#7 - The ruins of the prehistoric Bolivian city of Tiwanaku

[Administrator]

Complete Question Explanation

Evaluate the Argument. The correct answer choice is (A)

Your task in this Evaluate the Argument question is to select the answer choice containing a
question the answer to which would be most useful in evaluating the support for the conclusion. The
argument, reordered for clarity, proceeds:

Premise: stones weighing up to 40 tons featured in the prehistoric city of Tiwanaku
were quarried at Copacabana, which is across a lake about 90 kilometers away

Premise: experimenters transported a 9-ton stone from Copacabana to Tiwanaku using a
reed boat with locally available materials and techniques traditional to the area

Conclusion: the stones in Tiwanaku were brought from Copacabana to Tiwanaku using a
reed boat built with locally available materials and techniques traditional to
the area.

The correct answer choice in this Evaluate the Argument will contain a question, the answer to
which will help you evaluate the argument. To do so, the information in the answer choice must have
some effect on the conclusion. Here, a weakness in the argument is that it assumes the materials and
techniques locally available to the experimenters and traditional to the area were in use at the time
the prehistoric city was constructed. Since the terms “traditional” and
“ancient” do not inherently require the same time period, the evidence is unclear regarding the
relevant time periods.

The incorrect answer choices will not help you evaluate the argument, typically because they are not
relevant to the conclusion.

Answer choice (A): This is the correct answer choice. This answer is correct, because the potential
responses to this question would clarify the time frames involved. If the traditional techniques were
not in use at the time Tiwanaku was inhabited, then the conclusion based on an experiment using
those techniques would be weak. However, if the traditional techniques were in use at that time, this
evidence would support the conclusion that they were used to transport the ancient stones.

Answer choice (B): This choice does not help to evaluate the argument, because the stones having
been used at a site near Copacabana is irrelevant to the conclusion, and does nothing to resolve the
issue of timing.

Answer choice (C): Whether reed boats are used commonly today is irrelevant to the question of how
the ancient stones were transported, and so this choice has no effect on the conclusion.

Answer choice (D): Because the conclusion pertained only to the andacite stones, and not any others,
this choice is incorrect.

Answer choice (E): The future durability of the reed boat is not relevant to the conclusion concerning
whether the boating technique was used to transport the ancient stones.

[ericau02]

I got this ac correct but I just want to be sure because of blind review. The reason ac D is incorrect is because it states "green" andacite stones?

[Jay Donnell]

Hi Erica02!

You are correct that D is the incorrect response but you're a bit off in the reasoning as to why, so I want to jump in and help clear it up!

The argument claims that these giant green anthracite stones used in the city of Tiwanaku had been transported all the way across the lake from the quarry at Copacabana, and the supporting evidence is that recent experimenters transported a stone of equivalent size across the lake using "a reed boat built with locally available materials and techniques traditional to the area." The assumption then is that what is currently available as far as materials and 'traditional techniques' were all available to the civilization who allegedly first transported the anthracite.

In using the Variance Test, the truth or untruth of answer choice A has the power to greatly strengthen or weaken the argument, so A would present the idea that would be most useful to know in evaluating the argument.

Answer choice D mentions 'green' anthracite stones, but that was the only color of stone that the stimulus ever discussed, so that detail is irrelevant in dismissing the answer choice. Instead, D fails because it hinges on the idea that these anthracite stones were the largest stones at the Tiwanaku site. In using the Variance Test, whether or not these stones were the largest at the site has no bearing whatsoever on the validity of the conclusion, so D fails as a correct response in this Evaluate question.

Hope that helps!

Fun fact: I've actually been to this Copacabana in Bolivia, and the lake they allude to in this question is lake Titicaca, a lake I first learned about from my favorite irreverent Saturday Morning cartoon, Animaniacs link to video: https://www.youtube.com/watch?v=5I0Hee533Iw

[echopra]

Can someone explain why B is wrong? I initially liked this answer because I thought that if the stones were used at another site near Copacabana, then maybe they wouldn't have to take a boat over because this site could have been closer or something. But I guess then I would be making the assumption that they wouldn't need to take the boats. Is that why B is wrong?
Thanks in advance!

[Rachael Wilkenfeld]

Hi Echopra,

Let's look at what we know based on the stimulus.

1. The site in question used green andacite stones
2. These stones were quarried across a lake.

It doesn't really matter if the quarry was also supplying other sites. That still wouldn't explain how the stones that THIS site used got from the quarry across the lake to Tiwanaku.

If we look at answer choice (B) we could answer it with either extreme and still have no impact on the argument. If we say that yes, the stones at the quarry were used at sites closer to Copacabana, that doesn't tell us anything about those stones that did go all the way to Tiwanaku. And if we say NO, those stones weren't used at a closer site, that still doesn't help us understand how they got from Copacabana to Tiwanaku.

It looked a bit to me like you were reading answer choice (B) to indicate that the closer site was a substitute site for Tiwanaku, but it was an additional possible site. The issue of how the stones got to Tiwanaku still needs to be explained.

Hope that helps!
Rachael