T13-1-24，是否是答案错了？

winnie

T13-sec1-24
Until recently it was thought that ink used before the sixteenth century did not contain titanium. However, a new type of analysis detected titanium in the ink of the famous Bible printed by Johannes Gutenberg and in that of another fifteenth –century Bible known as B-36, though not in the ink of any of numerous other fifteenth-century books analyzed. This finding is of great significance, since it not only strongly supports the hypothesis that B-36 was printed by Gutenberg but also shows that the presence of titanium in the ink of the purportedly fifteenth century Vinland Map can no longer be regarded as a reason for doubting the map’s authenticity.
The reasoning in the passage is vulnerable to criticism on the ground that
A.    the results of the analysis are interpreted as indicating that the use of titanium as an ingredient in fifteenth-century ink both was, and was not, extremely restricted.
B.    If the technology that makes it possible to detect titanium in printing ink has only recently become available, it is unlikely that printers are artists in the fifteenth century would know whether their ink contained titanium or not
C.    It is unreasonable to suppose that determination of the date and location of a document’s printing or drawing can be made solely on the basis of the presence or absence of a single element in the ink used in the document.
D.    Both the B-36 Bible and the
Binland Map are objects that can be appreciated on their own merits whether or not the precise date of their creation or the identity of the per son who made them is known.
E.    The discovery of titanium in the ink of the Vinland Map must have occurred before titanium was discovered in the ink of the Gutenberg Bible and the B-36 Bible.
答案是A，可我感觉A不太好理解。C更象正确答案。哪位高人帮忙解一下，谢谢！

cranberry

看文中的结论，一是用墨水来判定古登堡印了那个圣经（理由就是墨水一样），然后又根据墨水，推断一种地图也是这个时代的产物。既然墨水被认为是判定古登堡的“标志”，就是“restrictly”，如何又可以泛泛地判定地图的年份呢？

winnie

谢谢cranberry！但小生还有一疑问，如大虾赏脸，能否再次指点：
cranberry的回答是直接反对结论。墨水被认为是判定古登堡的“标志”，是“restrictly”；结论根据墨水推断一种地图是这个时代的产物，因此墨水也可以被认为是判定某时代产物的标志，即用来判定地图的年份，也应该是“restrictly”，不知当否？

我考虑反对前提和结论之间的推理：即一个著名的圣经是古登堡印的，不一定能推出B-36也是由古登堡印的（理由就是墨水一样），象C说的那样。

cranberry

小子试着说说，c的意思是说不能单凭墨水中有否某种物质就判定什么东东，这个不是文章的flaw,因为通过墨水判定这种方法是否科学合理，文中你看不出，所以它的弱点不在于此，而接着看文章，古登堡的圣经证明15世纪墨水就有钛，但15世纪的墨水有钛不能证明所有用有钛墨水印制的圣经就是古登堡的“作品”，如果认为这是古登堡的专有（理由是十五世纪其他的印刷品的墨水里没有钛），那么除非这个地图也是古登堡的作品，否则就出现了专有和泛泛的矛盾。

winnie

很清楚了，谢谢谢谢谢！
这个疑团在我心中好久了。