Logical reasoning PrepTest 127 · Section 2 · Question 15

Incorrect. Immanuel's lab is a complete side note in this argument—it's unrelated to the conclusion or the reasoning behind that conclusion. Since the size of labs is only mentioned in relation to Immanuel's needs, this answer is out of scope.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:

(1) Agnes approved → Clean 4th floor lab
(2) Immanuel approved → Keep working on 2nd floor
(3) Approved → Director supports
(4) Director supports Agnes and Immanuel

Therefore: Clean 4th floor lab

Answer Anticipation:
There's a lot of conditional language in this argument, and so your first thought should have been about a conditional logic flaw—either an illegal reversal or negation. Seeing that (and which one it is) would require diagramming out the conditionals, most of which are straightforward. Most.

This entire question comes down to one challenge—diagramming that third conditional. If you diagrammed it incorrectly, then the argument is valid, and you'd have a hard time finding a flaw! If you properly identified "Only" as introducing a necessary condition and diagrammed the argument out correctly, it's much easier to see that this argument is committing an illegal reversal. The argument treats the Director's support of Agnes's proposal as guaranteeing it will be approved and thus the 4th floor lab would need to be cleaned. However, the conditional establishes that the Director's support is necessary—not sufficient—for approval. The correct answer should highlight that reversal.

Answer Explanation:
This answer doesn't abstractly describe an illegal negation, but it does describe the practical implications of it. If the director's support is necessary but not sufficient, then a proposal could be rejected despite having that support—as opposed to if it were sufficient. Since this is the reversal that the argument makes, this is the correct answer.

Key Takeaway:
Conditional logic in an Errors in Reasoning question will usually lead to a conditional logic flaw—an illegal reversal or negation. However, especially as you get further into the section and face harder questions, dig in to make sure that there is a conditional logic flaw and get an idea of which type it is so that you can get the correct answer. While most Errors in Reasoning questions with conditional logic have a conditional logic flaw, not all do.

Incorrect. The Director's enthusiasm is not noted as being relevant in considering the proposals.

Incorrect. As in (A), Immanuel is out of scope of the conclusion of the argument. His feelings after approval are, in particular, out of scope, since there's no note that he can change anything at that point.

Incorrect. The premise establishes that Agnes's proposal being approved will result in her using the 4th floor lab, so other labs that could accommodate her are out of scope.