PrepTest 153

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Argument Structure

Stimulus Summary:
An astronomer concludes that our solar system is probably more favorable to life than most. That's because life depends on elements heavier than hydrogen and helium, and our sun has more of those elements than most comparable stars of the same age.

Answer Anticipation:
The statement whose role we're looking for supports the conclusion that our solar system is extra friendly to life, and nothing else in the stimulus supports our statement. That makes it a premise. Look for an accurate description of a premise. The correct answer may also mention that this premise by itself isn't enough to support the conclusion. We need the other premise as well.

Answer Explanation:
Right up front, this is the textbook definition of a premise: a "because I said so" from the author that helps to support the conclusion. It's also correct that there's only one conclusion here.

Key Takeaway:
Argument Structure questions sometimes catch LSAT students unawares simply by making the correct answer so linguistically unwieldy it's hard to convince yourself to choose it. The cure for that problem is anticipation. If you're anticipating correctly, you'll know that you can only choose an answer that describes the correct part of an argument, no matter how it's worded.

Incorrect. No, the premise we've singled out isn't directly supporting the other premise. Ask yourself why we believe that the sun has more of these elements. "Because the author said so," not because the other premise supports it. (That would be a subsidiary conclusion, which we don't have in this argument.)

Incorrect. This describes a subsidiary conclusion, which this premise is not. It doesn't receive direct support from any other component of the argument.

Incorrect. No, the conclusion is that our solar system is unusually favorable to life.

Incorrect. There's only one conclusion in the argument, and our role statement isn't it.