Question

Editorial: Critics of nuclear power complain about the allegedly serious harm that might result from continued operation of existing nuclear power plants. But such concerns do not justify closing these plants; after all, their operation has caused no more harm than that caused by pollution generated by coal-and oil-burning power plants, the most important other sources of energy.
Which of the following is an assumption on which the argument depends?

• A. Existing nuclear power plants should be closed only if it can be conclusively demonstrated that their continued operation is likely to cause harm more serious than the harm their operation has already caused.
• B. Closing existing nuclear power plants would require greatly increased reliance on coal-and oil-burning power plants.
• C. The harm that has resulted from operation of existing coal-and oil-burning power plants has been significant.
• D. The harm that a nuclear power plant is likely to cause as it continues to operate can be reliably predicted from the past history of nuclear power plants.
• E. The only harm that has resulted from operation of existing coal-and oil-burning power plants has resulted from the pollution generated by these plants.

Hint:

When an argument's main evidence is a comparison between two things (A and B), always ask yourself: "Why is B the correct thing to compare A to?" The assumption often lies in the answer to that question—that B is the relevant alternative, benchmark, or consequence.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
This question asks for a necessary assumption of the editorial's argument. An assumption is an unstated premise that is required for the conclusion to be valid.
Step 2: Key Formula or Approach:
The argument's structure is a comparison: it dismisses concerns about nuclear power by saying it's "no more harm[ful]" than coal and oil. This comparison is only relevant if coal and oil are the necessary alternative to nuclear power. If we could replace nuclear with a harmless alternative (like solar), then comparing it to a harmful one (coal) would be a meaningless distraction. The argument assumes we are stuck with a choice between nuclear and coal/oil. The negation test is useful here.
Step 3: Detailed Explanation:
- Argument Core: Don't close nuclear plants, because they are not worse than coal/oil plants.
- Logical Gap: The argument's entire force rests on the comparison to coal and oil. Why is that the relevant comparison? The unstated reason must be that if we close nuclear, we will have to use more coal and oil.
- (B) This states the assumption explicitly. If closing nuclear requires more coal and oil, then the comparison is valid and we are faced with choosing the lesser of two evils.
- Negation Test for (B): Let's negate the statement. "Closing existing nuclear power plants would NOT require greatly increased reliance on coal-and oil-burning power plants (because we could switch to renewables)." If this is true, the editorial's argument collapses. The comparison becomes irrelevant. Who cares if nuclear is better than coal if we don't have to use either? Since negating the statement destroys the argument, it is a necessary assumption.
- (A) This provides a different standard for closing plants but isn't what the argument itself relies on (it relies on a comparison to other energy sources).
- (D) This is a major assumption the argument makes, but it's arguably a flawed one. However, the assumption in (B) is even more fundamental to the structure of the argument as presented. The comparison to coal is the central pillar, and that pillar only stands if coal is the alternative. The argument is weak because it compares future risk (nuclear) to past harm (coal), but it depends on the idea that coal is the relevant benchmark.
Step 4: Final Answer:
The argument's comparison of nuclear harm to coal/oil harm is only logically relevant if it is assumed that closing nuclear plants would force an increased use of those same coal/oil plants.