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- Joined: Feb 02, 2011
- Sat Mar 30, 2013 11:00 pm
#35308
Complete Question Explanation
Strengthen—PR. The correct answer choice is (E)
This stimulus consists of two premises and a conclusion. The first premise is that the government
study shows that raising the speed limit to actual average speeds on level, straight, high-speed
roadways reduces the accident rate. Next, we are told that the average speed for such roads is 75
miles per hour (120 kph) and the author thus concludes that all such roads should have that speed
limit. Note that the scope in all three sentences is identical and consistent (i.e, “level, straight
stretches of high-speed roadways”). Since the scope is appropriate, the author could justifiably
conclude that raising the speed limit to 75 mph on these roadways would reduce the accident
rate. Instead, the author concludes that the speed limit should be raised. While this may seem an
insignificant leap in logic, the author’s shift from a predicted outcome to a recommended approach is
unsupported without first establishing the desirability of the outcome. The correct answer will be a
principle that supports this leap.
Answer choice (A): The author’s argument is not strengthened by demonstrating that such changes
should not be made on any other kind of road. The consistent scope of both premises and the
conclusion eliminates the need to deal with other kinds of roads and renders this principle irrelevant.
Answer choice (B): By the same token as (A), the consistent scope throughout our stimulus frees
us from the need to consider other roads. Furthermore, suggesting that the speed limit on all roads
should be raised to 75 mph mistakenly generalizes the findings of the government study, which was
specific to level, straight stretches of high-speed roadways.
Answer choice (C): Our premises indicate that the speed limit for these types of roads “tends to be”
75 mph. If “tends to be” is interpreted as “all such roadways have roughly equal average speeds”,
then we have satisfied a necessary condition of this principle, which would allow but not justify our
reasoning. If this principle is understood to imply a higher standard than our premise has met, then
(C) would weaken the reasoning above. In neither case does this principle help to justify the author’s
conclusion.
Answer choice (D): (D) raises a number of questions. Are current speed limit laws long-standing?
Does an average speed of 75 mph indicate that laws are “widely violated” or could a few extremely
fast cars account for the average speed? If speed limit laws are long-standing and widely violated,
does classifying them as “probably bad laws” justify the conclusion? What does this principle have
to do with the rationale of reducing accidents? There are far too many issues with (D) to use it as
justification of the reasoning in the stimulus.
Answer choice (E): This is the correct answer choice. The government study gives us a
measure that reduces the rate of traffic accidents. The author concludes that this measure should
be implemented. The best way to justify this reasoning is apply a principle that “any measure that
reduces the rate of traffic accidents should be implemented.” Such a principle effectively bridges the
gap between the expected outcome of the measure and the desirability of implementing it.
Strengthen—PR. The correct answer choice is (E)
This stimulus consists of two premises and a conclusion. The first premise is that the government
study shows that raising the speed limit to actual average speeds on level, straight, high-speed
roadways reduces the accident rate. Next, we are told that the average speed for such roads is 75
miles per hour (120 kph) and the author thus concludes that all such roads should have that speed
limit. Note that the scope in all three sentences is identical and consistent (i.e, “level, straight
stretches of high-speed roadways”). Since the scope is appropriate, the author could justifiably
conclude that raising the speed limit to 75 mph on these roadways would reduce the accident
rate. Instead, the author concludes that the speed limit should be raised. While this may seem an
insignificant leap in logic, the author’s shift from a predicted outcome to a recommended approach is
unsupported without first establishing the desirability of the outcome. The correct answer will be a
principle that supports this leap.
Answer choice (A): The author’s argument is not strengthened by demonstrating that such changes
should not be made on any other kind of road. The consistent scope of both premises and the
conclusion eliminates the need to deal with other kinds of roads and renders this principle irrelevant.
Answer choice (B): By the same token as (A), the consistent scope throughout our stimulus frees
us from the need to consider other roads. Furthermore, suggesting that the speed limit on all roads
should be raised to 75 mph mistakenly generalizes the findings of the government study, which was
specific to level, straight stretches of high-speed roadways.
Answer choice (C): Our premises indicate that the speed limit for these types of roads “tends to be”
75 mph. If “tends to be” is interpreted as “all such roadways have roughly equal average speeds”,
then we have satisfied a necessary condition of this principle, which would allow but not justify our
reasoning. If this principle is understood to imply a higher standard than our premise has met, then
(C) would weaken the reasoning above. In neither case does this principle help to justify the author’s
conclusion.
Answer choice (D): (D) raises a number of questions. Are current speed limit laws long-standing?
Does an average speed of 75 mph indicate that laws are “widely violated” or could a few extremely
fast cars account for the average speed? If speed limit laws are long-standing and widely violated,
does classifying them as “probably bad laws” justify the conclusion? What does this principle have
to do with the rationale of reducing accidents? There are far too many issues with (D) to use it as
justification of the reasoning in the stimulus.
Answer choice (E): This is the correct answer choice. The government study gives us a
measure that reduces the rate of traffic accidents. The author concludes that this measure should
be implemented. The best way to justify this reasoning is apply a principle that “any measure that
reduces the rate of traffic accidents should be implemented.” Such a principle effectively bridges the
gap between the expected outcome of the measure and the desirability of implementing it.