牛人们，帮帮忙啊！

sunnysunny11

X-ray examination of a recently discovered painting- judged by some authorities to be a self-portrait by Vincent Van Gogh- revealed an underimage of a woman's face. Either van Gogh or another painter covered the first painting with the portrait now seen on the surface of the canvas. Because the face of the woman in underimage also appears on canvases van Gogh is known to have painted, the surface painting must be an authentic self-portrait by Van Gogh.
The conclusion above is probably drawn by if which of the following is assumed?
A. If a canvas already bears a painted image produced by an artist, a second artist who uses the canvas to produce a new painting tends to be influenced by the style of the first artist.
B. Many painted canvases that be reliably attributed to van Gogh contain underimages of subjects that appear on at least one other canvas that Gogh is known to have painted.
C. Any painted canvas incorrectly attributed to van Gogh would not contain an underimage of a subject that appears in authentic paintings by that artist.
D. A painted canvas cannot be reliably attributed to an artist unless the authenticity of any underimage that painting might contain can be reliably attributed to the artist.
E. A painted canvas cannot be reliably attributed to a particular artist unless a reliable x-ray examination of the painting is performed.
这道题为什么选c啊，请说一下解题思路以及别的选项为什不选，谢谢了。

sunnysunny11

怎么没人回答啊。

gracezz

这个题太绕了，试着答一下：

题干：可能是凡高（V）也可能是另一个画家（叫他X吧）画了那个画，因为那画里的女人也在V以前的作品里出现过，所以结论：是V画的。

简单说就是因为V以前画过类似的，那这画就是V画的

选C：Any painted canvas incorrectly attributed to van Gogh would not contain an underimage of a subject that appears in authentic paintings by that artist. 被错误认定为是凡高作品的画作不会也含有真正的凡高作品里的那些underimage(查词典没查到什么意思，感觉是背景的意思？）

取非：被错误认定为凡高作品的画作“含有”真正的凡高作品里的那些underimage，那说明作者根据这个unerimage做出的判断可能就是错的了

铮岚瑗

題目比較繞，理解清楚就好了。
題目大致的邏輯是：
1.W在S底下。
2.W要么是V畫得，要么是其他人畫得。
3.W出現在V其他的真畫裡了。
結論：S一定是V畫的。

C. 不是V畫的畫，一定不會有曾在V的真畫里出現過的W。這樣整個邏輯才正確。

sunnysunny11

还是不理解啊，大家能解释的再清楚些吗？

小伊YSY

我不懂,为什么D不对？
为什么D不对呀？

杨东芳

翻出以前的帖子明白了，这是mindfree大牛的解释，
1. B的错误在many. 取非后不是exclusive. 既很多都没有下面的那幅画, 但是没有排除有的情况.如果是all, 取非就对了.所有的都没有, 原结论就错. 你说的削弱是没有错, 因为削弱不需要是必要条件或充分条件, 但是assumption必须是必要条件.

D最好是用排除法. 你要注意到这部分"authenticity of any underimage that painting might contain can be reliably attibuted to the artist". 文章并没有提到authenticitiy of underimage can be reliably attributed to VG. 这里存在一个gap! 正确答案中也只是说appear.

白冬冬

愚见：
C : 任何帆布上被误认为是梵高画的画，底层都不会有真正该图的画家画过的画
原文： 因为底层是证明了的梵高的画，所以整个帆布上的画也是梵高画的
无果即无因，逆否命题的假设！

Nicole530

杨东芳 发表于 2010-8-11 16:47
翻出以前的帖子明白了，这是mindfree大牛的解释，1. B的错误在many. 取非后不是exclusive. 既很多都没有下 ...

authenticity of underimage 不是就是指woman face 确认是V画的嘛？？
啊啊啊啊我还是不懂，为毛D不对啊

贺赫赫盒

窃以为D选项的问题出在充分必要条件的顺序之上
D选项讲的是 a painted canvas can be reliably attributed to an artist ----> the authenticity  of any underimage that painting might contain can be reliably attributed to the artist 也就是从判定一幅画来自于一位画家，我们可以推出这幅画的底影来自于这位画家
而正确的思路应该是反过来，我们可以通过确认这幅画的底影来自于这个画家来判断这幅画来自于这个画家