Logical Reasoning

PT130 · S3 · Q24 The asteroid that hit the Yucatan Peninsula

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The asteroid that hit the Yucatán Peninsula 65 million years ago caused both long-term climatic change and a tremendous firestorm that swept across North America.

Conclusion (hence)

We can’t say that the asteroid impact caused the T’s extinction.

Evidence

The asteroid impact caused a huge fire, and it caused climate change. We can’t prove that the fire caused T’s extinction, nor can we prove that climate change caused T’s extinction.

Evaluation

This is probably one where many students aren’t sure exactly what to call the flaw, but they could still think about the structure of the argument and make eliminations based on mismatches in the answers.

This argument is flawed because you can sometimes be sure that something had a certain effect, even if you’re unclear on the exact specifics of how. Say that someone dies in a helicopter crash.

You might not know whether they died on impact or died from the resulting fire, but you still know that the helicopter crash killed them.

Similarly, we might know that the asteroid impact killed off the T’s, even if we don’t know whether it was the fire or the climate change that ultimately did them in (maybe it was a combination of both).

This is a subtle variation of part vs. whole. We can’t say that either part of the asteroid’s impact killed the T’s, but maybe we can still say that asteroid impact as a whole killed the T’s.

Goal

X did thing A and thing B. We can’t prove that Z happened because of thing A. We can’t prove that Z happened because of thing B.

Thus, we can’t prove that X made Z happen.

24.

Which one of the following has flawed reasoning most similar to the flawed reasoning in the argument above?

  1. I know that one cannot

    Weak Premise Match / Weak Conclusion Match

    Almost. This is a part vs. whole flaw. Even if each person can’t move the piano alone, they might collectively have the ability to do so. We could match that with the asteroid example, by saying that even if neither the fire nor climate change could individually be assured to wipe out the T’s, they might collectively be able to do so. But the language of “I doubt that X and Y can do A” is not as good a match for “we cannot attribute Y to X” as the conclusion of D, which says “we cannot claim X caused Y”.

    3% picked this

  2. Since we are quite sure

    Not a Flaw / Bad Conclusion Match

    This is pretty sound logic. The conclusion is an either/or claim, whereas the original conclusion was not. So we have a pretty safe Conclusion Mismatch to use for elimination.

    1% picked this

  3. It has not been conclusively

    Weak Premise Match / Weak Conclusion Match

    Close. The premises sound similar to the original argument. We can’t prove the accident was specifically caused by speeding or by weaving, but we still might be able to say with confidence that the accident was caused by some combination of speeding and weaving. This only had two premises though. We’re missing a premise that says “thing X had effect 1 and effect 2”. And the language of the conclusion is stronger than that of the original. “We have conclusively proven X and Y were not the cause of Z” is a weak match for “We cannot attribute X as the cause of Z”.

    9% picked this

  4. Correct

    The flooding in the basement

    Why this is right

    We know the flooding did thing A and thing B. We can’t prove that thing A did Z (the fire), nor that thing B did Z. The author similarly concludes that we don’t know that the flooding did Z. But we may be fully convinced that the flooding cause the fire, through some combination of thing A and B.

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

    86% picked this

  5. We have good reason to

    Trap

    Not a Flaw / Bad Premise Match / Bad Conclusion Match This is pretty sound reasoning. This seems to take the original argument and flip it on its head, as it’s talking about things we can “prove”. It’s also missing the 3rd premise. It’s also creating a causal chain, which wasn’t present in the original argument: sun/moon → high tides → flooding.

    1% picked this

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