Logical Reasoning

PT133 · S3 · Q24 Physician: The rise in blood pressure

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Physician: The rise in blood pressure that commonly accompanies aging often results from a calcium deficiency.

Conclusion

Some older people can lower their blood pressure by drinking milk.

Evidence

When people get older, it's common for them to get a calcium deficiency, which is caused by a lack of the active form of vitamin D that the body needs and which leads to a rise in blood pressure.

One glass of milk per day can make up for a calcium deficiency.

Evaluate

This is a causal mouthful. The overall causal chain that ends in higher blood pressure goes like this:

1. not enough active form of vitamin D 2. body isn't absorbing calcium 3. calcium deficiency causes rise in blood pressure

How does our hero milk enter the story?

Milk makes up for any underlying calcium deficiency.

I have two questions, as I try to remain skeptical of the idea that milk can help older people lower their blood pressure...

1. Does milk provide the "active form of vitamin D" needed for body to absorb calcium?

2. Even if we say milk is making up for the underlying calcium deficiency, that would prevent a rise in blood pressure from calcium deficiency, but would it trigger a lowering of blood pressure?

Goal

Since this is sufficient assumption, one of my two worries is apparently wrong (in LSAT's mind). There's only one missing vulnerability here, but I can't figure out which one they want to address.

It isn't clearly established that milk provides , and it seems like we're prescribing milk as a solution for that specific ailment.

But it also isn't clear to me that we take this causality backwards the way the conclusion is doing. I can understand how not enough milk could lead to a rise in blood pressure, but am I allowed to say that more milk would lead to a lowering of blood pressure?

24.

The physician's conclusion is properly drawn if which one of the following is assumed?

  1. Correct

    There is in milk, in

    Why this is right

    This establishes that milk is a plausible way to address the cause of the calcium deficiency: not enough active form of vitamin D for the body to absorb calcium. Now that we know that most older people could plausibly consume a version of milk that provides them with enough active vitamin D that their body can absorb the calcium in milk, we know that the calcium in the milk they drink will actually be absorbed, which will make up for their calcium deficiency, which will then avoid the rise in blood pressure caused by that deficiency, which means they will have lower blood pressure. Basically, if we know that some older people currently have a rise in blood pressure because of an underlying calcium deficiency, then being told that people can drink a form of milk that will remove that underlying calcium deficiency means that "we have a way for some older people to avoid that rise in blood pressure". i.e., "milk can lower their blood pressure" I must say, this is one of the loosest correct answers I've ever seen on Sufficient Assumption. Haunting, even. It definitely does not 100% prove the conclusion, given that this answer is only saying that most older people can use this form of milk. We have no way to prove that the 51% of older people who can use this milk overlaps with the unknown percent of older people who have this high BP / calcium deficiency issue. And it doesn't do anything to remove the concern that there could be aspects of milk that increase your blood pressure, so it's highly possible that milk does some good things and some bad things for blood pressure, thus highly calling into question the conclusion. In short, this question is deeply, deeply flawed, and I'm not sure how it escaped their quality control filters. Apparently, enough 170+ test takers aggregated around this correct answer, so LSAT didn't have to banish it into "item removed from scoring" fate.

    Skill tested: Sufficient Assumption · how this choice captures the argument's function is the move to repeat next time.

    68% picked this

  2. Milk does not contain any

    Necessary, not Sufficient

    We are definitely assuming this, yes. If milk did have some chemical agent that increases BP, that would be a big objection to the argument. You know what else would be a big objection to the argument --- if drinking milk gave your body calcium but not the ability to absorb that calcium. (A) rules out that objection. (B) rules out this objection. We have no real way to rank one above the other, other than thinking, "Well, on a broken question such as this ... is the test writer likely to think the affirmational LINKING answer in (A) was sufficient or that the protective DEFENDER answer in (B) was sufficient?" The tone this answer has of "ruling out an objection" feels more at home on Necessary Assumption. That's not an excuse for their poor test writing; it's just advice for a crappy, unfair situation.

    11% picked this

  3. Older people’s drinking one glass

    Too Weak

    This is something that needs to be assumed, but it doesn't prove the conclusion true, as the correct answer should. Just because "milk doesn't subtract the active form of vitamin D" doesn't mean that it does provide it. In order to prove this conclusion we need to know that milk fixes the "deficiency in the active form of vitamin D needed in order for the body to absorb calcium". This answer doesn't establish that.

    14% picked this

  4. People who consume high quantities

    Out of Scope: normal

    There's nothing in this argument about normal / abnormal blood pressure. We're talking about relative shifts up or down, from whatever baseline a given older person is at before they get or get rid of a calcium deficiency.

    3% picked this

  5. Anyone who has a deficiency

    Not Quite

    We're trying to argue that drinking milk can lower an older person's blood pressure. We know that drinking milk can provide enough calcium to make up for any underlying calcium deficiency, but that won't matter if the body doesn't have enough active vitamin D to allow for calcium absorption. We need to know that if we get rid of ? we also get rid of calcium deficiency vitamin D deficiency This is saying if we have vitamin ? we have calcium D deficiency deficiency This feels pretty close to being the contrapositive, but "have / not have" is not the same as "get rid of / don't get rid of", so it's not actually helping to convince us that, "If you drink enough calcium to get rid of your calcium deficiency, even if you have a vitamin D deficiency, your body will still be able to absorb it".

    4% picked this

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