Logical Reasoning

PT151 · S3 · Q12 A recently discovered fossil

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A recently discovered fossil, which is believed by some to come from Archaeoraptor liaoningensis, a species of dinosaur, can serve as evidence that birds evolved from dinosaurs only if the entire fossil is from a single animal.

Conclusion (so)

The fossil does not provide evidence that birds evolved from dinosaurs.

Evidence

The fossil is a composite of bones collected from various parts of the discovery site.

And if the entire fossil is not from a single animal, then it can't serve as evidence that birds evolved from dinosaurs.

Evaluate

We're trying to prove that this fossil , so our first question is:

Did the evidence provide any rule, like "If such-and-such, then does not provide evidence"?

Yes! We have a rule saying,

Entire fossil is not → does not provide evidence from a single animal birds evolved from dinos

So to prove our conclusion that this fossil doesn't provide evidence, we must establish that .

Do we know anything about this fossil?

Yes, we know that the fossil is a composite of bones collected from various parts of the discovery site.

Goal

So, we need to be convinced that, .

12.

The conclusion drawn in the argument follows logically if which one of the following is assumed?

  1. The only paleontologists who believe

    Too Weak

    We need to establish that this fossil is not from a single animal, because that's the only way that we can prove that it does not provide evidence that birds evolved from dinosaurs. This is suggestive innuendo that "the only people who think it is an entire fossil seem to have confirmation bias ... thus, they're probably fooling themselves ... thus, it's probably not an entire fossil". But we can't prove the conclusion 100% just through innuendo. We need to know factually that the entire fossil is not from a single animal.

    1% picked this

  2. Correct

    If the fossil is a

    Why this is right

    This argument was missing a connective piece between premises. It used this familiar Sufficient Assumption argument structure. Conclusion A ------------------------> Z Evidence A ----> B Y -----> Z Missing link B ---------> Y Conclusion this ------------------------------> doesn't provide fossil evidence Evidence this ----> composite not from ---> doesn't provide fossil of bones 1 animal evidence Missing link composite ---> not from of bones 1 animal In conversational terms, we know that this fossil is a composite of bones. According to this answer, that means it has pieces of more than one animal. And we know that if an entire fossil isn't from a single animal, then it can't provide evidence that birds evolved from dinos. So, this allows us to derive the conclusion.

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

    94% picked this

  3. There are other fossils that

    Unrelated to Goal

    We need to establish that this fossil is not from a single animal, because that's the only way that we can prove that it does not provide evidence that birds evolved from dinosaurs. But this answer doesn't do that at all.

    1% picked this

  4. If the entire fossil is

    Out of Scope: well-preserved

    We need to establish that this fossil is not from a single animal, because that's the only way that we can prove that it does not provide evidence that birds evolved from dinosaurs. This answer is a conditional that would allow us to provide that it's not from a single animal: if not a well ? then entire fossil not preserved specimen from single animal Okay, do we know that this fossil is not a well preserved specimen? No, we don't. We know it's a composite of bones collected from various parts of the site, but we'd have to add our own additional assumption that, "if composite of bones from various parts of site, then not a well-preserved specimen".

    3% picked this

  5. The fossil was stolen from

    Unrelated to Goal

    We need to establish that this fossil is not from a single animal, because that's the only way that we can prove that it does not provide evidence that birds evolved from dinosaurs. But this answer doesn't talk about whether it was from a single animal at all.

    0% picked this

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