#19 - When permits for the discharge of chemicals into a

[LAM]

Can someone help me understand how I could choose A over B? I understand B's flaws - I was hesitant to choose it because of the answer stated, 'there is a swift flow' when in fact we don't know if there is a swift flow or that there has to be a 'swift' flow - just that the flow amount affects the dilution. I thought the faster it flows the more the water is diluted, thus lessening environmental impact. For some reason, I translated 'amount' into speed. But, even considering this, answer B looked off because of the assertion that there absolutely is swift flow. But I chose it anyways because I was thinking, who cares about the various chemicals stated in Answer A? The stimulus only states that different chemicals have different dispersion requirements. In retrospect, I can see why A could be the correct answer, but I just sped past it thinking different chemicals interacting was irrelevant.

[Robert Carroll]

LAM,

I'll start with answer choice (B). There is no need to assume a "swift flow" because the stimulus already claims that the permitted amount is based on "an estimate of the effect of the dilution of the chemical by the amount of water flowing through the waterway." Thus, if the flow were not swift, that slow flow would be accounted for by the estimate. If that caused the chemical to become diluted at a slower rate, thus possibly polluting the waterway worse, then the permitted amount would be reduced - because it's based on an estimation of dilution that includes the actual amount of water flowing. If that water flows slowly, swiftly, or anything in between, the estimate is taking that into account. Thus, you don't need to assume any specific rate of flow. This is why answer choice (B) is not something that must be assumed.

Answer choice (A) is correct because it addresses a potential weakness in the argument. Think about it - you get a permit for each chemical based on a separate calculation for each chemical of the effect of dilution by the water flow. I'll use an example. Imagine that in waterway W, the amount of water flowing dilutes chemical X to such an extent that discharging 100 pounds of it per day is acceptable. Also in waterway W, the amount of water flowing dilutes chemical Y to such an extent that discharging 50 pounds of it per day is acceptable. The separate calculations for each chemical would tell me that a company would get a permit for discharging up to 100 pounds of chemical X per day, and a permit for discharging up to 50 pounds of chemical Y per day. What if chemical X and chemical Y interact so that they're more dangerous together - what if they react to form chemical Z, which is not diluted by the flow of waterway W at a sufficient rate to render it harmless? Then perhaps 100 pounds of chemical X (which the calculated estimate says is fine) and 50 pounds of chemical Y (again, fine by the estimate) cannot safely be discharged together in waterway W.

Answer choice (A) addresses this weakness and negates it. Thus, it's a Defender Assumption of the stimulus.

Robert Carroll

[nusheenaparvizi]

Hi,

I was wondering if someone could please re-phrase or explain to me the conclusion of the stimulus? I am having trouble understanding it. The way I worded it to make it easier for myself was like this:

• — Permits are issued for the discharge of chemicals based on # of pounds of chemicals released in the waterway.
  — The permits are issued based on the effects of the amount of chemicals administered in the waterway.
  — This is done to protect the waterway from the negative or potentially harmful effects of the chemicals released under the permits.

Did I interpret this correctly? I am asking because my understanding of the stimulus made sense in the moment, but I had no idea what I was doing when I got to the answers.

I also wanted to know if my negation of answer choice A is correct: "No relatively harmless chemicals do not interact with each other in the water to form harmful compounds" which translates to "Relative harmless chemicals DO interact with each other in the water form harmful compounds."

Could you explain how this is an ATTACK on the conclusion? After negating the others this seemed like the best option but I still didn't understand it to attack the conclusion and the example scenario mentioned above only confused me more.

Thank you so much!
Nusheena

[Jeremy Press]

Hi Nusheena,

I think you've done a very good job of distilling the argument to make it understandable for yourself. But I would phrase the conclusion even more sharply than you have. You've said, "This is done to protect the waterway from the negative or potentially harmful effects of the chemicals released under the permits," which is only a claim about why they issue permits, and not a claim about whether the permits actually work to protect the waterway. The conclusion goes further, in saying, "The waterway is therefore protected..." That's a factual claim. The permits work to protect the waterway.

If the permits work, then that assumes there isn't something that the process of issuing the permits misses. Notice how the permits are "calculated separately for each chemical." That means when the permits are issued, we're only thinking about the negative effect of that chemical by itself (and about how much dilution of that chemical by itself is enough to make it safe).

But what if, as you accurately phrased in your negation of answer choice A, "relatively harmless chemicals DO interact with each other in the water to form harmful compounds?" Uh oh. The method in the premise allows Chemical A by itself to be dumped in a certain quantity, and Chemical B by itself to be dumped in a certain quantity. But the method didn't account for what would happen if they were dumped together (and then combined to form something harmful). That would destroy the conclusion, which says that the waterway is protected. Under the negation of answer choice A, the waterway is NOT protected. That makes answer choice A a classic Defender Assumption answer.

I hope this helps!

Jeremy