LSAT 黄皮书下册SET 4 SECTION 2 Q21

mythicalman

21. Newspaper editor: Law enforcement experts, as well as most citizens, have finally come to recognize that legal prohibitions against gambling all share a common flaw no matter how diligent the effort, the laws are impossible to enforce. Ethical qualms notwithstanding, when a law fails to be effective it should not be a law. That is why there should be no legal prohibition against gambling.

Which one of the following if assumed. allows the argument's conclusion to be properly drawn?

(A) No effective law is unenforceable

(B) All enforceable laws are effective

(C) No legal prohibitions against gambling are enforceable

(D) Most citizens must agree with a law for the law to be effective

(E) Most citizens must agree with a law for the law to be enforceable.


A

请问ANSWER A如何理解
No effective law is unenforceable.
A represents effective law, B represents enforcable
The above structure is:
~A->~B
or
A->~~B, i.e. A->B
换句话说，这个NO到底否定的是A还是~b?

番茄炒蛋

文中就是三个词在搞，law  effective  unenforceable
文中的道理要成立，这三个词就必须两两之间都要有关系
原文中已经有两对搭上了，剩下的也就是答案中的那一对了
可以理解为 enforceable law 才是 effective law
感觉这种题目就是让你找联系，假设题的这种方法很有效

Bensontuo

mythicalman 发表于 2003-11-16 16:35
21. Newspaper editor: Law enforcement experts, as well as most citizens, have finally come to recogn ...

番茄炒蛋講得亂七八糟, 雖然是十幾年前的回覆, 也可能沒人看, 但是既然有個機會攢個人品, 幫助我們大漢民族同胞, 請讓海峽兩岸的華人弟兄解釋。

P1 - Regardless how much the effort dedicated to the legal prohibitions for gambling, the laws, legal prohibitions are impossible to enforce.

Inference: Legal prohibitions for gambling as the laws -> ~ enforceable

P2 - if laws = ~ effective, then ~ law

Inferences: Law -> effective

C - ~ law for gambling shall be correct.



第一,

C and P2 的 inference 為

Laws of gambling prohibitions are ineffective. （ 必要條件）

第二, 回來看p1

laws of gambling prohibitions are not enforceable

所以, Laws of gambling prohibitions are not enforceable, then the laws must be ineffective.

Inference:  ~ enforceable -> ~ ineffective.

Contrapositive: Effective -> Enforceable.

答案Ａ： Effective -> ~ " un " Enforceable.

*重點來了, 請看混淆選項B。

All enforceable law are effective.

為何此選項不對

1. 我們在講的是 unenforceable law的群體, 而不是 enforceable law的群體
2. 此為充分假設之題型, 我們不用去證明所有“ enforceable laws " 都必須為effective
3. 我們要去證明的為” unenforceable laws 的這個群體“ 都必須要有一個必要條件的產生 -> must be ineffective.

給個範例

1.不管如何高效能或是消息的管理罪犯的手段, 在監獄裡立法不允許犯人抽菸都是無法真正實行的
2. 如果立法沒有效能方式, 那這法乾脆別立了
3. 不允許犯人抽菸的法不立是對的

不允許犯人抽菸的法無法真正實行, 其必然是沒有效能方式的作用

無法實行的法必然沒有效能, 跟所有可實行的法必然有效能, 這是邏輯上面的mistaken negate.

沒有白富美的女友的男生必然不高,  難道有白富美的女友的男生就必然高嗎？