The key to this question is noticing the words 'twin goals.' The correct answer must show how both goals are being undermined.

(A) is a very alluring answer choice. After all, if tourists do not want to see the manatees then the plan of providing manatee tours falls apart. But remember, the conclusion is based on twin goals: 1. Giving hunters a good income 2. Ensuring manatee's survival. If many tourists are uninterested in manatees, then that doesn't completely compromise both goals. After all, some manatee tours may still carry on, albeit with mixed results and manatees may actually end up being less endangered than before (assuming that those manatee tour guides who are working won't be hunting).

(E) shows that the hunters will not receive a good income. Indeed, they will struggle to make the same amount as they were before. And by struggle, they will have to get a bigger boat and make more frequent trips, which will destroy the manatees habitat. Remember, the whole point of the plan was to protect the manatees. Now not only do you have financially struggling tour guides but you've further jeopardized the manatee population.

Hope that helps .
_________________

This is a clear E.

A: Many tourists are uninterested, but not all. The passage says that tourist interest is high so quite possibly a small niche of tourists would be willing to pay top dollar. This doesn't negate the plan. Additionally this choice goes against a premise that tourist interest is high, so Id avoid this choice. (regardless, it can be proved that just because many are uninterested, this does not mean all and tourist interest could still be high).

B: Doesn't negate the plan.
C. Doesn't negate the plan.
D. Maybe, but this doesn't mean that the plan wouldn't work. In fact if there aren't enough hunters then this would suggest that hunters would then get paid even more. Simply put high demand for a small supply would increase the amount paid and would definitely probably improve the chances of manatee survival since being a guide is profitable.

E. key word here "fragile." This suggests that the boats have a direct effect on the manatees safety. So if former hunters threaten the manatee's safety w/ big boats, this negates the argument that the plan will work.

I think you've explained why it is irrelevant if 'many tourists are not interested' - as you point out, it is a premise of the argument that 'Tourist interest is high'. A premise is a fact; it must be true. So even if many people are not interested, we know as an absolute fact that tourist interest is high, so it must be true that many people are interested. And as long as many tourists are interested, the plan can succeed.

This is a very important point in GMAT CR. When you are trying to weaken an argument, you are never trying to disprove the premises of the argument. Any answer that appears to contradict a premise cannot be the right answer (and if you think an answer contradicts a premise, you've misinterpreted what the answer choice means). Many trap answers in questions like these are answers which superficially appear to contradict a premise, and you can rule those answers out immediately.
_________________

This is a peculiar conversation. I have the impression that LogicGuru has not understood what I've written, especially when he claims I said anything "regarding the use of new information" in a CR question. And Raghav, I appreciate your effort to be diplomatic, but when you say that LogicGuru is (partly) right when discussing "new information", you're saying he is right about a straw man, about words he put in my mouth, words that I never said. If you read my original posts, I never said anything about "new information".

In case anyone else has misunderstood what I wrote, I'll say it again, with more detail: in a weaken CR question, the premises in the stem should always be taken as absolute facts. The correct answer, the answer which weakens the argument, is never correct because it contradicts or disproves one of the facts stated in the stem. To illustrate with a very simple example, suppose you have this CR stem:

Tim will make lemonade at a cost to him of $1 per glass. Because he will sell the lemonade at $2 per glass, he expects to make a profit. Which of the following, if true, would suggest Tim is incorrect?

On the GMAT, no answer choice can possibly say "Tim will actually sell the lemonade at $0.75 per glass". That is, an answer choice can never say "we were lying to you in the stem above and in fact something completely different is true". Anything stated as a fact in the stem is an absolute fact and cannot be false no matter what an answer choice says. The correct answer to this question would be something more like "Tim will only sell one third of the lemonade he produces". That is new information, and obviously you often get new information from the answer choices in such questions. But it is new information that in no way contradicts the other information you've been given. All of the information in the stem and in that answer choice is logically consistent. The same is true in the original question, by the way: tourist interest can be high even if many tourists have no interest. There is no logical inconsistency there - we already know that many tourists do have interest. But you could not possibly even see an answer choice in the original question which read "there is no tourist interest", because that would directly contradict a fact in the question stem.

What I'm saying is fundamental to GMAT CR, and is in no way controversial; any other reputable GMAT expert will tell you exactly the same thing. If LogicGuru wishes to continue to insist I'm wrong about this, then there is a straightforward way for him or her to prove that: find a single official CR weaken question where the correct answer (or any answer choice) contradicts one of the factual premises stated in the stem. Or, since it will take an eternity to find such an example, a faster way would be to ask any other GMAT expert, if you are not inclined to believe me.
_________________

You are saying exactly the opposite of what is required to weaken an argument. The best way to weaken an argument is to weaken the premises.
Even this question says so itself -"Which of the following IF TRUE ...."
Heck !! GMAT itself is telling the test taker to take the answer choices in given options as "True".
Perhaps you have forgotten that NEW INFORMATION can be liberally used in weaken,strengthen,assumption,justify, paradox, and evaluate the argument family of question.
A is incorrect because of contraposition in logic :- MANY IS NOT THE LOGICAL OPPOSITE OF ALL
The logical opposite of ALL is NOT ALL
In syllogistic and propositional logic ==>Many = some
So Option A is saying some tourist might not want to see the animal. This does not weaken the argument.
The correct answer is E but not because of the reasons you are telling. I humbly suggest you take a quick look into tautology and truth-tables to rectify your misconception.
_________________

could someone explain me why c is an strengthener? i was between C and D and my reasoning was the following:

C- if natives could easily replace manatee´s meat with seafood but they haven´t, the may hunt it because of a bond with that specific meat, so that even a good income will not make them to stop hunting.

D- I was really tempted, but then it though that the manatee´s survival could be unrelated with it´s habitat.

I am very humbly and civilly resting my case. Your answer is wrong. I have no doubts about it and perhaps a quick brushing of your concept will make you realise that you made a novice mistake in evaluating, analysing and applying the concept of GMAT logic and reasoning. If you still insist that you have NOT made the gravest and most unpardonable error regarding the use of new information in weaken questions, then I too have nothing to add to this discussion. You can confirm your mistake by contacting a unbiased referee or expert from this forum (only if you are interested to)

Like the rule of thermodynamics doesn't change whether you are talking about a small test-tube filled with gas or a carnot engine or a heat sink or the entire universe, similarly the rules of logic doesn't change whether you are talking about philosophical, mathematical, propositional, syllogistic, GMAT, LSAT or any other kind of logic. Thats the beauty of logic that along with math, it is probably the only subject that does not have weird exceptions when it comes to its rules. LOGIC NEVER CHANGE.


HOWEVER FOR THE BENEFIT OF OTHER USERS/READERS COMING ACROSS THIS QUESTION, I MUST ADD THAT YOUR REASONING IS ABSOLUTELY INCORRECT AND HENCE SHOULD NOT BE FOLLOWED. (AT LEAST FOR THIS QUESTION FOR THE TIME BEING!!)
IN THE PRESENT FORM THE ABOVE MENTIONED ANSWER IS MOST HALF BAKED AND ILL-INFORMED POST IN THIS ENTIRE THREAD AND SHOULD BE AVOIDED WITHOUT FAIL.
_________________

In parts of the Caribbean, the manatee, an endangered marine mammal, has long been hunted for its meat. Having noted the manatee hunters’ expert knowledge of manatees’ habits, local conservationists are encouraging the hunters to stop hunting and instead to take tourists on boat rides to see manatees. Tourist interest is high, so the plan has promise of achieving the twin goals of giving the former hunters a good income and helping ensure the manatees’ survival.

Which of the following, if true, raises the most serious doubt about the plan’s chance of success?

A. Many tourists who visit these parts of the Caribbean are uninterested in manatees and would not be willing to pay what the former manatee hunters would have to charge for boat rides to see manatees.
The choice is alluring since it questions the feasibilty of the plane by providing a point that the hunters will not be earning as mush as they are doing now.But we cannot select this until reading all the choices.and after reading all the choices we find that option E is a better choice.Since the ultimate goal is to protect mantee and not provide employment to the hunters.

B. Recovery of the species would enable some hunting to continue without putting the manatees’ survival in jeopardy again.
out of the current scope

C. In areas where manatees have traditionally been hunted for food, local people could easily replace the manatee meat in their diets with other foods obtained
from the sea.
This is actually a strengthener because is supports the plan.

D. There would not be enough former manatee hunters to act as guides for all the tourists who want to see manatees.
This point does not weakens the point because other hunters can be trained easily to act as travel guides.

E. To maintain their current income, manatee hunters who switched to guiding tourists would have to use far larger boats and make many more trips into the manatees’ fragile habitat than they currently do.
Correct answer since not only the hunters turned guide would not be earning as much as they are earning currently but also they would have to use bigger boats to make up for their profits.Bigger boats are threat tho the fragile natural habitat of mantee.

a choice which is relevant but not strong enough to affect the argument is a trap . this trap is popular in og and gmatprep questions.

this trap is normally not enough quantitatively . if "most"not "many" is used, choice A can be correct.

What would be the best way to approach weaken questions? Consider every argument as a cause -effect relationship or just look for an option, which is the negation of the conclusion of the argument??

Posted from my mobile device