Logical reasoning PrepTest 132 · Section 4 · Question 5

Incorrect. There's no indication that expensive sunscreen is better than the cheap stuff, so this answer is out of scope.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Weaken

Stimulus Summary:
Despite more people using sunscreen, skin cancer caused by sun exposure keeps increasing. Therefore, sunscreen doesn't work.

Answer Anticipation:
This argument falls into a common pattern on the LSAT, where a correlation between something that's viewed as a solution (sunscreen) and the problem getting worse (more skin cancer) is shown, and the conclusion is anti-causal—it concludes that the solution doesn't work.

This type of argument has two main flaws that show up on the LSAT.

The first is that it doesn't look at what the problem would have been like without the solution. Would skin cancer rates have gone up even more? It's possible that sunscreen lowered the speed of growth, thus preventing a large number of cases of skin cancer even if that number is still climbing.

The second is lag time between implementing a solution and the problem being solved. Maybe it takes time for the solution to kick in, or maybe the problem develops over a long period of time and so the effects will be felt until the solution catches up. This flaw is particularly common when the LSAT is discussing health issues, as many health issues—such as cancer—develop only after a long time.

Weaken questions have answers highlighting these flaws, so we should look for an answer that either suggests the skin cancer rate would have been even higher without sunscreen, or that skin cancer takes a while to develop and so we're still seeing cases that were caused by exposure before sunscreen use became widespread.

Answer Explanation:
This answer highlights the second reason that this type of correlation/anti-causal argument is flawed. If skin cancer is the result of sun exposure from decades earlier, then it'll take a bit of time before the sunscreen's effect on cancer rates can be expected to be seen.

Key Takeaway:
Anti-causal arguments—ones that use correlations in an attempt to prove that a solution doesn't work—generally have one of two issues (sometimes both):

(1) Even if the problem persists or worsens after the solution was implemented, that doesn't mean the solution didn't work. The problem may have become even worse without the solution.

(2) The problem might have a lag time to it—this is true in many medical cases, where diseases develop years after exposure to the cause. If that's the case, then a solution recently implemented might not yet have its effect seen in the data.

The first is much more common than the second, but the second does frequently show up when there's a disease mentioned, for the aforementioned reason.

Incorrect. This answer doesn't have an effect on the argument because it doesn't provide enough information. Was this research on skin cancer? Did it show that the chemicals in sunscreen were effective? Without knowing what the research was on and what the results were, we can't know the effect of this on the argument.

Incorrect. Do these people wear sunscreen? And have they changed their behavior over the past 25 years? This is another answer that doesn't provide enough information to know how it affects the argument.

Incorrect. Belief doesn't determine reality, so there's no way to know if these people are actually susceptible to skin cancer.