• Choose a category
• All
• Classic-Fiction

Here’s a related but simpler example:

Jacques: If you want to keep your pet dog alive, you must give it water every day.

Pierre: That’s not true. It takes a lot more than water to keep your pet dog alive.

Pierre’s response is inaccurate because he mistakenly believes that what Jacques has said is that

A) Giving water is necessary to keeping your pet dog alive.

B) Only the giving of water will keep your pet dog alive.

C) If your pet dog is to be kept alive, it must be given water.

D) Giving water is enough to keep your pet dog alive.

E) Your pet dog will not be kept alive by giving it water.

Choice D above is, of course, the correct answer. Jacques’s statement correctly identifies water as a necessary condition for keeping your pet dog alive. Pierre has mistakenly assumed that Jacques has said that water is a sufficient condition for keeping your pet dog alive.

Back to problem

Problem 36: Sales

Choice B. Let’s repeat what Debra said:

To be a good salesperson, one must be friendly.

Debra’s statement above is also equivalent to the following:

If a person is a good salesperson, then he or she must be friendly.

Now let’s summarize what Tom thought Debra said:

If a person is friendly, then he or she will make a good salesperson.

Tom has effectively reversed the original “If … then” statement and erroneously committed the fallacy of affirming the consequent. Tom would have been correct had he instead responded, “Oh, what you mean is that only friendly people are capable of making good salespersons,” or “I agree, a good salesperson must be friendly,” or “That’s right. If you’re not friendly, then you’re not going to make a good salesperson.”

Choice B is a correct transcription of Debra’s original statement comment. It cannot be correct because Tom disagrees with her. Choice E is a logical inference based on Debra’s original statement (it is the contrapositive!). Choices A and D are not correct because regardless of whether the statements are true in themselves they do not lie at the crux of Tom’s misunderstanding.

Back to problem

Problem 37: Football

Choice A. According to the rules of logical equivalency, the statement, “Every person on the Brazilian World Cup football team is a great player,” may be translated as, “If a person is on the Brazilian World Cup football team, then he is a great player.” And this may be further translated as, “Only great players are Brazilian World Cup football players.”

Choice A cannot be true. The statement, “Only Brazilian World Cup football players are great players” is exactly what Beth has misunderstood Marie’s remark to mean. Beth thinks Marie has said, “Brazil has all the great World Cup football players.”

Choices B, C, D, and E are all unwarranted inferences.

Back to problem

Problem 38: Medical Hierarchy

Choice A. With reference to the diagram below, the dotted circle representing researchers crosses into the solid inner circle representing surgeons, so we know for certain that at least some surgeons are researchers. Note that the solid circle representing surgeons is inside the larger solid circle representing doctors, which is inside the still larger solid circle representing medically licensed individuals.

For answer choices B through E, check for why each of these “could be true” and, in this way, eliminate them from contention as possible correct answers. choice B could be true, as indicated by the area within the circle representing surgeons that appears above the dotted line (see embedded letter “B”). Choice C could be true, as indicated by the area outside the circle representing surgeons but within the circle representing doctors and within the dotted line (see embedded letter “C”). Choice D states basically the same thing as choice B. Some doctors/surgeons are researchers, but not all doctors/surgeons are researchers. Choice E could be true if the dotted circle extends beyond the solid circle representing