LSAT 109 | Section 1 | Logical Reasoning: Q25

LR Question 25 Explanation

QUESTION TEXT: The number of airplanes equipped with a new…

QUESTION TYPE: Weaken

CONCLUSION: The new anti-collision device must be responsible for the data loss from air traffic controllers’ screens.

REASONING: The new anti-collision device has been installed in more and more airplanes over the past two years. The data have gone missing at an increasing rate over those same two years. Lastly, the anti-collision device operates on the same frequency as air traffic radar.

ANALYSIS: This argument sounds very persuasive. But really it hasn’t shown anything more than a correlation. There could be some other thing interfering with the data.

We can weaken a causation-correlation argument using at least three methods:

1. Finding an alternate cause.
2. Showing that the proposed cause could not have produced the effect.
3. Showing that the effect started occurring before the proposed cause.

Number three is answer choice D.

___________

1. This would show that the anti-collision device is useful, but it doesn’t prove that it’s not to blame for the data loss.
2. This would strengthen the argument. We want to weaken it. 
3. This would let us test the theory. But this data doesn’t let us make any judgment now.
4. CORRECT. This shows that the effect (data loss) came before the proposed cause (anti-collision device.) It strongly weakens the argument. 
5. This doesn’t tell us whether the data loss was or was not from anti-collision devices.