Logical ReasoningDifficulty: Hard

PT8 S1 Q13 Explanation

Five years ago, during the

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

TopicsWeaken

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Stimulus

Five years ago, during the first North American outbreak of the cattle disease CXC, the death rate from the disease was 5 percent of all reported cases, whereas today the corresponding figure is over 18 percent. It 5 years, CXC has increased in virulence.

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
13.

Which one of the following, if true, most substantially weakens

Answer choices

  1. Opposite (if anything)20% picked this

    Many recent cattle deaths that have actually been caused by CXC have been mistakenly attributed to another disease that

    The idea that many recent cattle deaths from CXC have been misdiagnosed as another disease means there's even more death from CXC than we thought. That would if anything help the author argue, "See? CXC is getting so virulent." If this answer had said that a bunch of deaths that were from other causes were misdiagnosed as CXC, then that would have provided an alternate explanation for why the CXC death rate appears to have increased.

  2. No Impact11% picked this

    During the first North American outbreak of the disease, many of the deaths reported to have been caused by CXC were

    If we were being told that the old death rate was misleadingly low then that could offer an alternate explanation for why the death rate seems so high now. But this answer is saying that the old death rate was misleadingly high.

  3. No Impact7% picked this

    An inoculation program against CXC was recently begun after controlled studies showed inoculation to be 70 percent effective in preventing

    This option discusses an inoculation program that just started, so it has nothing to do with debunking the idea that virulence has increased or offering an alternate explanation for the uptick in the death rate.

  4. Correct57% picked this

    Since the first outbreak, farmers have learned to treat mild cases of CXC and no longer report them

    Why this is right

    If farmers have learned to treat mild cases of CXC and no longer report them, then today's reported cases would be skewed towards more severe and likely fatal cases. This would explain the increased death rate without implying the disease itself has become more virulent, as mild cases aren't reflected in the statistics, leading to an apparently higher death rate among the reported cases.

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

  5. No Impact4% picked this

    Cattle that have contracted and survived CXC rarely contract the disease

    This answer talks about disease recurrence, stating that cattle rarely contract CXC again after surviving it. This information doesn't affect the reported death rate's increase or undermine the increased virulence claim.

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