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标题: L2004/12-1-12 [打印本页]

作者: jieyulike 时间: 2007-6-4 13:52
标题: L2004/12-1-12

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

Which one of the following statements, if true, most seriously weakens the argument?

C.Normal river currents carry the dioxin present in the river far downstream in a few hours.

百思不得其解，总觉得答案Ｃ是加强而非削弱啊？

作者: fredshen 时间: 2007-6-6 15:39

causal relationship.

toxin not causing fish to die. why? because when plant shut down, fish recovers and toxin decomposes slowly. Implying there is still toxin when plant shut down around fish

C says the toxin are carried out far far away in short time. So when plant is closed, there is actually no toxin. no cause -> no effect strengthens toxin is the cause, and therefore weakens the argument.

作者: icewarm 时间: 2007-6-7 01:57

I have problem with this question too. I agree with jieyulike that C actually strengthens
the conclusion: dioxin is unlikely to be the cause.



The author argues since the fish recover normal hormone concentrations
relatively quickly during occasional mill shutdowns and dioxin decomposes very
slowly in the environment, dioxin is unlikely to be the cause.



Option C basically provides another reason why dioxin is not likely the cause
and strengthens the conclusion.



The weakness of the author's argument is his premise: fish recover normal hormone
concentrations, which is different from
fish recovering fully. Even if hormone concentrations fall back to normal, the detrimental
effect caused by elevated hormone level may still persist.



I think the right answer is D, which attacks this hole in author's argument and
weakens the evidence the author provides to support his conclusion.



D. Some of the fish did not recover rapidly from the physiological changes that
were induced by the changes in hormone concentrations.

作者: icewarm 时间: 2007-6-7 02:18
After second thought, I think fredshen is right.

Disregard my previous post, please.

作者: fredshen 时间: 2007-6-7 04:58

以下是引用icewarm在2007-6-7 1:57:00的发言：

The weakness of the author's argument is his premise: fish recover normal hormone
concentrations, which is different from
fish recovering fully. Even if hormone concentrations fall back to normal, the detrimental
effect caused by elevated hormone level may still persist.

You freewheel a little bit here. Recover(regain) normal hormone concentration means the fish goes back to normal condition. Dont let D confuse you.

Now D says there is some lasting effect because of this hormone fluctuation. So what. The issue is about Doxin causing abnormal hormone concerntration, not lasting effect.

This one is actually quite difficult because it prepsents a puzzle that requires careful analysis.

[此贴子已经被作者于2007-6-7 5:09:36编辑过]

作者: jimhou 时间: 2007-6-16 22:40

我同意答案C．原因在于毒素在" environment"中缓慢分解,而不是鱼体内缓慢分解.

答案C说水很快把毒素冲到下流去了,那么" environment"中就没有毒素了,然后鱼就恢复正常了.

所以鱼中毒仍是造纸厂排出的毒素造成的.削弱了原文逻辑.

如果理解为毒素在鱼体内缓慢分解就变成了加强.

鄙人第一次在CD发贴,不知对不对.请大家包涵.

作者: balabala1 时间: 2007-9-25 12:00

以下是引用fredshen在2007-6-6 15:39:00的发言：

causal relationship.

toxin not causing fish to die. why? because when plant shut down, fish recovers and toxin decomposes slowly. Implying there is still toxin when plant shut down around fish

意思是说，因为环境中一直有毒素，所以鱼适应了，然后就调解了自己的hormone,就不会不正常了。那又为什么要强调shut down的时候recover quickly呢？

还是不明白啊。。。。

作者: icewarm 时间: 2007-9-26 00:26
This question is probably the most controversial LR question in the LSAT history. Until today, there is still hot debate between C and D.

Not every LR question is airtight.

This one is an anomaly. Don't be bothered too much if you got it wrong.

I was misled by a little outside knowledge about dioxin because I happen to be a toxicologist. Dioxin is a major component of Agent Orange that the US army used during the Vietnam War as herbicide and defoliant to deforest the jungle to expose secret passages (Hu Zhi Ming Xiao Dao) used to supply insurgents in the south. Once ingested or got into one's body in other ways, dioxin stays with you almost forever because it is very hard to be metabolized and excreted by the body. Dioxin is stored in one's body fat. If you recall the passage about the mysterious death of dolphins, you might remember they mentioned once those dolphins started consuming their body fat, stored synthetic pollutants are released into their system exacerbating their condition. The toxicity of dioxin is long term. That's why a lot of Vietnamese are still suffering horrible disease associated with dioxin years later. So, from a toxicologist's view, the fish is not likely to recover even after they ceased the contact with dioxin.

Even though we know that we should NOT take in outside knowledge and stay within the facts provided by the arguments, sometimes you just do it without even realizing it. That's why D makes so much sense to me, although from the point view of pure logic, C should be the credited option .

This question is about casual relationship.

The essence of C is that when the cause is absent (dioxin washed away), the effect is absent (fish not sick anymore). This strengthens a causal relationship and weakens the conclusion.

作者: rosemsem 时间: 2007-11-4 21:31

can anybody post the complete question? thank you.

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