QUESTION TEXT: Geologists recently discovered marks that closely resemble…
QUESTION TYPE: Weaken
CONCLUSION: The marks are probably from a geological process, and not from worms.
REASONING: The marks are earlier than any known traces of multicellular life.
ANALYSIS: This question has a flaw that’s common on LSAT questions that involve time: it mixes up the difference between the earliest existence of something, and the earliest evidence of the existence of something.
Something can exist even if we haven’t found evidence yet. Evidence is hard to come by, especially when we’re searching for evidence of events that happened billions of years ago.
So it’s possible the worms existed back when the tracks were made, even though we have no other evidence they existed. Note also that the argument has given no evidence that geological processes can make patterns that look like worm tracks.
___________
- This is irrelevant. The stimulus says that we were able to figure out the date of the sandstone in question. So it doesn’t matter if it’s sometimes not possible. This time it was possible!
- This strengthens the argument by showing it’s possible for geological processes to leave many kinds of marks. We’re trying to weaken the argument.
- If anything, this strengthens the argument. It shows that even if life existed back then, the marks might have been made by other life forms, not worms.
- CORRECT. This eliminates geological processes as a possible cause. This doesn’t prove that worms were the cause, but this certainly weakens the argument that geological processes were the cause.
- This has no impact. We have no evidence that any life existed at the time the marks were made. Yes, worms were among the earliest life forms, but they still might not have existed back at the time the marks were made. Maybe no life did!
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MemberPeng Han says
Hi! I am not sure how C strengthens the argument.
In introducing an alternate explanation, an answer choice would weaken the argument. But the problem with C, I think, is that it actually cannot explain the source of marks found, because those early life forms known to have left similar marks at most are among the earliest known life, otherwise we would not have studies and known about their marks. Therefore, answer choice C cannot weaken the argument.
But can we strengthen this argument by saying other life forms and worms could both have left the marks?
TutorLucas (LSAT Hacks) says
I’d agree that it’s difficult to argue that this strengthens the argument. However, I think the primary reason we can say that (C) doesn’t weaken the argument is that the answer choice still does not address the issue that the marks were made half a billion years earlier than the earliest known traces of multi-cellular animal life. So, it’s still more likely that the marks were caused by geological processes rather than worms.
Hannah says
What I find confusing here though is that the argument specifically says multi-cellular ANIMAL life, which does not exclude other forms of life! Answer choice C explicitly says other forms of life, so this could be bacteria for instance. So, answer choice C provides an alternate explanation to the geological one that still fits with the information in the stimulus. I can understand why answer choice D makes since, but I still don’t get why C is wrong.
FounderGraeme Blake says
The conclusion excludes other forms of life though. The final sentence says “worms probably didn’t make these marks.”. So if anything else makes the marks, that supports the arguments. This includes geological processes, other life forms, etc.
Note: This is an old comment but I wanted to clarify the point.