sameerballani wrote:A newly discovered painting on wooden panel by Michelangelo must have been completed after 1507 but before 1509. It cannot have been painted earlier than 1507 because one of its central figures carries a coin that was not minted until that year. It cannot have been painted after 1509 because it contains a pigment that Michelangelo is known to have abandoned when a cheaper alternative became available in that year.
Which of the following is an assumption on which the argument depends?
A)No stocks of the abandoned pigment existed after 1509.
B)Michelangelo did not work on the painting over the course of several years.
C)The coin depicted in the painting was known to general public in 1507.
D)The wooden panel on which the painting was executed cannot be tested accurately for age.
E)Michelangelo's painting style did not change between 1507 and 1509.
[spoiler]OA: Later[/spoiler]
The answer is B, but it's difficult to see without trying to predict what the answer should do before going to the answer choices. For many assumption questions, the key is to think critically - think about what would weaken the conclusion. Attacking an argument is a good way to expose the underlying assumptions that the author makes, but does not state.
There are actually two sets of premises and conclusions in this argument:
Premise: the painting contains a coin that was not available before 1507.
Conclusion: the painting was not painted before 1507.
AND
Premise: Painting contained a pigment that Michelangelo abandoned in 1509.
Conclusion: The painting was finished by 1509
the second one is easier to attack: the fact that the painting contained a pigment (not painted entirely in the pigment - just
contained the pigment) does not by itself say that Michelangelo could not continue working on painting beyond 1509 using different kinds of pigments.
The first is attacked in the same manner: the fact that part of the painting (in this case, a coin) has a "not before 1507" date does not meant that the painting as a whole was painted after 1507: It is possible that other parts of the painting were painted before 1507, with the coin added AFTER 1507 at a later stage.
These are weakening hypotheses, not found in the text, but they expose the assumption - the author is assuming that "expiry dates" on parts of the painting represent the entire painting as a whole - that if he started on the coin in 1507, he started the entire painting at 1507, and if he finished with the pigment in 1509, he must have finished the entire painting before that time.
B works against that assumption: If Michelangelo paused in his work on the painting, that would explain why the painting could be painted outside of the range, with only the relevant parts painted within the range. Therefore, in reaching his conclusion that the parts represent the whole, the author must assume that the painting was painted more or less within a short period of time - a year or two. B is a necessary assumption because it eliminates a possible counter explanation that would weaken the conclusion.
So only left with option B 
