LSAT Explanation PT 25, S2, Q20: Physicist: Determinism is the view that

LSAT Question Stem

The physicist's reasoning is most vulnerable to criticism on which one of the following grounds? 

Logical Reasoning Question Type

This is a Flaw question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

To understand this LSAT problem, let's first break down the argument in the passage. The physicist is arguing against determinism, which is the view that every event has a preceding cause sufficient for its occurrence. In other words, if determinism is true, the current events couldn't have failed to happen given the state of the universe a moment ago. The physicist claims that determinism is false because it is impossible to know the complete state of the universe at any given time, as we cannot accurately measure both the position and velocity of any given subatomic particle at a particular time.

The structure of the argument is as follows:

- Premise: It is impossible to know the complete state of the universe at any given time (due to the impossibility of measuring both position and velocity of subatomic particles).

- Conclusion: Determinism is false.

An "Evaluate" question for this argument could be: "Does the impossibility of knowing the complete state of the universe at any given time necessarily mean that determinism is false?"

Now, let's analyze the question type and answer choices. This is a Flaw question, which asks us to identify the ground on which the physicist's reasoning is most vulnerable to criticism.

a) While this answer choice points out that not being able to measure both position and velocity doesn't mean we can't know either of them, it doesn't directly address the main flaw in the argument, which is the connection between knowing the complete state of the universe and determinism being false.

b) This answer choice reverses the relationship in the argument and doesn't address the main flaw. The argument doesn't imply that the states of individual subatomic particles are unknowable because the complete state of the universe is unknowable.

c) This answer choice is similar to (a) and doesn't address the main flaw in the argument. The argument doesn't suggest that position or velocity cannot be accurately measured separately, but rather that both cannot be measured accurately at the same time.

d) This is the correct answer. It points out that just because it is impossible to know the complete state of the universe at any given time doesn't imply that there is no complete state of the universe at that time. The physicist is making an unwarranted assumption that the lack of knowledge about the complete state of the universe means that determinism is false.

e) This answer choice doesn't make sense because the argument already states that it's impossible to measure accurately both the position and velocity of any given subatomic particle, which implies that this is the case for all subatomic particles.

In summary, the correct answer is (d), which points out that the physicist's reasoning is vulnerable to criticism because the impossibility of knowing the complete state of the universe at any given time doesn't necessarily imply that there is no complete state of the universe at that time or that determinism is false.