QUESTION TYPE: Role in Argument
CONCLUSION: Life on Earth may have started when a Martian meteorite carried microbes to Earth.
REASONING: Earth used to be sterile. Mars could have had life at that time. Many meteorites from Mars bombarded Earth.
ANALYSIS: I couldn’t prephrase this one. I scanned the answers and saw there were two questions:
- Was there justification for saying that there could have been life on Mars?
- Was life on Mars necessary, sufficient or neither for the argument’s conclusion?
The justification for the claim is that Mars wasn’t sterilized. Mars could have had life.
This is a necessary condition for the argument. Mars couldn’t send life unless Mars had life. But it’s not sufficient. Just because you have life doesn’t mean you would send it.
- There is some justification. We know Mars wasn’t sterilized by asteroid bombardment. That’s not proof that Mars did have life, but it’s evidence Mars could have had life. The second half of this answer is right.
- This has the same problem as A, and the second half is wrong too. Even if Mars could have had life, that doesn’t ensure that a meteorite would have carried it to Earth.
- CORRECT. The justification is that Mars was not sterilized by bombardment. The fact that Mars could have had life is necessary. Otherwise how could Mars have sent life to Earth?
- The first part is a bit strong. The language in C (‘some justification’) is better. The argument didn’t prove this point very well. Second, the conclusion is not justified. The fact that Mars might have had life doesn’t establish that the life could have reached Earth.
- Wrong. The possibility of life on Mars is definitely required for the argument’s conclusion. If there were no life on Mars, how could Mars have sent life to Earth?
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