恳求版主和牛牛们解答 一个逻辑问题

妖怪毛毛

GWD-9-Q40:

Agricultural societies cannot exist without staple crops. Several food plants, such as kola and okra, are known to have been domesticated in western Africa, but they are all supplemental, not staple, foods. All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams. Therefore, discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.

 

Which of the following is an assumption on which the argument depends?

 

1. People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.

2. There are no plants native to western Africa that, if domesticated, could serve as staple food crops.

3. Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa.

4. Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are.

5. Kola and okra were domesticated in western Africa before rice and yams were introduced there.

问一个关键问题  我看了lawyer 的逻辑 上面写 without后面的都是做的是必要条件 那个上文第一句话 是 农业社会=)  有主要耕作物？  但是题目的结论正好相反 。。。。。。。。。。 

恳求 版主和其他nn解答一下？

LittleMike

那我就来凑个热闹尝试解释一下吧嘿嘿

先说题目：说有了staple corps才有农耕社会，西非有过kola和okra但是这俩不staple，还说所有recorded的staple食物都是从别的地方进口的，但是不知道是啥时候进口的，然后题目中开始作结论了，说找到最早recorded进口的时间，就找到什么时候开始有农耕社会了

注意这个recorded啊，看到A很容易联想到万一我之前有staple食物，我有农耕社会，只不过你没记录而已，那你去找那个被记录了的时间不是不对么，那不就没有找到我之前真正刚开始形成农业社会的时间么，所以有了A这个假设，说我之前没有这样的“没被记录（也就是A中说的stopped cultivating）的staple作物”，那么我去找这个被记录了时间的进口物，才能得出我题目中的结论

至于你的问题我其实没看懂……我也没有看过lawyer的那个总结，不知道具体是？

LittleMike

答案是A不？

妖怪毛毛

right.

妖怪毛毛

up up up~~~~~~~~~

我之前做过一道 有由于因果倒置导致错误的题目

所以现在对这类题目和关键词 比较敏感

妖怪毛毛

“先说题目：说有了staple corps才有农耕社会，”

我的问题就出在  这句话的表达上面Agricultural societies cannot exist without staple crops ， lawyer说过 without后面的表示 都是只的是必要条件 也就是说  先有了农耕社会才有了 主要农作物 
        

充分必要条件指示词

1.introduce a sufficient condition: if/when/whenever/every/all/any/people who/in order to/to

2.introduce a necessary condition: then/only/only if/must/require/no,none(在句子开头)

3.unless equation: unless/except/until/without(其后面部分变成必要条件，其它加NOT变充分条件)

4.特例：the only way to achieve success is to work hard.  achieve success(充分条件)

only a professional consultant can solve the organization’s problems. a professional consultant(必要条件)

no citizen can be denied the right to vote. denied the right to vote(充分条件). no citizen(必要条件)

http://forum.chasedream.com/dispbbs.asp?BoardID=24&ID=73506&replyID=&skin=0

LittleMike

我觉得是不要那么拘泥于形式吧……你就仅仅就这句话来理解的话，Agricultural societies cannot exist without staple crops，对的确实这里面without后面是必要条件（也就是所谓的有的这个社会一定有staple crops，但是有了staple crops不一定有农业社会），但是必要条件不代表先后顺序，你不能说是先有农耕社会后有主要农作物，这样说是不对的

关于这个，我举个小例子吧，比如说，假设我们认为有钱并且还热爱跑车的人才买跑车，那么有钱是买跑车的必要条件，可是这里有钱这个必要条件一定发生在前面，而不是买跑车

举了这么个蹩脚例子只是想说我认为因果上的充分必要性与时间上的先后性没有一定得关系

LittleMike

而且其实我觉得这道题从常识上也可以知道先有吃的才有社会……有时候记太多规则我不觉得一定有好处……

妖怪毛毛

谢谢这位同学的回答 我给你看个例子吧让我不得不引起重视， 也许学的还比较表面 ，没有抓住关键的东西 。我也是刚刚才学起来

Unless tiger hunting decreases, tigers will soon be extinct in the wild. The countries in which the tigers’ habitats are located are currently debating joint（共同的） legislation that would ban tiger hunting. Thus, if these countries can successfully enforce this legislation, the survival of tigers in the wild will be ensured. E

除非老虎的狩猎下降，否则老虎会灭绝。Not extinct=) hunting decrease.国家们联合起来制定法规来禁止狩猎，老虎的生存得到保障。Hunting decrease =) not extinct.

The reasoning in the argument is most vulnerable to criticism on the grounds that the argument

Unless tiger hunting decreases, tigers will soon be extinct in the wild. --- 说明减少打猎是必须的（必要条件）。

请问同学qq多少？

妖怪毛毛

还有我想说的是 我承认错误 时间上没有先后性 但是 推理上 有先后性