Open to question 论取非削弱的非充分性 A proposed change to federal income tax laws

soulwangh

A proposed change to federal income tax laws would eliminate deductions from taxable income for donations ataxpayer has made to charitable and educational institutions. If this change were adopted, wealthy individualswould no longer be permitted such deductions. Therefore, many charitable and educational institutions wouldhave to reduce services, and some would have to close their doors. The argument above assumes which of the following? A Without the incentives offered by federal income tax laws, at least some wealthy individuals would not donate as much money to charitable and educational institutions as they otherwise would have. B Money contributed by individuals who make their donations because of provisions in the federal tax laws provides the only source of funding for many charitable and educational institutions. C The primary reason for not adopting the proposed change in the federal income tax laws cited above is to protect wealthy individuals from having to pay higher taxes. D Wealthy individuals who donate money to charitable and educational institutions are the only individuals who donate money to such institutions. E Income tax laws should be changed to make donations to charitable and educational institutions the only permissible deductions from taxable income. 正确答案是A，我知道。 D答案错误，作为Assumption 要求minimum requirment. D中的only 属于extranous information，过于绝对了。 我的问题是关于取非削弱作为assumption的判断是否是正确的。 我现有的假设是取非削弱（weak）判断是不准确的，应该改为取非证伪（invalid） 我的evidence如下： 1、 如果D取非：有钱人不是唯一的捐助者；那么即可推出这些机构还会收到其他的捐助，也就不会关门了，构成了削弱。这完全可以说的通。 按照取非削弱的标准，所以D就可以判断为正确答案。但D是错误答案，说明取非削弱作为判断assumption的标准不准确。 原帖地址：http://forum.chasedream.com/thre ... d0%2526page%253d248 2、 在Ron的帖子里，Ron从来不说取非是削弱Weaken的。而是说取非是“make the conclusion invalid”，“damage/destory the conclusion”，“make the conclusion die”.  也即证伪结论。 证伪结论相当于证实结论的取非。这个根据符号逻辑可以证明。Assumption是necessary的。 所以有 conclusion->assumption. 原命题等价于逆否命题，所以有：取非（assumption）->取非（conclusion） 如果将A取非 ：No rich people would reduce their donations.  then clearly the argument makes no sense anymore, because removing the deductions would have no effect at all in that case. 也即取非了结论，而不是削弱结论。 原贴地址：http://www.manhattangmat.com/forums/cr-a-proposed-change-to-federal-income-tax-laws-would-elim-t16899.html 以上内容希望大家一起探讨！ Open to question！

soulwangh

Open to Question.

以上论证有问题：
1、
如果D取非：有钱人不是唯一的捐助者；那么即可推出这些机构还会收到其他的捐助，也就不会关门了，构成了削弱。这完全可以说的通。
这个不是削弱，而是无关。其削弱结论是insufficient的。根据Data sufficiency 的做题思路。函数F 是F=Y 还是 F=XY 对F本身的变化不起任何作用。
这个不同于建立在供求关系上的题目。Profit=Price * Demand  一般前提会提出Price increase；削弱选项会是Demand decrease. 这种削弱变化是sufficient的。
以下论证自然不成立
按照取非削弱的标准，所以D就可以判断为正确答案。但D是错误答案，说明取非削弱作为判断assumption的标准不准确。
原帖地址：http://forum.chasedream.com/thre ... d0%2526page%253d248

2、削弱=证伪=结论取非 在逻辑中要么是invalid 要么是valid 没有介于两者之间的状态。削弱= possible invalid = impossible valid=invalid.
在Ron的帖子里，Ron从来不说取非是削弱Weaken的。而是说取非是“make the conclusion invalid”，“damage/destory the conclusion”，“make the conclusion die”.  也即证伪结论。

证伪结论相当于证实结论的取非。这个根据符号逻辑可以证明。Assumption是necessary的。 所以有 conclusion->assumption.
原命题等价于逆否命题，所以有：取非（assumption）->取非（conclusion）

如果将A取非 ：No rich people would reduce their donations.  then clearly the argument makes no sense anymore, because removing the deductions would have no effect at all in that case. 也即取非了结论，而不是削弱结论。