Unplugged Practice Test: Logical Reasoning Set 1, Question 7 (Flaw)
Taking the test? Finish it first. This page shows the answer.
- Flaw questions ask you to name the reasoning error the argument commits, not to judge whether its conclusion is true.
- Before you read the choices, describe the argument's error in your own words. Most Flaw questions reward 1 of a small set of recurring patterns, so naming the pattern first keeps the trap answers from sounding right.
- Every question on this test is original, written to the same logical skeletons as real questions, and Steve checked every one himself before release.
The question
Dmitri: The consultant who audited our network told me that switching to the Halvorsen encryption standard would sharply reduce our risk of a data breach, because that standard replaces its keys every hour instead of once a quarter. Renata: That is simply false. The consultant's firm is paid to install the Halvorsen standard.
7. Renata's argument is most vulnerable to criticism on the grounds that it
- (A)sets aside technically credible testimony solely on the ground that its source lacks formal credentials
- (B)assumes that a standard is defective if it is recommended without published test results
- (C)treats a recommendation as false solely on the ground that its source would profit from its adoption
- (D)rejects an explanation without offering any competing explanation in its place
- (E)draws a conclusion about why someone advanced a recommendation without establishing that it was in fact advanced
CWhy (C) is correct
Renata calls Dmitri's claim about switching to Halvorsen simply false, and her only reason is that the consultant's firm profits from installing that standard. She never engages with the actual point, that Halvorsen replaces keys every hour instead of once a quarter. A source's financial stake in a recommendation doesn't make the recommendation wrong: the firm could stand to gain and still be giving sound advice about key rotation.
Why the other answers are wrong
AWhy (A) is wrong
(A) doesn't fit because Renata never questions the consultant's credentials, she questions his motive.
BWhy (B) is wrong
(B) misses too: she never argues the standard lacks published test results, and she never raises testing at all.
DWhy (D) is wrong
(D) doesn't help. Even if Renata had offered a rival explanation for the breach risk, dismissing the recommendation purely for the profit motive would still be the flaw.
EWhy (E) is wrong
(E) fails because Dmitri already told her what the consultant recommended, so nothing here turns on whether a recommendation was actually made.
Common questions
What type of question is this?
Flaw. Flaw questions ask you to name the reasoning error the argument commits, not to judge whether its conclusion is true.
How do I get better at Flaw questions?
Before you read the choices, describe the argument's error in your own words. Most Flaw questions reward 1 of a small set of recurring patterns, so naming the pattern first keeps the trap answers from sounding right. The free LSAT cheat sheet lists the wrong-answer patterns to watch for on every type.
