Logical reasoning PrepTest 125 · Section 2 · Question 22

Incorrect. If there's evidence that the majority opinion of experts is wrong, then there's nothing wrong with reaching a conflicting conclusion. That doesn't happen here—there's evidence only that their conclusion is unsupported.

Incorrect. Here's the trap answer that we noted would be wrong because the conclusion is qualified. The argument doesn't assume the Professor's claims are true. Rather, it qualifies the conclusion as applying if the Professor's claims are true. Without that qualification, this answer would be correct.

Incorrect. The argument doesn't need to establish what, exactly, constitutes sufficient evidence since it establishes that if Professor Vallejo is correct, the evidence is insufficient. It doesn't matter how it's insufficient, just that it is.

Incorrect. The final sentence establishes that the majority view is the traditional view, so there's no mistake here. If the argument switched between discussing two different views, then this answer could be correct.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Most historians - Glassblowing began in Egypt
Prof. Vallejo - There's not enough evidence to reach that conclusion
Conclusion - If Prof. Vallejo is correct, glassblowing originated outside of Egypt

Answer Anticipation:
This question is interesting in what it can teach us about a specific flaw on the LSAT, so it's a good one to review!

As with all Errors in Reasoning questions, we should be reading the argument looking for specific elements that tend to be flawed. Here, we see three elements that require more exploration—the qualified nature of the conclusion, the reliance on supposed experts, and the way that the opposing viewpoint (most historians) is addressed.

For the first, the conclusion is based on Professor Vallejo being correct. In this case, that doesn't introduce a flaw but rather eliminates a flaw. Without that qualification, the argument would be assuming that Professor Vallejo's argument is correct. Since it qualifies its conclusion by stating it only applies if Prof. Vallejo is correct, it avoids that flaw.

For the second, there's no reason to believe that anyone involved isn't an appropriate authority. In fact, we can eliminate this flaw as being present with the same reasoning as the preceding paragraph. Since the conclusion is explicitly based on Professor Vallejo being correct, it's not inappropriately relying on expert opinion—it's stating if this Professor is correct, then here's the implication.

For the third, it's important for us to track all three viewpoints—most historians, Professor Vallejo, and the Student. It's easy to conflate the latter two, but they're different in an important and relevant way. The Professor concludes that there's "insufficient evidence" to reach the conclusion that most historians reach. However, the Student goes a step further—the conclusion of most historians is wrong (they say glassblowing originated in Egypt, but it didn't—it originated elsewhere). Since that conclusion is based only on the argument of Professor Vallejo, the Student is jumping from evidence that a conclusion isn't fully supported to one that says it's wrong. That's an absence of evidence flaw, so let's find an answer reflecting that.

Answer Explanation:
This answer reflects the absence of evidence flaw. Professor Vallejo claims that there's insufficient evidence for the conclusion; the Student concludes from that that the conclusion is wrong and glassblowing must have originated elsewhere.

Key Takeaway:
When the conclusion of an argument reaches the opposite conclusion of the opposing point, there's a chance that you're dealing with an absence of evidence flaw. If that main point is based on a shortcoming in the opposing point, then that flaw is present.