Logical reasoning PrepTest 146 · Section 2 · Question 16

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Argument Evaluation

Stimulus Summary:
Caffeine causes irritating stomach acid. Darker roasts cause NMP, which causes less stomach acid. Therefore, darker roasts irritate stomachs less.

Answer Anticipation:
This argument features causality and comparisons. However, the premises are causal, so this isn't a correlation/causation flaw. Since that flaw isn't present, we should focus on the comparisons.

Here, the stimulus does establish that darker roasts suppress the production of stomach acid, and stomach acid irritates the stomach. All other things being equal, that would mean that darker roasts irritate the stomach less. But that's a big caveat—all other things being equal. The stimulus hasn't established that the only relevant difference between darker roasts and lighter roasts as far as stomach irritation is concerned is the NMP and stomach acid system. In evaluating if this will result in less irritation overall, it'd be helpful to know if there are other differences between darker and lighter roasts that would be relevant in this comparison. And the stimulus even suggests one for us—caffeine causes acid to be produced, so is the caffeine content higher in darker roasts?

Answer Explanation:
If extending the roasting time increases the caffeine content, and caffeine causes irritating stomach acid to be produced, it's possible that the increased caffeine content could balance out the NMP production. If the caffeine content doesn't increase (or goes down), then the conclusion is looking better. The answer to this question would help evaluating that overall balance by providing information about another potential point of comparison relevant to the conclusion.

Key Takeaway:
When one difference between two items is used to justify another conclusion comparing the two items, be sure that the argument has left open the possibility that there's another relevant difference that could create issues for that conclusion. Especially when the argument itself has already established another relevant factor!

Incorrect. The conclusion is about stomach irritation, not stomach function. Without information connecting stomach dysfunction leading to irritation, this answer is out of scope.

Incorrect. Without knowing the relative caffeine content of darker and lighter roasts, this answer is out of scope.

Incorrect. Without knowing the balance of impact of the darker roasts on a stomach, there's no way to know if this is relevant. It's possible the NMP production is such that drinking darker roast coffee actually helps settle a stomach! Or it's just not as bad as lighter roasts. Or, even, that it's worse.

Incorrect. The conclusion is limited to the impact on stomach irritation, so other health benefits are out of scope.