Q8 - Environmentalist: When bacteria degrade

[ManhattanPrepLSAT1]

I think you're close. The big issue with answer choice (E) is the word "any." It doesn't need to be true for any landfill, but rather at least some landfills - those that have been converted into parks. Exactly what you were saying...

Answer choice (E) is simply too strong a claim to be required in order to draw the conclusion. This is a necessary assumption question and for these, you don't need to add an assumption that will prove the conclusion, but rather find an assumption that the argument can't live without.

Answer choice (E) would guarantee that the conclusion is true, whereas, we are seeking an answer that is required for the conclusion to be true.

(A) is necessary to the argument. If no landfills that have been converted into public parks have bacteria that degrade household products, the conclusion would not stand.
(B) restates a relationship given in the stimulus in the form of a reversal - so does not even relate a true relationship.
(C) is not necessary. It doesn't need to be true of all practices, but rather just the practice of degrading household products.
(D) undermines the conclusion. Definitely does not help.
(E) bridges a gap in the argument and so should be tempting, but again is too broad. It doesn't need to be true of any landfill, but rather at least some.

Let me know if you like me to spend some more time on any part of the explanation to go a little deeper. This one is tricky, especially for it being question 8 in the section!


#officialexplanation

[bnuvincent]

I found E tempting, could you please explain?

[ManhattanPrepLSAT1]

Could you check the labeling on the question. I couldn't find a question about bacteria degrading in PT53, S3, Q8.

Thanks!

[bnuvincent]

I've reedited it again now, by the way, I went over the choices, and came up with an idea. It seems like E talks about landfill, but does not refer to the one that changed into park, is this the problem?

[mrudula_2005]

Well aren't (C) and (E) also wrong because we don't even know if the vapors produced by bacteria degrading household cleaning products are present in converting landfills into public parks.

(C) and (E) hinge on toxic vapors being present (that is a critical part of their sufficient clauses), but nothing in the stimulus says that there are definitely these toxic vapors in the converting of landfills into public parks (only that household cleaning products merely exist in landfills...not that the bacteria degrade them to produce the toxic vapors) so there is nothing to kick off (C) and (E)'s sufficient conditions.

[mrudula_2005]

Also, if we negate (A), it would read "No landfills that have been converted into public parks [had] bacteria that degrade household cleaning products."

The tense has me tripped up - well even if no landfills that HAVE BEEN converted into public parks had these degrading bacteria, doesn't mean that the practice is not CURRENTLY damaging to human health.

Also, that negated (A) does not, in technical terms, rip apart the argument's conclusion - because the conclusion could very well still be true - that is, the common practice of converting landfills into public parks could very well still be damaging to human health (in some other way - surely not through the toxic vapors, but through some other means for sure).

So what makes (A) necessary then? Are necessary assumptions not about what is necessary for conclusion to hold, but what is necessary for the whole line of reasoning to hold (that is, what is necessary for the conclusion to hold BASED ON what the author gives us as evidence)????

insight on this would be MUCH appreciated.

Thank you!

[ManhattanPrepLSAT1]

Well aren't (C) and (E) also wrong because we don't even know if the vapors produced by bacteria degrading household cleaning products are present in converting landfills into public parks.

Great point. This would be especially useful to see if this were a sufficient assumption, since we wouldn't know that the principles outlined in answer choices (C) and (E) would apply.

Also, if we negate (A), it would read "No landfills that have been converted into public parks [had] bacteria that degrade household cleaning products."

Try negating it this way...

No landfills that have been converted into public parks have bacteria that degrade household cleaning products. You accidentally swapped the tense yourself when conducting your negation.

To your second and broader point about whether the negation of the correct answer should negate the assumption or just the reasoning. I would say that the LSAT is not consistent. If you have to make a choice between answer choices that that do one or the other, I would say to choose the one that undermines the conclusion directly. But if the negation test does not completely undermine the conclusion but only the reasoning steps taken to reach the conclusion, I would say that such answer is enough.

E tells us nothing about landfills that are converted into parks. I believe that the author is just refering to a practice where some landfills are turned into parks. E is tempting but A is much more stronger answer that bridges the gap between converted landfills and the bacteria.

[shirando21]

I think you're close. The big issue with answer choice (E) is the word "any." It doesn't need to be true for any landfill, but rather at least some landfills - those that have been converted into parks. Exactly what you were saying...

Answer choice (E) is simply too strong a claim to be required in order to draw the conclusion. This is a necessary assumption question and for these, you don't need to add an assumption that will prove the conclusion, but rather find an assumption that the argument can't live without.

Answer choice (E) would guarantee that the conclusion is true, whereas, we are seeking an answer that is required for the conclusion to be true.

(A) is necessary to the argument. If no landfills that have been converted into public parks have bacteria that degrade household products, the conclusion would not stand.
(B) restates a relationship given in the stimulus in the form of a reversal - so does not even relate a true relationship.
(C) is not necessary. It doesn't need to be true of all practices, but rather just the practice of degrading household products.
(D) undermines the conclusion. Definitely does not help.
(E) bridges a gap in the argument and so should be tempting, but again is too broad. It doesn't need to be true of any landfill, but rather at least some.

Let me know if you like me to spend some more time on any part of the explanation to go a little deeper. This one is tricky, especially for it being question 8 in the section!

I do it this way: First, public parks is a new term in the conclusion. Second, only A and D contains this new term. Third, if we apply D into the argument, we cannot get the conclusion. So D is out, that leaves A to be the correct answer.

[boy5237]

So basically E is too strong in a sense that it talks about "any land fills" whereas the argument is specifically talks about the landfills that converted into parks?

[shodges]

Random question about this one.

Would C have been right if it had said "If converting landfills into public parks involves the exposure..." instead?

[aradunakhor]

I'm confused because I'm accustomed to "any" being used in at least two senses. The first one being used to indicate all -- if someone says "This is true for any student", then he means that it is true for all students.

The second meaning I've seen it used is to indicate at least one. So if I say "If any of you object, then I'll change my mind," then my meaning is that if at least one of you object, then I'll change my mind.

For choice E, it seems like either meaning (all or at least one) would be plausible, which is problematic since one would rule out this answer choice, while the other would make it seem like the correct answer. Is there something I'm missing here? Thanks!

[raziel]

I am not sure how changing the interpretation of any affects the answer choice (E) to make it correct. Notice that even if (E) is true, it doesn't help the argument in any way. Assuming (E) is true still does not tell us whether the sufficient condition "toxic vapors are present" is triggered. Because of this, we can't help the conclusion that the author is trying to establish "converting parks is damaging" because we don't know whether there are bacteria or vapors in the landfills in the first place!

In order to show that the conclusion is true "converting parks is damaging", the author is assuming that there are toxic vapors being produced in the landfills (because bacteria doing their work) and that these vapors will affect humans even after they are converted to parks. It is this assumption that you should be looking for when you look at the answer choices. Notice how (A) tells us about this assumption.

[timsportschuetz]

@raziel: If you notice, a previous poster pointed out why "any" in answer choice (E) is bad. The argument is more specific than "any landfill" - the argument's scope is about "landfills that have been converted into public parks".

Since the stimulus is much more specific in scope, any answer choice that goes beyond this scope MUST BE INCORRECT.

[seychelles1718]

I am still not crystal clear on why C is wrong. Can someone please explain why C is wrong?
Also, for Necessary Assumption Qs where there is a new term in the conclusion, are there any cases in which the right answer doesn't actually include the new term? I thought this strategy only works for sufficient assumption questions?

Thanks

[ManhattanPrepLSAT1]

I am still not crystal clear on why C is wrong. Can someone please explain why C is wrong?
Also, for Necessary Assumption Qs where there is a new term in the conclusion, are there any cases in which the right answer doesn't actually include the new term? I thought this strategy only works for sufficient assumption questions?

Thanks

While the argument is about vapors released when bacteria degrade household cleaning products, answer choice (C) is about the vapors from household cleaning products themselves. Notice that answer choice (A) discusses vapors released when bacteria degrade household cleaning products, a better match to the toxin discussed in the argument.

As to your larger question about Necessary Assumption questions, it may be helpful to remember that when linking together a chain of reasoning, any new term in the conclusion is likely going to be in the right answer. But remember, the right answer doesn't need to include this new term. The right answer may simply defend the argument from some consideration, that if true, would destroy the argument's reasoning.

You're right that applying that trick (and remember it's a trick, not a guarantee) is safer on Sufficient Assumption questions.

Hope that helps!

[andrewgong01]

Just curious, but in a NA question and the conclusion is not a conditional, can a correct NA answer choice be conditional because in this question all the wrong choices were also posed as conditionals. Moreover, if the original stimulus was not a conditional conclusion then the argument was giving something absolute that "must" occur regardless but if we added a conditional as an assumption that is required it makes the argument loose its "absolute"/ "must" strength where now the validity of the conclusion hinges on meeting a conditional as its assumption.

To previous posts, I disagree "E" is sufficient because in the given stimulus we do not know if the conversion to parks would still have the vapor (maybe the conversion eliminates it?). More importantly, as "A" suggests, we do not even know if the vapor existed to begin with in the landfill before the conversion. My pre-phase was actually the former -- conversion does not eliminate the toxin - since I did not read it carefully enough that said bacteria is needed to degrade the products to produce the toxin

[PatrickW522]

I'm still struggling with being able to pick out E as incorrect. If using the negation method would E negated be "If vapors toxic to humans are NOT produced by the degradation of household cleaning products by bacteria in any landfill, then the health of no human will suffer?" That obviously wouldn't weaken the stimulus, so E would be incorrect, right?

Also, is the fact that E doesn't address public parks automatically raise a red flag?

[KenM242]

I'm still struggling with being able to pick out E as incorrect. If using the negation method would E negated be "If vapors toxic to humans are NOT produced by the degradation of household cleaning products by bacteria in any landfill, then the health of no human will suffer?" That obviously wouldn't weaken the stimulus, so E would be incorrect, right?

Also, is the fact that E doesn't address public parks automatically raise a red flag?

When negating an [If A, then B] statement, you have to make it [If A, then NOT B].

For (E), the negation would be "(Even) If blah blah, then the health of NO humans suffer." In other words, the bacteria can produce all the toxic vapor they want; no human will be harmed by it.

The biggest problem with (E) is it does not GUARANTEE that the toxic vapors will be produced. Unless it is provided for certain that the garbage in landfills has live bacteria that produce these toxic vapors, we will never be able to reach the conclusion in the stimulus.

MY QUESTION is,

I've been told that the negation technique is a fool-proof way to pick out the necessary assumption. However, if you negate (E), then with that alone you can render the conclusion of the stimulus invalid. Yet (E) is the wrong answer nonetheless.

Is the reason that the negated version of (E) not compatible with the argument the fact that it contradicts the stimulus itself?

The stimulus says when bacteria degrade.. it makes fumes toxic to humans, while the negation of (E) says the exact opposite.

ANYONE??

[bobjon1259]

Hoping an expert can help me out here. I still don't see why (A) is required. It is clearly required if the conclusion regards landfills that were converted into public parks in the past, but how do we know this to be true? It could be that in the past, there were no bacteria in such landfills, but today there is (thus, the common practice of converting landfills into public parks is damaging human health -- note the present tense of the conclusion here).

Here's an analogous situation to drive the point that I'm making (since I don't think I was very clear above, despite my best-efforts). If a recently enacted law prohibits speeding over 50 mph, and only one person so far has driven past 50 mph since the law's enactment, it's still accurate to say "the common practice of speeding over 50 mph is illegal." This is despite the fact that in the past, speeding was over 50 mph was permissible. Likewise, why can't it be the case that despite there being no bacteria in landfills that were converted in the past, the conclusion nevertheless holds true since the landfills that are being CURRENTLY converted do contain such bacteria?