Logical reasoning PrepTest 142 · Section 1 · Question 17

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
Question Ð How did the ancient Chinese make Han purple pigment?
History Ð Chemists used the same process for Han purple as a common white glass.
Answer/conclusion Ð Chemists probably discovered Han purple accidentally while making the white glass.

Answer Anticipation:
The argument here puts forward an explanation (luck/accident) for a phenomenon (the discovery of Han purple). Whenever there's an explanation put forward for a given phenomenon, we should start to think about other explanations.

Here, the argument explains the discovery of Han purple by bringing up luck or chance—since Han purple uses similar ingredients and a process to a common type of glass, it was probably a happy accident during that process.

However, that's not the only explanation! Maybe it was discovered during the making of a separate material. Maybe Han purple was discovered first, but the white glass was more popular and thus more common. Maybe they were both created intentionally by chemists who knew exactly what they were doing.

There are many possible alternative explanations here. To strengthen the argument that this one particular explanation is "probably" true, we need evidence that rules out others, or evidence that elevates this explanation to being likely.

Answer Explanation:
Many people immediately rule this answer choice out as out of scope. However, this answer choice does eliminate some alternative possibilities—namely, that the two pigments/glass were independently created in different locations. By having the production of these two things concentrated in one area, it establishes that places likely produced both, and thus one could have been accidentally discovered while making the other.

Key Takeaway:
If you're struggling with this question, then you're not alone. Especially if you picked (C)—it's a frequently selected incorrect answer. When you come across a question like this during practice, review it a few times to make sure you've learned everything you can from it. When you come across a question like this during test day, pick your best guess and then move on—don't spend minutes on a question that you know you're likely to get wrong!

Incorrect. The purpose of the pigments/glass isn't necessarily related to its production, and there's no indication it is in this case, so this answer is out of scope.

Incorrect. This is a tempting incorrect answer. After all, if something is not widely known, then it can't be something that was easily discovered or obvious. However, an equally compelling argument could be made in the other direction—if something is intentionally discovered but difficult to recreate, then the makers of that thing might keep the process to make it a closely guarded secret (just think about the recipe for Coke). Since this answer can serve as the basis for an argument both for and against the conclusion, it's not correct.

Incorrect. The availability of the ingredients doesn't speak to how the process to make something was discovered. It's what's done with the ingredients once they're obtained that counts. Additionally, since the stimulus has already established the two used the same chemical ingredients and white glass was common, this doesn't add much new information.

Incorrect. This answer is trying to get you to pick it by suggesting that the Han purple must have been derived from the white glass since there's less of it. However, the more common white glass might have been more popular even though it was developed after Han purple, or it could be sturdier. This answer doesn't establish anything about which material was discovered/created first, so it doesn't affect the argument.