INTRODUCTION TO LOGIC
EXERCISES ON INCOMPLETE ARGUMENTS[1]
a. Determine which part is missing in each argument. Write P or C.
b. Then, supply the missing statement. Write your answers on a Size 2.
Set A
1. Communism is opposed by reform liberals precisely because it violates individual freedom.
2. Communism, simply because it is a godless philosophy, contains within itself the seeds of its own destruction.
3. Encouraging toy gun play gives children a clear message that the best way to deal with frustration and conflict is with a gun. Is this the message that we want to be sending our kids?
4. Everyone who hates his brother is a murderer. And you know that no murderer has eternal life in him.
5. He would not take the crown; therefore ‘tis certain he was not ambitious.
6. No cars with internal combustion engines are energy efficient, so no American-made cars are energy efficient.
7. Norway has a right to continue whale hunting, because whale hunting is a traditional part of Norwegian national culture.
8. Only she had the means, the motive and the opportunity to kill him. She must be the killer.
9. Small countries tend to remember history especially well, since it often turns out badly for them.
10. Socialism was doomed to failure because socialism did not provide the incentives needed for a prosperous economy.
11. The human soul is spiritual, and whatever is spiritual is immortal.
12. The open shop is good for unions because it makes them more democratic.
13. Tomato prices will go up, since farmers were hit by a hard freeze last week.
14. The roof is leaking. So it must have snowed.
15. We cannot trust this man, for he has perjured himself in the past.
Set B
1. Only nonprofit organizations are exempt from paying taxes, so churches must be exempt.
2. Wherever water exists, human life can be sustained, and water exists on the moon.
3. Any form of cheating deserves to be punished, and plagiarism is a form of cheating.
4. Some police chiefs undermine the evenhanded enforcement of the law, because anyone who fixes parking tickets does that.
5. A few fraternities have dangerous initiation rites, and those that do have no legitimate role in campus life.
6. The corporate income tax should be abolished; it encourages waste and high prices.
7. If the Defense Department is so intent on fighting alcohol abuse, why does it make alcohol so readily available and acceptable? Alcohol is tax free at post liquor stores, and enlisted men’s and officer’s clubs make drinking almost a mandatory facet of military life.
ANSWER KEY
Set A
1. / Premise; Reform liberals oppose anything that violates individual freedom.2. / Premise; A godless philosophy contains within itself the seeds of its own destruction.
3. / Conclusion; We should not encourage children to engage in toy gun play.
*The question “Is this the message that we want to be sending our kids?” is actually meant to be a statement: “This is not the message that we want to send our kids.”
4. / Conclusion; Anyone who hates his brother has no eternal life in him.
5. / Premise; Whoever takes the crown is ambitious.
6. / Premise; American-made cards have internal combustion engines.
7. / Premise; Norway has a right to continue its traditions. OR A country has a right to continue its traditions.
8. / Premise; A killer would have the means, motive, and opportunity to kill him.
9. / Premise; We remember especially well whatever turns out badly for us.
10. / Premise; Anything that does not provide the incentives needed for a prosperous economy is doomed to failure.
11. / Conclusion; The human soul is immortal.
12. / Premise; Anything that makes unions more democratic is good for them.
13. / Premise; Farm prices go up when a hard freeze hits.
14. / Premise; If the roof leaks, then it must have snowed.
15. / Premise; We cannot trust someone who has perjured himself in the past.
Set B
1. / Premise; Churches are nonprofit organizations.2. / Conclusion; Human life exists on the moon.
3. / Conclusion; Plagiarism deserves to be punished.
4. / Premise; Some police chiefs fix parking tickets.
5. / Conclusion; A few fraternities have no legitimate role in campus life.
6. / Premise; Anything that encourages waste and high prices should be abolished.
7. / Conclusion; The Defense Department is not intent on fighting alcohol abuse.
[1] Answers are found on the last page.