Strategies for Logical Reasoning

• Look at the question before you look at the argument
• Pay attention to signal words
• Eliminate incorrect answers
• Look out for false assumptions

Most persons who oppose gun control are conservatives; therefore, since Lindsay favors gun control, she is probably not a conservative.

Question:
The above argument most resembles which of the following?
(A) Most sociology professors are liberals; therefore Dr Wood, who is a liberal, is probably a sociology professor.
(B) Most corporation presidents own country homes; if Mr Beacham is a corporation president, he may or may not have a country home.
(C) Few major publishing firms publish much poetry; since Snore Press publishes only poetry, it is probably not a major publishing firm.
(D) Most sports cars are extremely expensive; since the new Desiree Panther is not a sports car, it is probably inexpensive.
(E) Most desert plants are cacti; therefore the cholla, a desert plant, is probably a cactus.

Answer: D

Explanation: The original argument states that most X (opponents of gun control) are Y (conservatives); therefore, someone who is not X is probably not Y. The flaw in this reasoning is that many people other than X may also be Y. Choice D makes the same error: most X (sports cars) are Y. But many kinds of cars other than other than sports cars may be expensive. The other arguments have logical structures different from that of the original argument. Choice A wrongly argues: most X are Y, therefore a Y is probably X.

Mike: I wish you wouldn’t drink so much beer. It’s bad for your health
Marie: How can you say that? I do not weigh a pound more than I did a year ago.

Question:
Which of the following responses would most strengthen Mike’s argument?
(A) You weight ten pounds more than you did six years ago.
(B) Most people who drink a lot of beer do put on weight.
(C) If you keep drinking so much beer, you will soon put on weight.
(D) Putting on weight is not the only harmful effect of drinking beer.
(E) You can put on weight in other ways than by drinking beer.

Answer: D

Explanation: Marie assumes the only harmful effect of beer drinking is gaining weight. The best way to strengthen Mike’s argument and refute Marie’s is to dispute this assumption. D points out the obvious and explodes her argument. The other choices all fail to challenge Marie’s illogical reasoning.

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