A newly discovered painting on wooden panel by Michelangelo

OFFICIAL EXPLANATION

The conclusion of the argument is that Michelangelo must have completed the painting between 1507 and 1509. The basis for that claim is that the painting depicts a coin that did not exist before 1507 and that it contains a pigment that Michelangelo ceased using in 1509. We are asked to find an assumption that completes the logic of this argument.

Choice A is incorrect. We do not need to assume that no stocks of the pigment existed after 1509. The argument is concerned only with the year in which Michelangelo stopped using the pigment.

Choice B is correct. In order to conclude that the painting must have been completed before 1509 on the basis of the pigment, we must assume that he did not begin the painting before 1509 using the old pigment and complete the painting after 1509 with the new pigment.

Choice C is incorrect. The fact that the general public knew of the coin in 1507 is irrelevant to the conclusion.

Choice D is incorrect. The fact that the panel cannot be tested for age does not relate to either the coin or the pigment, the two bases for the conclusion.

Choice E is incorrect. Whether Michelangelo's painting style changed during this period does not relate to either the coin or the pigment.

'B'

'A' says that "No stocks of the abandoned pigment existed after 1509". The question is not whether there were any stocks of the pigment available after 1509, it is whether michaelangelo used it or not. And the CR says that "it is known that MA did not use this pigment after 1509".

So I think 'A' assumption is not valid.

What is the OA and OE?

Assumptions fit in the logical gap between premises and the conclusion. Here the conclusion is that the painting must have been COMPLETED 1507-1509. Premises are 1 - the coin inclluded that was minted in 1507 and 2 - Pigment used that M. was KNOWN to abandon in 1509.

A - Existence of pigment is irrelevant because the premise says he was known to abandon the pigment regardless of its existence
B - The conclusion discusses the paintings COMPLETION, so you are assuming that if it contained pigment abandonded in 1509 it was also completed that year. You can also try negation here: Michealangelo DID work on the painting over the course of several years. The negated assumption destroys the conclusion, making it a necessary assumption.
C - This provides additional information about an already established premise, not an assumption.
D - Wooden panel age is out of scope.
E - M's painting style is not discussed in the argument therefore it is also out of scope.

KW

E is a tempting choice because it specifically mentions the years in question, but you need to remember that the purpose of the assumption is to bridge the logical gap between the premises and the conclusion. The premises do not discuss his painting style, only the coin and the pigment, so information about the painting style doesn't bridge the gap between premises and conclusion.

Part of the reason why answer choice B is tricky, though correct, is that it doesn't specifically mention either the coin or pigment. However, the length of time spent painting does directly relate to the pigment premise. If he started the painting in 1508 he would be using the old pigment, but if the painting took several years to finish he wouldn't have COMPLETED it until sometime after 1509. For our conclusion to be true (the painting was completed before the end of 1509) we have to assume that he started after 1507 and completed it before 1509, as option B states.

KW

Negation is a powerful technique for confirming that a statement is an assumption of the argument. The fundamental concept behind negation is that a statement is an assumption of the argument if it must be true for the conclusion to be true. Expanding on that concept, the "negative" version a necessary assumption INVALIDATES the conclusion. To test a statement to see if it's an assumption, assume that the negative version of the statement is true (negate the assumption) and see if the conclusion has been invalidated. It's a great cross-check on trickly CR questions.

The hardest part of negation is learning how to create the negative (or inverted) version of a sentence. In this problem, creating the negative isn't difficult at all. Michaelangelo did not work...Michaelangel DID work (inverted/negated). On this problem you see that the negated version of the assumption invalidates the conclusion, so it is a necessary assumption to the conclusion.

KW

OE
(1) Identify the Question Type

The question stem asks what would be most useful in evaluating the argument, so this is an Evaluate the Argument question.

(2) Deconstruct the Argument

The author claims that the painting in question must have been completed between 1507 and 1509. What support is there for this claim? The part about 1507 seems fairly reasonable. How could Michelangelo paint a coin that did not exist yet? However, it’s possible that Michelangelo had advance notice of what the new coin would look like. Perhaps he was shown the design in advance. He might even have designed the coin himself!

The second restriction makes sense, too. If Michelangelo abandoned the pigment in 1509, then it shouldn’t show up on his paintings after that point. However, this argument is specifically about when the painting was completed. Perhaps Michelangelo started with the old pigment and then finished in 1510 or later with the cheaper pigment.

(3) State the Goal

In an Evaluate the Argument question, the goal is to choose a question or piece of information that would make it easier to determine if the conclusion is valid. In this case, information about either of the two limiting dates would be useful. Did Michelangelo have advance notice about the coin? Did he start in one year and finish later?

(4) Work from Wrong to Right

(A) An answer of “yes” to this one might seem to cause trouble for the argument. Maybe Michelangelo still had the chance to use the more expensive pigment after 1509. However, the premise states definitively that Michelangelo abandoned that pigment sometime in 1509, and you do not want to contradict the premise! This answer choice would be helpful if the premise had said that the pigment was no longer produced, but that’s not the issue. The pigment may well have been around after 1509, but Michelangelo wasn’t using it.

(B) CORRECT. This addresses the 1509 side of the conclusion. If Michelangelo worked on the painting for several years, he might have started with the more expensive pigment and then finished in 1510 or later with a different pigment. However, if he did not work on the painting for several years, then he must have completed it in 1509 or earlier, since he stopped using the expensive pigment after that year.

(C) This is an interesting question, but it does not help to evaluate the conclusion. An answer of “yes” wouldn’t impact the argument at all, as it’s already clear that Michelangelo knew of the coin—he painted it! An answer of “no” would make it less likely that Michelangelo had seen the coin even in 1507, but if anything, this would just narrow the range further (maybe the coin became well known in 1508 or 1509).

(D) It would certainly be helpful to test the painting for age. However, notice that like all of the answer choices in this problem, (D) is a yes/no question. A yes/no answer by itself won’t help you to evaluate the author’s conclusion. “Yes” just means that the claim can be tested scientifically, and “no” means that it can’t. In order to evaluate, you would need to know the results of such a test!

(E) This question is out of scope. The argument dates the painting between 1507 and 1509. Knowing that Michelangelo’s style changed in that same period wouldn’t make it any easier to tell if the painting was completed before 1507 (in the old style) or after 1509 (in the new style).

What helped me to get to Answer (B) was visualizing the progress that he made on the picture.
The question tells us that he COMPLETED the picture after 1507 (because of the coin that wasn't minted until that year), but before 1509 (because he stopped using a specific pigment).

When he finished the picture within a few weeks/months, everything is fine.
But what if it took him several years to finish the picture, because it was really big or because he was painting on several other pictures?
This could have an influence on the upper boundary (1509).

What if he finished the areas with the specific pigment in 1508, but still needed to fill huge areas for which he didn't need neither the specific pigment, nor the replacement?
It is possible that he continued to work on the picture after 1509 without using the pigment, and therefore finished it after 1509.

This possibility destroys the argument. Therefore, Answer (B) is a necessary assumption

Let’s start off by looking at the facts that have been presented.

Here’s all the info at one glance



Based on this info, it has been concluded that Michelangelo must have completed this painting after 1507 but before 1509. We have to figure out what has been assumed to come to this conclusion.

Let’s look at the options:

A) No stocks of the abandoned pigment existed after 1509.

The argument tells us that the pigment was abandoned when a cheaper alternative came along. In that case, whether this pigment existed or not is not relevant to the argument. To draw the conclusion, we do not need to assume whether stocks of the pigment existed or not. Eliminate!

B) Michelangelo did not work on the painting over the course of several years.

If the author is concluding that Michelangelo must have completed this painting after 1507 but before 1509, the author is clearly assuming that the painting was completed within two years and that Michelangelo did not work on this painting over the course of several years. If this has not been assumed, then the conclusion cannot be drawn.

Let's be certain. Let's negate!

Michelangelo worked on the painting over the course of several years.



If he worked on the painting over the course of several years then how can the author conclude that the painting was completed within two years? The conclusion cannot be concluded anymore. If the conclusion falls on the negation of an option, then the option that was negated is the correct option. Select!

C) The coin depicted in the painting was known to general public in 1507.

We already know from the argument that the coin was minted in 1507. So it is obvious that the coin would be known to the general public. This is the reason this opinion is so tempting. Even if this is a known fact, we do not need to assume this to conclude that Michelangelo must have completed this painting after 1507 but before 1509. Remember! Always connect back to the conclusion! Ask yourself – “Do I need to assume this to draw the conclusion?” Eliminate!

D) The wooden panel on which the painting was executed cannot be tested accurately for age.

Hold on! Why do we want to test the age of the wooden panel? Michelangelo could have used a brand-new panel or an old one…or whatever! Fine! Even if we take into consideration that knowing the age of the panel would tell us approximately how old the painting was, do we need this information to conclude when Michelangelo must have completed this painting? Surely not! Not just that, this option tells us that the panel cannot be tested. So, this option is absolutely useless! Eliminate!

E) Michelangelo's painting style did not change between 1507 and 1509.

Some may choose this option saying that we can compare the style to understand at what stage of his career Michelangelo painted this painting. But just like Michelangelo's painting style did not change between 1507 and 1509, it is possible that he had the same style in 1519 also. So the fact that the style did not change in these two years does not help us conclude that Michelangelo must have completed this painting after 1507 but before 1509. Eliminate!

Nitha Jay
GMAT Verbal SME

egmat KyleWiddison CrackverbalGMAT GMATNinja @gmatexperts KarishmaB ][/url] still not clear about B. I do not see how saying the negation: 'worked for many years' breaks the conclusion that they completed necessarily b/w 1507 or 1509. Even if they worked for many years, they could have very well started in 1507 and completed in 1509, thereby working over several years and completing b/w 1507 and 1509 and here it does not break the conclusion. Even 2 years of work can be considered several years.

Also since the conclusion is about ;completed', even if they did work on it for many years, they could have started it before 1507 and still completed it between "1507 and 1509'. Also here, how to interpret 'after 1507' and 'before 1509'?

I agree with you Elite097.

Coin minted January 1507.
Started painting March 1507.
Finished painting September 1509.
Stopped using the pigment November 1509.

I'll also add that he may have started the painting many years earlier and not gotten to the portion depicting the coin until after it was minted.

Sure looks possible to have worked on the painting for multiple years. Note that this was NOT an official GMAT question...

Hello DmitryFarber , ReedArnoldMPREP!

I think there is a subtle error in this question:

The conclusion states that the painting must have been completed AFTER 1507 but BEFORE 1509. Therefore, this conclusion specifically narrows down the completion year to 1508. (Nothing is said about the starting date though in this conclusion).

The premises support this conclusion by stating that:

1. The coin depicted in the painting was minted in 1507;
2. Michelangelo abandoned the pigment in 1509;

Therefore, the gap in the argument is that given the premises, it is not necessary that Michelangelo had to complete the painting in 1508. He could have very well have completed it in 1509.

Now, the supposedly correct answer B states that the assumption is that he didn't work on it over the course of 'several' years. But imo, this is not an assumption that the argument needs to have. The conclusion nowhere mentions about the starting date of the painting - it just talks about the completion of the painting. So Michelangelo may very well have started the painting in 1507 - as soon as the coin was minted - and finished in 1508, as the conclusion states. This situation could, imo, fall under 'several' years, and thus still within the scope of the argument (that is the assumptions negation would not destroy the argument).

To make this question more airtight, the assumption that the argument does need imo is that Michelangelo did not work on this painting in 1509 - the assumption that is the actual gap in this argument.

Much appreciate your advice on this! Thanks!

Hmm. I think you should think about what 'several' constitutes. I don't think starting in 1507 and finishing in 1508 would constitute 'several' years. 'Several' means 'more than two, but not a lot more than two.' 1507 to 1508 would be about a year, and certainly less than 2 years.

If you allow this definition of 'several,' does that clarify the reasoning here?

Hi ReedArnoldMPREP

Thanks for your reply. I just looked up the definition of 'several', and indeed it means more than two but not a lot more than two.

However, in that case we don't NEED the assumption that it did NOT take Michelangelo SEVERAL years to complete the painting (considering that we take the premises as given to be true). The premises are -

1. It cannot have been painted earlier than 1507 because one of its central figures carries a coin that was not minted until that year; and
2 . It cannot have been painted after 1509 because it contains a pigment that Michelangelo is known to have abandoned when a cheaper alternative became

From these premises, the conclusion drawn is -

A newly discovered painting on wooden panel by Michelangelo must have been completed after 1507 but before 1509;

So the only assumption that the argument NEEDS is that Michelangelo completed the painting BEFORE the start of 1509.

Thanks for clarifying!
bt

So let me run my 'Three key question' analysis on the argument.

1). What is the OPPOSITE of the conclusion?

The painting was completed BEFORE 1507 or AFTER 1509.

2). How could that happen, GIVEN THAT THE PREMISES (about the coin and the paint pigment) ARE TRUE?

Completed before 1507:
-The design of the coin was known before the coin itself was minted (Perhaps, even, the coin was designed after the coin Michaelangelo painted)

Completed after 1509:
-Michaelangelo started painting the painting before 1509 with paint that had that pigment, then continued painting the painting after 1509 with paint that didn't have the pigment.

3). What assumptions, then, must be true to save the argument?

-The coin-design was not in the painting *before* the coin itself was minted.
-Michaelangelo didn't start the painting with one pigment, then switch to paints without that pigment.


The right answer 'B' seems to be dealing with this second assumption. Now, it's a little vague, right? Which is annoying. Because, hey, could not he have worked on the painting for 'several years' and still finished in 1508? Sure, why not?

(It seems like the conclusion should have been about 'starting and completing the painting in the year 1508'--my guess is they thought that made the problem too obvious).

But here's the issue. If Michaelangelo worked on the painting for 'several years,' it completely obliterates the reasoning used in the 'pigment' premise. It makes that aspect of the argument completely null and void.

This is subtle, but in Critical Reasoning you're really dealing with the REASONING of an argument, not its TRUTH... These are often co-mingled, but they technically don't need to be.

If Michaelangelo worked on the painting for several years, the REASONING the author is using to say 'it must have been completed before 1509' is obliterated EVEN IF the painting still could have been completed before 1509 after several years of work. We just now have no reason to *think* it was. The argument RELIES on the assumption that the painting was done 'quickly.'

I agree there's some kind of annoying eyebrow raising stuff in this question, but mostly still think B is an objectively good and fair answer.

Thank you so much, Reed.

My concern is that these assumptions are present in the premises themselves, and not between the premises and the conclusion. Can we attack the validity of the premises themselves in an argument. [The premises themselves are causal statements, which makes this question a bit confusing].

bt

I don't quite understand what you mean by 'present in the premises themselves.' These are the assumptions that make the premises 'work,' but that does not mean they are PART OF the premises. Quite the opposite--this is what makes them 'assumptions.'

We are not attacking the 'validity of the premises.' The premises are still completely true: the coin was minted in 1507, and Michaelangelo stopped using the pigment in 1509. We aren't attacking those at all.

If we're as generous as possible with the 'coin' premise,' meaning Michaelangelo did not start the painting until after that coin was minted, BUT HE PAINTED FOR "SEVERAL YEARS, then he could have stopped using the pigment mid-painting in 1509, and the conclusion falls apart.

Thanks.

Ah, okay. I think I get it now. I thought the entire causal sentences below are premises:

1. "It cannot have been painted earlier than 1507 because one of its central figures carries a coin that was not minted until that year"; and
2 . "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"

Whereas, each of these above sentences are part premise and part intermediate conclusion.

Intermediate Conclusions:

1. "It cannot have been painted earlier than 1507" and
2. "It cannot have been painted after 1509"

The premises are just:

1. "one of its central figures carries a coin that was not minted until that year"
2. "it contains a pigment that Michelangelo is known to have abandoned when a cheaper alternative became available in that year."


The main conclusion of the argument is:

"A newly discovered painting on wooden panel by Michelangelo must have been completed after 1507 but before 1509"


I was wrongly looking for an assumption just between the intermediate conclusion and the main conclusion. Whereas Answer choice B highlights an assumption between the premises and the intermediate conclusion

Thanks again, Reed!