LSAT Explanation PT 37, S4, Q17: A year ago the government reduced

LSAT Question Stem

The argument is most vulnerable to the criticism that it takes for granted that 

Logical Reasoning Question Type

This is a Flaw question. 

Correct Answer

The correct answer to this question is E. 

LSAT Question Complete Explanation

Let's first analyze the argument in the passage. The argument states that a year ago, the government reduced the highway speed limit, and since then, there have been significantly fewer highway fatalities than the previous year. The conclusion drawn is that speed limit reduction can reduce traffic fatalities. The argument is structured as follows:

Premise: A year ago, the government reduced the highway speed limit.

Premise: In the year since the speed limit reduction, there have been significantly fewer highway fatalities than in the previous year.

Conclusion: Speed limit reduction can reduce traffic fatalities.

The question type is a Flaw question, asking us to identify the criticism that the argument takes for granted. An "Evaluate" question for this argument could be: "Was there any other factor that could have contributed to the decrease in highway fatalities?"

Now, let's discuss each answer choice:

a) highway traffic has not increased over the past year

- This answer choice is incorrect because an increase in highway traffic would not necessarily provide an alternative explanation for the reduction in traffic fatalities. In fact, one could argue that an increase in traffic would lead to more fatalities, not fewer.

b) the majority of drivers obeyed the new speed limit

- This answer choice is tempting but incorrect. The argument does not need to assume that the majority of drivers obeyed the new speed limit for it to have an impact on traffic fatalities. Even if only some drivers obeyed the new speed limit, it could still potentially lead to a reduction in traffic fatalities.

c) there is a relation between driving speed and the number of automobile accidents

- This answer choice is incorrect because the argument does not need to assume a connection between driving speed and the number of accidents. It could be that the reduced highway speed doesn't reduce the number of accidents, but it does reduce the severity of those accidents so that more people survive them.

d) the new speed limit was more strictly enforced than the old

- This answer choice is incorrect because the argument does not need to assume that the new speed limit was more strictly enforced than the old one. The new speed limit could have been equally enforced as the old speed limit, and yet the new speed limit could still have reduced the number of highway traffic fatalities.

e) the number of traffic fatalities the year before the new speed limit was introduced was not abnormally high

- This is the correct answer. If we negate this answer choice, it would read "the number of traffic fatalities the year before the new speed limit was introduced was abnormally high." If that were true, the argument couldn't claim that the fewer fatalities were the result of the reduced highway speed limit because it could have been the result of the fatality rate returning to normal. The negation of this answer choice provides an alternative cause to the one proposed in the conclusion, which would undermine the argument.

In conclusion, the correct answer is E. The argument is most vulnerable to the criticism that it takes for granted that the number of traffic fatalities the year before the new speed limit was introduced was not abnormally high.