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.
请问各位大神,这道题为什么选c啊,请说一下解题思路?我自己选的是D,不能理解C为什么对。
万分感谢!
看题目,问的就是assumption;
看选项:
A:画家之间的互相影响与CORE无关;
B:这个考察的是第一个assumption,但是它并不是assumption1的完整逆反命题,assumption1的完整逆反命题应该是:every authentic van gogh contains a subject in his other works,而B选项用的是many,也就是一部分,并不能建立必要的逻辑关系;
C:这个其实就是assumption2的完整逆反命题:如果下层画是梵高画的,那么上层画就是梵高画的,当然整幅画也就是梵高画的;逆反过来就是:任何只要不是梵高画的画,那么它的下层画也不是梵高画的;
D:选项要表达的意思是,只有确定了下层画的作者,才能确定整幅画的作者;看起来这个很正确,但是要知道assumption在逻辑中对应的应该是充分条件,而D陈述的是一个必要条件,两者之间天差地别;
E:无关