LSAT 108 | Section 3 | Logical Reasoning: Q21

LR Question 21 Explanation

QUESTION TEXT: Advertisement for a lactase supplement …

QUESTION TYPE: Weaken

CONCLUSION: At least 50 million people in North America should take lactase supplements.

REASONING: Many subjects who drank a liter of milk on an empty stomach showed signs of lactose intolerance. So, many people have insufficient lactase.

ANALYSIS: The argument assumes that if people had trouble digesting a liter of milk on an empty stomach, they probably need lactase supplements in everyday life.

But … do you drink a liter of milk at a time in your daily life? I’d assume not.

The easiest way to weaken is to show that the experiment involved unusually extreme conditions that don’t resemble normal consumption.

If most people don’t consume that much lactose at once, then the experiment may dramatically overstate how many people actually need supplements.

___________

1. This says eating solid food with milk decreases lactase production. If anything, that could make lactose intolerance more common, strengthening the ad.
2. CORRECT. The study tested people under an unusually heavy lactose load. Someone who struggles with 1 liter of milk on an empty stomach may have no problems consuming normal amounts of dairy.
3. If lactase production increases with age, that might even weaken the conclusion somewhat, but we don’t know the ages of the subjects or the population.
4. This strengthens. If lactose intolerance interferes with proper nutrition, that actually makes taking supplements seem more important.
5. Some dairy foods being harder to digest doesn’t undermine the conclusion. If anything, it suggests digestive problems may be even more serious.