PHI1101 G final exam A Fall 2021 PDF

Preview

Summary

Name Student NumberPHI1101G: Reasoning and Critical Thinking (Fall 2021): Final Exam AI. True/false questions (4/40):(a) An invalid argument with all true premises and a false conclusion is unsound.—True (b) An argument which is neither valid nor invalid is sound. ——False(c) Any argument with all tr...

Description

Name

Student Number

PHI1101G: Reasoning and Critical Thinking (Fall 2021): Final Exam A

I. True/false questions (4/40): (a) An invalid argument with all true premises and a false conclusion is unsound.—True (b) An argument which is neither valid nor invalid is sound. ——False (c) Any argument with all true premises and a true conclusion is valid. —— True (d) No sound arguments are invalid.—— False II. Put the following arguments into standard form, and then diagram them. (4/40) (a) Once you have killed someone, there’s no way to bring him back to life. So, if the state mistakenly executes someone, there’s no way to fix the mistake. Yet the justice system is known to make mistakes even in trials for murder and other serious crimes, as is proved by the cases of Donald Marshall and Guy Paul Morin. Thus, if we reinstate the death penalty, it is entirely possible that we will commit irreversible injustice by killing innocent people. For this reason, if for no other, we should not do so.

1. Once you have killed someone, there’s no way to bring him back to life. 2. So, if the state mistakenly executes someone, there’s no way to fix the mistake. 3. Yet the justice system is known to make mistakes even in trials for murder and other serious crimes, as is proved by the cases of Donald Marshall and Guy Paul Morin. 4.Thus, if we reinstate the death penalty, it is entirely possible that we will commit irreversible injustice by killing innocent people. 5. For this reason, if for no other, we should not do so.

1

(b) If the detective really is a racist—which he is—then he never should have been allowed to testify at all, since white racists are especially unreliable witness when the accused is a person of color. So, the detective should not have been allowed to testify at all.

1. If the detective really is a racist—which he is—then he never should have been allowed to testify at all. 2. Since white racists are especially unreliable witness when the accused is a person of color. 3. So, the detective should not have been allowed to testify at all.

III. (A) Symbolize the following arguments using the letters provided, and (b) show that each argument is valid by constructing proofs of their conclusions from their premises using the rules of inference we have studied in this course. (9/40) (a) If Smith once beat the fireman at billiards, then Smith is not the fireman. Smith once beat the fireman at billiards. If the brakeman is Jones, then Jones is not the fireman. The brakeman is Jones. If Smith is not the fireman and Jones is not the fireman, then Robinson is the fireman. If the brakeman is Jones and Robinson is the fireman, then Smith is the engineer. Therefore, Smith is the engineer. (O— Smith once beat the fireman at billiards; M— Smith is the fireman; B— the brakeman is Jones; N— Jones is the fireman; F— Robinson is the fireman; G— Smith is the engineer.)

2

1. O ⊃ ~M 2. O 3. B ⊃ ~N 4. B 5. (~M & ~N) ⊃ F 6. (B & F) ⊃ G // G 7. ~M MP, 1,2 8. ~N MP, 3,4 9. ~M & ~N Conj, 7,8 10. F MP, 5,9 11. B & F Conj, 4,10 12. G MP, 6,11

(b) If Anderson was nominated, then she went to Boston. If she went to Boston, then she campaigned there. If she campaigned there, she met Douglas. Anderson did not meet Douglas. Either Anderson was nominated or someone more eligible was selected. Therefore, someone more eligible was selected. (A— Anderson was nominated; B— Anderson went to Boston; C— Anderson campaigned in Boston; D— Anderson met Douglas; E— Someone more eligible was selected.)

1. A ⊃ B 2. B ⊃ C 3. C ⊃ D 4. ~D 5. A v E //E 6. A ⊃ C HS, 1,2 7. A ⊃ D HS, 3,6 8. ~A MT, 4,7 9. E DS, 5,8

3

(c) If Santacruz is injured, then she will not play. And if Santacruz does not play, then Khumalo must play. What’s is more, if Khumalo and Nakata both play, then Jones must be moved to the center. In fact, Santacruz is injured and Nakata will play. Thus, Khumalo will play Jones will be moved into the center. (I— Santacruz is injured; S— Santacruz will play; K — Khumalo must play; N— Nakata plays; J— Jones must be moved to the center.)

1. I ⊃ ~S 2. ~S ⊃ K 3. (K & N) ⊃J 4. I & N // K & J 5. I Simp, 4 6. I ⊃ K HS, 1,2 7. K MP, 5,6 8. N Simp, 4 9. K & N Conj, 7,8 10. J MP, 3,9 11. K & J Conj, 7,10

4

IV. Draw a Venn diagram for each of the following categorical syllogisms, and then circle whether it is valid or invalid. (4/40) (a) Some students work full time. Everyone who works full time is busy. So, some students are busy.

Valid

Invalid

(b) All fascists are extremists. Some radicals are not extremists. So, not all radicals are fascists.

5

Valid

Invalid

V. Identify exactly why each of the following arguments is unconvincing overall (explain whether the premise(s) are acceptable, relevant, and sufficient) (5/40). a) Withholding information is just the same as lying and lying is wrong, so withholding information is wrong.

Yes, the above given argument is very true and convincing, therefore the premise is relevant.

Because this is true that we must never withhold any information if we are withholding information because of any reason then we are lying.

b) If you believe in God, you will be happier. That shows that God really does exist.

6

No, the argument is not convincing. Because God will help people become happier but it doesn’t necessarily exist. People may also be happy for other reasons.

c) Paul is the best person to be put in charge of the arrangements for our club’s trip to the International Debate Meet next year. After all, he does hold the number-one position on our team.

Yes. The argument is convincing and the premise is relevant. Because Paul occupies the first position, he can be responsible for representing the club.

d) Most intellectuals cannot explain the mathematical supposition called “Goldbach’s Conjecture.” My calculus professor is an intellectual, so he wouldn’t know about the Goldbach thing.

No, the argument is not convincing. My calculus professor may also be another part of the intellectual who can explain the conjecture.

e) The days when natural disasters such as earthquakes, hurricanes, or volcanoes had the power to bring death to thousands are fortunately behind us. Unlike the times of such catastrophes as the 1906 San Francisco earthquake or the hurricane of 1900 in Galveston, these days modern construction methods for building, sophisticated advanced warning systems, mass communication and modern health-care developments mean that we are able to keep the toll from even the worst natural events to tens or at most one or two hundred.

Yes. The argument is convincing and the premise is relevant. Because the development of modern technology has reduced the impact of natural disasters on people.

VI. Discuss the strengths and weaknesses of the following arguments, which involve inductive and/or causal reasoning. (4/40)

7

(a) Fewer than 2 percent of people who work in New York live in Connecticut, so you should infer that Allen, who works in a Times Square bookstore, does not live in Connecticut.

Strong The premise is that less than 2% of people working in New York live in Connecticut. Moreover, 2% is very low, so Allen, who works in New York, is likely not to live in Connecticut.

(b) Your mother always told you to bundle up when the weather is cold, and it turns out she was right—statistics prove that colds occur much more frequently when the temperature is lower, so it is obviously exposure to cold temperatures that causes us to catch colds. Weak The reasoning that the weather is not the direct cause of the cold. But it will spread more at low temperatures. Therefore, bundling will not save you from catching a cold.

VII. (A) Name the fallacy involved in each passage, and (b) explain it. (10/40) (a) After-death experiences are a reality. Despite years of attempts at debunking, no one has ever been able to show that reports from beyond the grave are all due to error, deception, or simply wishful thinking. Appeal to Ignorance. It mainly means that it has not been proven to be wrong, or there is no evidence against it, so it is considered true. But in fact, it cannot prove anything.

8

(b) Nobody wants to say so in public, but we all know that immigrants do not have as strong a commitment to this country as those of us who were born here. Ad Hominem. draws conclusions based on the race or background of others.

(c) Dr. Chance Tang told our class that a human embryo is a person just like me or you and entitled to the same treatment. Dr. Tang is an obstetrician, so I’m prepared to believe what he says, and reject the destruction of embryos as equivalent to murder. Appeal to Authority. Abuse the opinion of authority to support the argument.

(d) When can I make up the exam I missed? Sunk Cost. I have already prepared for the exam, so I have a certain cost. But I missed it.

(e) The Universe is spherical in form, because all the constituent parts of the universe, that is the sun, moon, and the planets appear in this form.

Causal Fallacy. Wrongly concluded that the cause is related to the result. For example, in this example, the sun, moon and planets are round, and it cannot be considered that the universe is also.

(f) Adultery can never be justified, for it is never acceptable for a married person to have sex with anyone but his or her spouse.

Causal Fallacy. "it is never acceptable for a married person to have sex with anyone but his or her spouse" was mistaken for the cause. In fact it is wrong.

9

(g) Why do so many people keep wanting to become friends with me? Is it because I am more intelligent that others around here? Or do I have something natural leadership qualities?

Hasty Generalization. It is based on a few examples, for example, I am smarter than others or natural leadership. But it has no actual evidence to support it.

(h) According to a recent poll 80% of United States citizens think that taxes are too high. Doesn’t that prove the point?

Bandwagon Fallacy. Because others agree with it. In other words, the fallacy is that if everyone thinks in a certain way, then you should think so too. However, most people think that taxes are too high, which does not mean that this argument is reasonable.

(i) The economist’s model for determining the price of Gold is absolutely brilliant. No wonder he won the Noble Prize. It’s true that the predictions produced by the model turned out to be off by a wide margin in almost all cases. But this is a minor point.

Circular Argument. This fallacy seems to be just an argument, but in fact it is just restating one's assumptions. That is, the goodness of the model led him to win the Nobel Prize. The award also verified the wonderfulness of his model.

(j) Every society that has collapsed throughout history has done so because of rottenness within. The collapse has always been preceded and thus triggered by the slackening of shame typified by widespread public nudity.

Post-Hoc. It mainly generates hypotheses based on facts that have already happened. 10

11...