LSAT 158 | Section 2 | Logical Reasoning: Q14

LR Question 14 Explanation

QUESTION TEXT: Unlike stars, planets do not generate light …

QUESTION TYPE: Flawed Reasoning

CONCLUSION: There are objects in the galaxy that generate light but are not stars.

REASONING: Stars generate light, planets do not (they only reflect it). There are celestial objects that are neither stars nor planets.

ANALYSIS: The author splits things into planets and “other celestial objects,” then treats that second group as if it must contain light-generating objects.

But slow down. What do we actually know? Only that planets don’t generate light. We are never told that planets are the only things that don’t generate light.

So the author is assuming a clean divide: planets = no light, everything else = generates light. That’s the problem. There could be other celestial objects that also don’t generate light, which would break the conclusion.

___________

1. This allows us to infer something about reflecting light, but we care about generating light.
2. The whole argument is only about this galaxy, so it doesn’t matter what’s happening in the rest of the universe.
3. Similar to B, we only care what happens in this galaxy. So it doesn’t matter that there’s other things out there.
4. Great. But the argument is only about this specific difference.
5. CORRECT. If some other objects also do not generate light, then the conclusion is wrong.