The cost of flood damage since 1980 has been greater in areas that hav

Question

The cost of flood damage since 1980 has been greater in areas that have adopted flood-control measures than in those that have not. Thus, flood-control projects are expensive engineering mistakes and a substantial waste of resources.

Which of the following, if true, would be most damaging to the argument above?

A. Those areas that had not suffered flood damage before 1980 are the only ones that have not adopted flood-control measures.
B. Since 1980, those areas that have taken flood-control measures have suffered greater flood damage than they did in the previous decade.
C. The cost of flood damage has increased every year since 1980.
D. Faulty engineering has not been the only cause of the failure of flood-control projects.
E. The amount of rainfall since 1980 has been substantially greater than normal.

800orDie · Answer

The first sentence is factual whereas the second is purportedly a conclusion based on the first. The correct answer should therefore weaken the link between the fact and the argument.

Spend 2 seconds trying to predict what could possibly weaken the conclusion. My prediction: something that differentiates the areas that adopted flood-control from those that didn't, an unmentioned variable.

(A)  indicates that floods are not uniformly distributed: some areas are affected more than others. Affected areas could be more likely to seek protective measures. That the measures are not perfect does not mean they're mistakes. Very solid candidate answer.

(B)   is consistent with the stem's conclusion. Although it doesn't strengthen the argument, it sure doesn't weaken it.

The only thing we could conclude from   (C)   is that flood-control measures have been getting more expensive. Because it points to higher costs, this choice is consistent with the main argument ("expensive...mistakes", "substantial waste of resources").

(D)   suggests that there might be another factor, other than faulty engineering, contributing to the failure of flood-control projects. This is in line with what we're looking for in an answer, because it mildly weakens the argument by questioning its scope. But this choice is also, in a way, consistent with the argument... it's a "yes, but not only" statement. " ailure" is also a strong word given that the argument does not specify the objectives of flood-control projects--could be to eliminate, minimize, or reduce damages.

(E)   is good but it takes an unwarranted leap of judgment to make it work in context. We're looking for something that differentiates two areas, so a general statement that could apply to both areas does not help.

b9n920 · Answer

Hi experts,

I could not understand why A is a better choice than B. I am presenting what I understood so far: Some places use Flood Control measures (X); some do not (Y).
Cost of flood damage is more for X than for Y. So, author concludes:  flood-control projects are expensive engineering mistakes and a substantial waste of resources. 
We need to weaken this.
So, we basically need to show that some other reason for more cost is in play and not the  expensive engineering mistakes and a substantial waste of resources .

A may indicate: that Y are less prone to flood damage than X are. BUT we are interested in flood damage cost - i.e. the cost of damage after one flood. How the less probability of flood is useful?

B says: X have suffered greater flood damages after 1980 than previous decade. Partly suggests a different reason, though do not compare X and Y properly.

What am I missing here? Pls suggest. 
Any idea about the source?

Thanks.

dominicraj · Answer

Hi Binit,

B actually in a way strengthens the argument IMO by saying that "the areas have suffered greater flood damage than they did in the previous decade."

Conclusion:flood-control projects are expensive engineering mistakes and a substantial waste of resources.

This is a weaken question so we either need an alternate reason for the observed ineffectiveness of the flood control measures or find out a reason that did not fix the initial problem in the first place(ie. with respect to the argument).

Now as per A, we notice that the problem persisted in say X area and not in Y area and hence X resorted to flood-control projects in 1980.

When floods cant affect Y(say they are high altitude or so) it directly implies that still even till date.."The cost of flood damage since 1980 has been greater in areas that have adopted flood-control measures".

Hope it helps.

b9n920 · Answer

Hi dominicraj , Thanks for your response. I got it. I totally misunderstood the argument. Somehow, I thought the first line of the argument talks about the cost of damage per flood after 1980 . That's funny

A obviously is a weakener and B strengthens the argument and gives some incentive to doubt the engineering dept. Thank you so much.

Mahmud6 · Answer

The cost of flood damage since 1980 has been greater in areas that have adopted flood-control measures than in those that have not. The the cost of flood damage BEFORE 1980 had ALSO been greater in areas that had adopted flood-control measures than in those that had not, because (A) before 1980, there had no flood damage in non-controlled area. So, the conclusion that flood-control projects are expensive engineering mistakes and a substantial waste of resources can not be justified.

straykid · Answer

Someone was asking about the source. This was also on a really old paper test. Maybe from the early 1980s.

PSP92 · Answer

I was stuck between answer choices A & D. 
The argument says "The  cost of flood damage  since 1980 has been  greater  in areas that have adopted flood-control measures than in those that have not." It is inferred from this that there has been some amount of damage that has happened in areas that have not adopted flood control measures.
I eliminated A thinking that whatever happened earlier is irrelevant here. Maybe the areas weren't getting flooded earlier but somehow they are now and that's what we are comparing in the argument.

Is there an error in my understanding?

Tobey · Answer

Had the same point of doubt as yours. My understanding is that,
if we accept A as a fact, we can derive the fact that flood-control measures were adopted since 1980. From this, we can assume whether to adopt the measures has been decided based on how much vulnerable the place is from floods. 
The point is 1980 is the year they decided on whether to adopt the measures or not. It is a far stretch for us to think that the weather or the frequency of floods could have changed drastically since 1980, which would have otherwise made A an out of scope.

The cost of flood damage since 1980 has been greater in areas that hav

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