#10 - One year ago, a municipality banned dishwasher

[Administrator]

Complete Question Explanation

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

Answer choice (A):

Answer choice (B):

Answer choice (C): This is the correct answer choice.

Answer choice (D):

Answer choice (E):

This explanation is still in progress. Please post any questions below!

[carnegie49]

Hi,

I'm struggling to understand why D is wrong/C is correct.

To me, D gets at the possibility that there may be an alternate explanation for the decline in phosphates in the waterways though I realize the stimulus only says taht "some residents" switched to phosphate-free detergents, not necessairly many.

Can someone please explain where D goes wrong and why C is correct?

Many thanks!

[Emily Haney-Caron]

Hi Carnegie,

The issue with D is that phosphates in the municipality's waterways are actually irrelevant to the question. Even if only 1% of the phosphates in the waterways comes from the treatment plant, it could still be true that residents used less phosphate dishwasher detergent and that resulted in a decrease of phosphate pollution from the municipal wastewater treatment plant. Because the stimulus only talks about a reduction in pollution from the plant, we don't need to be concerned at all with pollution more broadly.

C, on the other hand, suggests there could be an alternate cause in the reduction of pollution from the plant. If the plant has improved the phosphate treatment methods it uses, then there could have been a reduction in phosphate pollution from the plant even if every single resident continued to use phosphate dishwasher detergent.

Hope that helps!

[emilysnoddon]

I had a hard time understanding what answer choice D was even saying. I was thinking it could be right because if we found out that most of the phosphate pollution comes from another source than this could account for the decrease in the pollution rather than from residents use. Can someone please clarify this for me?

Thank you,

Emily

[Matt_JB]

This question is annoying. Answer choice D states, “Does most of the phosphate pollution in the municipalities waterway’s come from the municipal treatment plant.”

How wouldn’t this be helpful.

If most did, that helps solidify the evidence of the ban working. This is because if most does come from the treatment plant, it is a better indication that the ban is working because in order to help solidify the argument, it shows that levels dropped where the majority phosphate pollution came from. Which would help evaluate the strength of the argument.

On the other hand, if most of the pollution didn’t come from there, it would weaken the evidence in that it may not be strongly representative of the overall municipality.

[Adam Tyson]

Phosphates in the municipal waterways is simply not an issue in this question, Matt_JB, and that's why answer D isn't relevant to the argument. We are trying to evaluate the claim that some residents switched to phosphate-free detergents, which is based solely on the evidence that pollution from the wastewater treatment plant went down. There's a causal claim underlying this - the author seems to think the cause of the reduced amount of pollution from the plant was caused by people switching detergents. Now let's evaluate the two possible responses to answer D, and see how they impact the argument:

"Yes, most of the phosphate pollution in the municipal waterways comes from wastewater treated at the plant." Does this do anything to either support or else weaken the claim that some people switched? It does not have any impact on that issue, and for that reason we don't even need to supply the opposing answer of "no, most of it does not come from the plant." Remember, we aren't trying to decide whether the ban has been good or bad! All we are trying to analyze is whether the reduced amount of pollution indicates that some people switched.

Go back to answer C, though, and supply the two opposing answers to the question:

"Yes, changes were made in the way they treated phosphates." This weakens the argument because it offers a potential alternate cause for the reduced amount of phosphate pollution coming from the plant. Maybe nobody switched, and the reduction in pollution is do to the changes in treatment?

"No, no changes were made in the way they treated phosphates." This strengthens the argument by eliminating that alternate cause. If they are doing things the same way as before, but the pollution coming out is reduced, that suggested that the pollution going in has been reduced. That doesn't prove that some people switched, but it does help at least a little.

These Evaluate questions are very rare! When you get them, you need to focus on the conclusion, look at the evidence that was offered in support of that conclusion, and ask yourself "what else do I need to know to help or hurt this argument?" That's how to prephrase in cases like this. A good prephrase here would be a very general one - "is there some other cause for the reduction in pollution coming out of the plants?"

I hope that clears up the task here, and gives you a useful strategy for attacking these questions down the road!

[lanereuden]

On another site, it says why D is wrong like so:
“What if there are other sources of phosphates in the water that enters the waste treatment plant.”
This answer isn’t referring to water that enters the plant for treatment. Water that isn’t treated at the plant is irrelevant, because the evidence was only about a change in phosphate pollution from the plant.
——////-/////
My question:
Shouldn’t this be referring to water that leaves the plant after treatment? I.e. as opposed to “entering for treatment”

Admin note: we do not answer questions about explanations from other sources.

[Juanq42]

Phosphates in the municipal waterways is simply not an issue in this question, Matt_JB, and that's why answer D isn't relevant to the argument. We are trying to evaluate the claim that some residents switched to phosphate-free detergents, which is based solely on the evidence that pollution from the wastewater treatment plant went down. There's a causal claim underlying this - the author seems to think the cause of the reduced amount of pollution from the plant was caused by people switching detergents. Now let's evaluate the two possible responses to answer D, and see how they impact the argument:

"Yes, most of the phosphate pollution in the municipal waterways comes from wastewater treated at the plant." Does this do anything to either support or else weaken the claim that some people switched? It does not have any impact on that issue, and for that reason we don't even need to supply the opposing answer of "no, most of it does not come from the plant." Remember, we aren't trying to decide whether the ban has been good or bad! All we are trying to analyze is whether the reduced amount of pollution indicates that some people switched.

Go back to answer C, though, and supply the two opposing answers to the question:

"Yes, changes were made in the way they treated phosphates." This weakens the argument because it offers a potential alternate cause for the reduced amount of phosphate pollution coming from the plant. Maybe nobody switched, and the reduction in pollution is do to the changes in treatment?

"No, no changes were made in the way they treated phosphates." This strengthens the argument by eliminating that alternate cause. If they are doing things the same way as before, but the pollution coming out is reduced, that suggested that the pollution going in has been reduced. That doesn't prove that some people switched, but it does help at least a little.

These Evaluate questions are very rare! When you get them, you need to focus on the conclusion, look at the evidence that was offered in support of that conclusion, and ask yourself "what else do I need to know to help or hurt this argument?" That's how to prephrase in cases like this. A good prephrase here would be a very general one - "is there some other cause for the reduction in pollution coming out of the plants?"

I hope that clears up the task here, and gives you a useful strategy for attacking these questions down the road!

This explanation really helps me understand how answer C applies to the stimulus. Is it the case that every evaluate answer choice will either strengthen / weaken the conclusion? Because answer C was a yes/no question, it was easier to identify how it would evaluate the argument, but what approach should i have if a conclusion cannot be evaluated with a yes/no?

[Dave Killoran]

This explanation really helps me understand how answer C applies to the stimulus. Is it the case that every evaluate answer choice will either strengthen / weaken the conclusion? Because answer C was a yes/no question, it was easier to identify how it would evaluate the argument, but what approach should i have if a conclusion cannot be evaluated with a yes/no?

Hi Juan,

Yes it will! This is the essence of the Variance Test, which we cover in the LR Bible and in our courses. We also talk about these questions in Episode 8 of our Podcast, at the 49:40 mark!

Thanks!

[ssnasir]

Hi there,

I was wondering if I could get some clarification on why E is wrong. If we say that officials did not try to stop people form bringing detergent then that could help the argument, suggesting the ban worked, but if we say that the officials did try to stop people then that really doesn't have an impact because they could have tried but whether or not they succeeded is something we don't know. And if they did succeed in stopping people from bringing detergent then the ban worked however if they did not succeed then the ban still potentially worked?

Thank you! Sorry for the rambling.
Stay safe