LSAT－10－2－23

swimmingfrog

23.(A)      A poor farmer was fond of telling his children: “In this world, you are either rich or poor, and you are either honest or dishonest. All poor farmers are honest. Therefore, all rich farmers are dishonest.”

The farmer’s conclusion is properly drawn if the argument assumes that

(A) every honest farmer is poor

(B) every honest person is a farmer

(C) everyone who is dishonest is a rich farmer

(D) everyone who is poor is honest（A）

(E) every poor person is a farmer

像这种题目我一见就害怕，不知道考场上大家是怎么应付的，要在草纸上推出过程吗，那不是很费时间吗？

BTW, anyone helps me to find the reasoning line. I am too dizzle to figure it out ,after spending all a day in reviewing those wrong questions. Thanks advance!

chelseayang

my approach to this questio is: look for the contrapositive of the conclusion

Conclusion is: rich----dishonest

Contrapositive: honest----poor

I am not sure if such method works for all questions of similar type.

swimmingfrog

I see ,thanks!!

        

dalunzi

斑竹的方法很好！

这种题我通常是这么考虑的（自认为也不错）：结论是“all rich farmers are dishonest”，为了使它成立，只需要排除它不成立的情况即可，它不成立的情况只有一种（如果情况多了我这也就不叫什么方法了）即“一部分rich farmers are honest”，A 表明honest的人都是poor，正好排除这种使它不成立的情况，所以是答案。反复想几遍，以后碰到包你5秒钟之内搞定。

其实这种题还有一种更简单的解决办法，我叫它 “ABCD”法。应用到本题A－poor，B-rich,C－honest，D－dishonest。AB之间、CD之间不用管，考察的是A与CD，B与CD之间的关系，要想让B与D结婚，只要表明A与C结婚了且没有婚外情就可以了。题干中All poor farmers are honest就是A只爱C一个，答案A则表明C也只爱A一个，那么B只有和D结婚了，蛮符合国情的！这种题你就找C也只爱A一个的答案就行了，三秒钟搞定！

chelseayang

Bensontuo

swimmingfrog 发表于 2004-12-17 09:50
23.(A)      A poor farmer was fond of telling his children: “In this world, you ...

If you are rich, it must be true that you are not poor

if you are poor, it must be true that you are not rich

If you are honest, it must be true that you are not dishonest

If you are dishonest, it must be true that you are not honest

SO 1. R ---> ~P 2. P ---> ~R. 3. H ---> ~D. 4. D ---> ~H.

Conclusion seek to establish

If you are poor famers, you must be honest, so, if you are rich farmer, you must be dishonest

( If you are honest, you must be poor farmers ) => Assumption to be made.



What is the necessary assumption of the argument ?

Bensontuo

dalunzi 发表于 2004-12-24 01:33
斑竹的方法很好！这种题我通常是这么考虑的（自认为也不错）：结论是“all rich farmers are dishonest”， ...

完全同意

All rich farmers are dishonest 的必要假設是什麼？

1. None of the honest farmers are rich farmers.

我用一個比較淺顯易懂的圖形方式解說, Dishonest 是一個大圓, 然後這個大園裡面包括了另外一個較小的圓, 而這個圓就是rich farmers. 那如果大圓已經包括了小圓, 那這個小圓絕對不可能超出這個大圓去跟另外一個邏輯定義相反的圓- ( Honest 做交集）, 那如果富裕的農夫此小圓的邏輯相反的小圓為貧窮的農夫, 那我們完全可以定義所有不能夠跟富有農夫交集的的圓（ honest ), 全部屬於跟富有農夫的小圓的邏輯相反的小圓裡面, 因為貧窮農夫以及富裕農夫的此兩圓是完全不可以有任何交集的。

至於結不結婚有沒有婚外情, 這個好像不錯, 但是考試的時候我完全不會這樣想, 因為要是題目資訊一多, 亂掉的可能會是有的, 不過就看人啦。