Logical ReasoningDifficulty: Easy

PT155 S1 Q1 Explanation

Advertisement: Omnicide kills more

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

TopicsWeaken

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Stimulus

Advertisement: Omnicide kills more species of insects than any other insecticide. So Omnicide is the best insecticide for home gardeners, especially gardeners who are destroying their plants.

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
1.

Which one of the following, if true, most weakens the reasoning in

Answer choices

  1. No Impact4% picked this

    Some of Omnicide's competitors kill almost as many species of insects

    This is saying that one of the competitors is almost as good as Omnicide when it comes to one good thing we know about Omnicide (kills the most types of insects). Since the competitors are almost as good, they're still not as good as Omnicide, so this doesn't go against the author's claim that Omnicide is the best option.

  2. Correct92% picked this

    Many insect species are beneficial to garden plants, and Omnicide kills most of

    Why this is right

    This points to a bad thing about Omnicide -- it will kill most of the insect species that are beneficial to garden plants. Since this is a negative thing about Omnicide, and since we can presume that other insecticides would have less of this negative (since they kill a more limited spectrum of insects), this hurts the author's claim that Omnicide is the best option. Sure, it might kill the mystery insects that are messing up the garden, but it will also kill most of the beneficial insects that are helping the garden, so the garden may end up worse off overall.

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

  3. Too Weak / No Distinction2% picked this

    Merely protecting plants from attack by insect pests does not guarantee that the plants

    This is incredibly weak (X does not guarantee Y), and weak answers are almost always wrong on Strengthen, Weaken, Paradox, and Sufficient Assumption. Scoring a 180 does not guarantee you'll get into Harvard. Does that mean a 180 isn't the best score you can get? Of course not. So saying that "killing off all the pests doesn't guarantee healthy plants" doesn't in any way indicate that "killing off all the pests isn't the best strategy". This answer is just acknowledging you also need to give your plants light and water. Merely protecting them from pests isn't enough. This answer also provides no distinction between Omnicide and other pesticides, all of which are designed only to protect against pests., so it wouldn't provide a reason for thinking Omnicide isn't the best choice.

  4. No Impact0% picked this

    Omnicide is more profitable for the manufacturer than most other insecticides made by

    The fact that the company who makes Omnicide has a higher profit margin on this insecticide than it has on other insecticides they make has nothing to do with a consumer's decision about whether Omnicide is the best option for their garden.

  5. No Distinction / No Impact2% picked this

    Omnicide does not kill weeds or mammalian pests such as gophers,

    Similar to (C), this conveys the idea that an insecticide is not a cure-all. You still have to worry about food, water, sunlight, weeds, and mammalian pests. But all we're doing here is picking an insecticide. The job of an insecticide, as the name suggests, is to kill insects. We wouldn't hold it against Omnicide (or any other insecticide) that it's fails to kill weeds and mammals. This answer, like (C), would apply equally to all insecticides, so it doesn't give us a reason to choose an insecticide other than Omnicide.

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