Monday, March 20, 2017

Simple Arguments

Some very simple arguments, to form into syllogisms:

1. Her shoes are new so they must be expensive.
2. He must drive a sports car; after all, he is having a mid-life crisis.
3. They are very sad because they lost their dog.
4. We should help poor people because we can.
5. Abortion is wrong since fetuses are living.

What's the conclusion of each argument? What's the stated premise? What premise to you have to add to make the argument a syllogism? 

Answers are below the "fold," but don't look until you try yourself.



1. Her shoes are new so they must be expensive.

P1. Her shoes are new.
P2. All new things are expensive. (Or, if something is new, then it's expensive).
C.  So, her shoes are expensive. 


2. He must drive a sports car; after all, he is having a mid-life crisis.

P1. He is having a mid-life crisis.
P2. All people having mid-life crises drive sports cars. (Or, if someone is having a mid-life crisis, then they drive a sports car). 
C.  So, he drives a sports car. 


3. They are very sad because they lost their dog.

P1. They lost their dog.
P2. If someone loses something, they are sad.  =(Or, All people who lose something are sad). 
C.  So, they are sad. 

4. We should help poor people because we can.

P1. We can help poor people.
P2. If we can do something, then we should do it. (= All things we can do, we should do). 
C.  Therefore, we should help poor people. 

5. Abortion is wrong since fetuses are living.

P1. Fetuses are living.
P2. If something is living, then it's wrong to kill it. (Or, all living things are wrong to kill). 
C.  Therefore, abortion (=killing fetuses) is wrong. 

More sample argument here!

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More sample arguments to make logically valid by adding a premise to make into a syllogism:

An argument about drugs:

1. Many currently illegal drugs are dangerous.
2. ____________________________________
3. Therefore, many currently illegal drugs should be outlawed.

An argument about extra credit:

1. Extra credit helps students' grades.
2. ____________________________________
3. Therefore, we should have extra credit.

An argument about IVF:

1. Having children by IVF (in vitro fertilization) is unnatural. 
2. ____________________________________
3. Therefore, having children by IVF is wrong. 

An argument against homosexuality:

1. People who are homosexual cannot reproduce.
2. ____________________________________
3. Therefore, it it wrong to be homosexual. 

An argument about helping one's grandparents:

1. Eve can help her grandparents carry their groceries. 
2. Eve can easily help her grandparents carry their groceries. 
3. ____________________________________
4. Therefore, Eve is morally obligated to help her grandparents carry their groceries. 

Are the above arguments sound? What counterexamples -- when relevant -- can be used to show that they are not sound?

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