Logical reasoning PrepTest 151 · Section 4 · Question 25

Incorrect. The conditional here features an OR in the necessary condition, so this answer isn't parallel.

Incorrect. The conditional here has a little bit of weirdness ("together with . . . "), and you could view that as a separate condition, which might be enough to eliminate this answer choice. However, ignoring that for a second, the premise after the conditional is about demand, which isn't a concept included in the conditional, so we can rule this answer choice out because it's invalid/it features a term shift not present in the stimulus.

Incorrect. The AND in the sufficient condition here makes this questionable from the get-go, but it also arrives at its conclusion by establishing the sufficient condition is present and concluding the necessary condition. That's different from the stimulus, where the necessary condition was negated to conclude the sufficient condition was also absent. (In other words, this answer directly applies the conditional instead of applying the contrapositive.)

Incorrect. This answer choice establishes a conditional, but then the premise negates the sufficient condition, not the necessary condition, so it features an illegal negation. It's flawed and not parallel.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Valid

Question Type:
Parallel Reasoning

Stimulus Summary:
Ecology and physical sciences judged by same criteria → not Ecology successful science
But: Ecology successful science
Therefore: not Ecology and physical sciences judged by same criteria

Answer Anticipation:
There's a lot of obfuscating language in here, but this Parallel Reasoning question starts with a conditional indicator word, so we should try to understand it using that type of logic.

When we do that, the argument establishes a conditional rule, and then it shows that the necessary condition isn't met (ecology is a successful science). From that, it concludes that the sufficient condition also isn't met (ecology and physical sciences aren't judged by the same criteria). There are a few other statements thrown in there as distractors, but let's find an answer that, at its core, brings up a conditional rule, and then uses the contrapositive to reach a conclusion.

Answer Explanation:
Economic theories adequate → Accurate forecasts. However, not Accurate forecasts, so not Economic theories adequate. This argument presents a conditional, negates the necessary condition, and concludes the sufficient is also absent. That's the same structure—application of a contrapositive—as the stimulus, and so this is the correct answer.

Key Takeaway:
When there's conditional logic in a stimulus, don't get distracted by extraneous information. Start by identifying the core of the conditional logic. You can take a look at those extraneous statements if more than one answer matches the conditional backbone of the question, but start with a pass on the answer choices just looking at the conditional logic. You'll frequently find, as you did here, that the conditional logic is enough to get to the correct answer.