Q23 - Some vegetarians have argued

[pgerretsen]

How is this D? How does the health benefit make it so the other argument is not sufficient?

Thanks.

[bbirdwell]

I'm not sure I understand your question, so I'll just explain the argument as a whole and see if that helps.

Some vegetarians... (At this point I am already anticipating a "BUT these vegetarians are stupid and wrong" statement and I'm actively looking for this two-sided structure. If you haven't noticed already, this happens on almost every single question on the test in one form or another -- use that to your advantage.)

Some vegetarians say there are two reasons for not eating meat:
health, and "conscious creatures."

BUT... (here it is)... If meat were essential --> less clear that "conscious creatures" is a good reason not to eat meat

So this is kinda funky, right? The conditional statement at the end is sort of confusing. I'm not going to take the bait, though. I'm gonna pay attention to structure instead of getting sucked into the details, and quickly get right answer instead of wasting my time "over-reading."

Why does the author mention "meat = essential?" To support his argument that the vegetarians are wrong! That's all I need to know!

(D) says this clearly. "It's used to weaken the vegetarians' claim." Yep. Without a doubt.

Does that help?

[tzyc]

So...(A) is wrong because "disprove" is too strong, right
Thank you

[ManhattanPrepLSAT1]

So...(A) is wrong because "disprove" is too strong, right
Thank you

Exactly. Notice that the argument goes on to say that "it would be less clear that [one of the reasons to not eat meat offered by the vegetarians is correct]."

So while the vegetarian's claim is weakened, it is not completely proven false.

[contropositive]

so does disprove mean that they compeletly prove it to be false?

can you give me an example of disproving and weakning because i feel as though they are the same.

[ohthatpatrick]

Yes, exactly.

“Disprove” or “refute” means to prove wrong.

“Weaken” / “undermine” / “call into question” / “impugn” / “cast doubt upon” means to increase doubt or lessen plausibility.

Say that my friend Bob has a theory that his girlfriend Karen went out to see a movie last night.

To DISPROVE his theory, we have to prove that Karen did NOT go out to see a movie last night.

To WEAKEN his theory, we just have to say anything that makes us LESS inclined to believe she saw a movie.

Examples of disproving:
- Sarah was at her house all night with Karen.
- Karen died mid-afternoon yesterday.
- Karen has never seen a movie outside of her house

(all of these prove that Karen did NOT go see a movie last night)

Examples of weakening:
- Karen was feeling very sick
- Karen has recently complained that there are no good movies out
- Karen is broke and all the local theaters are very expensive

(none of these PROVE that Karen didn’t see a movie, but they all make us less likely to think that she did)

Does that make sense?

[contropositive]

thank you for the explanations. It raises a question for me in regards to weakening questions.

On weakening questions I have sometimes came across answer choices that seem to just disprove the conclusion or premise and another answer choice that weakens it (casts a bit doubt on the conclusion or premise). I never pick the one that seems to disprove because I think that would be arguing against the argument but we just want to weaken the argument. Am I thinking about this correctly?

[ohthatpatrick]

That would not be correct. You always want the answer with the most effect, because the question stem says, “Which of these choices, if WE say they’re true, would have the most effect on the argument?”

I think you’re correctly inclined to think something smells fishy if an answer is just contradicting the conclusion. You might think, “Have I confused myself? LSAT doesn’t normally give ideas that just contradict the conclusion?”

But if you tightly check the wording and find that the answer is just kinda saying the opposite of what the conclusion says, then you should absolutely pick it! Refuting an argument definitely weakens it.

LSAT does not contradict the truth of a premise, so be careful if you read something and think that that is what is happening.

However, LSAT can severely undermine the credibility of a premise.

If they tell me that “a recent survey found that 87% of people polled preferred iPhones to Android phones”, they will never tell me, “No it didn’t. It didn’t say that.”

But what they MAY do is say “the survey was conducted on the campus of Apple’s corporate headquarters.” Suddenly, you don’t care about or trust that 87%. Yes, that was the survey result, but you no longer consider the sample to be trustworthy.

Similarly, a premise might be “According to Diane, the perpetrator wore a yellow hat.”

and we could weaken this by saying “Diane is colorblind” or “There was not enough light available for her to make an accurate discrimination of hat-color”.

In other words, it’s still true that she said “yellow hat”, but we can destroy her credibility and take away that premise’s force.

[lym]

I'm still a little bit confused about the "individually sufficient" part.

According to the argument the vegetarians not only propose two reasons but also argue that they are individually sufficient. I don't think the argument explicitly opposes the "individually sufficient" part. I did noticed, though, that the argument goes on to SUPPOSE that the first reason (health) is wrong, and conclude that that supposition would lead to our doubting on the second one.

Now,

If the truth of the claim that the two reasons proposed by vegetarians are individually sufficient is not questioned, then supposing one reason to be wrong tells us nothing about the validity of the second one;

If the "individually sufficient" claim is really what's been questioned upon here... well I don't see why supposing one of the reasons to be wrong could have that effect.

Actually I chose C. I thought it's just paraphrasing what's been said in the argument. Now I've learned the difference between "disprove" and "weaken" though, so thank you guys!

[roflcoptersoisoi]

I'm still a little bit confused about the "individually sufficient" part.

According to the argument the vegetarians not only propose two reasons but also argue that they are individually sufficient. I don't think the argument explicitly opposes the "individually sufficient" part. I did noticed, though, that the argument goes on to SUPPOSE that the first reason (health) is wrong, and conclude that that supposition would lead to our doubting on the second one.

Now,

If the truth of the claim that the two reasons proposed by vegetarians are individually sufficient is not questioned, then supposing one reason to be wrong tells us nothing about the validity of the second one;

If the "individually sufficient" claim is really what's been questioned upon here... well I don't see why supposing one of the reasons to be wrong could have that effect.

Actually I chose C. I thought it's just paraphrasing what's been said in the argument. Now I've learned the difference between "disprove" and "weaken" though, so thank you guys!

As explicitly shown in the stimulus, vegetarians think that there are two independently sufficient reasons for not eating meat:

Sufficient reason one: Health considerations, (it's not good for you)
Sufficient reason two: An aversion to living based on at the expense of other reasons.

The author the supposes that eating meat is essential to good health, thereby negating the first independently sufficient condition. If this supposition were true, then it would cast doubt on the other independently sufficient reason for not eating meat, i.e., aversion to living at the expense of other creates.

Think about it, if we're told that eating meat is essential to health, then being averse to living (eating meat) at the expense of living creatures is less likely to be a sufficient justification for not eating it. This is exactly what the author is trying to illustrate in employing his supposition.

You were being too abstract in your thinking, you need to relate it to this particular context. You're precisely that if there are two independent sufficient reasons for doing something, if one of those reasons were negated, it need not have a bearing on the other since they are independent. However that does not preclude one independently sufficient reason/condition from influencing the other.

(C) is wrong because the author is employing the supposition to disprove the claim that a vegetarian diet is healthy. He never even makes mention of the vegetarian diet. For all we know the author is a vegetarian that thinks the vegetarian diet is healthy. The author is simply trying to impugn the vegetarian's reasoning by casting doubt one of their independently sufficient conditions.