Self-paced
Until recently it was thought that ink used before the sixteenth century did not contain titanium. ████████ █ ███ ████ ██ ████████ ████████ ████████ ██ ███ ███ ██ ███ ██████ █████ ███████ ██ ████████ █████████ ███ ██ ████ ██ ███████ █████████████████ █████ █████ ██ █████ ██████ ███ ██ ███ ███ ██ ███ ██ ████████ █████ █████████████████ █████ █████████ ████ ███████ ██ ██ █████ █████████████ █████ ██ ███ ████ ████████ ████████ ███ ██████████ ████ ████ ███ ███████ ██ █████████ ███ ████ █████ ████ ███ ████████ ██ ████████ ██ ███ ███ ██ ███ ███████████ █████████████████ ███████ ███ ███ ██ ██████ ██ ████████ ██ █ ██████ ███ ████████ ███ ███████ █████████████
Argument Summary
The argument starts by giving us some context: until recently, people thought that ink never contained titanium before the 16th century. But then, surprise! Two 15th-century books were found to use titanium ink: the Gutenberg bible, and another bible, "B-36". Many other 15th-century books were tested, but did not use titanium ink. The author uses these facts to support two separate conclusions: first, that B-36 was in fact printed by Gutenberg, and second, that the Vinland Map's use of titanium ink is no longer a reason to doubt it's truly from the 15th century.
Objective: Identify a Flaw
This is a complex argument: not only is the subject matter a bit technical, but it unusually has two conclusions. So to simplify our analysis, let's separately consider the strength of the support for each conclusion.
First, the conclusion that Gutenberg printed B-36 is supported by the presence of titanium ink in both the Gutenberg bible and B-36, but not in any other 15th-century book analyzed. This conclusion is supported by the rarity of titanium ink in 15th century books. If Gutenberg used a particular rare ink, it makes sense that a bible printed with that ink would have been printed by him.
Second, the conclusion that the titanium ink used for the Vinland Map isn't evidence of its inauthenticity is supported by the fact that titanium ink actually was used in the 15th century. However, the same rarity that supports the first conclusion undermines the second conclusion. Even if titanium ink existed in the 15th century, if it was very rare, the map's use of titanium ink is still evidence it wasn't truly from the 15th century.
This is the issue with the argument: it uses its evidence in contradictory ways to support each of the two conclusions. The first conclusion is supported by titanium ink being very rare in the 15th century, whereas the second conclusion is undermined by this same rarity. We're looking for an answer choice that identifies this internal contradiction.
24.
The reasoning in the passage ██ ██████████ ██ █████████ ██ ███ ██████ ████
a
the results of ███ ████████ ███ ███████████ ██ ██████████ ████ ███ ███ ██ ████████ ██ ██ ██████████ ██ █████████████████ ███ ████ ████ ███ ███ ████ █████████ ██████████
To support the first conclusion that Gutenberg printed B-36, the argument relies on titanium ink being rare—so rare that only one printer was known to use it. But for the second conclusion that the Vinland Map could actually be from the 15th century, the argument acts as though titanium ink had been common, or at least common enough that a random map could use it.
(A) identifies the internal contradiction in the argument: one of its two conclusions relies on titanium ink being very rare, whereas the second conclusion is actively undermined by how rare titanium ink was in the 15th century.
b
if the technology ████ █████ ██ ████████ ██ ██████ ████████ ██ ████████ ███ ███ ████ ████████ ██████ ██████████ ██ ██ ████████ ████ ████████ ██ ███████ ██ ███ █████████ ███████ █████ ████ ███████ █████ ███ █████████ ████████ ██ ███
Whether 15th-century ink users had knowledge of their ink containing titanium doesn't come up in the argument. There's no claim that Gutenberg deliberately used this rare titanium ink; the question is just whether ink at that time actually contained titanium, and how rare it was.
c
it is unreasonable ██ ███████ ████ █████████████ ██ ███ ████ ███ ████████ ██ █ ████████████ ████████ ██ ███████ ███ ██ ████ ██████ ██ ███ █████ ██ ███ ████████ ██ ███████ ██ █ ██████ ███████ ██ ███ ███ ████ ██ ███ ████████
This may or may not actually be unreasonable—without an ink historian on hand, it's hard to say. But either way, the argument doesn't discuss the specific date and location of any document's creation. The closest it gets is addressing whether the Vinland Map was truly printed in the 15th century—and even then, it never claims to have fully determined the answer. All the argument says is that the use of titanium ink shouldn't be seen as evidence against this claim.
(C) might be a flaw if the argument claimed the Vinland Map (or another document) truly was created at a specific date and location. But in this argument, the real issue is the contradictory treatment of titanium ink in the 15th century as simultaneously rare enough to identify a publisher, and common enough to not act as evidence that the map comes from a later time.
d
both the B-36 █████ ███ ███ ███████ ███ ███ ███████ ████ ███ ██ ███████████ ██ █████ ███ ██████ ███████ ██ ███ ███ ███████ ████ ██ █████ ████████ ██ ███ ████████ ██ ███ ██████ ███ ████ ████ ██ █████
The argument doesn't talk about appreciation, of these specific documents or about anything else. Whether these documents can be appreciated on their own merits or not doesn't impact the conclusions about who created the documents, and when.
e
the discovery of ████████ ██ ███ ███ ██ ███ ███████ ███ ████ ████ ████████ ██████ ████████ ███ ██████████ ██ ███ ███ ██ ███ █████████ █████ ███ ███ ████ █████
The argument tells us as a fact that all three documents use titanium ink. When each of these discoveries happened isn't relevant, beyond adding flavor to the argument. The important question is what this ink implies about the authorship and/or age of each document.