LSAT Explanation PT 37, S4, Q18: A plausible explanation of the disappearance

LSAT Question Stem

Which one of the following statements, if true, most seriously weakens the argument? 

Logical Reasoning Question Type

This is a Weaken question. 

Correct Answer

The correct answer to this question is B. 

LSAT Question Complete Explanation

In this Weaken question, we are presented with an argument about the "comet theory" as a plausible explanation for the disappearance of dinosaurs. The argument is structured as follows:

Premise: A large enough comet collision could have led to a dust cloud covering the Earth, cooling the climate long enough to kill all of the dinosaurs.

Conclusion: The comet theory is a plausible explanation of the dinosaurs' extinction.

To help you understand this better, imagine a hypothetical situation where a large enough ice cream truck collides with a playground, causing a massive cloud of ice cream to cover the area, making it too cold for the children to play. The argument is similar to saying that this ice cream truck collision is a plausible explanation for why the children stopped playing in the playground.

Our task is to find the answer choice that, if true, would most seriously weaken the argument.

Evaluate Question: "Did any other animals with similar physiology and habitat to dinosaurs survive during the same time when the dinosaurs went extinct?"

Now, let's discuss each answer choice:

a) This answer choice mentions that another school of paleontology has a different explanation for the disappearance of dinosaurs. However, the argument only claims that the comet theory is a plausible explanation, not the only one. So, this choice does not weaken the argument.

b) This is the correct answer choice. If there were other animals with similar physiology and habitat to dinosaurs that did not go extinct when the dinosaurs did, it would cast doubt on the comet theory as a plausible explanation for the extinction of dinosaurs. This is like saying that some children who were very similar to those in the playground and also loved ice cream did not stop playing when the ice cream truck collided. This weakens the argument that the ice cream truck collision was the main reason for the children stopping their play.

c) This choice points out that we cannot determine from dinosaur skeletons whether they died from the effects of a dust cloud. However, a lack of evidence does not disprove a theory, and the argument only claims that the comet theory is a plausible explanation. So, this choice does not weaken the argument.

d) The fact that many other animal species from the era of the dinosaurs did not become extinct at the same time as the dinosaurs does not necessarily weaken the argument. The author does not claim that the comet collision would have killed every species on the planet, just that it could have killed the dinosaurs. So, this choice does not weaken the argument.

e) The consequences of a comet colliding with Earth not being fully understood does not affect the strength of the argument. The comet theory can still be considered a plausible explanation for the disappearance of dinosaurs even if the consequences are not fully understood. So, this choice does not weaken the argument.

In conclusion, the correct answer choice is (b), as it introduces information that casts doubt on the comet theory as a plausible explanation for the extinction of dinosaurs.