Self-study
Several carefully conducted studies showed that Support 75 percent of strict vegetarians reached age 50 without developing serious heart disease. ██ ███ ████████ ████ ████ ████ ████████ ████ █████████ █████ ███████ ██ ████████ ███████ █████ ████████ ██████████ ██████ ███ ████ ██ ██████ ███ ████ ██ ███████ █████ ███████ ██████ ███ ███ █████
Method of Reasoning
The author concludes that one should adopt trait X (vegetarianism) if one wants to causally lower outcome Y (risk of heart disease). His reasoning is that, where you find trait X, you’re very likely to find low outcome Y.
Identify and Describe Flaw
The author makes a recommendation based on the cookie-cutter flaw of assuming that correlation proves causation. To know if vegetarianism is causally related to heart disease, we need to know how often non-vegetarians suffer from heart disease. (In other words, we need a control group.) If only 10% of non-vegetarians suffer from heart disease, we would have no reason to suppose vegetarianism reduces the risk of heart disease.
23.
The flawed pattern of reasoning █████████ ██ █████ ███ ██ ███ █████████ ██ ████ ███████ ██ ████ █████████ ██ ███ ████████ ██████
a
The majority of ██████ ███ █████████ █████ ████ ███ █████ █████ ████ ██████ ████████ ██ ███████ ██████████ ██ █████ ████ ██ ██████ ███ ██ ███ █████ ████ ███ █████ ██████ ██ ██████ ████ ████ ██████ ████████ ██ ███████ ███ █████ █████
This has a similar flaw: we don’t know how often people who drive under the speed limit get into accidents. But it doesn’t parallel the argument of the stimulus. (A) considers a situation in which not having trait X (i.e. not obeying the speed limit) is associated with high negative outcome Y (traffic accidents). By contrast, the stimulus considers a situation where having trait X (being a vegetarian) is associated with low negative outcome Y (heart disease). They both conclude we should increase trait X on the basis of insufficient evidence, but they use different evidence.
(A) would be a better parallel if the stimulus were saying that meat-eaters have a high incidence of heart disease, so increased vegetarianism would reduce heart disease.
b
Studies have shown ████ █████████ ███████ ████ █ ███████ ██████ ██ █████████ █████ ███████ ████ ██████ ███ ██ ███ ██████ █████ █████████ ███████ █████████ █████ ███████ ██ █████████ █████ ████████ ██████ ███ ████ ██ ███ ██ █████ █████ ███████ ██████ ████ ██ █████████ ████████
This is not clearly flawed, unlike the stimulus. (B) compares the rate of heart disease in smokers and non-smokers. By contrast, the flaw in the stimulus is that it only considers the rate of heart disease in vegetarians—it doesn’t consider the rate for non-vegetarians.
c
The majority of ██████ ███ █████████ █████ ██████ ██████████ ██████ ████████ ██ ███ ██████ ████ ██ █████ ██████ █████ █████ ██ ████ ███████████ ███████ ████████ ██████ ███ █████████ ██████ █████████ ███ ██████████ ██████ ████ ██████ ████ ██████████ ██ ███ ███████ ███████
This has a similar flaw to the stimulus: we don’t know how common dental problems are among people who don’t drink coffee. But the conclusion of (B) is that the government should reduce the availability of coffee. By contrast, the stimulus concludes that, if you want to reduce heart disease, you should become a vegetarian.
In other words, the stimulus isn’t necessarily telling anyone to become a vegetarian: if you don’t care about heart disease, you can still eat meat. But (B) makes a definitive judgment.
d
Studies show that ██████ ███ ██ ███ ████████ █████████ ████ █ ███████ ████ ██████████ ████ █████ ███ ████████ ██████████ ██ ████ ████████ █████ █████████ ████ ███████████ ███████ ██████ █████████ ███████ ████████ ██ █████ █████████
This doesn’t have the same clear flaw as the stimulus. (D) compares the life expectancy of high-exercisers vs. low-exercisers. By contrast, the flaw in the stimulus is that it only considers the rate of heart disease in vegetarians—it doesn’t consider the rate for non-vegetarians.
e
Most people who ████████ █████████ ███ ████ ██ ██████ ███████ ████ █████ ████ ██████████ █████████ █████████ █████ ███████ ██ █████ ███████████ ██ ███████ ██ ██████ ███ ████ ██ ██ ████ ██ ██████ ██████ ██████ █████████ ██████ ██ █████████
(E) concludes that one should adopt trait X (regular exercise) if one wants to causally reduce outcome Y (being overwhelmed by stress). The reasoning is that, where you find trait X, you’re very likely to find low outcome Y.
This is the same cookie-cutter flaw of confusing correlation and causation as the stimulus. We don’t know how well people who don’t regularly exercise handle stress. Without that comparison, the author’s conclusion is not justified. Furthermore, this is the same conditional recommendation as the stimulus: if you want this result, you should increase this trait.