#12 - Biologists have noted reproductive abnormalities in

[Administrator]

Complete Question Explanation

Weaken—CE. The correct answer choice is (C)

This was one of the two hardest Logical Reasoning questions on this test (the other is question #20
of section 4). The argument can be reduced as follows:

Premise: Biologists have noted reproductive abnormalities in fi sh that are immediately
downstream of paper mills.

Premise: One possible cause is dioxin, which paper mills release daily and which can
alter the concentration of hormones in fi sh.

Premise: However...since the fi sh recover normal hormone concentrations relatively
quickly during occasional mill shutdowns and dioxin decomposes very slowly
in the environment.

Conclusion: Dioxin is unlikely to be the cause.

This stimulus begins with the presentation of one hypothetical cause of fi sh abnormalities: dioxin,
a chemical which can alter the concentration of hormones in fi sh. The author concludes that dioxin
is unlikely to be the cause, based on the fact that fi sh recover normal hormone levels quickly during
mill shutdowns, even though dioxin remains present in the environment (“it decomposes slowly”).
The conclusion is notable in that it concludes that dioxin is not a likely cause, and thus it asserts that
a causal relationship does not exist.

This is a very controversial LSAT problem, with a number of test takers suggesting that the credited
may strengthen the argument and that (D) is a better weakening answer even if (C) does weaken
the argument. Test takers were clearly confused by the problem, selecting the fi rst four answers
in roughly equal proportions. In the responses to (C) and (D) we will address some of the issues
underpinning the controversy as it was the answer choices that were trickier than the stimulus itself.

Answer choice (A): This answer attempts to weaken the argument by presenting a source attack. A
source attack is logically invalid, and does not undermine the argument.

Answer choice (B): The problem with this answer is that it does not give you any concrete evidence
with which to attack the argument. Yes, the dioxin decomposition rate varies, but how much does it
vary in the environment where the fi sh are?
Using an analogy, selecting this answer is like saying that the statement “the temperature in the
environment changes depending on the season” weakens the argument that “it is not usually hot in
Norway.” Sure, the seasons may have an effect, but how much of one, and perhaps that effect is to
simply make it mildly warm during the summer and bitterly cold during the winter. Without concrete
information, there can be no way to know that this answer weakens the stimulus.

Answer choice (C): This is the correct answer choice. The argument is that dioxin is not the likely
culprit, based on the fact that the fi sh recover quickly during shutdowns despite their continued
access to the chemical (based on its slow decomposition). If, as this answer choice provides, dioxin
gets washed quickly downstream, it seems more likely that the fi sh benefi t from these occasional
shutdowns because their environment is temporarily free of this chemical. This makes dioxin a more
likely culprit, thus weakening the argument in the stimulus.

In Law Services’ view, “The conclusion of the argument is that dioxin is unlikely to be the cause
of reproductive abnormalities in fi sh that are immediately downstream of paper mills. The reasons
given are that those fi sh recover normal hormone concentrations relatively quickly when the paper
mills are shut down even though dioxin decomposes very slowly in the environment. Thus, if
dioxin is the cause of the abnormal hormone concentrations that may be causing the reproductive
abnormalities, those fi sh should not recover normal hormone concentrations relatively quickly when
the paper mills are shut down, since dioxin would remain in the waters immediately below the mills
even though it is not being released by the mills. So, this suggests that it is not dioxin, but, perhaps,
something that decomposes rapidly in the environment, that is the cause of the abnormal hormone
concentrations that may be causing reproductive abnormalities in the fi sh immediately downstream
from the paper mills.

The credited response weakens the argument by indicating a mechanism by means of which dioxin
does not continue to be in the area immediately downstream of the paper mills when they are shut
down in spite of the fact that it decomposes very slowly in the environment. Thus, recovery of
normal hormone concentrations in the fi sh when the paper mills shut down could be due to their
not being exposed to dioxin during the period, even though dioxin decomposes slowly. In that case,
dioxin could be the cause of the alteration of hormone concentrations and of resultant reproductive
abnormalities despite the evidence offered in the stimulus.”

Part of the controversy arises because some students interpret this answer as seeming to support
the conclusion rather than weaken it, as it states that dioxin is quickly removed from the fi sh’s
habitat (i.e. those fi sh that are “immediately downstream of paper mills”) and would therefore be
an unlikely cause for the observed reproductive abnormalities. Answer choice (C) certainly does not
seem to promote the idea that dioxin could be the cause for these abnormalities, as it is carried far
downstream too quickly to have any signifi cant effect on the fi sh in question.

By way of addressing the controversy, Law Services has stated that “the stimulus indicates that the
paper mills release dioxin daily. Thus, even if normal river currents carry the dioxin far downstream
in a few hours, while the paper mills are operating the dioxin in the water immediately downstream
of the paper mills is being regularly replenished and the fi sh in those waters are being exposed
to dioxin on a daily basis. This is consistent with dioxin being the cause of the reproductive
abnormalities in the fi sh immediately downstream of the paper mills. And the fact that the release of
dioxin stop when the mills are shut down, allowing the currents immediately below the mills to fl ush
away the dioxin for a signifi cant period of time, would explain why the fi sh recover normal hormone
concentrations during occasional mill shutdowns. Thus, (C) weakens the argument by describing
conditions that would allow the fi sh to recover normal hormone concentrations if dioxin were the
cause of the hormone changes, even though dioxin decomposes slowly in the environment.”

Answer choice (D): If you selected this answer, do not feel bad. Many good test takers selected this
response, and there is serious debate about whether this answer is incorrect.

On one hand, this choice states that, despite the fi sh recovering relatively rapidly from the abnormal
hormone concentrations, the physiological effects are more long-lasting. This would appear to
weaken the conclusion, as it shows that reproductive abnormalities could still be present in the
dioxin-exposed fi sh (due to the more permanent physical effects induced by the dioxin), regardless
of the hormonal adjustment.

On the other hand, Law Services claims that “(D) does not weaken the argument because it does
not address the argument that is made. The argument made would cast doubt on dioxin as the cause
of the abnormalities even if (D) were true. As noted above, the conclusion of the argument is that
dioxin is unlikely to be the cause of the abnormalities, and the reason given for the conclusion is
that abnormal hormone concentrations that might cause the abnormalities return to normal during
the mill shutdowns even though dioxin decomposes very slowly in the environment and, thus, fi sh
immediately downstream of the paper mills would still be exposed to dioxin even during the mill
shutdowns. If (D) is true, this does nothing to undermine the focus of this argument. The argument
does not call into question dioxin as the cause of the abnormalities by casting doubt on the link
between dioxin and the hormone changes. While (D) might explain how the abnormalities could
persist even if the hormone levels returned to normal, this does not address the reason given in the
argument why dioxin is unlikely to be the cause, and, hence, does not weaken the argument. The
credited response (C) does, however, provide an explanation of how dioxin can cause the changes in
hormone levels that could be the cause of the abnormalities even given the facts about the return to
normal of hormone levels when the plants are shut down and dioxin decomposing very slowly in the
environment. Thus, it addresses the reason given in the argument why it is unlikely that dioxin is the
cause of the abnormalities.”

Answer choice (E): This was, by far, the least frequently chosen answer choice. The fact that the
interaction between hormone concentrations and reproductive abnormalities is not fully understood
does not weaken the assertion that hormone concentrations cause those abnormalities. The lack of
understanding does not suggest that the hormone/abnormality connection is either stronger or weaker
than previously believed, and without concrete information, there is no way this answer choice
can attack the argument (again, like answer choice (B), a gray area or uncertainty does not serve to
strengthen or weaken an argument).

[PowerSteve]

I'm having trouble understanding question 12 from the first logical reasoning section of the December '04 LSAT (and the fact that only 21% got this question correct leads me to believe I'm not alone). How exactly does choice C weaken the argument? Thanks in advance!

~Steve

[Steve Stein]

Thanks for your question--you're right--this was one of the two hardest Logical Reasoning questions on this test. The argument, as discussed in PowerScore's Three LSATs Deconstructed, can be reduced as follows:

Premise: Biologists have noted reproductive abnormalities in fi sh that are immediately downstream of paper mills.
Premise: One possible cause is dioxin, which paper mills release daily and which can alter the concentration of hormones in fish.
Premise: However...since the fish recover normal hormone concentrations relatively quickly during occasional mill shutdowns and dioxin decomposes very slowly in the environment.
Conclusion: Dioxin is unlikely to be the cause.
This stimulus begins with the presentation of one hypothetical cause of fish abnormalities: dioxin, a chemical which can alter the concentration of hormones in fish. The author concludes that dioxin is unlikely to be the cause, based on the fact that fi sh recover normal hormone levels quickly during mill shutdowns, even though dioxin remains present in the environment (“it decomposes slowly”). The
conclusion is notable in that it concludes that dioxin is not a likely cause, and thus it asserts that a causal relationship does not exist.

Answer choice C is the correct answer choice: the argument is that dioxin is not the likely culprit, based on the fact that the fi sh recover quickly during shutdowns despite their continued access to the chemical (based on its slow decomposition). If, as this answer choice provides, dioxin gets washed quickly downstream, it seems more likely that the fi sh benefi t from these occasional shutdowns because their environment is temporarily free of this chemical. This makes dioxin a more likely culprit, thus weakening the argument in the stimulus.

Tough one! Let me know whether that clears this one up--thanks!

~Steve

[PowerSteve]

Thanks Steve! Yes, that totally clears it up for me

[moshei24]

I have spent a long time looking at this question trying to understand why the answer is what it is, and I don't completely see why it is what it is. Would you be able to explain it, please?

Thanks!

[Steve Stein]

Hey Moshe,

That is a very tough question. It breaks down as follows:

Premise: Biologists have noted reproductive abnormalities in fish that are immediately downstream of paper mills.

Premise: One possible cause is dioxin, which paper mills release daily and which can alter the concentration of hormones in fish.

Premise: However...since the fish recover normal hormone concentrations relatively quickly during occasional mill shutdowns and dioxin decomposes very slowly in the environment.

Conclusion: Dioxin is unlikely to be the cause.

This stimulus begins with the presentation of one hypothetical cause of fish abnormalities: dioxin, a chemical which can alter the concentration of hormones in fish. The author concludes that dioxin is unlikely to be the cause, based on the fact that fish recover normal hormone levels quickly during mill shutdowns, even though dioxin remains present in the environment (“it decomposes slowly”). The conclusion is notable in that it concludes that dioxin is not a likely cause, and thus it asserts that a causal relationship does not exist.

The correct answer is C. The argument in the stimulus is that dioxin is not the likely culprit, based on the fact that the fish recover quickly during shutdowns despite their continued access to the chemical (based on its slow decomposition). If, as this answer choice provides, dioxin gets washed quickly downstream, it seems more likely that the fish benefit from these occasional shutdowns because their environment is temporarily free of this chemical. This makes dioxin a more likely culprit, thus weakening the argument in the stimulus. 

Tough one--let me know whether it's clear--thanks!

~Steve

[moshei24]

I think it makes sense now.

I had chosen B, because I thought that the environment meant not in the water, and that maybe in the water it decomposes differently. I'm assuming now that environment DOES include the water?

But yeah, so it's C because if the river didn't carry it down stream then it still should be by the fish to cause problems, even when there isn't a constant flow of the chemical? But now that they're saying that is flows downstream, that could explain why they aren't affected, because now that they aren't having a constant outflow from the factory, there isn't anything affect them?

Thanks, Steve!

[brittany1990]

Hi!

I identified the conclusion of the argument to be that "dioxin is unlikely to be the cause" and the question stem as a weaken question. I eliminated answer choices A and E so I was left with B, C, and D. Apart from that, I had no idea how else to attack the problem and why answer C is correct.

Please help!

Thanks,
Brittany

[Steve Stein]

This was one of the hardest Logical Reasoning questions on that test. The argument breaks down as follows:

• Premise: Biologists have noted reproductive abnormalities in fish that are immediately downstream of paper mills.
  
  Premise: One possible cause is dioxin, which paper mills release daily and which can alter the concentration of hormones in fish.
  
  Premise: However...since the fish recover normal hormone concentrations relatively quickly. During occasional mill shutdowns and dioxin decomposes very slowly in the environment.
  
  Conclusion: Dioxin is unlikely to be the cause.

This stimulus begins with the presentation of one hypothetical cause of fish abnormalities: dioxin, a chemical which can alter the concentration of hormones in fish. The author concludes that dioxin is unlikely to be the cause, based on the fact that fish recover normal hormone levels quickly during mill shutdowns, even though dioxin remains present in the environment (“it decomposes slowly”). The conclusion is notable in that it concludes that dioxin is not a likely cause, and thus it asserts that a causal relationship does not exist.

The problem with answer choice B is that it does not give you any concrete evidence with which to attack the argument. Yes, the dioxin decomposition rate varies, but how much does it vary in the environment where the fish are? Using an analogy, selecting this answer is like saying that the statement “the temperature in the environment changes depending on the season” weakens the argument that “it is not usually hot in Norway.” Sure, the seasons may have an effect, but how much of one, and perhaps that effect is to simply make it mildly warm during the summer and bitterly cold during the winter. Without concrete information, there is no basis on which to conclude that this answer weakens the stimulus.

Choice C is the right answer. The argument is that dioxin is not the likely culprit, based on the fact that the fish recover quickly during shutdowns despite their continued access to the chemical (based on its slow decomposition). If, as this answer choice provides, dioxin gets washed quickly downstream, it seems more likely that the fish benefit from these occasional shutdowns because their environment is temporarily free of this chemical. This makes dioxin a more likely culprit, thus weakening the argument in the stimulus.

I hope that' helpful--let me know--thanks!

~Steve

[Kp13]

Hi,

I am still unclear as to why C) is the correct answer to this question.

I picked A) because I thought that it attacks one of the premises used in support of the conclusion (that fish recover normal hormone concentrations relatively quickly). Although this answer does not disprove the premise 100%, it casts doubt on its validity. Thus, if fish a) don't recover relatively quickly and b) dioxin decomposes very slowly in the environment, then dioxin is likely the cause of reproductive abnormalities in fish.

Thanks!