LSAT Explanation PT 34, S3, Q11: The present goal of the field

LSAT Question Stem

The argument above is based on which one of the following assumptions? 

Logical Reasoning Question Type

This is a Necessary Assumption question. 

Correct Answer

The correct answer to this question is C. 

LSAT Question Complete Explanation

First, let's analyze the structure of the argument in the passage. The argument can be summarized as follows:

Premise 1: The ability to transplant organs such as hearts, lungs, livers, and kidneys allows us to live longer.

Premise 2: We can never achieve brain transplants.

Conclusion: As the transplantation of organs allows more and more people to live longer, those with degenerative brain disorders will form an ever-increasing proportion of the population.

To better understand the argument, let's use a simple example. Imagine a group of people who are all living longer because they receive successful organ transplants. However, some of these people have degenerative brain disorders that cannot be cured by organ transplantation. Since they are living longer, the proportion of people with degenerative brain disorders in this group will increase over time.

Now, let's come up with an "Evaluate" question: "Are there degenerative brain disorders that can only be cured by brain transplants?"

The question type for this problem is Necessary Assumption, and we need to identify the assumption that the argument is based on.

Let's discuss each answer choice:

a) Degenerative brain disorders will increasingly strike younger and younger patients.

This answer choice is not necessary for the argument to hold. The argument is about the increasing proportion of people with degenerative brain disorders in the population, not about the age at which these disorders strike.

b) It is still quite rare for people to live long enough to need more than one transplant of any given organ.

This answer choice is also not necessary for the argument to hold. The argument is about the increasing proportion of people with degenerative brain disorders in the population, not about the rarity of needing multiple transplants.

c) There are degenerative brain disorders that will not be curable without brain transplants.

This answer choice is the correct one. The argument assumes that there are degenerative brain disorders that cannot be cured without brain transplants. If this assumption is false, the argument falls apart because it would mean that these disorders could be cured through other means, and the proportion of people with degenerative brain disorders in the population might not increase.

d) Degenerative brain disorders account for a very small proportion of deaths in the population at large.

This answer choice is not necessary for the argument to hold. The argument is about the increasing proportion of people with degenerative brain disorders in the population, not about the proportion of deaths caused by these disorders.

e) More is being spent on research into degenerative brain disorders than on research into transplantation.

This answer choice is not necessary for the argument to hold. The argument is about the increasing proportion of people with degenerative brain disorders in the population, not about the amount of research spending on these disorders compared to transplantation research.

In conclusion, the correct answer is C, as it is the necessary assumption for the argument to hold.