SOS：大家帮忙看看我在假设题中遇到的问题

Joseph_lin

今天刚上好XDF的逻辑课，被那个老师搞晕了。
第一个问题是：假设的答案选项可以是一个充分条件吗？我觉得不可以，但是新东方的老师说只要和原文有关的充分条件也是可以作为一个假设的答案的，因为充分条件就直接可以使结论成立了，真的是这样的吗？不是说假设的正确选项应该是一个必要条件吗？因为充分条件是说有A这件事情，必有B这件事情，而没有A这件事情，未必没有B这件事情，而必要条件是说没有A这件事情，必定没有B这件事情。所以充分条件应该是不能做为选项的吧，我觉得。因为必要条件是一定没有B这件事情，而充分只是未必没有B这件事情，这个还是有很大的区别的吧？

第二个问题，我现在做假设题很困惑的是有的时候我会去选择一个支持的选项，而不是选择一个假设的选项，这个怎么解决？

第三个问题：如果做到削弱题的时候，选项是削弱前提是不可以的对吗？那么如果是假设题和支持题，如果选项是支持前提的可以吗？

望高手赐教，谢谢

littlexian

I cant answer your question QQ.. but you might wanna try the question here: "求nn帮忙理解下这题,答案并不能让人信服,求反驳 "  

powers

哈哈,欢迎,I can't answer any of these.

Joseph_lin

哪位大神能帮忙解答下呀？谢谢拉

sdcar2010

There are two types of assumptions, one is necessary assumption, the other is sufficient assumption.

For NECESSARY assumption, if you negate the correct answer, the argument 完全不能成立

For SUFFICIENT assumption, negation method won't work.

Both Necessary Assumption and Sufficient Assumption questions contain the word "assumption", but they ask for different things. So how could you tell the difference?

FOCUS on the verb in the question stem.

Necessary Assumption questions often contain the words:

1) Depend
Example #1: "Which one of the following is an assumption that the manager's argument depends on?"

Example #2: "Which one of the following is an assumption on which the argument depends for its conclusion to be properly drawn?"

2) Require
Example: "Which one of the following is an assumption the President's argument requires?"

Example: "Which one of the following is an assumption required by the dietitian's argument?"

3) Rely
Example: "Which one of the following is an assumption on which the argument relies?"

4) Necessary
Example: "Which one of the following is an assumption necessary for the critic's conclusion to be properly drawn?"

Sufficient Assumption questions often contain the following words:

1) Follow logically if something is assumed
Example #1: "The argument's conclusion follows logically if which one of the following is assumed?"

Example #2: "The critic's conclusion logically follows if which one of the following is assumed?"

2) Properly inferred if something is assumed
Example: "Which one of the following, if assumed, allows the conclusion of the doctor's argument to be properly inferred?"

3) Properly drawn if...assumed
Example: "The argument's conclusion is properly drawn if which one of the following is assumed?"

4) Enable
Example: "Which one of the following, if assumed, enables the conclusion of the argument to be properly drawn?"

5) Allow
Example: "Which one of the following is an assumption that would allow the conclusion above to be properly drawn?"

6) Justify
Example: "Which one of the following is an assumption that would serve to justify the conclusion above?"

sdcar2010

第二个问题，我现在做假设题很困惑的是有的时候我会去选择一个支持的选项，而不是选择一个假设的选项，这个怎么解决？

For a necessary assumption question, the above won't happen if you use the negation method since ONLY one choice, when negated, will make the argument fall apart.

For a sufficient assumption question, ONLY one choice would enable you to reach the conclusion of the argument.

A general strategy for CR is to
1) Recognize the key words such as Therefore, Thus, Since, Because, Conclusively, Clearly, etc., which indicate either a premise or a conclusion.
2) Know which is the premise and which is the conclusion.
3) Recognize the logic chain involved from premise to conclusion.
4) Notice the gap between premise and conclusion, if there is any.
5) Become crystal clear about the scope of the argument. Most wrong choices are out of the scope.
6) Be familiar with common logical fallacies.
7) Then label 5 answer choices as contenders and losers. If only one contender left, that is the correct answer.
8) If there are more than one contender left, focus ONLY on these contenders and figure out why one is the best, thus, the correct answer.

Joseph_lin

多谢，这里有个问题，照你这样说的话必要型假设和充分型假设是不会同时出现在选项里的？还是说如果同时出现了，我就得选一个必要型假设？

sdcar2010

必要型假设和充分型假设是不会同时出现在选项里的？

Of course not. ONLY one correct answer for each question.

Joseph_lin

我的意思不是同时出现在一个选项里，而是5个选项里有1个是充分型假设，一个是必要型假设，这时我该怎么选？还是不可能有这种情况的发生？

sdcar2010

5个选项里有1个是充分型假设，一个是必要型假设，这时我该怎么选？

If this happens, for necessary assumption questions, choose 必要型假设. For sufficient assumption questions, choose 充分型假设.

But I doubt it would happen in a real test.