Logical Reasoning

PT137 · S2 · Q20 Astronomer: Earth was bombarded

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Astronomer: Earth was bombarded repeatedly by comets and asteroids early in its history.

Conclusion

Life may have come to Earth from Mars.

Evidence

There was this period where Earth was getting pummeled by comets and asteroids and couldn't possibly support life. Meanwhile, Mars was in the clear. It could have had microbial life. Sometimes chunks of Mars fall off and fly over to Earth, so they could have served as the transport mechanism for these microbes.

Evaluate

The author is just pitching a theory here. Since there was a period way back when, during which Earth was inhospitable for life but Mars was good to go ... , simple microbial life may have actually started on Mars and then gotten randomly carried to Earth on top of a meteorite.

The claim they're asking us about is part of the author's Support.

The hypothesis is that

The claim that "Mars could have had microbial life" is a necessary assumption of this hypothesis. The author says it to establish the plausibility of her causal story.

Goal

Look for something sounding like

20.

Which one of the following most accurately describes the role played in the astronomer's argument by the statement that there could have been microbial life on Mars prior to there being such life on Earth?

  1. It is a claim for

    Opposite: Justification is Provided

    This is a mean answer. This claim is necessary for the conclusion that "life on Earth could have come from Mars". But there was justification provided. In fact, we can even see that this claim was prefaced by the word "so", indicating that the claim is a conclusion. Why should we believe that there could have been microbial life on Mars? Because Mars was not getting pummeled by comets and asteroids.

    6% picked this

  2. It is a claim for

    Opposite: Justification is Provided Not Sufficient

    This claim is not sufficient. The fact that there could have been microbial life on Mars does not prove that "life on Earth could have come from Mars". And there was justification provided. In fact, we can even see that this claim was prefaced by the word "so", indicating that the claim is a conclusion. Why should we believe that there could have been microbial life on Mars? Because Mars was not getting pummeled by comets and asteroids.

    3% picked this

  3. Correct

    It is a claim for

    Why this is right

    Is there justification provided for the idea that microbial life could have started on Mars? Yes, that's why it's wearing the word "so", which is a conclusion indicator. The support was the previous fact, that Mars was not getting ravaged by incoming objects. Is this claim required for the conclusion? Yes, try negating it: if "microbial life couldn't have started on Mars" would that hurt the author's story? Of course! The meteorite delivery service from Mars to Earth would be carrying no packages of life.

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

    61% picked this

  4. It is a claim for

    Not Sufficient

    The first half is true, as we've discussed in (A), (B), (C). The second half is not, as we've discussed in (B). Knowing that "microbial life could have started on Mars", does not establish the certain truth of "life on Earth could have started with microbes delivered via meteorite from Mars".

    16% picked this

  5. It is a claim that

    Is Necessary

    It does provide support for the conclusion. It isn't sufficient. But it is necessary, as discussed in (A) and (C).

    14% picked this

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