Logical ReasoningDifficulty: Easy

PT104 S1 Q11 Explanation

A local chemical plant produces

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

TopicsParallel Flaw

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Stimulus

A local chemical plant produces pesticides that can cause sterility in small mammals such as otters. Soon after the plant began operating, the incidence of sterility among the otters that swim in pesticides are definitely contaminating the river.

What this question is testing

Parallel Flaw

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
11.

Which one of the following arguments contains a flaw in reasoning that is similar to one in

Answer choices

  1. Bad Evidence Match Bad Conclusion Match2% picked this

    The bacteria that cause tetanus live in the digestive tract of horses. Tetanus is a highly infectious disease. Consequently it must be that horses

    There's no before/after curious fact in the evidence. The conclusion is not offering us an explanation for a curious fact. It's offering a predicted comparison. The flaw in this argument is that the conclusion compares horses to most other animals, but the evidence never told us whether most other animals also have the bacteria that cause tetanus living in their digestive tracts. So, the flaw here is Assuming a Difference, whereas the flaw in the original argument was Failing to Consider Alternate Explanations.

  2. Correct89% picked this

    A diet low in calcium can cause a drop in egg production in poultry. When chickens on a local farm were let out in

    Why this is right

    We identify a potential cause. This plant's pesticides can cause sterility. A low calcium diet can cause a drop in egg production. We show a before / after. When the plant started up, the otters soon got less sterile When the chickens went foraging, their egg production dropped We conclude that the possible cause is definitely the cause. The river where these otters swim is contaminated with those pesticides. The food the chickens foraged gave them a low calcium diet. And in both cases, the original argument and this argument are Failing to Consider Alternate Explanations.

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

  3. Bad Evidence Match3% picked this

    Animals that are undernourished are very susceptible to infection. Animals in the largest metropolitan zoos are not undernourished, so they surely must

    We identify a potential cause. This plant's pesticides can cause sterility. Being undernourished can lead to infection. We show a before / after? When the plant started up, the otters soon got less sterile The animals in the largest zoo are not undernourished. This answer goes off the rails with that second ingredient. In order for it to match, it should have been describing something that had gotten an infection. Then it could conclude, that the thing that got the infection clearly / definitely was undernourished.

  4. Not Causal at All5% picked this

    Apes are defined by having, among other characteristics, opposable thumbs and no external tail. Recently, fossil remains of a previously unknown animal were found.

    This is just about classifying some weird fossils. There's no cause/effect relationship identified in the evidence. There's no before/after relationship identified in the evidence. The conclusion isn't given us a causal storyline for how one thing caused another.

  5. Valid Logic Bad Evidence Match1% picked this

    The only animal that could have produced a track similar to this one is a bear. But there are no bears in this area

    The fact that the argument seems pretty valid already tells us this can't be a match. There is a causal claim in the evidence, but it's way stronger than what the original argument has: Pesticides can cause sterility in otters vs. Only a bear could cause this track If we had said, "ONLY pesticides can cause sterility in otters, then it wouldn't have been a flawed argument". So that's distinction is enough to kill this answer. There is also no before/after premise.

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