LSAT Explanation PT 26, S2, Q10: Commercial passenger airplanes can be equipped

LSAT Question Stem

Which one of the following is an assumption on which the argument depends? 

Logical Reasoning Question Type

This is a Necessary Assumption question. 

Correct Answer

The correct answer to this question is C. 

LSAT Question Complete Explanation

Let's first summarize and analyze the argument in the passage. The passage states that commercial passenger airplanes can be equipped with a collision-avoidance radar system that provides pilots with information about the proximity of other airplanes. The argument claims that passengers are safer on airplanes equipped with the system than on comparable airplanes not so equipped, even though the system frequently warns pilots to evade phantom airplanes. The structure of the argument is as follows:

Premise: Commercial passenger airplanes can be equipped with a collision-avoidance radar system.

Premise: The system warns pilots to take evasive action when it indicates a possible collision.

Premise: The system frequently warns pilots to evade phantom airplanes.

Conclusion: Passengers are safer on airplanes equipped with the system than on comparable airplanes not so equipped.

The question type for this problem is Necessary Assumption, which means we need to identify the assumption on which the argument depends.

An "Evaluate" question for this argument could be: "Do pilots react appropriately to the system's warnings?"

Now let's discuss each answer choice:

a) Passengers feel no safer on airplanes equipped with the radar system than on comparable airplanes not so equipped.

- This answer choice is irrelevant because the argument is focused on the actual safety of the passengers, not their feelings of safety. The assumption we're looking for should be related to the effectiveness of the system in making passengers safer.

b) Warnings given by a collision-avoidance system about phantom airplanes are not caused by distorted radar signals.

- This answer choice is also irrelevant because it doesn't address the safety of passengers on airplanes equipped with the system compared to those without the system. The cause of the phantom warnings is not important in determining whether the system makes passengers safer.

c) The frequency of invalid warnings will not cause pilots routinely to disregard the system's warnings.

- This is the correct answer. The argument assumes that pilots will continue to respond to the system's warnings despite the frequency of invalid warnings. If pilots started to routinely ignore the warnings due to the high number of false alarms, the system's effectiveness in ensuring passenger safety would be compromised.

d) Commercial passenger airplanes are not the only planes that can be equipped with a collision-avoidance system.

- This answer choice is irrelevant because the focus of the argument is on the safety of passengers on commercial passenger airplanes. Whether other planes can be equipped with the system does not affect the safety of passengers on airplanes equipped with the system compared to those without the system.

e) The greatest safety risk for passengers traveling on commercial passenger airplanes is that of a midair collision.

- This answer choice is too strong and not necessary for the argument. The system doesn't need to address the greatest safety risk for passengers in order to make them safer. As long as the system provides some benefit in avoiding collisions, it can still make passengers safer compared to those on airplanes without the system.

In conclusion, the correct answer is C because it highlights the necessary assumption that pilots will not routinely disregard the system's warnings, ensuring the effectiveness of the system in making passengers safer.