Q11 - A development company had proposed

[ohthatpatrick]

Question Type:
Flaw

Stimulus Breakdown:
Conclusion: The airport is unlikely to be built.
Evidence: If a majority favors the proposal, the airport will be built. But a majority of residents is unlikely to favor the proposal.

Answer Anticipation:
If we're doing a Flaw question and we see any conditional logic, such as the 2nd sentence, we should immediately be very wary of the Conditional Logic flaw. True to form, the author tries to reason via an illegal negation. She gives us "If majority approve, airport will be built" and then acts like "if majority don't approve, airport won't be built". So we could prephrase that the author "confused necessary and sufficient" or we could say that she fails to consider that there might be other conditions besides majority approval that would ALSO lead to the airport being built.

Correct Answer:
A

Answer Choice Analysis:
(A) Yes! The rule provided was that "majority approval" is sufficient for (guarantees) airport being built. The author acts like "majority approval" is necessary, because she reasons that WITHOUT majority approval, the airport won't be built.

(B) Most people believe "the airport will create noise problems", but the author doesn't conclude "therefore, the airport will create noise problems".

(C) This says our author concludes "that an events WILL not occur", which doesn't match the actual conclusion, which says "the airport is UNLIKELY to be built".

(D) Would this weaken? No, because the author isn't ever saying "NO ONE is going to favor this proposal. She is only concerned with whether it's more or less than 50% of people, and she's trying to draw an inference based on that threshold.

(E) The author isn't saying the airport would be good or bad, so we can't weaken her argument by pointing out possible benefits. And the author's reasoning problem is in how she applies the conditional rule in the 2nd sentence. The evidence is merely about whether most people would/wouldn't favor the proposal ... even if the airport actually WOULD improve the economy, they could still be against it because of the noise problems.

Takeaway/Pattern: The Conditional Logic flaw (aka "necessary vs. sufficient") is probably the most commonly occurring famous flaw on modern tests. That still means it's probably only involved in 1 out of every 5 or 6 Flaw questions, but it's worth keeping on our radar that "if we see any conditional logic offered in the evidence, we should make sure the author isn't using an illegal negation or reversal to arrive at her conclusion".

#officialexplanation

[ohsobecca]

Okay...I remember not liking any of these answers, really. And while E makes sense I guess, I have no idea how we're supposed to figure out that E is the flaw. I mean, we don't know WHY the airport is being built; structurally, the argument commits a negation but there wasn't anything like that in the answer choices. Is it because what development companies DO is 'develop' economies? I wasn't sure about that when I did the problem.

[kimyooji]

The correct answer choice is A.

IF the majoirty of Dalton's resident favor the P, THEN the airport built.

unlikely that the residents would favor P so unlikely the airport will be built.

IF A->B
not A->not B

this is a flaw.

benefit the local economy (E) is out of the scope.

[dtangie23]

I agree with kimyooji and thought of it in the same way.
Here's how I approached it...

Premise:

MAJORITY FAVORS --> AIRPORT BUILT

Let's take the contrapositive of the premise so that we have it handy.

AIRPORT NOT BUILT --> MAJORITY DOES NOT FAVOR

Conclusion:

Unlikely that majority will favor, therefore, unlikely that the airport will be built.

(A) is correct. "unlikely that the airport will be built" is basically saying "airport not built." That is the SUFFICIENT condition of the contrapositive. But the conclusion is treating it as a necessary condition.
(B) It's not concluding that something must be true. Note the cautious use of the word "unlikely," which does not mean must be true.
(C) Again, it's saying that the majority is unlikely to favor and the airport is unlikely to be built. It's not saying that it "will not occur."
(D) Actually it does...don't the residents live near the airport?
(E) So what? Just because it could benefit the economy doesn't mean that those benefits supersede the noise concerns.

[farhadshekib]

I agree with kimyooji and thought of it in the same way.
Here's how I approached it...

Premise:

MAJORITY FAVORS --> AIRPORT BUILT

Let's take the contrapositive of the premise so that we have it handy.

AIRPORT NOT BUILT --> MAJORITY DOES NOT FAVOR

Conclusion:

Unlikely that majority will favor, therefore, unlikely that the airport will be built.

(A) is correct. "unlikely that the airport will be built" is basically saying "airport not built." That is the SUFFICIENT condition of the contrapositive. But the conclusion is treating it as a necessary condition.
(B) It's not concluding that something must be true. Note the cautious use of the word "unlikely," which does not mean must be true.
(C) Again, it's saying that the majority is unlikely to favor and the airport is unlikely to be built. It's not saying that it "will not occur."
(D) Actually it does...don't the residents live near the airport?
(E) So what? Just because it could benefit the economy doesn't mean that those benefits supersede the noise concerns.

Close, but I disagree on this point.

If I say that "Jim is unlikely to get the job", I am not basically saying that "Jim won't get the job". I am making a prediction on the likelihood of something occurring.

In the stimulus, the argument concludes with a similar prediction; however, the premises do not provide much support for that prediction.

Essentially, it is arguing that if A (majority favor proposal), then B (airport built).

It then suggests that probably not A (unlikely that majority favor proposal), thus probably not B (unlikely that the airport will be built).

However, even if the majority of Dalton's residents are unlikely to favor the proposal, this does not necessarily lower the chances of an airport being built in Dalton.

The flaw here is that the argument assumes, without warrant, that there is probably no other way for that airport to be built.

In other words: it treats a sufficient condition (i.e. majority = favor of proposal) for the airport being built as a necessary condition.

[shirando21]

can anyone summarize the reference (PT, section, question number) of the questions involving unlikely so that we can take a closer look at the usage of unlikely.

Thanks a lot.

[steves]

I agree with kimyooji and thought of it in the same way.
Here's how I approached it...

Premise:

MAJORITY FAVORS --> AIRPORT BUILT

Let's take the contrapositive of the premise so that we have it handy.

AIRPORT NOT BUILT --> MAJORITY DOES NOT FAVOR

Conclusion:

Unlikely that majority will favor, therefore, unlikely that the airport will be built.

(A) is correct. "unlikely that the airport will be built" is basically saying "airport not built." That is the SUFFICIENT condition of the contrapositive. But the conclusion is treating it as a necessary condition.
(B) It's not concluding that something must be true. Note the cautious use of the word "unlikely," which does not mean must be true.
(C) Again, it's saying that the majority is unlikely to favor and the airport is unlikely to be built. It's not saying that it "will not occur."
(D) Actually it does...don't the residents live near the airport?
(E) So what? Just because it could benefit the economy doesn't mean that those benefits supersede the noise concerns.

I got this one right only by eliminating the other answers (B) - (E). DTangie's response is very helpful. A related way to look at it is that the conclusion is a negation of the premise--and negation of a necessary condition would destroy it. That identifies why the premise is treated as a necessary condition.

[mshinners]

can anyone summarize the reference (PT, section, question number) of the questions involving unlikely so that we can take a closer look at the usage of unlikely.

Thanks a lot.

I don't have specific references, but "unlikely" means "under a 50% chance of happening" on the LSAT.