弱智关于either...or的理解一问

夏未未

一段话大意是
A tour group plans to visit exactly five archaeological sites. Each sites dates from the 8th,9th,or 10th(A.D.).
The sites visited third dates from a more recent century than does either the site visited first or that visited fourth.

对于粗体标出的这段话，kaplan解释上的理解是
                1号site
3号site>       and
                4号site
我的弱智问题是。。。为什么不能理解为
                   1号site
3号site>        or
                   4号site

原句：The sites visited third dates from a more recent century than does either the site visited first or that visited fourth.
和
改编句：The sites visited third dates from a more recent century than do both the site visited first and that visited fourth.

有什么区别？？？

谢谢，谢谢

wangx10

我今天也刚好看到这道题，貌似解释也是等同于both，莫非在LSAT里either or等同于both？ 求高人解答。

cdprotein

同问，powerscore的解释好像是and。

小火凤儿

能把原题完整写出来吗？我觉得从语法上either or包括both and那种情况的，但不必然是。
所以会不会是题目中的其他限制条件，使得这边的either or等同于both and。

taoransk

either or 应该是这个或者那个吧......
就是可能两个一起, 也可能只有一个

因为A有可能, B有可能, 那么AB有一个也是可以的, AB一个都没有是不可以的, 但是没说AB不能同时都可以啊

taoransk

今天读Kaplan Logic Reasoning Bibile来着,刚好读到了

... ...

In the everyday use outside of the LSAT, 'either/or' has come to mean 'one or the other, but not both', but this usage is incorrect on the LSAT. For the purposes of the test, the definition of 'either/or' is 'at least one of the two', Note that this definition implicitly allows for the possibility that both elements occur, and the existence of this possibility makes diagramming sentences containing the 'either/or' term confusing. A careful examination of the definition of 'either/or' reveals that a conditional relationship is at the heart of the construction: since at least one of the terms must occur, if one fails to occur then the other must occur.

... ...

To further complicate the issue, occasionally our 'outside' (but public domain ) knowledge of the elements involved the 'either/or' construct allows us to make additional inferences,
Eg.  You are either in Los Angeles or Sanfrancisco

... ...

according to 'either/or' term, the statement is diagrammed as follow:

LA X -> SF
SF X -> LA

... ...

but we also know that if you are in one of the cities, then you are not in the other. However, this knowledge does not come to us from the 'either/or' term above, but from our public domain knowledge of geography. Thus, another set of diagrams may apply:

LA -> SF X
SF -> LA X

... ...

Note that makers of the LSAT could creat a statment about two fictional or little-known cities, such as 'You are either in Monroe or Tipiwanee'. Whthout being provided further information about these cities, we could only diagram for the 'either/or' term, A diagram that attempts to reflect geographic knowledge such as :

Monroe -> Tipiwanee X

would not apply since we cannot be sure that Monroe and Tipiwanee do not overlap geographically

.....

(打字真辛苦 -.-)

taoransk

either or 根据conditional reasoning 和 formal logic 两部分的综合结果是

一个推理型陈述题干里, 每个逻辑关系都有一个sufficient和一个necessary的区别,sufficient出现意味necessary即将或已经,总之必然出现,但并不直接造成其激发. eitheror的作用在于,两个问题是并列的(formal logic里的并列分and / or),所以在无其他因素的情况下,这两个都可以又做sufficient又做necessary.

举个例子

The dinner won't be ready untill all dishes have been prepared

这里前面一部分是sufficient,后面一部分是necessary. 如果晚餐好了,那么意味着必然所有菜都准备好了, 但是所有菜准备好了不代表晚餐必然好了.

插一下, 两个单元部分着重说了关于对换句的问题, 这里简单说下结果
Dinner Ready ----> Dishes have been prepared
标准对换句是
Dishes have been prepared (X)  ----> Dinner Ready (X)

好了现在把例子代入either or

I am either Chinese or Canadian

Chinese   (X) ----> Canadian
                 or
Canadian (X)  ----> Chinese

不是中国人就是加拿大人, 不是加拿大人就是中国人

这里表现了如果不是一个国籍,那么一定是另一个国籍,好像下面摘录里陈述的, at least one of the two, 但是这里,并没有包括一个可能,就是我也可以是双重国籍,那么两个都存在, 这就是原来那位仁兄提出的both问题, 而这个问题在S/N逻辑关系里是无法表达的, 我们只能记住必须出现一个, 但是出现一个的结果是另一个可以出现或不出现, 但是无法强制


然后,这里要提到另一个问题了,限定

I am either at London or New York

上面那个例子里, 国籍是有双重可能的, 但这里, 伦敦和纽约是地球人都知道的两个城市, 所以显然一个人不可能同时在两个地方出现
虽然在很多情况下LSAT要求不要代入除了题目给出信息之外的其他知识, 但是也是有例外的, 这里就是一个, 至少, 出题的是严格的人,但不是笨蛋. 所以, 这种情况是common sence, 而应该被注意到. 这个问题在综合了整本书后, 有两种可能, 一个是common sence, 一个是如果使用的方式是 either... or... , but not both, 也就是说, 这两种情况下, but not both是自动起作用的

那么, 上面那两重的S/N关系就变成了:

London   (X) ----> New York
New York (X)  ----> London

London  ----> New York  (X)
New York  ----> London (X)

kamme

LZ还是没能解释这道题啊 LZ说的都对

但是问题是Bible的解释是直接默认为Both了 没考虑只有一种可能的情况啊


麻烦哪位大神解释一下呗！！这是Oct 2004的GAME题！！

chiko将

今天读Kaplan Logic Reasoning Bibile来着,刚好读到了

... ...

In the everyday use outside of the LSAT, 'either/or' has come to mean 'one or the other, but not both', but this usage is incorrect on the LSAT. For the purposes of the test, the definition of 'either/or' is 'at least one of the two', Note that this definition implicitly allows for the possibility that both elements occur, and the existence of this possibility makes diagramming sentences containing the 'either/or' term confusing. A careful examination of the definition of 'either/or' reveals that a conditional relationship is at the heart of the construction: since at least one of the terms must occur, if one fails to occur then the other must occur.

... ...

To further complicate the issue, occasionally our 'outside' (but public domain ) knowledge of the elements involved the 'either/or' construct allows us to make additional inferences,
Eg.  You are either in Los Angeles or Sanfrancisco

... ...

according to 'either/or' term, the statement is diagrammed as follow:

LA X -> SF
SF X -> LA

... ...

but we also know that if you are in one of the cities, then you are not in the other. However, this knowledge does not come to us from the 'either/or' term above, but from our public domain knowledge of geography. Thus, another set of diagrams may apply:

LA -> SF X
SF -> LA X

... ...

Note that makers of the LSAT could creat a statment about two fictional or little-known cities, such as 'You are either in Monroe or Tipiwanee'. Whthout being provided further information about these cities, we could only diagram for the 'either/or' term, A diagram that attempts to reflect geographic knowledge such as :

Monroe -> Tipiwanee X

would not apply since we cannot be sure that Monroe and Tipiwanee do not overlap geographically

.....

(打字真辛苦 -.-)

-- by 会员 taoransk (2010/9/17 15:38:58)

hanjzhang

co-ask!!