LSAT Explanation PT 35, S4, Q20: Archaeologist: A skeleton of a North

LSAT Question Stem

Which one of the following, if true, most seriously weakens the archaeologist's argument? 

Logical Reasoning Question Type

This is a Weaken question. 

Correct Answer

The correct answer to this question is A. 

LSAT Question Complete Explanation

We are dealing with a Weaken question, which asks us to find an answer choice that undermines the conclusion or the relationship between the premises and the conclusion. The argument in the passage is made by an archaeologist who discovers a mastodon skeleton containing a human-made projectile that is dissimilar to any found in the part of Eurasia closest to North America. The archaeologist concludes that the first Eurasian settlers in North America probably came from a more distant part of Eurasia.

To simplify the argument, imagine you find a toy in your backyard that doesn't resemble any toys made by the factory next door. You might conclude that the toy must have come from a more distant factory.

The argument's structure can be broken down into the following parts:

- Premise: A mastodon skeleton with a human-made projectile was found.

- Premise: The projectile is dissimilar to any found in the part of Eurasia closest to North America.

- Premise: Eurasians did not settle in North America until shortly before the peak of the Ice Age.

- Conclusion: The first Eurasian settlers in North America probably came from a more distant part of Eurasia.

An "Evaluate" question for this argument would be: "Is the projectile found in the mastodon of Eurasian origin?"

Now let's discuss each answer choice:

a) The projectile found in the mastodon does not resemble any that were used in Eurasia before or during the Ice Age.

- This is the correct answer. If the projectile is not of Eurasian origin, it undermines the conclusion that the first Eurasian settlers in North America came from a more distant part of Eurasia. The projectile could have come from a completely different place, and the argument's assumption that it is of Eurasian origin is weakened.

b) The people who occupied the Eurasian area closest to North America remained nomadic throughout the Ice Age.

- This answer choice does not weaken the argument. The fact that these people were nomadic within the area of Eurasia closest to North America does not provide any information about the origin of the projectile or the settlers' origins.

c) The skeleton of a bear from the same place and time as the mastodon skeleton contains a similar projectile.

- This answer choice actually strengthens the argument by showing that the projectile was not a one-time occurrence. It does not provide any information that would weaken the conclusion.

d) Other North American artifacts from the peak of the Ice Age are similar to ones from the same time found in more distant parts of Eurasia.

- This answer choice also strengthens the argument by connecting other artifacts of the same age as the projectile to parts of Eurasia more distant than the area closest to North America. It does not weaken the conclusion.

e) Climatic conditions in North America just before the Ice Age were more conducive to human habitation than were those in the part of Eurasia closest to North America at that time.

- This answer choice supports the argument by suggesting that the part of Eurasia closest to North America may not have been inhabited just before the Ice Age. If this area was uninhabitable, then it is more likely that settlers coming to North America came from more distant regions. It does not weaken the conclusion.

In conclusion, answer choice (a) is the correct answer as it weakens the archaeologist's argument by suggesting that the projectile is not of Eurasian origin, undermining the conclusion that the first Eurasian settlers in North America came from a more distant part of Eurasia.