#12 - Biologists have noted reproductive abnormalities in

[ltowns1]

So just to be clear about this one, the argument assumes that dioxin is there with the fish during the shutdowns when the reality is, they are actually far down stream. D is wrong because it really adds to the argument in way by acknowledging the causal relationship?

[ltowns1]

So just to be clear about this one, the argument assumes that dioxin is there with the fish during the shutdowns when the reality is, they are actually far down stream. D is wrong because it really adds to the argument in way by acknowledging the causal relationship?

Actually I think (D) is just making the effects worse, but it’s not really identifying a cause

[Adam Tyson]

Correct! Answer D tells us nothing about the cause, just about the effects, so it neither strengthens nor weakens the argument.

[Catallus]

I now get why (C) weakens the argument, but even after reading the explanation, I struggle to see why (D) is wrong. Law Services' explanation focuses on the argument's stated reasons for its conclusion. Equally important, however, are unstated assumptions, and (D), in fact, directly addresses one of these assumptions: the unwarranted assumption that restoration to normal hormone concentrations means that dioxin is not causing reproductive abnormalities. Not so fast, according to (D). Even if the fish quickly go back to their normal hormone levels, the disruption of their hormones can have longer-lasting physiological effects, which could entail reproductive abnormalities. (D) thus seems to attack a major flaw of the argument, which does not justify its assumption.

So, the only real problem I can see with (D) is the phrase "some," which dilutes its impact. "Some" could mean anywhere from 1 fish (not significant) to all the fish (definitely significant). There may not be a definitive answer to this, but I'll ask anyway: can "some" answer choices ever weaken a claim about an entire population? For instance, if the argument concludes that "eating tin cans makes goats sick," would the statement "some goats that eat tin cans do not get sick" ever be able to weaken that argument, or is "some" just too vague and potentially insignificant to have any impact? Or is there any other reason (D) is suspect that I'm just missing?

[lsatstudent99966]

Complete Question Explanation


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.

Can someone explain what the bold and italic part means (I added the bold and the italic )? It doesn't really make sense to me. I get that the stimulus would suggest that dioxin is not the cause, but I don't see how it suggests that it should be something that "decomposes rapidly" that causes the abnormal hormone concentrations.

[lsatstudent99966]

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.”

Could someone please explain this other bold and italic part too (I added the bold and the italic )?
It says "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." I thought that's exactly what the argument did

[Adam Tyson]

Catallus and lsatstudent99966, we generally don't attempt to explain what another company means in their explanation. What I'll tell you is that answer D is irrelevant, because the issue is not whether the fish recover from the physiological changes (the reproductive abnormalities) that were caused by the changes in hormone concentrations. The issue is what caused the changes in hormone concentrations in the first place. To illustrate:

1. Something in the environment - maybe dioxin, maybe not - causes their hormones to change

2. The fish grow a third eye in the middle of their forehead

3. We stop adding dioxin to the environment

4. Their hormones go back to normal, but they still have a third eye in their foreheads

The fact that they still have that third eye tells us nothing about what did or did not cause their hormone concentrations to change in the first place. Was it the dioxin, or something else? The author thinks that the dioxin is still lingering in the environment, since it decomposes slowly, and so it cannot be the cause of the hormonal changes. If dioxin was the cause, the hormone levels wouldn't have returned to normal so quickly.

What weakens the argument is the dioxin NOT lingering in the environment. If it's quickly carried downstream, it doesn't matter how slowly it decomposes, because it's not here in this environment. It's decomposing somewhere else, far away.

The physiological abnormalities - the third eye, the reproductive abnormalities, whatever - aren't the issue. That's just an effect of the hormonal changes. We need to focus on what may have caused the hormone concentrations to change, not on the effects of those changes.