Logical Reasoning

PT135 · S1 · Q11 Inspector: The only fingerprints

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Inspector: The only fingerprints on the premises are those of the owner, Mr. Tannisch.

Conclusion

Whoever has the diamonds belonging to Mr. Tannisch's guest must have worn gloves.

Evidence

Mr. Tannischs fingerprints are the only ones at his house.

Evaluation

The flaw here is overconfidently deciding on one causal possibility. Who says they used gloves? Maybe they fished for the diamonds with a long candy cane! More plausibly, why are we letting Mr. Tannisch off the hook? Shouldn't he be the primary suspect?

Goal

Look for an answer with a curious fact, and a conclusion in which the author reaches some specific causal hypothesis while failing to consider a possibly more obvious possibility.

11.

Which one of the following exhibits a flaw in its reasoning most similar to that in the inspector's reasoning?

  1. Correct

    The campers at Big Lake

    Why this is right

    There is a curious fact, "why did everyone at camp get sick", a leading suspect "they've only eaten at the cafeteria", and then a conclusion that bizarrely ignores this suspect and looks elsewhere.

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

    76% picked this

  2. The second prototype did not

    Bad Conclusion Match

    The original conclusion was sure of itself. That was the flaw. This conclusion is super softly worded. It's pretty reasonable to say a curious fact might be explained by a given causal hypothesis.

    3% picked this

  3. Each of the swimmers at

    Not Part to Whole

    This commits a part to whole flaw: because each swimmer loses most of the time, the author concludes that the no one from the batch is likely to win. The original argument wasn't a Part to Whole flaw; it was a Causal flaw.

    2% picked this

  4. All of Marjorie's cavities are

    Plausible Hypothesis

    This has a curious fact and arrives at a certain causal conclusion, but this doesn't match the original argument because this conclusion actually calls out the leading suspect. Since all the cavities are on the left, the hypothesis that she eats more on that side is the more obvious possibility.

    17% picked this

  5. All of these tomato plants

    Bad Conclusion Match Not Comparison Flaw

    This conclusion is conditional, whereas the original argument's conclusion was causal. This argument is making a comparison flaw: what was true of tomato plants will also be true of pea plants. The original argument make a causal flaw.

    1% picked this

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