Q15 - Few, if any, carbonated beverages

[Laura Damone]

Question Type:
Weaken

Stimulus Breakdown:
Conclusion: The higher incidence of broken bones in teens who drink carbonated beverages with caffeine is probably due primarily to caffeine consumption.

Evidence: Consuming caffeine causes people to excrete more calcium than they otherwise would. Teens who drink large amounts of carbonated, caffeinated beverages suffer more broken bones than those who do not. Calcium deficiency can make bones more brittle.

Answer Anticipation:
Causation Flaw! The evidence expresses a correlation between the drinks and the broken bones, but that doesn’t mean one caused the other. The causal chain here actually has three links: Beverages cause calcium deficiency, and calcium deficiency causes broken bones. The second link in the chain is a premise, so that's an established fact. Anticipate an answer that disrupts the first link in the chain, showing that the beverages aren't causing a calcium deficiency. Also, keep an eye on degree words. The conclusion includes probability (probably) and ranking (primarily). If we can disrupt either of these, showing that it's not a probable cause or not the primary cause, we'll effectively weaken the argument.

Correct answer:
A

Answer choice analysis:
(A) Bingo. This disrupts the first link of the causal chain. If the teens in question also drink smaller quantities of calcium-rich beverages, maybe that contributes to calcium deficiency as much or more than the carbonated, caffeinated beverages. Notice that this doesn't attack the idea that the carbonated, caffeinated beverages contribute to calcium deficiency. It just suggests that something else may contribute, too. In so doing, it attacks the idea that calcium deficiency and broken bones are due primarily to the carbonated, caffeinated beverages. That ranking word is what allows this to be a correct answer.

(B) This is tempting because it provides an alternate cause for a high incidence of broken bones. Problem is, this applies to all teens, not just those who drink carbonated, caffeinated beverages. We need an answer to distinguish between teens that drink these beverages and teens that don't, not an answer that distinguishes between teens and the general population.

(C) "Some" is a big red flag here. Whenever I see "some" on the LSAT, I replace it with "one" because that's all that's necessarily implied. So if one teen that doesn't consume caffeine has a calcium deficiency, does that mess up my argument? No way. We don’t need every incidence of calcium deficiency to be caused by caffeine intake to establish the first link in our causal chain. "Some" answers are almost never correct on Weaken questions.

(D) Let's put that to the test again: One of the less popular carbonated beverages has even more caffeine than the popular ones. Does that mess up our argument? Nope. We don't know whether teens drink that beverage, so it doesn't impact our situation.

(E) More calcium in, more calcium out. Ok. But so what? This doesn't attack any of the links in our causal chain. Eliminate (pun intended)!

Takeaway/Pattern:
Weaken questions are dominated by cause and effect reasoning, so if you spot it, take the time to really break it down. There's usually at least one premise the presents a correlation, and a conclusion that explains that correlation by positing a causal relationship. Some causal arguments are more complicated than that, though. Knowing that this argument has a three-link chain, and that the last link in the chain is factually established, tells us that we need to turn our attention to the first link in the chain. That is the weak link, so to speak. We also need to stay vigilant for degree words and consider how they impact our task. If we are tasked with weakening a claim like "A is primarily due to B," we don't need to prove that B doesn't cause A. We only need to suggest that something else might cause A as frequently or more frequently than B.

#officialexplanation

[PretzelL30]

Laura, I'm a big fan of your explanations. I find many of your takeaways extremely valuable on how to attack individual questions. Having been studying for several months, these are patterns that I've seen but maybe I was less aware to really watch out for. Great job.

[LawrenceR550]

This weaken question is a perfect example of how NOT to go about answering a weaken question. Do NOT attack the argument's conclusion; attack its logic.

Of all the choices, B is clearly the trap answer choice. It offers an alternate explanation, which is basically the #1 way to expose a causal flaw. And of course, the fact that the argument makes a causation flaw already is a weakness in and of itself that can be exposed. However, if the argument's conclusion can't even stand on its own premises, because they contradict each other, then it weakens the argument deeper because the conclusion is no longer worth even considering. After all, even if a causal flaw is made, perhaps the given explanation is the correct one.

Thanks