#17 - How the pigment known as Han purple was synthesized

[James Finch]

Hi,

It looks like you're focusing on the wrong part of the stimulus; the key here is understanding the causal relationship posited, which is that production of the white glass caused the accidental discovery of Han purple, because they both used the same ingredients. To make that more likely, we have to tie the two processes together, either by eliminating an alternate cause (which would be hard to Prephrase in this case), or by showing either both the cause and effect together, or no cause, no effect. The other issue is that this is one of the rare stimuli in which reverse causation could potentially be in effect (making Han purple led to discovery of how to make the white glass), so taking that possibility away would be my initial Prephrase.

(A) works to strengthen the causal relationship by showing not only the cause and effect together (which we already knew from the stimulus) but also by showing that that was where most of the production happened, and thus that most other areas of China had no cause (the glass production) and no effect (discovery of Han purple). It is relatively weak evidence, but still strengthens the conclusion (and we can't really expect millennia-old archaeology to help too much).

Contrast that to (D), which makes it more likely that someone would make a chance discovery, as the ingredients were easily obtainable. But we already know a discovery was made; the point we're trying to help is that glass production was the specific, sole actual cause of the discovery of Han purple. The fact that more people would have an opportunity to make glass doesn't make it any more likely that the glass-making was the actual cause for the discovery of Han purple, as it doesn't make it likelier that one thing led to the other; reverse causation could still be in effect, and just as likely.

Hope this clears things up!

[MusaMuneer9898]

I have an objection to the way answer choice A is written, it says "Both items were made within a small geographical radius." This does not imply that they were made in the SAME geographical radius. They could have been made within a small geographical radius, which were far apart?

Could you please clarify?
Thanks!

[atierney]

Ah, it's been rather dry today, so I thank you for this one! So, let's examine precisely what is stated in Answer Choice A:

"Chemical analysis shows that most of the known fragments of both Han purple and the white glass were produced within a small geographical radius."

I would kind of agree with you, if they had worded it exactly how you did. Both items, generally speaking, were made within a small geographical radius, but these radii were across the sea from one another. The problem here is that the answer choice, as read, really does group the known fragments of both Han purple and white glass together; it's not the fact that we are speaking of two items, potentially as individual subjects, but rather most of the known fragments, a set of items that the answer choice states includes both Han purple and white glass. Because the answer choice treats the operative phrase here as known fragments, and says that most of them were from a small geographical radius, there is an inherent grouping of the two that occurs here.

Let me know if you have further questions on this.

[arad1377]

"The stimulus tells us that white glass and Han purple are made with the same chemicals and in similar processes"

Dear administrator, how can we conclude that HP and WG have the same compounds? The stimulus says that the chemist added all of the ingredients of HP in the process of making WG. There could be a scenario where the assistant of the chemist gave her the wrong batch of ingredients that ended up in making HP.

How can we conclude that HP and WG have the same chemical compounds? We only know that they have Lead and the same manufacturing process. Aside from that, we know nothing about what the chemical compounds of the two are.

[Rachael Wilkenfeld]

Hi arad1377,

The stimulus tells us to make white glass they used the same compounds as Han purple. We don't argue against the facts in the stimulus--we take the premises as they are, but challenge the reasoning that the author uses to draw their conclusion.

Let's look at a structurally similar argument: The discovery of pizza has long puzzled food historians. Chefs making baked ziti used the same basic ingredients for pizza in their production of baked ziti. Thus pizza was probably discovered during a fortuitous accident involving baked ziti.

We don't challenge the idea that they use the same basic ingredients. That would be a fact given to us by the stimulus. The evidence we see in the stimulus is not something that you can address with logic. You want to attack how they draw conclusions from those facts. So sure, pizza and ziti use the same ingredients, but that doesn't mean that one came from the other. They could have both been invented independently. Or invented in the other order.

Here too, we trust the information that the ingredients and process by which chemists made white glass were similar to the ingredients and process by which one would make Han purple. But just with that information, we can't determine that Han purple was discovered accidentally while attempting to make white glass. We'd need a lot more to prove that conclusion. Luckily, we don't have to prove it here, just support it. Answer choice (A) does so by giving another similarity between Han purple and white glass--they are both from the same geographic area. That strengthens the connection between the two, and thus strengthens the conclusion in the argument.

Hope that helps.

[arad1377]

Hi arad1377,

The stimulus tells us to make white glass they used the same compounds as Han purple. We don't argue against the facts in the stimulus--we take the premises as they are, but challenge the reasoning that the author uses to draw their conclusion.

Let's look at a structurally similar argument: The discovery of pizza has long puzzled food historians. Chefs making baked ziti used the same basic ingredients for pizza in their production of baked ziti. Thus pizza was probably discovered during a fortuitous accident involving baked ziti.

Hi Rachel, thank you very much for replying back to me. I am still confused because the stimulus specifically reads "The Chinese chemists employed the same chemical ingredients used for Han Purple in the production of a common type of white glass".

Your example does not capture the nuances of this sentence. We could maybe rephrase it as such:

"Chefs used all the same ingredients of a baked ziti in the process of a basic pizza"

Phrased this way, the sentence says that the chefs used all the ingredients of X in the process of making Y. Does this imply X and Y have the same ingredients? Not necessarily. They could have:
1) many ingredients in common,
2) some ingredients that are different from each other,
3) Y may be missing some key ingredients that X usually has, or
4) Y may have different ratios of all the same ingredients of X.

I am confused because saying X and Y have the same ingredients excludes the possibility of scenario 2 and 3, but the stimulus's specific wording does not eliminate such possibilities.

An obviously flawed example copied word for word from the stimulus would be:

"The Chefs employed the same ingredients used for an omelet in the production of a common steak dish"

This is word for word from the stimulus, but HP and WG have been replaced with omelet and steak dish respectively. In this example, can we conclude that the omelet and the steak have all the same ingredients? Not necessarily. There could be:
1) Omelet and Steak share all the same ingredients (both are steak omelet hybrid)
2) Omelet and Steak have some ingredients that are different from each other (omelet has eggs, steak has beef)
3) The omelet is missing some ingredients that the steak has (the omelet is missing beef, but has all other ingredients)
4) The omelet has 1 egg in it, where as the steak has 2 eggs in it (the 1 egg difference changes the dish from steak to omelet)

If I were to assume that they both have all the same ingredients, then possibility 2 and 3 are once again excluded.

Could you please explain why we differ on interpreting this line? I have been getting push back on my interpretation but I have yet to encounter a persuasive argument as to why I should believe HP and WG have all the same ingredients. All we know is that all the ingredients of HP was used in the process of making WG - maybe the chemist's assistant gave the chemist the wrong batch of chemical ingredients, hence why HP was made in the process of making WG.

Kind regards.

[Rachael Wilkenfeld]

Hi arad,

It seems like you are approaching this stimulus like a MBT stimulus, where you expect the argument in the stimulus to be a solid argument. It doesn't have to be here, and in fact, in a strengthen question, we know that the argument in the stimulus is flawed. So both in my example of the ziti and lasagna, as well as the stimulus example of Han purple and white glass we see that the argument is unclear as to how many of the ingredients are shared. There's some. It could be all. The fortuitous accident mentioned in the stimulus could have involved substitute ingredients or could have involved a slight change in the process. Any of these interpretations are fine ways to interpret the stimulus. It's unclear and it's meant to be unclear.

As I said above, we accept the premises as written. We don't try and get them to work together in a way that they do not. This test forces you to work with bad arguments. Bad arguments are much more common on this test than valid arguments. In strengthen, weaken, flaw, assumption, and justify questions we seek to find an answer choice that addresses the problems in the different arguments on this test. It requires you to understand where uncertainty is critical and where it is not. What flaws are central to the argument? What facts can we still use?

Here is the basic structure we can use:

1. Han purple was synthesized in Han China.
2. White glass was made in Han China
3. Both are made using heat and lead.
4. Both are made using the same chemical ingredients.

Conclusion: Han purple was probably discovered accidentally while making white glass

There's a pretty big gulf between those 4 premises and the conclusion. But ultimately, it doesn't matter if you read that they use all of the same ingredients or some of the same ingredients. Either way, it would help the argument that they were made in the approximate same geographic area.

Here's another way to think about the argument.

Han purple and white glass are made in similar ways. Therefore Han purple was discovered while making white glass.

Answer choice (A) gives us another similarity--another fact supports the idea that the color was discovered while making the white glass.

Hope that helps!

[CristinaCP]

I understand that A is right because it counters a possible objection that Han purple and white glass were produced independently of each other, in different places.

But I thought that C also nullified a possible objection, so I'm having trouble understanding why it's ultimately wrong. I chose C because I thought it countered the reverse explanation: that white glass was the accidental effect of Han purple production. If only very few people knew how to make Han purple and then created white glass later (by accident or not), then how would white glass have become so common, like the stimulus says? I don't think it's a huge jump to say that if very few people knew how a technique for making Han purple/white glass, then both were probably not very common. So this shows that an alternative explanation would not be consistent with the fact that white glass was common. Doesn't C, like A, also counter an alternative explanation?

Is it different from A because when we negate it, and say that a lot of people knew how to make Han purple, that negation doesn't clearly weaken the argument?

Any further clarification on why C isn't really doing the same thing as A (weakening an alternative explanation) would be very helpful!

[EmilyOwens]

I understand that A is right because it counters a possible objection that Han purple and white glass were produced independently of each other, in different places.

But I thought that C also nullified a possible objection, so I'm having trouble understanding why it's ultimately wrong. I chose C because I thought it countered the reverse explanation: that white glass was the accidental effect of Han purple production. If only very few people knew how to make Han purple and then created white glass later (by accident or not), then how would white glass have become so common, like the stimulus says? I don't think it's a huge jump to say that if very few people knew how a technique for making Han purple/white glass, then both were probably not very common. So this shows that an alternative explanation would not be consistent with the fact that white glass was common. Doesn't C, like A, also counter an alternative explanation?

Is it different from A because when we negate it, and say that a lot of people knew how to make Han purple, that negation doesn't clearly weaken the argument?

Any further clarification on why C isn't really doing the same thing as A (weakening an alternative explanation) would be very helpful!

Hi Cristina,

Answer choice (C) doesn’t tell us anything about making white glass, so we can’t assume — just because the white glass was common does not mean it wasn’t made by a few people either, just on a more mass scale. It also doesn’t offer any information about how the two were invented, let alone one before the other.

You’re also right to say that the negation doesn’t clearly weaken the argument because it says nothing about how Han purple was invented.

I hope this helps to clarify answer choice (C)!