Logical reasoning PrepTest 127 · Section 1 · Question 20

Flawed

Errors in Reasoning Questions

Study New - Drinking 3 glasses of wine per day cuts your risk of stroke

There are two studies and two conclusions here that interact in an interesting way in that the critics - the second viewpoint/conclusion - doesn’t really contradict the first one.

In that first study/conclusion, it’s stated that drinking 3 glasses of wine per day decreases risk of stroke. There’s no claim that drinking that much wine is healthy - just that it decreases stroke risk.

The Critics accept that as true. However, they do go on to bring up another study showing that binge drinking - drinking 3 or more glasses of one once per week - is bad for your heart. They then compare the results from these two studies and determine that it’s at least a wash, and drinking 3 glasses of wine each day doesn’t benefit overall health. After all, the increased risk of heart attack balances out the decreased risk of stroke, right?

Well, it would if the studies looked at the same behavior. However, the groups analyzed in the studies are different, and the study relied on by the Critics isn’t about the same group/behavior in their conclusion. That first study has a group that matches with the conclusion - those who drink 3 glasses of wine each day. However, the study cited by the Critics about heart attack risk brings up binge drinkers - those who drink only once per week (or less) but have 3 or more glasses of wine when they do drink.

While “3 glasses of wine” ties these two groups together, they’re different in two fundamental ways. First, the former group drinks every day instead of at most once a week, and second, the latter group drinks 3 “or more” drinks when they drink, not exactly three glasses. In conflating these groups - or, at least, the applicability of the results in the study - the Critics make a flawed argument, so we should look for an answer pointing that out.