PrepTest 14 - Section 1 - Question 9 | Explanation & Discussion

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Conclusion A scientific theory is a good theory if it satisfies two requirements: It must accurately describe a large class of observations in terms of a model that is simple enough to contain only a few elements, and it must make definite predictions about the results of future observations. ███ ████████ █████████████ ████████████ ███████ █████ ███████ ████ ██████████ ███ ████ ███ ██ ████ █████████████████ ████ █████ ███ █████████████████ ███ █████ ████████████ ███ ██ ███ ███ ████ ███ ████████ ████████████ █████ █████████████ ████████████ ██████ ███ ███ █ ████ ███████

Structure: Principle-Application

The main point of this argument is a general principle about what makes a scientific theory a "good" theory. The theory must fulfill two requirements: first, it must describe a "large class of observations" using a model "simple enough to contain only a few elements." So it should be able to explain many phenomena without being too complicated. Second, the theory should be able to make specific predictions about future observations.

The author illustrates this principle with the example of Aristotle's cosmological theory, which fulfilled the first requirement by explaining everything as made out of four elements, but which did not make specific predictions. Thus, by applying the author's principle, Aristotle's cosmological theory was not a good theory.

If all the statements in ███ ███████ ███ █████ ████ ██ ███ █████████ ████ ████ ██ ████ ███████

Question Type

Except (LR)

Must be true

For this question, we expect four answer choices to have to be true, and we're looking for one answer choice that doesn't necessarily have to be true. In terms of inferences we can make, the author has given us two conditions that are both necessary for a theory to be good: it must explain many observations with a simple model, and it must predict future observations.

good → simple AND predict

By the contrapositive, we know that if a theory fails to meet either one of these conditions, that theory is not good, which is the point of the author's example:

/simple OR /predict → /good

It's not clear that we can make any other major inferences, so let's go ahead to the answer choices and proceed by elimination.

Prediction about the ███████ ██ ██████ ████████████ ████ ██ ████ ██ ███ ████ ██████████ ███████

This isn't the answer choice we're looking for. (A) must be true. Making predictions about the results of future observations is a necessary condition for a good scientific theory, according to the author.

Observation of physical █████████ ███ ███ █ █████ ███████ ██ █████████████ ████████████ ███████

(B) doesn't have to be true. Just because Aristotle's cosmological theory failed to make specific predictions about the results of future observations doesn't mean that his theory was not "concerned" with observing physical phenomena. It's possible his theory was concerned with observing physical phenomena, but only in terms of describing present phenomena or explaining past ones, not in terms of predicting future phenomena. So (B) is the answer choice we're looking for.

76%

Four elements can ██ ███ █████ ██ █ ██████████ █████ ████ ██ ██████ ██████ ██ ████ ███ ██████████ █████████ ██ █ ████ ███████

Correct. The author tells us directly that Aristotle's cosmological theory, which explained everything in terms of four elements, met the first criterion for a good theory. This tells us that a theory with a model based on four elements certainly can meet the simplicity criterion.

A scientific model ████ ████████ ████ ████████ ██ ███ █ ████ ███████

This must be true. This is a rare case where the LSAT focuses on the lower bound of "many." If you're confused, it might be because the LSAT usually uses "many" as generally equivalent to "some" but not necessarily equivalent to "most." But the key here is to remember the basic meaning of "few" as "some but not many." By extension, we can think of "many" as meaning "some but not few."

So if a scientific model has "many elements", it doesn't have "only a few" elements, as required by the simplicity criterion. So it fails to be a good theory. Thus, (D) must be true, and it isn't the answer choice we're looking for.

11%

Aristotle’s cosmological theory █████████ █ █████ █████ ██ ████████████ ██ █████ ██ ████ ████ █████████

Correct. The author directly tells us that Aristotle's cosmological theory meets the first requirement of the principle. This tells us for sure that Aristotle's theory must have explained a "large class of observations" in terms of a simple model based on "only a few elements" — and the author tells us that this model specifically used four elements.

PrepTest 14 - Section 1 - Question 9

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