

Philosophy 103: Introduction to Logic
Exercises on Successive Immediate Inferences
Abstract: The
following exercises are taken from Irving M. Copi and Carl Cohen, Introduction to Logic,
10th edition (Upper Saddle River, NJ: Prentice Hall, 1998), 238239, IV: 110. 
Please note: The use of
"S" and "P" in these problems represents the terms
"socialists" and "pacificists" respectively. "S" and
"P" do not represent the subject and predicate positionsthe
subject and predicate positions cannot, of course, be moved and still make sense as an
English sentence. If you have any difficulty in solving these
exercises, study carefully these strategies. 


Statement 

Reason 

Truth
Value 
1 
1. All S is P. 
given 
true 

2. All nonP is nonS. 
contraposition 
true 
3. Some nonP is not
nonS. 
contradiction 
false 

2 
1. All S is P. 

given 

true 

2. No S is nonP. 
obversion 

true 

3 
1. All S is P. 

given 

true 

2. All nonP is nonS. 
contraposition 
true 
3. All nonS is nonP. 
conversion 
undetermined 

4 
1. All S is P. 

given 

true 

2. No S is nonP. 
obversion 
true 
3. No nonP is S. 
conversion 
true 

5 
1. All S is P. 

given 

true 

2. All nonP is nonS.*
NOTE 
contraposition 
true 
3. No nonP is nonS. 
contrariety 
false 
4. No nonS is nonP. 
conversion 
false 

6 
1. All S is P. 

given 

true 

2. All nonP is nonS. 

contraposition 

true 

7 
1. All S is P. 

given 

true 

2. No S is P.*
NOTE 
contrary 
false 
3. No P is S. 
conversion 
false 
4. All P is nonS. 
obversion 
false 
5. No P is nonS. 
contrariety 
undetermined 

8 
1. All S is P. 

given 

true 

2. Some S is not P. 
contradiction 
false 

9 
1. All S is P. 

given 

true 

2. All P is S. 
conversion 
undetermined 

10 
1. All S is P. 

given 

true 

2. No S is nonP 
obversion 
true 
3. No nonP is S. 
conversion 
true 
4. Some nonP is S. 
contradiction 
false 
After studying these inferences, try the quiz on Successive
Immediate Inferences.

