Reading Exercise: Introduction to Logic

Topic 5 Reading Exercises
Copi, Irving M. Introduction to Logic, 14th Edition. Routledge.
EXERCISE A INSTRUCTIONS
State the converses of the following propositions, and indicate which of them are equivalent to the given propositions:
PROBLEMS
1. No people who are considerate of others are reckless drivers who pay no attention to traffic regulations.
Answer: No S is P -> No P is S.
No reckless drivers are people who are considerate of others.
2. All graduates of West Point are commissioned officers in the U.S. Army.
Answer: All S is P -> Some P is S.
Some commissioned officers are graduates.
3. Some European cars are overpriced and underpowered automobiles.
Answer: Some S are P -> Some P is S.
Some overpriced and underpowered automobiles are European cars.
4. No reptiles are warm-blooded animals.
Answer: No S is P -> No P is S.
No warm-blooded animals are reptiles.
5. Some professional wrestlers are elderly persons who are incapable of doing an honest day’s work.
Answer: Some S is P -> Some P is S.
Some elderly persons are professional wrestlers.
EXERCISE B INSTRUCTIONS
State the obverses of the following propositions:
PROBLEMS
1. Some college athletes are professionals.
Answer: Are non-professionals.
2. No organic compounds are metals.
Answer: Are non-metals.
3. Some clergy are not abstainers.
Answer: Not non-abstainers.
4. No geniuses are conformists.
Answer: Are non-conformist.
5. All objects suitable for boat anchors are objects that weigh at least fifteen pounds.
Answer: Are non-objects that weigh at least fifteen pounds.
EXERCISE C INSTRUCTIONS
State the contrapositives of the following propositions and indicate which of them are equivalent to the given propositions.
PROBLEMS
1. All journalists are pessimists.
Answer: All S is P -> All non-P is non-S
All non-pessimists are non-journalists.
2. Some soldiers are not officers.
Answer: Some S is not P -> Some non-P is not non-S
Some non-officers are not non-soldiers.
3. All scholars are non degenerates.
Answer: All S is P -> All non-P is non-S
All non-degenerates are non-scholars.
4. All things weighing less than fifty pounds are objects not more than four feet high.
Answer: All S is P -> All non-P is non-S
All non-objects are non-things weighing less than fifty pounds.
5. Some noncitizens are not non residents.
Answer: Some S is not P -> Some non-P is not non-S
Some non-residents are not non-citizens.
EXERCISE D INSTRUCTIONS
If “All socialists are pacifists” is true, what may be inferred about the truth or falsehood of the following propositions? That is, which can be known to be true, which can be known to be false, and which are undetermined?
PROBLEMS
1. Some non-pacifists are not nonsocialists.
Answer: False; E; All non P is non S
2. No socialists are nonpacifists.
Answer: True; A; No S is non P
3. All nonsocialists are nonpacifists.
Answer: Undetermined; All S is P
4. No non-pacifists are socialists.
Answer: True; E; No non P are S
5. No nonsocialists are nonpacifists.
Answer: False; A; No non s is non P
6. All non-pacifists are nonsocialists.
Answer: True; A; All non P is non S
7. No pacifists are nonsocialists.
Answer: Undetermined; No P is non S
8. Some socialists are not pacifists.
Answer: False; O; Some S is not P