1 and P2, there exist actions that are both morally wrong and not morally wrong,
which is a contradiction.
C: Therefore, the assumption that some morally wrong actions are morally permitted is
false.
(8) “God exists outside of time, and we will meet Him someday.”
P1: Let me assume that God exists outside of time, and we will meet Him someday.
P2: Meeting Him someday will mean that he exist within time too since some day is
within time.
P3: This assumption that God exists outside of time, and we will meet Him someday
leads to a contradiction where God exists both outside and within time.
C: Therefore, the assumption is wrong.
(9) “There is a male barber in this town who shaves all and only the men in this town who do not
shave themselves.”
If he shaves himself, then he does not shave only the men in this town who do not shave
themselves, since he is shaving himself.
If he doesn’t shave himself, then that means there is another man who shaves him, which
would mean that our barber does not shave all the men in this town who do not shave
themselves.
Both possibilities leads to an impossible situation, therefore this barber cannot exist.
Ch. 17, Exercise VI (5 pts for completion)
(8) We can argue that the parallel reasoning doesn’t work very well since the likelihood to use
guns is not the same as the likelihood to have sex for teenagers. In other words, the premise
is false – many students do not use guns, many more than the number of students who do not
have sex.
(9) This parallel reasoning is also problematic since the relationship between research on human
cloning and the debate about human cloning is not the same as starting a fire and the debate
about a new fire engine. In other words, one might reject the claim that they have the same
5 form: the cloning argument involves a debate about cloning, whereas the parallel argument
involves a debate about a fire engine and not the fire. So one could resist the refutation by
denying that it is really parallel.
(10) We could say that this argument succeeds in refuting given that it challenges how we cannot
judge an action based on what it precipitates.
Ch. 6, Exercise III (5 pts for completion + 6 pts graded)
(1) p, p&q, p&q&r
(2) p, p&q, p&q&q
Ch. 6, Exercise V (5 pts for completion + 12 pts graded)
(1) Yes:
p&q
q
– q must be true if (p & q) is true.
(2) No:
p
p&q
– p can be true while (p & q) is false.
(3) Yes:
p
p&p
– if p is true, (p & p) will also be true.
(4) Yes:
p&q
r&s
p&s
– if the premises are true, the conclusion must be true.
(5) Yes:
p&q
q&p
6 – propositional order around the conjunction makes no difference to truth.
(6) Yes:
p&q
p
– if you don’t take ‘tied’ to mean tied to each other, then it is valid
– or –
No:
p
q
– If you interpret ‘tied’ to mean tied to each other, then the argument is not valid.
Ch.6, Exercise IX (5 pts for completion + 14 pts graded)
(1) ~R, where R: it will rain tomorrow
(2) R, where R: it might not rain tomorrow – ‘not’ here is not propositional negation
(3) ~R, where R: there is a chance that it will rain tomorrow.
(4) R, where R: I believe that it won’t rain tomorrow – ‘not’ here is not propositional negation
(5) S v C, where S: Joe is not too smart, and C: Joe is very clever
– or
~S v C (unlikely), where S: Joe is too smart.
(6) ~(S v R) or (~S v R), where S: Kristin is smart, and R: Kristin is rich.
(7) P & Q, where P: sometimes you feel like a nut, and Q: sometimes you don’t feel like a nut.
The preferred interpretation is tied to what the authors note about the candy bars: assuming
you want a candy bar, there are times when you want one with nuts (P) and there are times
when you want one without nuts (Q). Of course, there are times when you want neither
because you don’t want a candy bar. So this should be read: there are times when you want a
candy bar with nuts and there are times when you want a candy bar without nuts, or P & Q.
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