请lawyer关注－－请问OG-80，原80提问链接有误

david_348

The program to control the entry of illegal drugs into the country was a failure in 1987. If the program had been successful, the wholesale price of most illegal drugs would not have

dropped substantially in 1987.

80. The argument in the passage depends on which of the following assumptions?

(A) The supply of illegal drugs dropped substantially in 1987.

(B) The price paid for most illegal drugs by the average consumer did not drop substantially

in 1987.

(C) Domestic production of illegal drugs increased at a higher rate than did the entry of

such drugs into the country.

(D) The wholesale price of a few illegal drugs increased substantially in 1987.

(E) A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in

their wholesale price.

og解释如下：

he only choice that must be true in order to conclude legitimately from the drop in the

wholesale price of illegal drugs that the program was a failure is choice E, the best answer.

我不觉的这个假设有in order to 的作用，只是语义上较连贯，而不是逻辑上；很可能还有其他因素，但未必就是control啊，所以和control结合，也不构成充分必要嘛。

请问该类型的解题思路和方法，我是采用排除法解题的。

[此贴子已经被作者于2004-10-25 0:03:10编辑过]

kenshin

以下是引用david_348在2004-10-24 18:05:00的发言：

The program to control the entry of illegal drugs into the country was a failure in 1987. If the program had been successful, the wholesale price of most illegal drugs would not have

dropped substantially in 1987.

80. The argument in the passage depends on which of the following assumptions?

(A) The supply of illegal drugs dropped substantially in 1987.

(B) The price paid for most illegal drugs by the average consumer did not drop substantially

in 1987.

(C) Domestic production of illegal drugs increased at a higher rate than did the entry of

such drugs into the country.

(D) The wholesale price of a few illegal drugs increased substantially in 1987.

(E) A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in

their wholesale price.

og解释如下：

he only choice that must be true in order to conclude legitimately from the drop in the

wholesale price of illegal drugs that the program was a failure is choice E, the best answer.

我不觉的这个假设有in order to 的作用，只是语义上较连贯，而不是逻辑上；很可能还有其他因素，但未必就是control啊，所以和control结合，也不构成充分必要嘛。

请问该类型的解题思路和方法，我是采用排除法解题的。

OG说,正确答案，应该可以使，从“非法药物批发价格下降”（证据）推到“那个program是个失败”（结论）的这个推导过程合理，这是一句阐述assumption的含义的废话。

没太看懂你说的充分必要是什么意思，assumption应该是一个必要条件，可以通过取非则结论不成立来验证。

E说，需求减少不是其批发价格降低的唯一原因，而价格下降是由“供过于求”导致的，如果不是需求减少单方面的原因，那么还会有供应这方面增加的原因，而对于贩毒而言，与批发价格相关的供应增加，应该是从金三角或者南美进来的毒品多了，所以控制项目失败了。

也可以把E取非，需求减少是唯一原因，那么不关供应量什么事情，自然也推不到控制毒品输入的计划失败了。

david_348

谢谢！我觉得你的解释很正确！

但是我的理解：E是一个充分条件，添加后，可以推出controls失败的结论；以下文章出自lawyer的逻辑思路：

http://forum.chasedream.com/dispbbs.asp?boardid=24&id=65598

ASSUMPTION类。假设类分充分型和必要型。充分型是问题问你下列哪个假设，能使原文的结论PROPOERLY推出。必要型是问题问你原文的推理依赖下列哪个假设。他们的作题思路不同。充分类因为原文结论是必须能从证据推出（加上假设），所以方法较简单，将选项加到原文的推理中，如果结论必成立（MUST BE），则为答案，如果结论有不成立的可能性，则错，其中的特例是原文证据和结论的概念差异（GAP），说出这个GAP就是假设。

    我现在对大多数题目只要看懂了，稍微想想就ok了，从来不用推导或归纳的逻辑公式（若a--->b,c--->d,则如何如何等），因为我觉得对逻辑因子（不知这样的说法正确否）的提炼本身就很麻烦（偶是菜鸟，别扁我～～）；但是对于有些题目，我觉得本身的逻辑关系比较隐蔽或比较“绕”时，需要利用解题技巧；但楼上的和lawyer的说法都能说通，呵呵，那俺听谁的啊～～

kenshin

为什么E是充分条件？即使需求增加不是价格下降的唯一原因，也不一定能推导到就是从外国流入增加的原因，也可能是卖家急于出手套现，或者国内也能够生产了，呵呵。E只是保留了外国流入增加的可能性，不是绝对的指向这种可能性。

另外这道题的OG解释里面的“must be true”是说，为了使结论推导正确，E是唯一的“必须要正确的”选项，还是在解释assumption的逻辑概念，是一个“必须正确”的“必要条件”，也就是取非则结论就不成立了。

而lawyer说的题型里的must be true是问题里的标志词，要看清是问哪个选项使结论must be true，还是问要使结论成立哪个选项must be true，前者是要找一个充分条件，后者是要找一个必要条件。

lawyer_1

纠正一点，充分型假设正确选项本身不是结论的充分条件，而是和原文的其他前提结合在一起一定能推出结论。选项本身不足以推出结论，当然你可以说和原文前提结合在一起是结论的充分条件。

summersmile

80.

The argument in the passage depends on which of the following assumptions?

(A) The supply of illegal drugs dropped substantially in 1987.

(B) The price paid for most illegal drugs by the average consumer did not drop substantially in 1987.

(C) Domestic production of illegal drugs increased at a higher rate than did the entry of such drugs into the country.

(D) The wholesale price of a few illegal drugs increased substantially in 1987.

(E) A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in their wholesale price.

E is the best answer.

The only choice that must be true in order to conclude legitimately from the drop in the wholesale price of illegal drugs that the program was a failure is choice E, the best answer. If the drop in price was caused by a drop in demand, there is no reason to suspect that there has been any increase in supply caused by drugs entering the country.

我还是不明百！

1、文章推理是：drop in price-->the entry of illegal drugs(increase in supply)

2、E项取非：drop in demand --->drop in price

og解释说If the drop in price was caused by a drop in demand, there is no reason to suspect that there has been any increase in supply caused by drugs entering the country: E取非后－－>no increase in supply ?

我现在糊涂得恨，请nn帮我看看吧！

lawyer_1

原文的推理是基于供给对价格的变化来推出结论的，但价格还有一个影响因素，就是需求。E取非为需求是影响价格的唯一因素。这样原文的推理就不成立了。注意影响价格有两个因素：供给和需求。

summersmile

E取非为需求是影响价格的唯一因素。这样原文的推理就不成立了－为什么？

我认为需求下降－》价格下降，但原文推理是

价格下降－－—》entry,

假设题取非后思路是，价格下降不能推出entry--应该针对结论entry,而不是价格下降

还有可以帮我再分析一下其他选项吗？

不知道我说明白没有，我就是卡这里，出不来了？？！！

lawyer_1

这道题很BT，因为结论其实是最后的那句条件句。对于条件句的假设，正确选项是排除充分条件成立，必要条件不成立的可能。（见“考试时如何做逻辑题”置顶贴）。该题如果需求是影响价格的唯一因素（E取非），则供给的变化（限不限制进口）就不影响价格了。价格变化与供给无关。E排除这种可能。即供给的变化能影响价格。

lawyer_1

这道题很有意思，有个问题要说明一下。假如有个选项说the wholesale price of most illegal drugs would  have dropped substantially in 1987（价格下降）. 那它是答案吗。

1。不是。因为这样原文的推理为：如果项目成功，则价格没下降。所以该项目失败（结论）。将上面选项取非，价格没下降。结论一样可以成立。所以不是假设（必要型假设）

2。如果问题改为：The conclusion above follows logically if which one of the following must be assumed(充分型假设)。因为充分型假设的检验公式为：原文+选项=答案。该选项符合这公式。

请大家细心体会这个区别。这是一道很好的必要型假设和充分型假设的区别的题。

[此贴子已经被作者于2004-11-20 23:52:13编辑过]