Archaeologists have firm evidence that Norse explorers reached the

Question

Archaeologists have firm evidence that Norse explorers reached the coast of North America around A.D. 1000, long before Christopher Columbus’ first voyage to America in 1492. Some people claim to have excavated Norse weapons dating from the 1300‘s in areas far inland from Norse coastal sites. If these claims are true, then the Norse must have explored the interior of North America, as well as the coast, before Columbus’ first voyage.

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

A. The sites where weapons were found were the locations of relatively permanent Norse settlements.
B. The Norse weapons were not brought by Native Americans to the sites where they were excavated.
C. Norse explorers were more likely to travel far inland than were later explorers of North America.
D. Norse explorers would not have made expeditions far inland in North America without weapons.
E. The design of Norse weapons did not change significantly between A.D. 1000 and A.D. 1300.

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Official Answer

B

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MartyMurray · Accepted Answer

Archaeologists have firm evidence that Norse explorers reached the coast of North America around A.D. 1000, long before Christopher Columbus’ first voyage to America in 1492. Some people claim to have excavated Norse weapons dating from the 1300‘s in areas far inland from Norse coastal sites. If these claims are true, then the Norse must have explored the interior of North America, as well as the coast, before Columbus’ first voyage.

The conclusion of the argument is the following:

If these claims are true, then the Norse must have explored the interior of North America, as well as the coast, before Columbus’ first voyage.

The support for the conclusion is the following:

Some people claim to have excavated Norse weapons dating from the 1300‘s in areas far inland from Norse coastal sites.

We see that the reasoning of the argument is basically that the presence of Norse weapons in areas far inland indicates that the Norse traveled far inland.

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

This is an Assumption question, and the correct answer will state something that must be true for the evidence that Norse weapones were found inland to support the conclusion that the Norse must have explored the interior of North America.

A. The sites where weapons were found were the locations of relatively permanent Norse settlements.

If this choice were true, it would certainly confirm that the Norse explored the interior of North America.

At the same time, we aren't looking for a choice that just confirms the conclusion. We're looking for a choice that's necessary for the evidence already provided to support th conclusion, and this choice doesn't fit that criterion.

After all, even if the sites were not locations of relatively permanent Norse settlements, it could still be the case that the reason weapons were found inland is that the Norse went inland. After all, they could have explored the interior of North America without creating relatively permanent settlements there.

Eliminate.

B. The Norse weapons were not brought by Native Americans to the sites where they were excavated.

This choice is interesting. After all, if the weapons WERE brought by Native Amercians to the sites where they were found by Native Americans, then the fact that the weapons were found inland doesn't indicate that the Norse went inland. After all, if the weapons were brought there by Native Americans, then there's no clear connection between the location where the weapons were found and the Norse.

So, for the evidence about weapons being found inland to support the conclusion that the Norse must have explored the interior of North America, it must be true that the weapons were NOT brought by Native Americans to the inland sites.

Thus, this choice states an assumption on which the argument depends.

Keep.

C. Norse explorers were more likely to travel far inland than were later explorers of North America.

This choice may indicate that it's likely that the Norse traveled far inland. At the same time, it doesn't state a necessary assumption.

After all, even if the Norse were not  more likely  to travel far inland than other explorers, it could still be that they  did  travel far inland and that the reason why the weapons were found far inland is that the Norse traveled there.

Eliminate.

D. Norse explorers would not have made expeditions far inland in North America without weapons.

This choice is pretty tempting because it connects everything were concerned with: the Norse, weapons, and making expeditions far inland. At the same time, notice that this choice states basically the opposite of what must be assumed. Here's what I mean.

Weapons were found, and the argument concludes that the presence of the weapons means the Norse were there.

In other words, the argument assumes that  where weapons are, the Norse were .

This choice goes the other way. It says basically that  where the Norse were, weapons were .

So, this choice doesn't state an assumption on which the argument depends. After all, even if the Norse would have explored without weapons, the fact that Norse weapons were found somewhere would still tend to indicate that the Norse traveled there.

Eliminate.

E. The design of Norse weapons did not change significantly between A.D. 1000 and A.D. 1300.

This choice has the vibe of being something necessary for the argument to work. In other words, this choice could get us thinking something along the lines of "There it is. The argument depends on the fact that the design didn't change. After all, if it did, then maybe those weapons were mistaken for Norse weapons but weren't actually Norse weapons, in which case the argument wouldn't work."

So, we have to be careful to see that there's no way a change in design matters and that, therefore, we can easily eliminate this choice.

After all, the argument says the following:

If these claims are true , then the Norse must have explored the interior of North America ....

We see that the argument isn't saying that the weapons are for sure Norse weapons or that the Norse for sure explored the interior of North America. The point of the argument is that, if in fact Norse weapons were found inland, then the Norse traveled inland.

In other words, the argument doesn't assume that the weapons were Norse weapons or that Norse weapons were found inland. It just states a conclusion about what's true IF such weapons were found inland.

Eliminate.

Correct answer:  B

gmatophobia · Answer

Conclusion: The Norse must have explored the interior of North America, as well as the coast, before Columbus’ first voyage. Supporting Evidence : Some people claim to have excavated Norse weapons dating from the 1300s in areas far inland from Norse coastal sites Hence, while concluding the argument, the author believes that these weapons were brought by The Norse and not anyone else. Answer Choice Elimination A. The sites where weapons were found were the locations of relatively permanent Norse settlements. This assumption is not necessary for the argument's conclusion. Whether the sites were permanent settlements or not doesn't affect the conclusion of the argument. Therefore, we can eliminate A. B. The Norse weapons were not brought by Native Americans to the sites where they were excavated. This is a necessary assumption. The author assumed that the weapons were brought by the Norse explorers. If Native Americans brought the weapons, it wouldn't prove Norse exploration to the coast. Hence, we can keep B. C. Norse explorers were more likely to travel far inland than were later explorers of North America. This assumption is not necessary for the argument's conclusion. How far the Norse explorers traveled compared to other explorers is not the author's contention. D. Norse explorers would not have made expeditions far inland in North America without weapons. This option weakens the argument but is not an assumption. Firstly the conclusion made by the author is related to both the coast and the far inland, however, the presented option only refers to the expeditions made far inland. Also, the option does not necessarily need to be true. For example, even if not all Norse explorers made expeditions far inland in North America without weapons but some did, the conclusion can still hold. Hence, we can eliminate D. E. The design of Norse weapons did not change significantly between A.D. 1000 and A.D. 1300. This option is not essential to the argument's conclusion. Hence, we can eliminate E. Option B GMAT-Club-Forum-okarolfe.png

MalachiKeti · Answer

MartyMurray gmatphobia egmat If i negate D Norse explorers would have made expeditions far inland in North america without weapons - this means that weapons i found there wouldn't be brought by norse explorers rather someone else (such as example B)...so why is this an incorrect option? GMAT-Club-Forum-dm9p4gxq.png

MartyMurray · Answer

Here's the conclusion of the argument:

If these claims are true, then the Norse must have explored the interior of North America, as well as the coast, before Columbus’ first voyage.

Here's what's, in a sense, the support for the conclusion:

Some people claim to have excavated Norse weapons dating from the 1300‘s in areas far inland from Norse coastal sites.

So, the point of the argument is that, if there were Norse weapons inland, then the Norse must have gone there.

Notice how the argument works:

If Norse weapons were present inland, Norse were inland.

Notice that the argument is not the following:

If Norse were inland, then weapons were there.

So, the argument does not assume that Norse people always took weapons with them. Rather, we could say that it assumes that Norse weapons did not travel without Norse people.

So, the negation of (D) does not weaken the argument. After all, even if Norse explorers may have traveled without weapons sometimes, the weapons that were found could still be Norse weapons with which they traveled on occasions on which they did take weapons.

Also, there's another reason why (D) is not a necessary assumption, which is that the author does not even assume that the weapons are Norse weapons.

Rather, the author says, "IF these claims are true, then the Norse must have explored the interior of North America.'

So, the author is suggesting that the weapons may or may not be Norse weapons and that, if they are Norse weapons, then the Norse went inland.

Thus, the argument does not depend in any way on (D) being true.

MalachiKeti · Answer

Hi AjiteshArun can you pls help with option D. Conclusion: < If these claims are true>, then the Norse must have explored the interior of North America, as well as the coast, before Columbus’ first voyage. What claims? Evidence 1: Excavated Norse weapons dating from the 1300‘s in areas far inland from Norse coastal sites. Evidence 2: Archaeologists have firm evidence that Norse explorers reached the coast of North America around A.D. 1000, Option B : The Norse weapons were not brought by Native Americans to the sites where they were excavated. Negated - The Norse weapons were brought by Native Americans to the sites where they were excavated. Hence the connection that the presence of weapons indicates the presence of explorers breaks. In this case maybe the native Americans were the first explorers who were merely using the Norse weapons. The Norse didn't venture inland. Option D : Norse explorers would not have made expeditions far inland in North America without weapons. Negated - Norse explorers would have made expeditions far inland in North America without weapons. Maybe sometimes they made expeditions without weapons, sometimes they made with weapons. Still conclusion doesn't break. AjiteshArun is this the right way to eliminate D or something is missing? Here is why I got confused though with D. - Lets say I went to place without weapons. - Later weapons belonging to me were found. - Now we are saying Hey, just because her weapons are found it must be her who explored the place. But it contradicts the first statement! - Therefore if I negate D - it could happen that Norse explorers going without weapons breaks my argument because it could mean either they want after Columbus/someone else used their weapons in the 1300's GMAT-Club-Forum-zlbo55lp.png

sydneyxinning · Answer

Answer is B.

D is tempting...but if we negate D:

Even if Norse explorers would have made expeditions far inland in North America without weapons, that does not mean that Norse did not explore the interior of North America. But yes, D would have weakened the argument/evidence provided in the argument (ie. the weapons).

NushaT · Answer

I need help understanding the correct option here. I understood that it was a good reasoning however didn't choose it cause it brought outside information as the passage doesn't mention native americans anywhere. So I thought since the assumption must be true for the argument to hold true - it is not necessary to bring in new information in the assumption. Had this been a strengthen or weaken question, I would have chosen option B. Can someone please help?

egmat · Answer

An assumption is something the argument NEEDS to be true but DOESN'T SAY.
It's a hidden belief the argument relies on.

SIMPLE EXAMPLE 
Argument: "It's raining outside, so you should bring an umbrella."
What's the assumption?
"An umbrella protects you from rain."
The argument never says this, but it MUST be true for the advice to make sense. Without this assumption, the argument falls apart.

THE CRITICAL TEST: NEGATION 
To check if something is an assumption, flip it to the opposite:
Assumption: "An umbrella protects you from rain" Negation: "An umbrella does NOT protect you from rain"
Does the argument fall apart? YES - if umbrellas don't protect from rain, why bring one?
This proves it's an assumption.

KEY INSIGHT: ASSUMPTIONS FILL GAPS 
Every argument has a logical gap between evidence and conclusion.
Evidence: "It's raining" Gap:   Conclusion: "Bring an umbrella"
The assumption fills that gap.

TWO TYPES OF GAPS (AND ASSUMPTIONS)

Type 1: CONNECTION GAPS 
The argument mentions two things but doesn't connect them.
Example: "John studied hard. Therefore, John will pass the test."
Gap: Does studying lead to passing? Assumption: "Studying hard helps you pass tests"

Type 2: ALTERNATIVE EXPLANATION GAPS 
The argument gives one explanation but doesn't rule out other possibilities.
Example: "The window is broken and John's baseball is on the floor. Therefore, John broke the window."
Gap: Could something else have broken the window? Assumption: "The baseball broke the window" OR "No one else broke the window"

THE CRITICAL POINT FOR YOUR QUESTION 
Type 2 assumptions (ruling out alternatives) MUST introduce information not in the passage.
Why? Because the passage can't list every possible alternative!
Example: "Sales increased after our ad campaign. Our ads caused the increase."
The passage doesn't mention:
 
 Economy improving 
 Competitors closing 
 Holiday shopping season 
 Viral celebrity endorsement  
But we MUST assume none of these caused the increase. Otherwise, the conclusion doesn't follow.
These are all valid assumptions even though they introduce "outside information."

NOW LET'S APPLY THIS TO YOUR QUESTION 
Ready? Here's the argument:

Evidence: Norse weapons from 1300s found far inland Conclusion: Norse explored the interior

What's the gap? 
How did weapons get inland? The argument assumes Norse people brought them.
But is there an alternative explanation?
YES: Native Americans could have found Norse weapons at the coast and carried them inland.
This alternative would destroy the conclusion (Norse never went inland, but weapons still end up there).

Answer B rules out this alternative: 
"Weapons were NOT brought by Native Americans"

Negation Test: 
Flip it: "Weapons WERE brought by Native Americans"
Does the argument fall apart?
YES - if Native Americans moved the weapons, Norse might have stayed on the coast.  Conclusion destroyed.

This proves B is an assumption.

Psingh4249 · Answer

MartyMurray

Hi Marty, thanks for your detailed explanation but I have a doubt pertaining to option B which although seemed correct to me as well but negating it wasn't breaking the conclusion for me. What if Norse brought the weapon earlier and Native americans could have also brought it later. Both can co-exist I feel. Native Americans bringing it doesn't imply Norse could not have brought it. Pls help me correct my understanding.

MartyMurray · Answer

Here's (B):

B.  The Norse weapons  were not brought by Native Americans to the sites where they were excavated.

Notice that (B) is about "The Norse weapons." In other words, (B) means that "the" Norse weapons that were excavated were not all brought to the sites by Native Americans.

So, if (B) is not true, the argument doesn't work because, if all the weapons found were brought there by Native Americans, then the evidence doesn't support the conclusion.

egmat · Answer

Hi Psingh4249,

You've spotted something real: yes, in the actual world, the Norse bringing weapons and Native Americans bringing weapons  could  both be true. But that observation is aimed at the  conclusion , and an assumption question isn't testing the conclusion - it's testing the  support .

Look at what the argument actually runs on. Its only evidence is:

"Norse weapons ... in areas far inland."

And the whole inference is:  weapons found inland ⟹ the Norse traveled inland.  That arrow only works if the weapons couldn't have reached those sites by some other route. That is exactly the gap B protects.

Now negate B carefully.  Negation gives you: "The Norse weapons  were  brought by Native Americans to the sites." In that world, the weapons' inland location was  caused by  Native Americans carrying them. So the one thing the argument leaned on no longer points to the Norse at all - the evidence goes silent about who went inland.

Here's the piece your reasoning skipped: the negation doesn't have to  prove the Norse never went inland . You're right that they still  might  have. But "might have" isn't what the argument claimed - it claimed the weapons  show  they did. Once Native Americans are a live explanation, the evidence stops  proving  it. The support collapses, and that's all it takes to break an assumption.

A simpler stand-in to feel it:

"There are muddy footprints my size on the floor, so I walked through here."

Assumption: nobody else with my shoe size tracked that mud in. Negate it - someone else did. I  still might  have walked through! But the footprints no longer  prove  it. The evidence loses its force, even though the conclusion isn't disproven.

Same move in your question: co-existence keeps the conclusion  possible , but the negation kills the  proof  - and that's why B is a necessary assumption.

Answer: B

Archaeologists have firm evidence that Norse explorers reached the

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Archaeologists have firm evidence that Norse explorers reached the

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