Self-study
https://classic.7sage.com/lsat_explanations/lsat-67-section-2-question-20/
I am having a lot of trouble seeing how C and D are not saying the same exact thing. Here is how I broke down the structure of the argument.
Premise: Mars escaped severe bombardment by asteroids.
Major Premise/Minor Conclusion: There could have been microbial life on Mars prior to there being such life on Earth.
Premise: Many meteorites originating from Mars have landed on Earth.
Conclusion: Life on Earth may have started when a meteorite carrying living microbes were carried here from Mars.
Most explanations for this question say that D is wrong because it does not establish the truth of the main conclusion, saying that just because there was life on Mars does not guarantee that a meteorite carried life from Mars to Earth. But the thing I am having trouble understanding is that both the minor conclusion and major conclusion account for the possibility that they are not true by using could/may. So in order for the both conclusions to be true, all you would need to show is that it is possible.
After all, if the minor conclusion is true, if there is a possibility that there was microbial life on Mars, isn't it certainly true that this allows for the possibility for a meteor to carry such life to Earth (which is what the main conclusion is).
Ugh I hate how LSAC expects us to assume certain things but not others under their whole "commonsense" guideline. I guess I made the unsafe assumption that de-icing roads counts as road maintenance and picked B.
This reminds me of another question where the stimulus talks about amphibian populations declining worldwide. The author tries to causally connect a depletion of the Earth's ozone layer to this population decline. Anyways the question stem was a strengthen except type. One of the choices was "The natural habitat of amphibians has not become smaller over the past century." and although I got luckily got this question right, I guess many people said that this answer choice does not necessarily strengthen the argument unless you make the assumption that populations are affected by habitat size. Apparently so many people made this mistake that LSAC had to come out and say that they believe that the average person accepts that habitat affects population size.
It's kind of frustrating to get questions wrong due to the "commonsense" rule. All your reasoning may be correct but just because your sphere of common beliefs didn't align with the testmaker's you got the question wrong. And also, you can't really learn from your mistakes with questions like these. I mean, now I know that LSAC believes that road maintenance does not necessarily include de-icing roads but when will that ever help me again unless there is another test question that deals with the exact same topic.
Does anyone have any advice on how to deal with questions that force you to choose between two assumptions and decide which one is not the bigger assumption? How do all you 175+ers do it?