lsat-3-4-20

20.   The rise in the prosperity of England subsequent to 1840 can be attributed to the adoption of the policy of free trade, since economic conditions improved only when that policy had been implemented.

The reasoning in the above argument most closely parallels that in which one of the following?

(A) An exhaustive search of the marshes last year revealed no sign of marsh hawks, so it can be assumed that a similar search this year would reveal equally little sign of that kind of bird.

(B) Building a circular bypass road around Plainfield probably helped the flow of local traffic in the town center, since a circular bypass road generally cuts a city’s through traffic markedly.

(C) Before the banks raised their interest rates, people on average incomes could almost afford a mortgage for an amount twice their salary. Hence the rate increase has now put mortgages beyond their reach.

(D) Since the improvement in the company’s profitability began to occur after the vice president’s new morale-building program was put in place, that program can be credited with the improved result.  

(E) The extinction of the dinosaurs was brought about by an asteroid colliding with Earth, so their extinction could not have come before the collision.

The anwser is (D), why?

Thanks and Merry Christmas!

原来如此,谢谢斑竹!

节日快乐!

Lawyer:

I'm afraid that I can't agree with you over your analysis.

The reasoning of the stimulus is that Event A is caused by Event B because A happened after B.

Among the keys, only Answer D conform to this reasoning。

The signposts for causation is not limited to those well-known words and phrases (like because, so...).

In fact, 'brought in' in Answer E may be used to express causal relationship, too.

Other words, like reduce, increase, cut back.., can function in the same way.

Just two similar reasonings of necessary condition.

Only if A , then B ,=  with B , then A.

In D,  from B, improvement ,  get A, a program ==> A program can be credited with (=must can cause) the improved result.

hedonism555:

I'm afraid i can't agree with you.

Literally construing the first half of Answer D,  we can only know that  improvement happened after the programme was put in place. Your construction of the first half as a necessary condition reasoning doesn't literally comply with the wording.

But I have to admit that your analysis of the stimulus is right.

However, what we need is the best of 5 options but not a perfect one.

let me render D again.

since  B happened after A ==>  A cause B,  then  it is concluded that A can be creadited with B ==> A must bring out B ==> A is the necessary condition.

The above line of reasoning prefectly confirms that in stimulus.

If you dont agree "be credited with" is equal to "must" under this situation, then no other way can help you solve the problem.

Agree ?

A must bring out B  为什么不应该是充要条件？

A cause B    为什么不应该是充分条件呢？比如下雨导致地湿，下雨是地湿的充分，但地湿并不能推出下雨，我有可能是其他原因。

所以我认为好像有点问题？

if A, then B ,   A is sufficient condition.                A---->B

only if A, then B    A is neccesary condition.        B---->A

if only A, then B    A is 充要条件                          A---->B