Columnist: Contrary to what many people believe, the nu1nber

Question

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.

Source: LSAT

Kudos! :thumbup:

broall · Answer

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.

akela · Answer

abhi2707 · Answer

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.

prototypevenom · Answer

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.

unraveled · Answer

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?

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.

nikitathegreat · Answer

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?

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?
Thanks 
 GMATNinja   karishma

GMATNinja · Answer

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!

vasu1104 · Answer

the number of species on earths is probably not dwindling. 
 extinction is natural process and this year probably the same number of species are likely to go extinct as it happened in 1970. 
 emergence is also natural process. 
 conclusion- there is no doubt that new species are emerging at the same rates as they have been for the last several centuries.

passage is saying that extinction and emergence are natural process and this year same num of species are going to extinct as it happened in 1970, so there is no doubt that emergence is likely to follow the same rate this year as compared to what happened over last few centuries. 
 so basically comparing extinction rate with emergence rate and says emergence will follow the same route since both are natural process. what rubbish dude.

(A) In 1970 fewer new species emerged than went extinct. 
 this means there is no clear connection between both phenomenon. and if in 70s if few emerged then we cant say that given principle will work this year as well. keep.

(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. 
 so this gives more reason to believe columnist argument and conclusion. reject.

(C) The vast majority of the species that have ever existed are now extinct. 
 but other species can emerge. so this has not much impact. rejecrt

(D) There is no more concern now about extinction of species than there was in 1970. 
 this is talking about concern of extinction between now and 1970, but thats not point here. reject

(E) Scientists are now better able to identify species facing serious risk of extinction than they were in 1970. 
 good to know but has no impact on what we are discussing here. get out.

Columnist: Contrary to what many people believe, the nu1nber

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Columnist: Contrary to what many people believe, the nu1nber

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