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Columnist: Contrary to what many people believe, the nu1nber

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14 Sep 2017, 09:12

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59% (01:58) correct

41% (02:10) wrong

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15 Sep 2017, 03:04

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Masshole

Premise 1: The rate of extinction at present is the same as in 1970
Premise 2: The rate of the emergence of new species at present is the same as in the last several centuries.
Conclusion: the number of species on Earth is probably not dwindling

(A) In 1970 fewer new species emerged than went extinct.
Correct. This choice points out the flaw in the argument. If the rate of new species emerged is less than the rate of extinction, the number of species on Earth is dwindling

(B) The regions of the world where new species tend to emerge at the highest rate are also where species tend to go extinct at the highest rate.
This choice provides information that is too general. We can't conclude anything from this one.

(C) The vast majority of the species that have ever existed are now extinct.
We still can't conclude that whether the number of species on Earth is dwindling

(D) There is no more concern now about extinction of species than there was in 1970.
Concern about extinction of species is irrelevant.

(E) Scientists are now better able to identify species facing serious risk of extinction than they were in 1970.
This choice is irrelevant to the argument.

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18 Sep 2017, 10:45

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Quote:

Question Type:
Weaken

Stimulus Breakdown:
Conclusion: The number of species is probably not dwindling.
Evidence: Extinctions are natural. This year we have the same number going extinct as in 1970. But species emergence is also natural. We probably have the same rate of emerging species as we've had for the last several centuries.

Answer Anticipation:
The truth value of the author's conclusion hinges on whether the number of species emerging each year is at least as high as the number of species going extinct each year. We have no precise comment to that effect. Instead, we have two arbitrary benchmarks:
The rate of species going extinct is comparable to 1970's rate.
The rate of species emerging is comparable to that of the last several centuries.

So the author is assuming the rate species have emerged over the last several centuries is at least as great as the rate species went extinct in 1970.

Correct Answer:
A

Answer Choice Analysis:
(A) Ultimately, yes. Since the author uses 1970 as a benchmark year, to make us feel better about the comparative rate of extinction / speciation, this answer weakens by painting an unflattering picture about 1970. In 1970, the number of species on Earth dwindled. So this year provies poor support for an author drawing the opposite conclusion.

(B) Getting specific about regions is out of scope. Our conclusion is about Earth's total number of species.

(C) This doesn't say anything about whether the current rate of losing species is offset by the rate of getting new ones.

(D) "Concern" is out of scope. We need to know the actual numbers.

(E) This shows a difference In detecting endangerment. We need information about the actual number of species going extinct / being created.

Takeaway/Pattern: The conclusion is a very mathematically specific claim, so it behooves us to think about this argument in those terms. Once we pinpoint that we need to quantify how many species we've lost vs. gained, the relevant comparison between 1970 and 'the last few centuries' is clear. However, in the end, the correct answer just attacks one of those benchmarks as sketchy support.

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18 Jun 2019, 02:54

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broall

Masshole

Premise 1: The rate of extinction at present is the same as in 1970
Premise 2: The rate of the emergence of new species at present is the same as in the last several centuries.
Conclusion: the number of species on Earth is probably not dwindling

(A) In 1970 fewer new species emerged than went extinct.
Correct. This choice points out the flaw in the argument. If the rate of new species emerged is less than the rate of extinction, the number of species on Earth is dwindling

(B) The regions of the world where new species tend to emerge at the highest rate are also where species tend to go extinct at the highest rate.
This choice provides information that is too general. We can't conclude anything from this one.

Hi I had a doubt.
The rate of emergence of new species has been averaged over a century. A fluctuation in one or two years should not make a strong argument.

(C) The vast majority of the species that have ever existed are now extinct.
We still can't conclude that whether the number of species on Earth is dwindling

(D) There is no more concern now about extinction of species than there was in 1970.
Concern about extinction of species is irrelevant.

(E) Scientists are now better able to identify species facing serious risk of extinction than they were in 1970.
This choice is irrelevant to the argument.

Hi

I have a doubt.

The rate of emergence of new species is averaged over a century. I am not able to relate the impact of a mere fluctuation during a year or two. Could you please help.

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18 Jun 2019, 04:11

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there is no reason to doubt that new species are emerging at about the same rate as they have been for the last several centuries.

it just says that the rate of emergence is the same since last many hundred years. It doesn't say it is greater than rate of extinction, even A doesn't weaken it.

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25 Nov 2021, 08:54

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Columnist: Contrary to what many people believe, the number of species on Earth is probably not dwindling. Extinction is a natural process, and about as many species are likely to go extinct this year as went extinct in 1970. But the emergence of new species is also a natural process; there is no reason to doubt that new species are emerging at about the same rate as they have been for the last several centuries.

Which one of the following, if true, most weakens the columnist's argument?

As per the passage the rate of emergence of new species is almost same as it had been for several centuries. So, we this can't be disputed unless we have something concrete that defines the rates and signify something seriously flawed in that.
The key to passage is then the blue text because the argument of columnist is based on 1970's fact. Hence, a choice that touches upon this aspect elaborating key flaw then it must be our answer.

(A) In 1970 fewer new species emerged than went extinct. - CORRECT. If it had already been so that new species were less than extinct ones in 1970 then in present also such a situation must be there.
(B) The regions of the world where new species tend to emerge at the highest rate are also where species tend to go extinct at the highest rate. - WRONG. Scope is reduced because of which this loses. Otherwise it makes a well attempt.
(C) The vast majority of the species that have ever existed are now extinct. - WRONG. True and weakens but in real world. For this argument it's too generic.
(D) There is no more concern now about extinction of species than there was in 1970. - WRONG. Irrelevant.
(E) Scientists are now better able to identify species facing serious risk of extinction than they were in 1970. - WRONG. Strengthens actually.

Answer A.

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16 Aug 2024, 06:03

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Columnist: Contrary to what many people believe, the number of species on Earth is probably not dwindling. Extinction is a natural process, and about as many species are likely to go extinct this year as went extinct in 1970. But the emergence of new species is also a natural process; there is no reason to doubt that new species are emerging at about the same rate as they have been for the last several centuries.

Which one of the following, if true, most weakens the columnist's argument?

(A) In 1970 fewer new species emerged than went extinct.
(B) The regions of the world where new species tend to emerge at the highest rate are also where species tend to go extinct at the highest rate.
(C) The vast majority of the species that have ever existed are now extinct.
(D) There is no more concern now about extinction of species than there was in 1970.
(E) Scientists are now better able to identify species facing serious risk of extinction than they were in 1970.

Inference : So, if 100 species got extinct in 1970, the same no. of species have gotten extinct this year. I now need to know how many new are getting added every year because if the new added is less in this year, then it weakens the argument that no. of species if not dwindling.
Now, the next line says that new species are emerging at the same rate. So, if every year new species are added at 10%, there might be a scenario that while in 1970 the new species emerged were less but by adding 10% each after that, the no. of new species emerged in this year is > than 100 (no. of new species that got extinct. How is Ans A the correct ans choice?
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24 Sep 2024, 08:36

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nikitathegreat

Columnist: Contrary to what many people believe, the number of species on Earth is probably not dwindling. Extinction is a natural process, and about as many species are likely to go extinct this year as went extinct in 1970. But the emergence of new species is also a natural process; there is no reason to doubt that new species are emerging at about the same rate as they have been for the last several centuries.

Which one of the following, if true, most weakens the columnist's argument?

(A) In 1970 fewer new species emerged than went extinct.

(B) The regions of the world where new species tend to emerge at the highest rate are also where species tend to go extinct at the highest rate.

(C) The vast majority of the species that have ever existed are now extinct.

(D) There is no more concern now about extinction of species than there was in 1970.

(E) Scientists are now better able to identify species facing serious risk of extinction than they were in 1970.

Inference : So, if 100 species got extinct in 1970, the same no. of species have gotten extinct this year. I now need to know how many new are getting added every year because if the new added is less in this year, then it weakens the argument that no. of species if not dwindling.

Now, the next line says that new species are emerging at the same rate. So, if every year new species are added at 10%, there might be a scenario that while in 1970 the new species emerged were less but by adding 10% each after that, the no. of new species emerged in this year is > than 100 (no. of new species that got extinct. How is Ans A the correct ans choice?

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GMATNinja karishma

Remember that we are looking for something that WEAKENS the argument, not something that DISPROVES the argument.

The author argues that rates of species extinction and emergence probably haven't changed much since 1970, so there's no reason to think that the number of species is dwindling. But if those unchanging rates result in a net DECREASE every year, then the number of species would of course be going down.

In short, the fact that the rates have been steady doesn't tell us anything about the average net change. Choice (A) illustrates this flaw in the argument, so it's the best choice.

I hope that helps!

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