Professor: A marine biologist argues that transmission of sea lice fro

The marine biologist's conclusion is that "transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago, British Columbia." His/her evidence for this conclusion is that:

• Numerous studies suggest that salinities less than 30 parts per thousand are unfavorable to sea-lice survival.
• The archipelago has a salinity range of 25–30 parts per thousand between March and June, the critical period for wild salmon migration
• These conditions tend to suppress sea-lice proliferation

Notice that even though the word "concludes" is used later in the passage, the marine biologist's ACTUAL conclusion is stated in the first sentence. All of the subsequent information is there to SUPPORT the claim that "transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago, British Columbia." In this context, "concludes" just links one supporting premise to another.

Then, the professor (not the marine biologist) states: "But a review of the literature shows that salinities of 25–30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice."

This statement attacks a premise of the biologist's argument: that the conditions in the Broughton Archipelago "tend to suppress sea-lice proliferation."

So, how exactly does the professor undermine the biologist's argument?


The biologist never discusses a condition that is necessary for sea-lice survival -- he/she only talks about a condition (low salinity) that is unfavorable to sea-life survival.

Even if you squint your eyes really hard and say that the biologist's argument implies that somewhat higher salinity is necessary for survival, that would not be totally accurate. At most, we can infer that higher salinity is more favorable to sea-lice survival, which is different than the condition being absolutely necessary. Because the biologist never claims that anything is absolutely necessary to sea-lice survival, it is not accurate to say that the professor undermines such a claim.

Eliminate (A).


The professor doesn't think that the salinity measurements were inaccurate -- in fact, he/she uses the same numbers in his/her own argument. Eliminate (B).


The biologist thinks that sea lice transmission is unlikely because the conditions in the archipelago "tend to suppress" sea-lice proliferation. The professor provides additional information, and then says that, actually, the conditions "favor the flourishing of sea lice."

Because the information provided by the professor completely contradicts the biologist's premise, we can determine that this additional evidence shows that the biologist's premise is false.

(C) is looking good.


The professor never questions WHERE the biologist got his/her information, or the validity of those sources. (D) is out.


Nope, the professor doesn't attack the connection between the biologist's conclusion and premises. Instead, he/she provides additional evidence to attack a premise, which in turn calls the biologist's conclusion into question.

(E) is out and (C) is the correct answer.

I hope that helps!
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Prethinking: he gave a new example/evidence to disprove something


A)He didn't point out this , he rather gave a new example/evidence to disprove something
B) Reliable measurements were not at all discussed
D)He didn't question the source, he rather gave a new example/evidence to disprove something
E) He didn't say conclusion is inconsistent wrt premises

C. claiming that there is evidence showing that one of its premises is false: this is what he did as per the argument. He did this to undermine the Biologist's argument.
For better understanding this I marked Red: Biologist's premise and Green:Professor's conclusion( undermined) in the question.

Hope this helps.


Pls. HIT KUDOS
(need few kudos for needs )

GMATNinja Could you please explain the answer choices.

I picked option A - Though not very much convinced but picked this as best of 5 answer choices.

I Eliminated option C because the word false is too strong here. Moreover, nothing was shown as false. Rather an additional evidence was cited

I'm having some trouble wrapping my head around C.

The passage says "review of the literature" implying that already existing literature was reviewed and new findings came forth.

Option C, the right answer, says "claiming that there is evidence showing that one of its premises is false". Doesn't this kind of imply that new evidence/ new information is introduced into the mix? Isn't this at odds with what's going on in the passage?

To claim that “there is evidence” does not suggest that the evidence is new or based on new information. It merely means that evidence exists. If I said “there is literature showing that the biologist is wrong,” that does not mean that the literature is new. It simply means that there is literature out there showing that the biologist is wrong. So, the information in (C) does not contradict what is asserted by the professor.

I hope that helps!
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Most of the explanations say that "tends to suppress sea-lice proliferation" is a premise. But shouldn't it be a conclusion ? since the sentence contains the word concludes ---> "The biologist concludes that the archipelago’s 25–30 parts per thousand salinity range between March and June, the critical period for wild salmon migration, tends to suppress sea-lice proliferation. "

Be careful about assuming that just because a sentence contains some form of the word “concludes,” it is the main conclusion.

In this particular passage, the biologist does conclude that the salinity of 25-30 parts per thousand tends to suppress sea-lice on the basis of evidence that “salinities less than 30 parts per thousand are unfavorable to sea-lice survival.” But this is not the biologist’s main conclusion. It’s simply a subsidiary conclusion that functions as a premise in the biologist’s main argument that the “transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago, British Columbia.”

In other words, why does the biologist bring up the salinity range between March and June? That’s not the biologist’s main point. He/she brings it up to support his/her main conclusion that “transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago, British Columbia.”

So while the claim is a conclusion in and of itself, it functions as a premise in the biologist’s broader argument.

I hope that helps!
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Is this more of a method of reasoning question or logical flaw?
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We actually don't recommend trying to fit questions into question "types" -- while this kind of categorization works out cleanly for a good number of questions, there are many questions that don't fit perfectly into a neat category. So, it's best just to answer the exact question that is written on the page, rather than trying to shove it into a "question type" box.

The passage presents two conflicting viewpoints: that of the "professor," and that of the "biologist." The question asks us to determine how the professor attempts to undermine the biologist's argument. The best thing to do is deeply understand the biologist's argument, deeply understand the professor's argument, and then choose the answer choice that most accurately captures how the professor attacks the biologist's argument.

See this post for a full explanation of each answer choice.

I hope that helps a bit!
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Let’s look at the stimulus of the professor’s argument-

Premises/ evidence (He uses the Marine biologist’s argument as his premise)
Marine biologist’s argument-
Conclusion- transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago, British Columbia,

Premises/evidence-
numerous studies suggest that salinities less than 30 parts per thousand are unfavorable to sea-lice survival.
the archipelago's 25–30 parts per thousand salinity range between March and June, the critical period for wild salmon migration, tends to suppress sea-lice proliferation.

(Professor’s argument)
BUT

a review of the literature shows that salinities of 25–30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice.


The bold-faces phrases show a contradiction. And that is what the question asks for- the professor attempts to undermine the biologist's argument by?


A. pointing out that a condition claimed to be necessary for sea-lice survival is not sufficient for it

The professor does not point out that the condition claimed to be necessary for sea-lice survival is not sufficient for it. Rather he says that the condition favors the flourishing of sea lice. Eliminate.

B. citing studies that suggest that salinity levels were not measured reliably

The professor nowhere in his argument mentions studies that question the reliability of the measurement.That tone cannot be inferred from the argument. He does not say that the measurements are inaccurate. He only says that such a condition (25–30 parts per thousand) in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice. Eliminate.

C. claiming that there is evidence showing that one of its premises is false

The professor says that- But there is evidence that shows that salinities of 25–30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice.
This is contradictory to one of the premises of the marine biologist’s argument. Hence correct.

D. questioning the reliability of the biologist's scientific sources
Nope. The professor isn’t questioning the reliability of the biologist's scientific sources. Similar to B. Eliminate

E. showing that its conclusion is inconsistent with its premises
The professor doesn’t say that there is an inconsistency in the biologist’s argument. He simply brings in another evidence that contradicts one of the premises of the biologist’s argument. Eliminate.


Vishnupriya
GMAT Verbal SME

Professor: A marine biologist argues that transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago, British Columbia, citing numerous studies suggesting that salinities less than 30 parts per thousand are unfavorable to sea-lice survival. The biologist concludes that the archipelago's 25–30 parts per thousand salinity range between March and June, the critical period for wild salmon migration, tends to suppress sea-lice proliferation. But a review of the literature shows that salinities of 25–30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice.

In this passage, the professor attempts to undermine the biologist's argument by

A. pointing out that a condition claimed to be necessary for sea-lice survival is not sufficient for it
B. citing studies that suggest that salinity levels were not measured reliably
C. claiming that there is evidence showing that one of its premises is false
D. questioning the reliability of the biologist's scientific sources
E. showing that its conclusion is inconsistent with its premises


Hi AjiteshArun, GMATNinja, VeritasKarishma

I chose E because of the following thought process:

Professor's conclusion- "salinities of 25-30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice".

Marine Biologist's conclusion- Transmission of sea lice from farm salmon to wild salmon is unlikely as the archipelago's 25-30 parts per thousand salinity range(which is below 30 parts per thousand salinity range) between March and June tends to suppress sea-lice proliferation.

The Professor is saying the Marine Biologist missed the effect of British Columbia's cool spring temperatures ( in combination with 25-30 parts per thousand salinity). Hence this shows Marine Biologist missed one component in his/her premise and that is why his/her conclusion is inconsistent with its premises.


Please help me to understand where am I going wrong ?

Hi tt147,

If we say that a "conclusion is inconsistent with its premises", what we mean is that we can't get to that conclusion from its premises. But we can get to the biologist's conclusion as long as we assume that every premise is correct. So, if it is actually the case that

1. salinities less than 30 parts per thousand are unfavorable to sea-lice survival
and
2. the archipelago's salinity is 25–30 parts per thousand between March and June, the critical period for wild salmon migration

then we should be able to conclude that

3. transmission of sea lice from farm salmon to wild salmon is unlikely in the archipelago.

What the professor does is bring in new information that helps us see that (1) doesn't hold under certain conditions (a review of the literature shows that...). This is very different from saying "the premises are fine but we can't get to the conclusion using that support".
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This is what the Professor says:

- A biologist argues that transmission of sea lice from farm salmon to wild salmon is unlikely because salinities less than 30 parts per thousand are unfavorable to sea-lice survival.
- The biologist concludes that the archipelago's 25–30 parts per thousand salinity range will suppress sea-lice proliferation.
- But a review of the literature shows that salinities of 25–30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice.

So the Professor tells us that as per the Biologist, salinities less than 30 ppt are unfavourable to sea lice. But a review of lit shows that 25-30 ppt salinities with cool temp favours sea lice.

So the Professor claims that one of the Biologist's premises (salinities less than 30 ppt are unfavourable to sea lice) is false.

Hence answer is (C)

tt147 -

E. showing that its conclusion is inconsistent with its premises

The professor does not undermine the biologist's argument by showing that the biologist's conclusion is inconsistent with his premises.
The biologist's premises (salinities less than 30 ppt are unfavourable to sea lice, Archipelago has 25–30 ppt salinity range between March and June, March and June the critical period for wild salmon migration) are in line with his conclusion (transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago)

The Professor states that one of his premises (salinities less than 30 ppt are unfavourable to sea lice) itself is false.
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GMATNinja what is the role of "in combination with British Columbia's cool spring temperature" here? It looks like an additional premise to me? It reads like "well, the professor didn't read this one paper that found 30 part and less salines in combination with cool temperature flourishes the lice". If my argument has an added premise (x+y) with x being the common overlap how would this structure be considered as attacking x? To me it sounded the biologist wasn't aware of this one edge case (i.e., cool weather). Could you please help understand what I'm missing here?

Let's start by considering the structure of the marine biologist's argument.

The marine biologist concludes that "the archipelago's 25–30 parts per thousand salinity range between March and June...tends to suppress sea-lice proliferation." This conclusion is based on the premise that the salinity in this area is 25-30 parts per thousand in the spring, and that "salinities less than 30 parts per thousand are unfavorable to sea-lice survival."

So the marine biologist's conclusion relies on the premise that "salinities less than 30 parts per thousand are unfavorable to sea-lice survival." The professor then undermines the argument by attacking this premise. More specifically, the professor claims that "salinities of 25–30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice."

As a result, the premise that "salinities less than 30 parts per thousand are unfavorable to sea-lice survival" is false, which makes (C) correct.

You raise an interesting question about cool spring temperatures being an "edge case" of an otherwise reliable premise. Should we assume the premise that "salinities less than 30 parts per thousand are unfavorable to sea-lice survival" is generally sound? If so, would that make it true?

Unfortunately, the passage doesn't give us any evidence to help resolve this question. We know that the marine biologist has cited numerous studies, but we have no idea how complete or representative those studies are. All we know is that the professor claims the premise is not ALWAYS true. In other words, the professor claims the premise is false.

Yet even if we could somehow prove that the professor's point about cool spring temperatures was just an "edge case," how would that affect the premise?

Notice the premise doesn't say that salinities less than 30 parts per thousand are GENERALLY unfavorable to sea-lice survival, but simply that they ARE unfavorable to sea-lice survival. So if any situations arise where salinities less than 30 parts per thousand are favorable to sea lice, that would show the premise as written is false. So either way, (C) is the best answer.

I hope that helps!
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GMATNinja AndrewN AjiteshArun

Hi,

whereas I understand why all other answer choices are not suitable, I struggle to understand why (C) is correct:

(C) says that there is evidence for one of the premises of the biologists are false. The biologists premise is:

A salinity level of 25-30 tends to surpress sea-lice proliferation.

But nowhere I find evidence that this is not true. All I get to know is that:

If I have a salinity level of 25-30 and this specific temperature of water -> favorable for sea lice proliferation

To say that the premise is false, I would need evidence for:

Salanity levels of 25-30 DON'T tend to surpress sea lice proliferation. And just because it is true that salanity levels of 25-30 AND specific cold water temperatures are favorable for sea lice proliferation, it doesn't follow logically that salanity levels of 25-30 don't tend to surpress sea lice proliferation.

So it could be that still, 25-30 salinity tends to surpress the proliferation, but the temperature of the water outweighs that surpression, and ends up being favorable for the proliferation.


Please let me know where I went wrong

Thanks

Hello, hadimadi. I think the fullest treatment of (C) happens to be in the post right above yours, by GMATNinja. For my part, I would say your points are addressed. Please let me know if you think otherwise. Remember, you are bound by what you see on the screen, not by what you want to be there. If you can see how "all other answer choices are not suitable," then well done on a challenging question—you picked the best of the lot, and that is what CR is all about.

Thank you for thinking to ask.

- Andrew

Hi,

I highlighted it in green. Knowing that the premise is not always true, and the premise being 'Salanity levels from 25-30 tend to surpress sea lice proliferation', I get:

There exist cases where salinity levels at 25-30 don't tend to surpress proliferation. Let's call this whole statement B.

Would you agree to everything up until this point? If yes, then my concern comes now. In order to prove the above, the professor says that there exists a case in which:

Salinity is at 25-30 and specific cool temperatur of water -> Sea Lice Proliferation takes place. Let's call this whole statement A.

The overall point the professor tries to make:

A->B

But this conclusion is not necessarily correct, because it could be that in his example, it is true that:

Salinity levels at 25-30 tend to surpress proliferation of sea lice and the cool water temperature heavily supports that proliferation, so that I have a net surplus of sea lice. Thats why A->B is not true.

I hope this makes my point clearer, thanks again for your time, I appreciate it

Edit: Could it be that this doesn't have to be a logically sound attempt to attack the biologist, but rather, that the task is to show how the professor tried to attack that argument, regardless if what he did makes sense?

Hi hadimadi,

Let's use X ~salinities less than 30 parts per thousand, Y ~cool spring temperatures, and Z ~transmission of sea lice from farm salmon to wild salmon (BA ~Broughton Archipelago). Here's the biologist's argument:

B1. X is unfavorable to Z
B2. Between March and June is the critical period for Z
B3. BA has X between March and June
therefore
B4. Z will not happen in BA

The professor's argument is:
P1: X in combination with Y favors Z
therefore (not explicitly mentioned):
P2: {The biologist is wrong}

If we think about B1, we'll see that it's an absolute. X is unfavorable to Z. If that statement is true, we won't expect anything to be able to change the fact that X should always be unfavorable to Z. However, as soon as the professor says that X is actually good for Z when combined with Y, we can say that the absolute statement (without any conditions) that X is unfavorable to Z is false.
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