Q11 - Scientists have long thought

[dan]

11. (D)
Question type: Assumption
The author use a comparison between middle-aged people who eat fish and those who don’t in order to prove a point about the effectiveness of fish oil in promoting good health. LSAT arguments with causal conclusions are often supported by evidence similar to what we have here _ two different results for those who use or don’t use a certain product _ and this method of providing evidence is generally flawed.

Consider the following argument: "Those who buy purchase exercise clothing are generally in better shape than those who do not. Therefore, we can conclude that purchasing certain types of clothing is healthier than purchasing other types of clothing." What’s tempting, in this simple example and the harder question at hand, is that we only know of one variant _ whether people eat fish, or whether people buy exercise clothing _ and so it’s easy to limit the argument to just that one variant. However, it’s important to remember, in arguments such as this one, that there are generally going to be other factors that the author fails to mention, and this is a significant flaw. People who buy exercise clothes are more likely to exercise, and it is the exercise itself that most likely contributes to good health.

In this particular problem, certainly the fish oil could be the reason why a certain group is healthier than another, but it could also be that those who eat fish tend to eat healthier in general, or tend to live in environments with less pollution, or that those who don’t eat fish eat other things, and it is these other foods that cause them to have bad health. It’s unrealistic to try to predict every other factor; what’s more important is that you are suspicious of the argument because you know other factors are possible.

(D) may not be an assumption you anticipated, but it is nonetheless an assumption that is required. One way to test the necessity of an assumption is to consider its opposite: if the negation of an assumption significantly weakens the conclusion, it was an assumption that was necessary. The opposite of this answer would be that those who ate fish also engaged in other activities that helped them have better health_ this would significantly weaken the conclusion that it was the fish itself that was responsible for the disparity in heart disease.

(A) involves a factor that could contribute to the disparate results, but it is not required for this argument to work. In fact, by providing other reasons why one group might be different from the other, this answer may weaken the argument.
(B) provides information that seems to contradict the results, and is therefore not a required assumption.
(C) involves a factor that could contribute to the disparate results, but it is not required for this argument to work. In fact, by providing other reasons why one group might be different from the other, this answer may weaken the argument.
(E) provides information that seems to contradict the results, and is therefore not a required assumption.

[rbolden]

Thanks so much for this! Your explanation is very helpful!

[irene122]

Dan, could you please explain what exactly does B mean? The "otherwise" really confuses me, I don't understand the diet of test subjects besides fish whether contributed to heart disease or not.

Thanks a lot!

[maryadkins]

Dan, could you please explain what exactly does B mean? The "otherwise" really confuses me, I don't understand the diet of test subjects besides fish whether contributed to heart disease or not.

(B) is saying that apart from the fish, the REST of the people's diet wasn't conducive to heart disease. In other words, let's think about their diets. We know they're eating fish twice a week. OTHER THAN THAT ("Otherwise"), what was the rest of their diet like? Well, it wasn't conducive to heart disease. In other words, it was probably pretty healthy.

If the "otherwise" confuses you to the point of getting paralyzed, just try taking it out. Here, (B) would read, "The test subjects who ate fish twice a week did not have a diet that was conducive to the development of heart disease." Turns out, it basically means the same thing! This is often the case.

[u2manish]

Hi all,

How is A [ and C] different from B. I thought B weakened the argument but cant see how A and C would?

And how is D different from E (As I see it both the sets in the study do not exercise (D) and both do not have sedentary jobs (E)? Both seem to eliminate alternate cause. What am I missing?
Any help would be great..! Apologies for any inconvenience.

Thanks,
M

[ManhattanPrepLSAT1]

This is a classic structure. The argument concludes that an observed phenomenon (reduced likelihood of developing heart disease) is the result of a particular explanation (consumption of omega-3 fatty acids in fish oil). This argument assumes that something else is not the correct explanation - and answer choice (D) eliminates a possible competing explanation and represents the correct answer.

Let's look at the incorrect answers:

(A) eliminates vegetarianism as a possible explanation for something but never connects vegetarianism to heart disease.
(B) may sound tempting, but if you negate this answer choice and say that those who ate fish do have diets that would likely lead to heart disease, and yet they still had a reduced likelihood of developing heart disease, this would support the argument's reasoning. The negation of the correct answer should destroy the argument's reasoning.
(C) need not be assumed. Those who did not eat fish do not need to eat red meat. Supposing eating red meat increases one's likelihood of developing heart disease, this actually undermines the argument from the beginning, since maybe the lower rates of heart disease weren't from eating fish, but the lack of red meat. But there's a further issue since this answer choice does not connect red meat with the development of heart disease.
(E) suffers from a similar problem as answer choices (A) and (C) in that it fails to connect having a sedentary occupation with the development of heart disease. Even if we were to assume that having a sedentary occupation would increase your likelihood of developing heart disease, the negation of this answer choice would not undermine the conclusion but would rather support it since those who were eating fish would also be likely to have an increased chance of developing heart disease - and yet they didn't.

Hope that helps! Let me know u2manish if this does not answer your question...

[nflamel69]

could someone answer this please? i actually left B as a contender the first run since this seemed like a causal argument to me. So to contribute the good effects to the fish has to eliminate some other possibilities that could also caused effect right? Is B wrong because it only said the other diet did not increase risk of heart disease, but that doesn't mean it necessarily decreased it like D suggested? Does that make any sense?

[ManhattanPrepLSAT1]

could someone answer this please? i actually left B as a contender the first run since this seemed like a causal argument to me. So to contribute the good effects to the fish has to eliminate some other possibilities that could also caused effect right? Is B wrong because it only said the other diet did not increase risk of heart disease, but that doesn't mean it necessarily decreased it like D suggested? Does that make any sense?

That's right. Had answer choice (B) said that "the test subjects in the recent study who ate fish twice per week did not have a diet that was otherwise conducive to the prevention of heart disease," we'd have another correct answer. Instead ruling out something else (other than fish) that could explain the lower risk of heart disease, it rules out something that would strengthen the argument. This answer choice actually weakens the argument.

Does that answer your question?

[julia.korolkova]

I was going to pick D but got confused by cardiorespiratory health, I assumed that was referring to respiratory health only and had nothing to do with the heart. I have since googled it and it turns out that cardiorespiratory refers to both heart and respiratory. Now D makes perfect sense

[deedubbew]

I am still very confused about B. The only solution I can think up is that B addresses only the test group, while D establishes that there is a difference between the 2 groups. Other than the fish, the test group could have a diet that is exactly the same as the population (regardless of how unrealistic that sounds; it's the LSAT), whether or not the diet is conducive to heart disease.













-Hi Spinach Fairy -Kitty.

[AlisaS425]

I was at first tempted by (B) and (D), and during review I thought there might be some hint between the stimulus and the answer choices. Please correct me if I'm wrong.

Argument core:
middle-aged people who eat fish twice a week are nearly 30% less likely to develop heart disease than those who don't eat fish
-->
fish oil tend to lower blood cholesterol, and a modest amount of fish would provide substantial health benefits

There are lots of discussions above, but none of them seem to address the "scope shift" issue; that is, the author's using less likely to develop heart disease as evidence to draw the conclusion that fish could provide substantial health benefits. (I'm wondering if this could be an issue in this question)

The reason I thought about it is that, when I looked at (D), I didn't know why it says "augment cardiorespiratory health" (Even if it has something to do with "heart disease", I still feel uneasy to connect these two together, as we're not allowed to make too much assumption).

But the conclusion is about "health benefits" in general, and "augment cardiorespiratory health" seems to belong to "health benefits", so if as (D) suggested, those who ate fish twice a week didn't engage in activities known to augment cardiorespiratory health more than those who didn't eat fish, then it at least eliminates one possibility that could be the reason those who ate fish are healthier!

Any thoughts?