#8 - Studies suggest that, for the vast majority of people

[Administrator]

Complete Question Explanation

Weaken. The correct answer choice is (C)

The inference of this conclusion is that people with normal blood pressure who can process excess
sodium do not need to restrict their sodium intake. The clearest way to weaken this argument is to
demonstrate that that there is some compelling reason for these people (i.e. the vast majority who have
normal blood pressure) to also avoid excess sodium intake. Neither (A) nor (B) would provide these
people with incentive to limit their sodium intake. Answer choice (D) suggests that everyone must
consume some sodium and answer choice (E) would only concern those people whose bodies do not
simply excrete any amount of unused or unneeded sodium. Answer choice (C), if true, asserts that
excess sodium intake over time can be detrimental to anyone, including those people with normal blood
pressure, and would therefore seriously weaken the argument.

Answer choice (A): This answer would certainly help motivate persons with high blood pressure to
correct that problem. However, the vast majority of people would be unmoved by this argument, since
their blood pressure is normal and excess sodium intake does not significantly raise their blood pressure.

Answer choice (B): Remember that the goal is to prove that it is also necessary for people with normal
blood pressure to restrict their sodium intake. This answer choice only demonstrates that excess sodium
intake may worsen an existing high blood pressure condition. Therefore, people without this condition
would not be motivated to restrict their sodium intake and the author’s conclusion would be unaffected.

Answer choice (C): This is the correct answer choice. If it is true that excess sodium intake impairs
the body’s ability to process excess sodium, then even people who have normal blood pressure need to
restrict their sodium intake. Thus, the author’s claim that only certain groups of people need to restrict
their sodium intake is weakened by this answer choice.

Answer choice (D): The conclusion argues that certain groups of people need to restrict their sodium
intake, not eliminate it altogether. So stating that everyone needs some sodium does not weaken that
conclusion.

Answer choice (E): Since people with normal blood pressure do excrete any amount of sodium not used
by the body, this answer does not weaken the author’s conclusion.

[hershey15]

I got this question right, but when reviewing, I got a little confused, so I just wanted to clarify what the stimulus was saying. The studies are suggesting that the vast majority of people have normal blood pressure and can excrete excess sodium, and the minority of people with high blood pressure cannot process excess sodium, right?

My confusion was that I interpreted the statements as the vast majority of people with normal blood pressure can excrete excess sodium, but a minority of people with normal blood pressure maybe cannot excrete excess sodium. With the conclusion stating that only people with high blood pressure + no ability to safely process excess sodium having to restrict sodium intake, I thought there may be a gap for those who have normal BP and maybe can process sodium but may raise their BP in doing so. Also, I thought the conclusion left open those who have high BP and can safely process excess sodium but this again leading to worsening BP and a need to restrict sodium intake.

The above confusion led me to consider B and E as possible contenders as well. Hope what I said makes sense!

[Adam Tyson]

It is confusing, hershey15! The argument actually doesn't tell us about whether most people have normal BP or not. Rather, it is saying that of the people that have normal BP, most of them can safely excrete excess sodium and their BP doesn't go up. That group might be the majority or it might not.

It also doesn't tell us whether most people with high BP can or cannot excrete the excess sodium. Instead, it just says that the only people that need to worry about their sodium intake are those people who 1) have high BP and 2) cannot safely excrete the excess. Maybe that is just a tiny fraction of all people, and maybe it is just a small percentage of people with high BP, but the percentages don't really matter. What matters is the VERY strong statement that those are the ONLY people who need to concern themselves with their sodium intake. To weaken that, we need an answer that suggests that some other people might also need to be concerned.

I kept answer B as a contender. What if excess sodium intake ends up making things worse for the people who have high BP but who CAN safely excrete the excess? That's how I read it at first, and that seemed to me to weaken the argument a little. But then again, maybe that means those people are not able to safely process the excess sodium, and so they are not really a different group of people than the ones about whom the author drew a conclusion? I didn't love it, but I kept it.

Answer E struck me as having no impact, as the author is only concerned about the people who cannot safely excrete the excess sodium, and this answer does nothing to tell us we have to worry about people who can safely excrete it or who have normal BP. We need an answer that says excess sodium is bad for some other group of people, either the ones who have normal BP or the ones with high BP who can still excrete the excess sodium.

Answer C makes it a problem for everyone, because it can convert someone who can excrete it into someone who cannot, which could also convert people with normal BP into someone with high BP. Excess sodium becomes a problem for everyone, not just the group that the author was worried about! That's a big, powerful blow to the argument, and at this point we can reject B because even if it does a little damage to the argument, it doesn't do much, and does far less than the correct answer.

[hershey15]

Answer C makes it a problem for everyone, because it can convert someone who can excrete it into someone who cannot, which could also convert people with normal BP into someone with high BP. Excess sodium becomes a problem for everyone, not just the group that the author was worried about! That's a big, powerful blow to the argument, and at this point we can reject B because even if it does a little damage to the argument, it doesn't do much, and does far less than the correct answer.

That makes a ton of sense, thank you for this clarification Adam!

[valegria]

Question, I got this wrong. I feel I emphasized in the possible conditional logic. Is it wrong to view this with conditional logic?
My set up was
P:Normal Blood Pressure (NBP) w/ ANY extra sodium is excreted --> does not raise Blood Pressure (BP)
C: Peo need to restrict sodium intake --> (only) those w/ HBP + Incapable of processing extra sodium

I went with conditional logic because there are keywords indicating that it exists.

[Robert Carroll]

valegria,

I'm going to offer some fixes to your conditional diagrams, but I do want to note that I don't see how approaching this conditionally helps much at all.

The first sentence would look like this:

normal blood pressure excess sodium excreted AND sodium raises blood pressure

It's not truly a conditional - this is true not of ALL people with normal blood pressure, but of the "vast majority". The safest way to diagram that is to interpret it as a "most" statement. The first sentence is predicating two things of that majority of people with normal blood pressure, which is why both those facts should be on the right side of the arrow.

The "only" in your second diagram isn't needed. In the sentence it's from, it indicates the necessary condition. The diagram indicates that by putting the necessary on the right. Other than that stylistic quibble, your diagram looks good for that.

Now...use this to answer the question. The conclusion could be bad because other people might need to restrict sodium. So we have an "incomplete information" situation. If other people have some other need to restrict sodium, then the conclusion is weakened because it's being applied too broadly. I COULD use the conditional conclusion to help finding something that weakens by saying "maybe the conclusion is wrong because it's NOT only those people." Answer choice (C) gives me such an answer.

Robert Carroll