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#34930
Complete Question Explanation

Assumption. The correct answer choice is (B)

In this question the art historian asserts that a particular painting is a forgery, despite several
similarities to a Mary Cassatt original. The canvas on which the painting was created and the other
materials used in its creation are consistent with the majority of the artist’s paintings, and the subject
matter is much like that of her best works. Even so, the author concludes that the painting must be a
forgery, because the brush style is unlike that found in any of the artist’s known works.
The argument breaks down as follows:

..... Premise: ..... That canvas and other materials are consistent with those used by Mary
..... ..... ..... ..... Cassatt.

..... Premise: ..... The subject matter of the painting is like that of her finest works.

..... Premise: ..... However, the brush style is unlike any of Cassatt’s known works

..... Conclusion: ..... Therefore, the painting in question must be a forgery.

The stimulus is followed by an Assumption question. Since the author will rely on the assumption
provided by the correct answer choice, the right answer can be confirmed with the Assumption
Negation Technique: When logically negated, the correct answer choice will weaken the author’s
argument.

Answer choice (A): The canvas and materials used do not have to have been widely available
to others in order to conclude that the painting in question is a forgery. Since the art historian’s
argument does not rely on this assumption, this choice should be ruled out of contention.

Answer choice (B): This is the correct answer choice. In order to logically reach the conclusion
that is drawn in the stimulus, the author must assume that there are no Cassatt works that reflect
a brush style that is absent in all of her known works. The Assumption Negation Technique will
confirm this as the correct answer choice. The negated version of this answer choice would be as
follows:

At least one of Cassatt’s works is painted in a brush style that is not exhibited in her other known
works.


This would, of course, defeat the author’s conclusion, so this choice must be the assumption on
which the author’s argument relies.

Answer choice (C): This is not an assumption on which the art historian’s argument relies. To
confirm this, we can negate this answer choice and note the effect on the argument presented in the
stimulus. The negated version of this answer choice would be as follows:

Cassatt’s work generally did not have characteristic subject matter that distinguished it from the
work of other artists from the same era.


This would not defeat the art historian’s argument, because the painting in question could be a
forgery regardless of how distinguishable Cassatt’s works were from others of her time.

Answer choice (D): The art historian’s conclusion does not rest upon the assumption that Cassatt’s
brush style was her greatest point of distinction. To confirm this as an incorrect answer choice, we
can again apply the Assumption Negation Technique. The negated version of this choice would be as
follows:

Cassatt’s brush style is not the most characteristic feature of her work.

This negated version would not weaken the art historian’s argument, which is based on the fact that
the painting in question has a different brush style from those known to Cassatt. It is not relevant
where “brush style” falls on the list of Cassatt’s works’ most characteristic features.

Answer choice (E): The conclusion from the stimulus is based on the fact that the painting in
question reflects a different brush style, so this choice cannot be an assumption on which the art
historian’s argument relies. When we take away, or logically negate, this answer choice, we arrive at
the following negated version:

At least one painter other than Cassatt could have perfectly copied her brush style.

Since the possible forgery has a brush style that is different from Cassatt’s other works, this negated
version would have no effect on the art historian’s argument.
 KG!
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#94332
Thank you for this thorough explanation! One question I have when it comes to the negation technique is that I was looking to change the not in the answer choice as well. My negation was "some of Cassatt's work are painted using a brush style that IS in her known works." Why do I only negate the first part of this sentence?
 Adam Tyson
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#94367
Because two negatives make a positive, KG! The goal of negating a statement is to create a new statement that refutes the original. In other words, the negation should just be another way of saying "that's not true." Don't just replace all the positive words with negative ones and vice versa, because that won't negate (disprove) the original statement. Your negation here doesn't conflict with answer C, so it isn't a true negation of that answer.

Keep it simple - when you have a claim about "none," just turn it into "some," because that would prove it isn't none and the claim is incorrect. One negation should be enough!
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 Skylar Li
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#107489
For answer choice D, is it a condition that can strengthen the argument, but not necessarily guarantee the conclusion to be properly drawn?
 Adam Tyson
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#107567
Yes and no, Skylar Li. That answer does strengthen the argument, and it doesn't justify the conclusion, but we aren't necessarily looking for something to justify the conclusion in this case. Instead, we are looking for something that is a necessary assumption of the argument - the argument "depends on assuming which one of the following." So the reason answer D is incorrect is because the argument doesn't need it to be true! It could be that the most characteristic feature of her work is her use of color, or light, or a certain subject matter. Since this answer isn't necessary, it's not what we are looking for!

Answer B is an assumption of the argument, and it looks like it is strong enough to also justify the conclusion. Sometimes that happens, where one answer is both sufficient and necessary, but when they ask for something necessary, don't worry about whether it's also sufficient, and when they ask for something sufficient, don't worry about whether it's also necessary.

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