PHIL 1500 – Critical Thinking

Practice Exam for Unit II


Construct truth trees for the following arguments, then indicate whether the truth tree shows that the argument is deductively valid. (13 points each.)

1.
 P (Q · S)
  2.
P ~(Q R)
 
~(Q R)
   
(P S) T
 
   

 
~P
   
~S T
 

 

 

 

 

 

 

 

 

 

 

 

     
3.
P ~Q
  4.
~(P Q)
 
P R
   
~(P R)
 
~Q R
   
 
   
R
 
~R
     

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     

In each of the following, construct a Venn diagram and use it to answer the question. (12 points each.)

5. Some automobiles have diesel engines. No automobiles that have diesel engines burn gasoline. So some automobiles do not burn gasoline. Is this argument valid?

6. Plato was an ancient Greek philosopher. All ancient Greek philosophers were from Athens or Milos. Plato was not from Milos. So Plato was an Athenian. Is this argument valid?

7. Casey Jones was not a fireman. All locomotive crewmen were engineers or firemen. Casey Jones was a locomotive crewman. Was Casey Jones an engineer?

8. Not all actors are in movies. All actors who are not in movies audition for commercials. Are all actors who audition for commercials also in movies?


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