#14 - Geologists recently discovered marks that closely

[lsatstudy2023]

Correct me if I'm wrong; I see why D is correct after eliminating other choices.

What has me confused though is how exactly D weakens in the sense that the stimulus says "probably" not that it is 100% sure that it is a result of geographical processes. So if D is saying that kind of geographical process could not have existed, all it does is introduce a new cause.

My question is does it really weaken the probability of it being geographical processes?
I'll try to come up with an example:

The probability of sugar causing diabetes is 85%
The probability of family history causing diabetes is 70%
Conclusion: The probability of sugar causing diabetes is more than family history.

If I were to weaken this and there is an answer choice that says, the probability of physical inactivity causing diabetes is 90%, does this have an overall effect on the probability of sugar causing diabetes?
I really do not think it does because it introduces a new cause, but does not undermine the probability of sugar causing diabetes compared to family history.

(I hope this question and example makes sense; If it does, I would appreciate your help.)

Thank you as always!!!

[Luke Haqq]

Hi lsatstudy2023!

You ask,

What has me confused though is how exactly D weakens in the sense that the stimulus says "probably" not that it is 100% sure that it is a result of geographical processes. So if D is saying that kind of geographical process could not have existed, all it does is introduce a new cause.

My question is does it really weaken the probability of it being geographical processes?

Yes, answer choice (D) weakens the conclusion that "the marks are probably the traces of geological processes rather than of worms." Answer choice (D) is saying that geological processes couldn't possibly have caused the marks (it states that the only geological processes that could have done this could not have occurred when these marks were made).

If geological processes couldn't have possibly caused the marks, then the marks are definitely --not-- the traces of geological processes rather than of worms. In this way, answer choice (D) weakens the conclusion that the marks "are probably the traces of geological processes rather than of worms."

[shibascream]

I selected (E) for this question and I'm having a hard time understanding why it's wrong. I tend to do very poorly on Strengthen/Weaken questions in general so I want to make sure my understanding/approach to this question is sound.

I was between answer choices (E) and (C). The main reason given for the author making the conclusion that geological processes instead of worms made the markings was that there was a timing issue-- the worms couldn't possibly have made the markings because there's no *evidence* of there being multicellular life (i.e. worms) at the time the markings were made. However, just because there is *no evidence* of something having existed at a certain time doesn't mean that it didn't, right? Answer E seems to point out this flaw by leaving open the possibility that multicellular life (including worms) could've indeed existed far earlier than recorded and in fact did exist during the time the markings in the sandstone were made and the only reason there's no trace of their existence during this time is because they are made entirely of soft tissue and therefore do not readily create fossilized remains. Although this doesn't definitively prove that the worms made the markings instead of geological processes, I felt like it cast enough doubt on the timing issue given to reach the conclusion that it served the purpose of answering a Weaken question. In my understanding, the correct answer to a Weaken question doesn't have to completely destroy the argument but merely cast doubt on the argument. Anyway, there must be something wrong with my reasoning in the question and I would really appreciate some help in pointing it out, thank you!!

[attorneyatpaw]

commenting to follow

[Jeff Wren]

Hi shibascream,

First, if you haven't already done so, I'd recommend reading the earlier comments on this forum post as there's been some good discussion specifically on Answers C, D, and E.

Unfortunately, neither Answer C nor Answer E resolves the 500 million year time gap that is mentioned in the stimulus. The stimulus states that the markings "were made more than half a billion years earlier than the earliest known traces of multicellular animal life." Notice that this isn't claiming that the marks more that half a billion years before worms specifically, but all multicellular animal life.

Answer C simply states that were other life forms besides worms that made marks similar in appearance to the markings on the sandstone, but this doesn't resolve the time problem because those other life forms may not have existed at time the markings on this sandstone were made.

Answer E states that "worms are likely to have been among the earliest forms of multicellular animal life," but the stimulus tells us that the earliest traces of any multicellular animal life was half a billion years later than the markings were made. The fact that evidence of "their" (meaning the worms) earliest existence is scarce does not mean or imply that the worms were around 500 million years earlier than the earliest known traces of any multicellular animal life.

Answer D, on the other hand, directly attacks the notion that geological processes could have made the markings and most directly weakens the conclusion.

While it is true that the correct answer to a weaken question does not need to completely destroy the argument, but only cast doubt on the conclusion, you do need to select the best answer, the one that weakens the argument the most, so you need to compare the answers to each other.