Q10 - Anyone who fails to answer

[nbayar1212]

I got to D as the answer but I can't really figure out the problem with A.

The flaw seems to be that the stimulus concludes that the sufficient condition is true based on information about the necessary condition. BUT, the conclusion is actually pretty weak; it says that the necessary condition is simply a reason to have confidence in the sufficient condition being true....which doesn't seem logically problematic. I mean, yeah if my doctor can answer my questions, IT DOES give me a reason to think he or she is competent....

So I guess I have two questions:

1. Why is A wrong?

2. What's the flaw?

[maryadkins]

The flaw here is that we have reversed logic. We're told:

Fail to answer questions --> Not competent
(Contrapositive would be, then: Competent --> Does answer questions)

Based on this premise, the author concludes that since her physician does answer questions she must be competent. In other words, she's reversing the logic of the premise above:

Does answer questions --> Competent

We're looking for an answer that makes this same illegal reversal.

(D) is correct in that it exhibits the same flaw:

Work 2 or more jobs --> Can't find balance
[Contrapositive: Can find balance --> Don't work 2 or more jobs]
Conclusion: Maggie doesn't work 2 or more jobs --> can find balance

(A) would be:

Large fam --> accustomed to compromises
Accustomed to compromises --> MIGHT have grown up in large family

The conclusion is qualified here--which means it's not actually flawed! Think about it. We're just told Meredith might have grown up in a large family. Is that true? Sure. We don't know anything about Meredith. Maybe she did.

(B):

Not in favor --> ill informed
Jill is not in favor --> she's ill informed

No flaw!

(C):

Like music --> don't miss performance
Paul likes music but last week missed a performance.

It doesn't makes sense, but it's not an illegal reversal.

(E):

Hot-tempered and strong-willed --> won't succeed
Jeremy is strong-willed --> will not succeed

It's flawed because we don't know if he's also got a temper, so we don't know if he definitely won't succeed. But it's not an illegal reversal.

[Mab6q]

Would A be correct if it did not have that issue?

It would read:

large family --> accustomed to compromises

accustomed to compromises --> large families.

Now this is clearly a mistaken reversal (author confuses N condition for a S condition), not precisely what we have in our original argument but the negation matches our stimulus.

~large families --> ~accustomed compromises


I guess what I'm trying to figure our is whether the LSAT will give us an answer choice where the negation will be flawed in the same manner as the argument in the stimulus and not the answer choice as is.

[maryadkins]

Right, it would be flawed, but not in the same way as the stimulus. It doesn't matter that negating it, as you say, would then give us a matched flaw. It needs to be a matched flaw without our doing anything to it. It's CONTRAPOSITIVE would count as the same, but that's not what you did here.

Negating both sides gives us something that is not the same conditional statement. When we do that without flipping it, it becomes an entirely different conditional statement.