LSAT Explanation PT 38, S4, Q18: Anders: The physical structure of the

LSAT Question Stem

The statement "thinking machines closely modeled on the brain are also likely to fail" serves which one of the following roles in Yang's argument? 

Logical Reasoning Question Type

This is an Argument Part question. 

Correct Answer

The correct answer to this question is B. 

LSAT Question Complete Explanation

Let's first analyze the argument in the passage. Yang's argument can be broken down into the following structure:

P1: Structural similarity to the brain may be important, but this does not mean essential, for thinking.

P2 (analogy): No flying machine closely modeled on birds has worked; workable aircraft are structurally very different from birds.

Subsidiary Conclusion (SC): So thinking machines closely modeled on the brain are also likely to fail.

Main Conclusion (MC): In developing a workable thinking machine, researchers would therefore increase their chances of success if they focus on the brain's function and simply ignore its physical structure.

To help understand Yang's argument, think of it like this: Imagine you want to create a machine that can swim like a fish. You might initially think that modeling the machine after a fish's physical structure is essential. However, you later realize that submarines, which are not physically similar to fish, can still swim effectively underwater. This leads you to conclude that it's more important to focus on the function of swimming rather than the physical structure of a fish.

Now let's examine the question type and answer choices. The question type is an Argument Part question, which asks us to identify the role of a specific statement in the argument. In this case, the statement is "thinking machines closely modeled on the brain are also likely to fail."

a) the main conclusion of the argument

This is incorrect because the main conclusion is that researchers should focus on the brain's function and ignore its physical structure to increase their chances of success.

b) a subsidiary conclusion used in support of the main conclusion

This is the correct answer. The statement serves as a subsidiary conclusion, which is supported by the premises (P1 and P2) and, in turn, supports the main conclusion.

c) a principle of research invoked in support of the conclusion

This is incorrect because the statement is not a principle of research; it's a conclusion drawn from the premises.

d) a particular example illustrating a general claim

This is incorrect because the statement is not an example; it's a conclusion based on the analogy provided in the argument.

e) background information providing a context for the argument

This is incorrect because the statement is not merely background information; it plays an active role in the argument by serving as a subsidiary conclusion.

In summary, the statement "thinking machines closely modeled on the brain are also likely to fail" serves as a subsidiary conclusion in Yang's argument, which is supported by the premises and helps support the main conclusion.