Answer sheet 1

逻辑选题

Answer sheet 1

1 
A modus ponens: if A, then B. A. So, B.
If the spring comes (A), then birds will sing around (B). The spring is coming (A). So, birds will be singing around (B). 
“The spring comes” is the antecedent and “birds will sing around” is the consequent. The second statement “the spring is coming” is affirming the antecedent. The conclusion of final statement “birds will be singing around” is affirming the consequent.
B modus tollens: if A, then B. Not B. So, Not A.
If it rains (A), then I will fetch you back home (B). I didn’t fetch you (Not B). So, it didn’t rain (Not A).
“It rains” is the antecedent and “I will fetch you back home” is the consequent. The second statement “I didn’t fetch you (Not B)” is denying the consequent. The conclusion of final statement “it didn’t rain” is denying the antecedent.
2 
A disjunctive syllogism: A or B. Not A. so B.
Either Amy (A) or Ellen (B) will visit the cabin embraced by a valley. Amy didn’t visit the cabin (Not A). So, Ellen visited the cabin (B)
B Hypothetical syllogism: if P, then Q. if Q, then R. So, if P, then R.
If the burglars break into the doors (P), then alarms will scream (Q). If alarms scream (Q), then everyone will wake up (R). So, if the burglars break into the doors (P), then everyone will wake up (R). 
3
Central assumption
The central assumption in Virkram’s argument is that a husband would be a person who loves the girl as himself, not who wants to create her like a father or worships her like a son.
4
Modus pollens:
1. If the man painfully found the magic spell and brought her back to life (P), then he did only what a father not a husband ought to do (Q).
2. The man painfully found the magic spell and brought her back to life (P).
So, he did only what a father not a husband ought to do (Q).
5
Clue #1: “Your right hand is quite a size larger than your left. You have worked with it, and the muscles are more developed."
Deduction#1: Mr. Jabez Wilson has at some time done manual labour
Analysis: I suppose it’s not totally true. If Mr. Jabez Wilson does some excise in gym improperly maybe his right hand can also be quite a size larger than left one. 

Clue#2: "What else can be indicated by that right cuff so very shiny for five inches, and the left one with the smooth patch near the elbow where you rest it upon the desk?"
Deduction#2: Mr. Jabez Wilson has done a considerable amount of writing lately
Analysis: this clue can also produce some other deductions like painting or reading for a long time, right?
6
From: “The Red-headed League”
Clue #1: “Your right hand is quite a size larger than your left. You have worked with it, and the muscles are more developed."
Deduction#1: Mr. Jabez Wilson has at some time done manual labor
Modus pollens:
1 if your right hand is quite a size larger than your left(X), then you have at some time done manual labor(Y).
2 your right hand is quite a size larger than your left(X)
So, you have at some time done manual labor(Y).

Clue#2: "What else can be indicated by that right cuff so very shiny for five inches, and the left one with the smooth patch near the elbow where you rest it upon the desk?"
Deduction#2: Mr. Jabez Wilson has done a considerable amount of writing lately
Hypothetical syllogism:
1 if your cuff has the smooth patch(X), then you rest it upon the desk(Y). If you rest it upon the desk(Y), then you has done a considerable amount of writing lately (Z). So, if your cuff has the smooth patch(X), then you has done a considerable amount of writing lately (Z).
2 Your cuff has the smooth patch(X)
So, you has done a considerable amount of writing lately (Z).
7
Mark Twain: 
1. Don't go around saying the world owes you a living. The world owes you nothing. It was here first.
This quote is very funny because the author uses another layer meaning of “owe”. People complains about the world as if it owes them something but Mark Twain says the world didn’t borrow anything from you because it exists first.
2. Go to Heaven for the climate, Hell for the company
He uses the phrases “go to heaven” and “go to hell “subtly to describe how awful the climate and company work are simultaneously. It’s very surprising according with both Relief Theory and Incongruity Theory.
3. If you tell the truth, you don't have to remember anything.
This quote is very witty because he implies that nothing is truth and truth is relative. It’s kind of mistaken reasoning.
4. Age is an issue of mind over matter. If you don't mind, it doesn't matter.
This quote changes the meaning of the word “mind” and “matter”. It’s also a type of mistaken reasoning. But it’s interesting and encouraging. 
Oscar Wilde:
5. I can resist everything except temptation.
It’s really funny! Human beings only can deal with temptation is to resist. But he says he can resist everything except temptation. It seems he is strong in mind actually he criticizes himself ironically. 

8
A  
If X, then Y. Not Y, X, or Z. So, Z.
If the power is cut(X), then lights will be off (Y). Lights aren’t off (Not Y), the power is cut(X), or the fan will twirl (Z). So, the fan will twirl (Z).



B
If X, then Y. if Y, then Z.X or R. Not R. So, Y. So. Z.
If the burglars break into the doors (X), then alarms will scream (Y). If alarms scream (Y), then everyone will wake up (Z). The burglars break into the doors(X) or the owner opens it with the key(R). The owner doesn’t open it with the key (Not R). So, alarms will scream(Y). So, everyone will wake up (Z). 
C
If X, then not Y. X or R. Y. So, Not X. So, R.
If Amy visits the cabin embraced by a valley(X), then Ellen won’t (Not Y). Amy visits the cabin(X) or Amy sleeps at home(R). Ellen visits the cabin(Y). So, Amy doesn’t visit the cabin (Not X). So, Amy sleeps at home(R). 
9
The central assumption in Virkram’s argument is that stories out from people’s mouth are always true and we can judge whether men or women are bad based on how many frequencies of bad stories about them.
10
Modus pollens:
1 If we hear about many of them (P), then women are usually bad (Q).
2 we hear about many of them (P)
So, women are usually bad (Q).
11
Clue #1: “This account of you we have from all quarters received”
Deduction#1: A Frenchman or Russian could not have written that. It is the German who is so uncourteous to his verbs.
Analysis: so funny! I don’t know whether it’s true that only German are so uncourteous to his verbs. However, this kind of deduction process isn’t persuasive. 

Clue#2: Such paper could not be bought under half a crown a packet. It is peculiarly strong and stiff
Deduction#2: The man who wrote it was presumably welltodo
Analysis: Not true! How about people who just borrow or pick up these type of paper to write?
12
Clue #1: “This account of you we have from all quarters received”
Deduction#1: A Frenchman or Russian could not have written that. It is the German who is so uncourteous to his verbs. 
Modus pollens:
1 if people are so uncourteous to their verbs(X), then they must be German (Y).
2 the writer is so uncourteous to his verbs(X)
So, it is the German(Y)

Clue#2: Such paper could not be bought under half a crown a packet. It is peculiarly strong and stiff
Deduction#2: The man who wrote it was presumably welltodo
Modus pollens:
1 if the man bought such expensive, strong and stiff paper(X), then the man who wrote it was presumably welltodo(Y).
2 the man bought such expensive, strong and stiff paper(X)
So, the man who wrote it was presumably welltodo(Y)

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