prep2-50

psychepsyche

When people evade income taxes by not declaring taxable income, a vicious cycle results.Tax evasion forces lawmakers to raise income tax rates, which causes the tax burden on nonevading taxpayers to become heavier.This, in turn, encourages even more taxpayers to evade income taxes by hiding taxable income.



The vicious cycle described above could not result unless which of the following were true?问这个恶性循环的必要条件。


(A) An increase in tax rates tends to function as an incentive for taxpayers to try to increase their pretax incomes.-

(B) Some methods for detecting tax evaders, and thus recovering some tax revenue lost through evasion, bring in more than they cost, but their success rate varies from year to year.

(C) When lawmakers establish income tax rates in order to generate a certain level of revenue, they do not allow adequately for revenue that will be lost through evasion.

(D) No one who routinely hides some taxable income can be induced by a lowering of tax rates to stop hiding such income unless fines for evaders are raised at the same time.除非罚款增加，否则税率的降低不能使现在那些偷税的人不偷税。(这说的是解决这个必要循环必须用抬高税率的方法的assumption.)
(E) Taxpayers do not differ from each other with respect to the rate of taxation that will cause them to evade taxes.



选错了，我选了D，正确答案是C，请大家帮我看一下，还是迷糊中。。。。

YEWCHOW

此题问假设。
首先，纠正LZ一个错误：假设不是必要条件。必要条件是能从文章中推得出来的，既然是文章中可以推导出来的就不可能是假设，因为假设是使文章结论成立而必须成立的条件，可能是上述文章中的Gap，或者是容易遭受攻击的地方。
我记得这道题当时我也选的D。但是，文章中说的是税率提高的问题，所以D说税率下降必然不能使首选。
重点在Tax evasion forces lawmakers to raise income tax rates这句话，为什么有人逃税就一定会让lawmakers提高税率？如果他们在制定税率的时候充分考虑的逃税的问题，那即是有人逃税也不一定要通过提高税率来阻止。

不知道这么想对不对，请教牛人吧~~

psychepsyche

谢谢~~你说的必要条件和假设的区别很有道理~~我怎么记得新东方的课件里说unless后面是必要条件呢？难道是在题干里就是必要条件，像这题这样出现在问题里就是在问假设了？看来不能教条新东方~~~我再体会一下假设和必要条件~~谢谢~~~：）

Roro666

问题：以下什么条件成立才会导致这种恶性循环（逃税-"税收不足"-涨税率-更多逃税……）？
其中“税收不足”这一环不是必然产生的，如果能大致估计逃税的比例，那制定的税率还是会收到足够的税，不会导致税收不足，也就是C的答案

haoye12321

这是个恶性循环，如果人们能想到收入被逃掉了的话，就不会制作这个提高税率的政策了，因为这个政策会使收入逃掉更多。