PT69.S4.Q09 - archaeologists are currently analyzing plant remains

FerdaFresh

This is for the Ultimate and Ultimate+ers out there. I wish I could provide the link, but I don't have access to it...

Here's the deal. Sentence 1 we're given the context. Sentences 2 and 3 we're given separate conditional relationships.

I fell for trap answer (D), knowing fully well it was the "oldest trick in the book" (i.e. switching sufficient and necessary conditions), but still believing it was MSS. I knew it was weak, and I gave (B) -- the accredited response -- another look-over before committing to my answer, ultimately rejecting (B) because I felt like the conditional relationship from sentence 3 did not suggest unique use of plants.

(B): the people in question used plants in a unique way at the time

Sentence 2's conditional: If plants were cultivated --> the people discovered agriculture before anyone else
(yes, this would be unique)

Sentence 3's conditional: If plants were uncultivated --> the people ate a wider variety of plants than did any other people at the time
(unique? questionable...)

Here's my issue with sentence 3's conditional and thus its support for (B) -- let's say there's 5 different plants. In the whole world. 5 plants. Let's say the people in question ate 4/5 of those plants and everyone else in the world ate 1/5 of those plants. However, in my "LSAT bubble" brain, I did not conflate this scenario with saying that, of the people around the world eating 1/5 plants, none of them altogether ever ate any one of the 4/5 plants these people ate (e.g. the people in question ate plants 1, 2, 3, and 4; another group ate plant 1; another group ate plant 2; another 3; another 4; heck, another group ate 5, the elusive plant that the people in question did not have).

Thus, (B) would not be true. Granted, this is a MSS question, which means that I have incorrectly gauged the plausibility of (B) and (D) by assuming (D) is more likely in my thought experiment. My question, above simply "why is (B) the right answer" (which is still at the heart of my question), is why is (D) wrong? Are all answer choices for MSS questions that flip sufficient and necessary conditions traps? Or does the context make (D) wrong in this case?

https://7sage.com/lsat_explanations/lsat-69-section-4-question-09/

NotMyName

I just took this PT last week! I got it right despite an initial weariness of the language in B (just like you had) because logically, the others receive NO support whatsoever. I chose B and moved on.

It doesn't sound like you fully believe D is unsupported. It's not even weakly supported or kind of supported. It received zero support. That's because we have zero information about what happens when its known that these people "discovered agriculture..." since, as you say, this is a necessary condition. D says "Discovered ag before everyone --> Remains of cultivated plants". That is saying that unless we find remains of cultivated plants, then these people did not discover ag before everyone. But the stimulus doesn't say that at all! Think about what would be needed to make such a claim; these archeologists would need SOOO much evidence to rule out EVERY other piece of support for "discovered ag before everyone" leaving only this final piece so that if we rule it out, then it could not be the case that these people discovered ag before everyone else.

Do you see how bad that is? If it doesn't seem as wrong to you as it's described above, then you may not fully understand the significance underlying switching necessity for sufficiency. If that's the case, no problem! Go back and study it. Create your own examples. Have discussions on this forum and in question comments. But whatever you do, don't avoid this gap! It will burn you over and over again in the future.

As for B, I actually did not see the logical danger you're speaking about but you are raising a valid concern. However, we know that there are likely far, far more than 5 plants and so it could be the case that no other people were eating one of the plants that these people ate. The assumption to get there is not so big; especially when we consider the other ACs. Comparing assumptions is key here. I see the gap you are talking about, and there is a gap, but when we compare this gap to the gap in D, it is like comparing a sidewalk crack to the grand canyon. And then we recall that this is MSS...

FerdaFresh

@jkatz1488 thanks so much for your post. Maybe I need to refresh my knowledge on a more intuitive level. Mechanically, I know we can't infer anything from the necessary onward. But, when not thinking in terms of sheer lawgic, that's a weakness of mine that clearly got exploited in this question.

"sidewalk crack to the grand canyon" I like that XD. You know, even from a "common sense" perspective, I'm starting to see why expecting the plants to remain cultivated over thousands of years (if they even were to begin with) is still way more of an assumptive leap than assuming these people ate a unique kind of plant. This was a great question to learn from, and your response was excellent to learn from too.