Logical ReasoningDifficulty: Easy

PT139 S4 Q1 Explanation

Scientists generally believe that

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsMain Conclusion

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Stimulus

Scientists generally believe that no deep-sea creature can detect red light, but they need to reassess that view. Researchers recently discovered a foot-long deep sea creature of the genus Erenna with bioluminescent red lights on some of its tentacles. These red lights, which are fish, probably function as lures to attract prey.

What this question is testing

Main Conclusion

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
1.

Which one of the following most accurately expresses the overall conclusion drawn

Answer choices

  1. Intermediate Conclusion Last-Claim Trap2% picked this

    Red lights on the tentacles of a newly discovered deep-sea creature probably

    It's fair to call this a conclusion, because this idea is an opinion ("probably") and is supported (by the fact that the red lights resemble the shape of the food that some small fish usually look for), but this is not the main conclusion. The idea that these red-light tentacles are luring in small-fish is support for the author's main conclusion, that some deep-sea creatures can detect red light. Pun intended, they're luring us into picking this because it is a conclusion and because it's the final claim of the paragraph. (Remember, the conclusion can be the final claim on Main Conclusion, it just rarely happens so we want to be suspicious of ourselves when we're picking the final claim as the conclusion).

  2. Premise1% picked this

    Red lights on the tentacles of a newly discovered deep-sea creature are shaped like a common food source

    This looks nothing like the first sentence, so we shouldn't be bothering to read this carefully. If we do, we'll see it's basically stating one of the premises.

  3. Premise0% picked this

    A foot-long deep-sea creature of the genus Erenna has been

    This looks nothing like the first sentence, so we shouldn't be bothering to read this carefully. If we do, we'll see it's stating one of the premises. The fact that this claim is presented as something researchers recently discovered guarantees that it's not our conclusion.

  4. Opposing Position1% picked this

    Scientists generally believe that deep-sea creatures cannot detect

    This resembles the first sentence's language, but it's presenting the scientists' position. The main conclusion is the author's rebuttal: y'all need to reassess this view.

  5. Correct96% picked this

    Scientists need to reconsider the belief that deep-sea creatures cannot detect

    Why this is right

    This is the best match for our Main Conclusion, "they need to reassess that view": Scientists need to reassess (reconsider) the view (belief) that no deep-sea creature can detect red light.

    Skill tested: Main Conclusion · how this choice captures the argument's function is the move to repeat next time.

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