Herbicides allow cereal crops to be grown very efficiently

[MBA Applicant 2007/8]

Herbicides allow cereal crops to be grown very efficiently, with virtually no competition from weeds. In Britain, patridge populations have been steadily decreasing since herbicides use became widespread. Some environmentalists claim that these birds, which live in and around the cereal crops fields, are being poisoned by the herbicides. However, tests show no more than trace quantities of herbicides in patridges on herbicide-treatd land. Therefore, something other than herbicide use must be responsible for the population decrease.

Which of the following if true about Britain most seriously weakens the argument?

A) The elimination of certain weeds from cereal crop fields has reduced the population of the small insects that live on those weeds and that form a major part of the patridge chick's diet.

B) Since patridges are valued as game birds, records of their population are more carefully kept than those for many other birds.

C) Some of the weekds that are eliminated from cereal crop fields by herbicides are much smaller than the crop plants themselves and would have no negative effect on crop yield if they were allowed to grow

D) Birds other than patridges that lvie in or around cereal crop fields have also been suffereing population declines.

E) The toxins contained in herb. typically used on cereal crops can be readily identified in the tissues of animals that have ingested them.


H---> C to Grow
P (down) ---> H(increase)

BUT
Not H----P (down)

S A
--B
--C
S--D
W--E

But the correct answer is A. Please use the MGMT strategy described to explain why Choice A is right.

Thank you

[dbernst]

In order to correctly weaken an argument you must first be certain to clearly understand the argument's conclusion and the premises (facts) upon which the conclusion is based. In this particular argument, the author concludes that something other than herbicide use must be responsible for the population decrease. This is based on the fact that no more than trace quantities of herbicides are found in patridges on herbicide-treated land.

To weaken the argument, we must demonstrate that the herbicides ARE responsible for the population decrease, even though the birds on herbicide-treated land only contain trace amounts of herbicides.

A) The elimination of certain weeds from cereal crop fields has reduced the population of the small insects that live on those weeds and that form a major part of the patridge chick's diet.
-Big "W": H kills weeds -> kills insects -> kills birds. This directly suggests that the herbicides are responsible for the demise of the birds.

B) Since patridges are valued as game birds, records of their population are more carefully kept than those for many other birds.
- Not relevant: Comparisons with other birds do not relate to the argument.

C) Some of the weeds that are eliminated from cereal crop fields by herbicides are much smaller than the crop plants themselves and would have no negative effect on crop yield if they were allowed to grow
- Not relevant: Answer choice does not relate to the birds.

D) Birds other than patridges that live in or around cereal crop fields have also been suffering population declines.
-Not relevant: This choice does not relate to the partridge. Moreover, it offers no additional information concerning why these populations are in decline.

E) The toxins contained in herbicides typically used on cereal crops can be readily identified in the tissues of animals that have ingested them.
-little "w": I agree that this choice does confirm a premise from the argument - that the birds actually contain little pesticide residue - but it does not add any new information to suggest that the pesticides are nevertheless responsible for the demise of the birds.

The distinction between answer choices A and E is clear. Whereas E simply confirms a fact that is already stated in the argument (no new information to weaken the conclusion), A adds new, and relevant, information to support that the pesticides are in fact responsible for the demise of the partridge.

Hope that makes sense!
-dan

[singh.181]

In order to correctly weaken an argument you must first be certain to clearly understand the argument's conclusion and the premises (facts) upon which the conclusion is based. In this particular argument, the author concludes that something other than herbicide use must be responsible for the population decrease. This is based on the fact that no more than trace quantities of herbicides are found in patridges on herbicide-treated land.

To weaken the argument, we must demonstrate that the herbicides ARE responsible for the population decrease, even though the birds on herbicide-treated land only contain trace amounts of herbicides.

D) Birds other than patridges that live in or around cereal crop fields have also been suffering population declines.
-Not relevant: This choice does not relate to the partridge. Moreover, it offers no additional information concerning why these populations are in decline.

-dan

isn't D Strengthening the argument? If other birds population is going down, something other than herbicide is responsible.

[george.kourdin]

the argument is concerned with patridge, not with birds in general or other species of birds. this is simply out of scope.

[singh.181]

the argument is concerned with patridge, not with birds in general or other species of birds. this is simply out of scope.

I don't agree with your reasoning.

The question stem says that "Which of the following if true about Britain most seriously weakens the argument? "

So, the information given in the answer is taken for granted to be true. That means, we can bring out side information, but it must relate with topic in discussion. So, "out of scope" is not a correct reason to eliminate an answer choice.

Also, "patridge" is a type or bird. If I make some point regarding the "bird" category, that point holds for patridge as well.

[george.kourdin]

the argument is concerned with patridge, not with birds in general or other species of birds. this is simply out of scope.

I don't agree with your reasoning.

The question stem says that "Which of the following if true about Britain most seriously weakens the argument? "

So, the information given in the answer is taken for granted to be true. That means, we can bring out side information, but it must relate with topic in discussion. So, "out of scope" is not a correct reason to eliminate an answer choice.

agreed that the information that we bring in is considered to be true, but it does not mean that we can bring outside information. again, the argument is focused on partridges. the conclusion is focused on population decrease of partridges. any other species of birds/animals is irrelevant/out of scope. it is most definitely a correct reason to eliminate an answer choice.

choice (D) makes it easy for you to figure that out by literary spelling out that <Birds other than patridges>. if we are going to bring in birds other than partridges to weaken the conclusion, which is focused specifically on partridges, we may as well bring in octopus, squirrels and elephants.

Also, "patridge" is a type or bird. If I make some point regarding the "bird" category, that point holds for patridge as well.

[tim]

if octopus, squirrels, and elephants will weaken the conclusion, then YES by all means bring them in! i don't know where this idea comes from that you can't use out of scope information in a CR question, but for some question types it is ESSENTIAL - for instance, this one. out of scope answers are only automatically wrong in conclusion questions..

[sumit_pune]

STUMPED !! at first but later understand why A is right.

most of us think that why A right , when insects decrease is responsible not Herbicide for population decrease of birds. MEANS A is strengthening the argument.

but wait , read the conclusion again it is "herbicide use isn't causing the population decrease."

read again herbicide use , USE is game changer.

if "use" were not there , A would have strengthen the argument.

now because as per A "herbicide use" responsible for insects killing , which decrease birds population. A make sense !!

[patil.ambar]

I chose A , because that seemed to be the best .
But , nowhere does the argument or the Option A suggest that the Herbicide kills weeds . Can we assume that ?

Thanks

[RonPurewal]

STUMPED !! at first but later understand why A is right.

most of us think that why A right , when insects decrease is responsible not Herbicide for population decrease of birds. MEANS A is strengthening the argument.

but wait , read the conclusion again it is "herbicide use isn't causing the population decrease."

read again herbicide use , USE is game changer.

if "use" were not there , A would have strengthen the argument.

now because as per A "herbicide use" responsible for insects killing , which decrease birds population. A make sense !!

you have the right idea here, but the word "use" is not as essential as you seem to think.
even if "use" were absent, you can still blame the herbicides for all of their (direct and indirect) consequences.
so, if herbicides --> no weeds --> insects die, then you can say herbicides --> insects die.

[RonPurewal]

I chose A , because that seemed to be the best .
But , nowhere does the argument or the Option A suggest that the Herbicide kills weeds . Can we assume that ?

Thanks

the opening sentence states that "Herbicides allow cereal crops to be grown very efficiently, with virtually no competition from weeds." the italic words (together with the fact that herbicides, by definition, are chemicals designed to kill plants) imply that the herbicides kill the weeds.