LSAT Explanation PT 36, S3, Q26: Before 1986 physicists believed they could

LSAT Question Stem

Which one of the following, if true, most strengthens the argument that there is a fifth universal force? 

Logical Reasoning Question Type

This is a Strengthen question. 

Correct Answer

The correct answer to this question is B. 

LSAT Question Complete Explanation

Let's first analyze the argument in the passage. The passage states that before 1986, physicists believed there were four universal forces to describe the universe. However, experiments suggested a fifth universal force of mutual repulsion between particles of matter. This fifth force would explain the smaller measurement of gravitational attraction between bodies than the established theory predicted. The conclusion of the argument is that there is a fifth universal force.

Now, let's create an "Evaluate" question for this argument: "Are there any other explanations for the smaller measurement of gravitational attraction that are not accounted for by the established theory?"

The question type for this LSAT problem is Strengthen, which means we are looking for an answer choice that provides additional support for the argument that there is a fifth universal force.

Let's discuss each answer choice:

a) The extremely sophisticated equipment used for the experiments was not available to physicists before the 1970s.

This answer choice does not directly strengthen the argument for a fifth universal force. It merely explains why the fifth force might not have been discovered earlier. It doesn't provide any additional support for the existence of the fifth force.

b) No previously established scientific results are incompatible with the notion of a fifth universal force.

This answer choice strengthens the argument by eliminating potential conflicts with existing scientific results. If no established results contradict the idea of a fifth universal force, it makes the existence of such a force more likely. This is the correct answer.

c) Some scientists have suggested that the alleged fifth universal force is an aspect of gravity rather than being fundamental in itself.

This answer choice actually weakens the argument, as it suggests that the fifth force might not be a separate force but instead an aspect of gravity, which is already one of the four established universal forces.

d) The experiments were conducted by physicists in remote geological settings in which factors affecting the force of gravity could not be measured with any degree of precision.

This answer choice weakens the argument, as it suggests that the experiments supporting the existence of the fifth force were not reliable. If the measurements were not precise, it casts doubt on the validity of the conclusion.

e) The fifth universal force was postulated at a time in which many other exciting and productive ideas in theoretical physics were developed.

This answer choice is irrelevant to the argument. The timing of when the fifth force was postulated does not provide any additional support for its existence.

In conclusion, the correct answer is B, as it strengthens the argument by eliminating potential conflicts with existing scientific results, making the existence of the fifth universal force more likely.