Logical Reasoning

PT142 · S1 · Q17 How the pigment known as Han

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How the pigment known as Han purple was synthesized by the ancient Chinese of the Qin and Han dynasties has puzzled scientists.

Conclusion

Han purple was probably discovered by accident during glass production.

Evidence

The chemical ingredients of Han purple match those of white glass. Both are produced in processes that involve high heat and mixing in lead.

Evaluate

Since the conclusion is proposing a causal story, we can use our Curious Fact / Explanation mindset.

Curious Fact Where did Han purple come from?

Author's Story It came from people who were making white glass. They accidentally created Han purple, since it has the same chemical ingredients and similar mixing process that white glass has.

We can impact these arguments two ways: - Alternate Explanations for the Curious Fact - The plausibility of the Author's Explanation

Goal

Since this is Strengthen, we either want our correct answer to rule out an Alternate Explanation for where Han purple came from or add plausibility to the Author's Explanation that Han purple came by accident from people who were making white glass.

17.

Which one of the following, if true, would most strengthen the argument?

Correct
Chemical analysis shows that most
Why this is right
This adds some plausibility to the Author's Explanation. If most known fragments of these two things come from the same, small geographical area, then it's more plausible that these two things are linked, potentially in the way the author is thinking (an accidental discovery of HP while trying to make WG). (note: this correct answer kind of blew my mind when I first saw it. It felt so flimsy. Cool, most fragments are from a similar area. That's it? That's what I was supposed to care about? It taught me to be much looser about what I can use as a correct answer when we're dealing with Causal Explanations. In fact, this correct answer and the one from Q2, like "scale drawings were commonly used in many types of construction" really are why I created the two-prong causal prephrase that I use — Other Ways to explain the curious fact / Plausibility of the Author's Way. Plausibility can be added or subtracted in so many different ways. And making something somewhat more or less plausible doesn't feel that impactful, but it still might be the most impactful answer we're offered.)
Skill tested: Strengthen · how this choice captures the argument's function is the move to repeat next time.
58% picked this
Han purple was used for
Out of Scope: how they're used
It doesn't really matter what white glass and Han purple went on to be used for. This argument is only about assessing the causal mystery of their origin story.
5% picked this
The technique used for producing
No Impact
The fact that very few people knew how to make Han purple doesn't make it any more or less likely that Han purple was discovered by accident by white glass makers. If we knew that very few people also knew how to make white glass, then it would be slightly more suggestive that Han purple and white glass came from the same "secret club", but white glass was not a secret club. The stimulus says that it was a "common type" of glass.
14% picked this
The ingredients used in producing
Weakens, if anything
A potential Alternate Explanation is that Han purple was just discovered some other way. Even though it has the same chemical ingredients as white glass, maybe there's are still other things that also use those same chemical ingredients. Or maybe there were people specifically working on developing a new pigment and the chemistry they chose was just coincidentally similar to that of white glass. All of these alternate explanations are easier to believe if the ingredients for each thing were easily obtainable. An easier way to say it is this — the opposite of this answer would strengthen. If the common ingredients used in Han purple and white glass were very difficult to obtain, then that would strengthen the plausibility that Han purple emerged as an accident from people making white glass. It would hurt the plausibility that two separate entities each had access to these shared ingredients. Making the ingredients very easy to obtain creates more ways that independent parties could have each been messing around with the same ingredients, and so it lessens the connection between white glass and Han purple.
13% picked this
The white glass is found
No Impact
Just like (B), this is dealing with what society ended up using white glass and Han purple for, but we're only concerned with solving the causal mystery of Han purple's origins.
10% picked this

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