LSAT 149 | Section 4 | Logical Reasoning: Q4

LR Question 4 Explanation

QUESTION TEXT: It has been hypothesized that our solar system was…

QUESTION TYPE: Necessary Assumption

CONCLUSION: The hypothesis that our solar system formed from a supernova is wrong.

REASONING: If we formed from a supernova, iron-60 would have been around in the early years of our solar system. But we didn’t find iron-60 in meteorites that formed in the early years of our solar system.

ANALYSIS: The stimulus said there would have been iron-60 present in the early solar system. So we can say “no iron-60 ➞ no supernova”

But the argument gives different evidence. The argument didn’t say there was no iron-60. It says we didn’t find iron-60, in a meteorite. There are two flaws:

1. Maybe iron-60 existed, but we just failed to find it.
2. Maybe iron-60 could have existed even if it didn’t leave traces in meteorites.

___________

1. This weakens the argument. It shows that meteorites don’t give us a good view of what was in supernovas.
   Negation: Meteorites contain exact what was produced by supernovas.
2. Who cares about other solar systems? We’re talking about our own solar system. 
3. Who cares about other forms of iron? The evidence is only about iron-60.
4. This isn’t relevant. The stimulus says that a supernova would have led to iron-60 early in the solar system’s history. Meteorites that formed late in the solar systems history can’t tell us about the early history of the solar system. Maybe the iron-60 in those meteorites only appeared in the later years of the solar system.
5. CORRECT. This is essential to the argument. If you negate it, then it’s possible that iron-60 existed in the early years of the solar system, even though we didn’t find it.
   Negation: We might not have found iron-60 in the meteorites, even if there had been iron-60 in the early years of the solar system.