Phil 60 - Anderson
Fall 2012
Due Tuesday, Sept. 11
First Homework
1. In each of the following cases, state whether the given set of statements are
logically consistent or inconsistent.
(a) Joan is taller than Joe.
Joe is taller than Joan.
(b) Joan is at least as tall as Joe.
Joe is at least as tall as Joan.
(c) The ring contains five huge diamonds.
The ring’s price is ten cents.
(d) A recent poll shows that 90% of the citizenry support free speech for all, no
matter what the speaker’s views. But only 41% would allow college students
to invite any guest speaker to campus that they chose. And only 29% would
permit the American Nazi party or the KKK to state their views on TV.
Note: The question here is not whether the polling data is inconsistent. The
question is whether the data indicate that some of the people polled hold
inconsistent opinions.
(e) Either Yvonne or Zoe gave me this book last Tuesday. If Yvonne gave me
the book, then I was in Reno at noon last Tuesday. However, I was miles away
from Reno on that Tuesday and Zoe has never given me anything.
2. In each of the following, does q deductively follow from p? Does p
deductively follow from q? (Note: Each problem calls for two answers.)
(a) p: Pat is rich.
q: Pat is materialistic.
(b) p: Pat is 16.
q: Pat is a teenager.
(c) p: Some old neighborhoods have many new buildings.
q: Some neighborhoods with many new buildings are old neighborhoods.
(d) p: All mammals are warm-blooded.
q: All warm-blooded creatures are mammals.
3. Imagine an argument you know to have true premises and a true conclusion.
Given no other information you should regard the argument as being:
(a) valid
(b) invalid
(c) you cannot tell which
4. Imagine an argument you know to be deductively valid, but also to have a
false premise. As far as this argument is concerned, you should regard the
conclusion as being:
(a) true
(b) false
(c) probably false
(d) could be true or false
5. Imagine an argument you know to have all true premises but a false
conclusion. Given no other information, you should regard the argument as
being:
(a) valid
(b) invalid
(c) you cannot tell which
6. Suppose there were a statement that everyone in the world believed to be
true. If so:
(a) It would probably be true.
(b) It would probably be false.
(c) It could be true or it could be false.
7. What is the point of constructing a good argument for a proposition one
already believes to be true?
(a) There is no point; it is a waste of time.
(b) To assure oneself that one's belief is true rather than false.
(c) It can be therapeutic to do so.
(d) None of the above.
8. Is the following argument deductive or inductive?:
The great majority of 35 year old American males will survive for at least 5 more
years.
Joe Tuna is a 35 year old American male.
Therefore, Joe Tuna will probably survive for 5 more years.
9. Charlie, don’t worry about it. You’ll get a promotion someday. You’re working
for a good company. Right? And everyone who works for a good company gets
a promotion sooner or later. Assuming all the supporting statements are true,
the conclusion
(a) must necessarily be true.
(b) is probably true but might be false.
(c) is probably false but might be true.
(d) could not be true.
10. Assume it is true that not all the candidates are qualified to serve. It follows
deductively that
(a) None of the candidates is qualified to serve.
(b) At least one of the candidates is not qualified to serve.
(c) Someone qualified to serve is not a candidate.
(e) None of the above.
11. Assume it is true that only those seeking challenge and adventure should join
the Army. It deductively follows that
(a) If you seek challenge and adventure, you should join the Army.
(b) You shouldn’t seek challenge and adventure except by joining the Army.
(c) You shouldn’t join the Army unless you seek challenge and adventure.
(d) None of the above.
12. The microorganisms in this pond are of the kind that reproduce only in
water at a temperature above the freezing point. Now it’s winter and this pond
is solid ice. So, if there are any microorganisms of the kind we are researching
in the pond, they aren’t reproducing right now. Assuming all the supporting
statements are true, the conclusion
(a) must be true.
(b) is probably true, but might be false.
(c) is probably false, but might be true.
(d) could not be true.
13. One way of defining a deductively valid argument is to say it is not logically
possible for all the premises to be true and yet the conclusion to be false. That
amounts to saying: the assertion that all the premises are true but the
conclusion false forms an inconsistent set of statements.
T or F
14. Anything that is logically impossible is also physically impossible, but some
things that are physically impossible can still be logically possible. T or F