Logical ReasoningDifficulty: Easy

PT134 S1 Q8 Explanation

According to the

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

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Stimulus

According to the "bottom-up" theory of how ecosystems are structured, the availability of edible plants is what primarily determines an ecosystem's characteristics since it determines how many herbivores the ecosystem can support, which in turn determines how many predators it can support. This theory also holds that have little impact on the rest of the ecosystem.

What this question is testing

Weaken

Your task

Find the choice that makes the argument's conclusion less likely to be true.

Common trap

Answers that look negative but attack a claim the argument never relied on.

Winning move

Find the assumption the argument depends on, then pick the choice that undermines it.

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

The question
8.

Which one of the following, if true, would provide evidence against the

Answer choices

  1. Strengthen1% picked this

    In an effort to build up the population of a rare species of monkey on Vahique Island, monkeys were bred in zoos and released

    This supports the bottom-up theory because it shows that the number of edible plants can impact the rest of the ecosystem.

  2. Correct84% picked this

    After hunting virtually eliminated predators on Rigu Island, the population of many herbivore species increased more than tenfold, causing the density of

    Why this is right

    This provides a counterexample to the theory and shows that a reduction in the number of predators had a significant impact on the rest of the ecosystem.

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

  3. Strengthen5% picked this

    After many of the trees on Jaevix Island were cleared, the island's leaf-cutter ants, which require a forested ecosystem, experienced a substantial decrease in

    This supports the bottom-up theory because it shows that the number of edible plants can impact the rest of the ecosystem.

  4. Strengthen5% picked this

    After a new species of fern was introduced to Lisdok Island, native ferns were almost eliminated. However, this did not affect the population of

    This supports the bottom-up theory because it provides an example of the ecosystem depending on the number of edible plants.

  5. Too Weak4% picked this

    Plants that are a dietary staple of wild pigs on Sedif Island have flourished over the last three decades, and the population of the

    While this seems to decouple the relationship between the number of edible plants and pigs, it only shows that an increase in edible plants does not always result in a larger population of an animal that feeds on that edible plant. This has no impact on the assertion that a decrease in predators would have little impact on the rest of the ecosystem, since Jaevix Island did not experience a reduction in the number of predators.

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