LSAT Explanation PT 31, S3, Q17: Selena: Asteroid impact on the Earth

LSAT Question Stem

Trent's argument assumes that 

Logical Reasoning Question Type

This is a Necessary Assumption question. 

Correct Answer

The correct answer to this question is E. 

LSAT Question Complete Explanation

In this LSAT problem, we have an argument between Selena and Trent. Selena argues that an asteroid impact caused the extinction of dinosaurs by raising dust clouds that blocked the Sun's rays and cooled the planet. She supports her argument with evidence of a worldwide dust layer and a huge crater in Mexico. Trent, on the other hand, argues that the asteroid crater is not large enough to produce the required amount of dust and that the extinction of dinosaurs took many years, so the extinctions must have been due to some other cause, not an asteroid impact. The question type is Necessary Assumption, and we are asked to identify the assumption Trent's argument relies on.

Let's analyze the given answer choices:

a) Trent's argument does not assume that any asteroid collision would have occurred on a land area rather than an ocean. His argument is focused on the specific crater in Mexico, not on the location of potential asteroid collisions in general.

b) Trent's argument does not assume that dinosaurs near an asteroid impact but not within the zone of direct impact would have survived. His argument is focused on the size of the crater and the time it took for the extinction of dinosaurs, not on the survival of specific dinosaurs in certain areas.

c) Trent's argument does not assume that any event that takes place over a long period of time has many different kinds of causes. While he argues that the extinction of dinosaurs took many years, his focus is on the size of the crater and the insufficiency of the asteroid impact as a cause, not on the number of causes involved in the extinction event.

d) Trent's argument does not assume that dust from the impact of an asteroid on Earth would not have had any cooling effect on the climate. He argues that the asteroid crater is not large enough to produce the required amount of dust, but he does not deny the possibility of a cooling effect from the dust that was produced.

e) Correct answer. Trent's argument assumes that no more than one large asteroid struck the Earth during the period when the dinosaurs were becoming extinct. His argument is based on the size of the specific crater in Mexico, and if there were more than one large asteroid, it could potentially weaken his conclusion that the extinctions were not due to asteroid impact.

To further understand why E is the correct answer, let's consider the Evaluate question: "Were there any other large asteroid impacts during the period when the dinosaurs were becoming extinct?" The answer to this question would determine whether Trent's argument is valid or not.

In conclusion, Trent's argument assumes that no more than one large asteroid struck the Earth during the period when the dinosaurs were becoming extinct (Answer choice E).