The date of the Rimienti World Map, drawn in Italy, is unknown.

Question

The date of the Rimienti World Map, drawn in Italy, is unknown. The map accurately depicts the coastline of western Africa down to the Cape of Good Hope, near Africa's southern tip. In 1488 Portuguese explorers became the first Europeans to reach the Cape. Since it would have taken at least a year for their information to be brought back to Europe and incorporated into maps, the Rimienti World Map could not have been made before 1489.

Which of the following is an assumption on which the argument depends?

(A) Portuguese authorities generally tried to keep information about Portuguese voyages secret for as long as possible.
(B) A map as complicated as the Rimienti World Map would have required at least half a year for a professional cartographer of the 1400's to complete,
(C) It would not have taken more than a year for geographical information to travel from Portugal to Italy.
(D) Italian cartographers did not get the information for the Rimienti World Map directly from African sources.
(E) No accurate map of any parts of the coastline of western Africa appeared before the Rimienti World Map.

MartyMurray · Accepted Answer

The date of the Rimienti World Map, drawn in Italy, is unknown. The map accurately depicts the coastline of western Africa down to the Cape of Good Hope, near Africa's southern tip. In 1488 Portuguese explorers became the first Europeans to reach the Cape. Since it would have taken at least a year for their information to be brought back to Europe and incorporated into maps, the Rimienti World Map could not have been made before 1489.

The conclusion of the argument is the following:

the Rimienti World Map could not have been made before 1489

The argument supports the conclusion with the following premises:

the map accurately depicts the coastline of western Africa down to the Cape of Good Hope, near Africa's southern tip

In 1488 Portuguese explorers became the first Europeans to reach the Cape

it would have taken at least a year for their information to be brought back to Europe and incorporated into maps

We see that the reasoning of the argument is that, since the first Europeans to reach the Cape reached it in 1488 and since it would have taken a year for those Europeans to bring the information back to someone who could have used to to make a map, the Rimienti World Map must not have been made for at least a year after 1488.

Which of the following is an assumption on which the argument depends?

The correct answer will state something that must be true in order for the premises to effectively support the conclusion.

(A) Portuguese authorities generally tried to keep information about Portuguese voyages secret for as long as possible.

The argument works even if this statement is not true.

After all, even if the Portugese authorities did NOT try to keep information about Portuguese voyages secret for as long as possible, it would still have taken a year for the information about the voyage to the Cape to get to a mapmaker in Europe.

Eliminate.

(B) A map as complicated as the Rimienti World Map would have required at least half a year for a professional cartographer of the 1400's to complete.

The premises are that the Portugese explorers reached the Cape of Good Hope in 1488 and that it would have taken at least a year for their information about the Cape to be brought back to Europe and incorporated into maps.

A year after some time in 1488 is some time in 1489. So, even if it would not have taken a half a year for the map to be completed, it still could not have been made before 1489.

So, the argument works even if this choice is not true.

Eliminate.

(C) It would not have taken more than a year for geographical information to travel from Portugal to Italy.

This choice is a little tricky because we could get the impression that the conclusion of the argument is that the Rimienti World Map must have been made IN 1489.

If that were the conclusion, then the author would have to assume what this choice says. After all, if it COULD have taken more than a year for the information to travel from Portugal to Italy, then that conclusion would not be correct, since the Cape was first reached by Europeans in 1488 and it would have taken a year for information from that voyage to get back to Europe. So, if it could have taken an additional year for the infromation to get to Italy, then the map might not have been made in 1489. In that case, the conclusion that the map must have been made in 1489 would be incorrect.

However, that is not the conclusion. The conclusion is that the map "could not have been made BEFORE 1489." It's not necessary for this choice to be true for the premises to support that conclusion. After all, that conclusion allows for the possibility that the map was made after 1489. In other words, the conclusion that the map "could not have been made before 1489" would still be true even if the map was not made for more than a year after the information was brought back to Portugal.

Eliminate.

(D) Italian cartographers did not get the information for the Rimienti World Map directly from African sources.

The reasoning of the argument is basically that, since the Portugese explorers could not have gotten information about the Cape of Good Hope to an Italian mapmaker before 1489, the Rimienti map could not have been made before 1489.

That reasoning has a big gap in it. It jumps from the idea that the Portugese could not have brought back the information before 1489 to the conclusion that the map was not made before 1489. We see that the argument basically equates the time when the Portugese could have provided the information with the time the map could have been made.

Thus, the argument is based on the assumption that the only way an Italian mapmaker could have gotten information about the Cape of Good Hope is by getting it from those Portugese explorers. After all, if the mapmaker could have gotten the information in another way, then the mapmaker might have had the information before 1489 and could have made the map then.

Thus, we can see that the argument depends on the assumption that Italian cartographers (mapmakers) did not get the information from African sources, or anyone else other than the Portugese explorers.

So, the argument depends on this choice being true.

Keep.

(E) No accurate map of any parts of the coastline of western Africa appeared before the Rimienti World Map.

This choice does not have to be true for the argument to work.

After all, the argument is based on facts about the first Europeans to reach the Cape of Good Hope. Those facts would still support the conclusion about the Rimienti World Map even if some maps accurately depicted other parts of the coastline of western Africa.

In other words, it doesn't have to be the case that European mapmakers knew nothing about the entire coast of western Africa for it to be the case that this particular map, which depicts a particular part of Africa, the Cape of Good Hope, could not have have been made before 1489.

Eliminate.

Correct answer:  D

katkot · Answer

I was confused between C and D and choose C. This is a top-notch explaination. Thanks

GmatKnightTutor · Answer

The date of the Rimienti World Map, drawn in Italy, is unknown. The map accurately depicts the coastline of western Africa down to the Cape of Good Hope, near Africa's southern tip. In 1488 Portuguese explorers became the first Europeans to reach the Cape. Since it would have taken at least a year for their information to be brought back to Europe and incorporated into maps, the Rimienti World Map could not have been made before 1489.

Which of the following is an assumption on which the argument depends?

(A) Portuguese authorities generally tried to keep information about Portuguese voyages secret for as long as possible.
(B) A map as complicated as the Rimienti World Map would have required at least half a year for a professional cartographer of the 1400's to complete,
(C) It would not have taken more than a year for geographical information to travel from Portugal to Italy.
(D) Italian cartographers did not get the information for the Rimienti World Map directly from African sources.
(E) No accurate map of any parts of the coastline of western Africa appeared before the Rimienti World Map.

Which of the following is an assumption on which the argument depends?

The passage talks about a RWP map. How it was made in Italy but the date is unknown. How the map depicts the coastline of western Africa down to the southern tip and because Portuguese explorers only explored to that tip in 1488, the map must have been made at the earliest in 1499 since it would have taken a year or more to get back to Europe and for that info to be included into maps.

(D) Italian cartographers did not get the information for the Rimienti World Map directly from African sources.

(D) is the answer. If Italian cartographers DID get info for the RWP map directly African sources, the theory put forth by the passage which hinges upon the Portuguese explorers timeline is completely thrown out. What if the info from these African sources was shared across Europe before 1400?

Pr4n · Answer

Simply put the correct answer choice here when negated means that Italians might have not depended on portuguese at all for the info, hence the timeline is still blurry. Maybe Africans traveled before to give that info to Italians or passed it some other way. In the end the the conclusion is about determining the timeline which is dependent on the fact that as Portuguese were the first Europeans to reach the cape, Italians map maker must have gotten the info from it.

I personally feel this is great CR question, in this we need to look at the argument as a whole and just focusing on the conclusion might not actually lead to connecting these dots. As then one might only focus on the European part and not the Italian part.

I personally feel this is great CR question, in this we need to look at the argument as a whole and just focusing on the conclusion might not actually lead to connecting these dots. As then one might only focus on the European part and not the Italian part.

ameya.satyawadi · Answer

What if in option E it is assumed that Rimienti world map was copied from another map, which is why it could have been made earlier than the Portugal explorations, agreed it is a little far fetched though it still suffices as an important assumption.

Khushe · Answer

KarishmaB  Could you please explain the logic for eliminating option E? If there were any maps existing which accurately depicted the coastal line, it would undermine the author's conclusion.

KarishmaB · Answer

Context:

The date of the Rimienti World Map, drawn in Italy, is unknown.

Premises:

The map accurately depicts the coastline of western Africa down to the Cape of Good Hope, near Africa's southern tip. 
In 1488 Portuguese explorers became the first Europeans to reach the Cape. 
It would have taken at least a year for their information to be brought back to Europe and incorporated into maps,

Conclusion:

The Rimienti World Map could not have been made before 1489.

We are looking for an assumption - something that must be true to say that the Rimienti World Map could not have been made before 1489.

(A) Portuguese authorities generally tried to keep information about Portuguese voyages secret for as long as possible.

Irrelevant. We don't need this to be true. The argument depends on the time taken to bring back the info to Europe and incorporate it. It does not depend on any actions of the Portuguese authorities.

(B) A map as complicated as the Rimienti World Map would have required at least half a year for a professional cartographer of the 1400's to complete,

We don't NEED this to be true. 6 months doesn't figure anywhere. The argument does not assume that half a year would be required for the voyage back and half a year for the incorporation by the professional cartographer. It is possible that the voyage took 9 months and the incorporation took only 3 months.

(C) It would not have taken more than a year for geographical information to travel from Portugal to Italy.

We have been given that it would have taken   at least a year   for their information to be brought back to Europe and incorporated. It means that it could have taken longer too. The argument does not assume that it would not have taken more than a year for geographical information to travel from Portugal to Italy.

(D) Italian cartographers did not get the information for the Rimienti World Map directly from African sources.

Correct. This is an assumption of the argument. The argument assumes that the Portuguese explorers took the information to the Italian cartographers. But what if say much before 1488, African explorers had travelled to Europe and provided all the information? Then our conclusion falls.

(E) No accurate map of any parts of the coastline of western Africa appeared before the Rimienti World Map.

The argument only claims that the map accurately depicts the coastline of western Africa down to the Cape of Good Hope, near Africa's southern tip i.e. the entire western coastline. 
It is possible that parts of the coastline were depicted accurately by other maps before Rimienti. There is no conflict with the argument in that case. 
The argument does assume that the entire coastline info was not available in Europe before Rimienti, but it does not assume that info on any parts of the coastline was not available. 
That is why (E) is incorrect.

Answer (D)

The date of the Rimienti World Map, drawn in Italy, is unknown.

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­The date of the Rimienti World Map, drawn in Italy, is unknown.

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The date of the Rimienti World Map, drawn in Italy, is unknown.