#5 - Researchers announced recently that over the past 25

[Administrator]

Complete Question Explanation

Weaken, CE. The correct answer choice is (B)

Since the key to weakening an LSAT argument is to focus on the conclusion, it is essential to break down the argument, which is structured as follows:

• Premise: Over the past 25 years, the incidence of skin cancer caused by exposure to the sun has continued to grow.
  
  Premise: The growing incidence of skin cancer has occurred in spite of an increasingly widespread use of sunscreens.
  
  Conclusion: Using sunscreen is unlikely to reduce a person’s risk of developing such skin cancer.

The conclusion of the argument is the final sentence, which contains the conclusion indicator “this shows that.” By suggesting that sunscreen products are unlikely to reduce the risk of developing skin cancer, the author assumes that there is no causal relationship between sunscreen use and reducing cancer risk:

PowerScore Decon62 - Chapter 6 LR2.png

To weaken this argument, you need to show that a causal link does exist, i.e. that using sunscreen may still reduce a person’s risk of developing skin cancer, despite the growing incidence of skin cancer over the past 25 years. Almost all correct LSAT Weaken question answers leave the premises intact and focus instead on the conclusion of the argument. Thus, in prephrasing an answer, attempting to attack the facts concerning the increase in skin cancer or the increased use of sunscreen is unlikely to be fruitful. Instead, look to undermine the statement in the conclusion.

Because personalizing an argument can often yield a stronger prephrase, imagine how you would respond if you were, say, a dermatologist who spent her entire career advising patients to use sunscreen in order to protect themselves against skin cancer. What if people tend to spend a larger amount of time in the sun today than they did 25 years ago? In that case, it is possible that the incidence of skin cancer would have been even greater without the use of sunscreens. Or perhaps the effects of sun damage are cumulative and take a long time to develop into skin cancer. Given that the widespread use of sunscreens is a relatively recent phenomenon, we would not be able to observe a decrease in the cancer rates until much later, even if sunscreen do help reduce the risk of skin cancer later in life.

The key to prephrasing a good answer, especially to Weaken questions, is to personalize the argument and understand what the correct answer must do (not necessarily say). Do not get “boxed in” by your prephrase—sometimes there are multiple ways to weaken a given conclusion.

Answer choice (A): Even if most people who purchase sunscreens do not purchase the most expensive product, this does not suggest that sunscreens work, and therefore does not weaken the conclusion. If you found this answer choice attractive, you must have assumed that the effectiveness of sunscreens somehow depends on how expensive they are. Although such an assumption can potentially explain why most people do not see the benefits of using sunscreen (they do not buy the most expensive products), the stimulus contains no evidence that cost and effectiveness are associated. Therefore, this answer choice is incorrect.

Answer choice (B): This is the correct answer choice. If skin cancer generally develops among the very old as a result of sunburns experienced when very young, then the widespread use of sunscreens would not lower their own risk of developing cancer. However, sunscreen use can still prevent the very young from developing cancer later in life, but this benefit will not become apparent until much later. Consequently, the growing incidence of skin cancer in recent years cannot be interpreted as conclusive evidence that sunscreen products fail to protect against it. As a point of interest, note that because of the contradictory nature of the premises (sunscreen use increased but cancer incidence also increased), this answer choice has the feel of a Resolve the Paradox question answer choice.

Answer choice (C): If anything, this answer would serve to strengthen the argument. While the opinion of experts is often an irrelevant consideration in many arguments, in this case the argument concerns skin cancer, and dermatologists would have applicable expertise in that area. Thus, because at best this answer is irrelevant and at worst it strengthens the argument, this answer choice is incorrect.

Answer choice (D): If people who know that they are especially susceptible to skin cancer avoid spending a large amount of time in the sun, their behavior may lower their risk of developing skin cancer, regardless of whether they use sunscreen products or not. However, the fact that a particular group of people found another way to lower their risk has no impact on the effectiveness of sunscreen products, which is at the heart of this argument.

Answer choice (E): This answer choice states that those who use sunscreens most regularly are people who believe themselves to be most susceptible to skin cancer. However, it is unclear whether the use of sunscreen lowered their susceptibility to cancer. Just because the overall incidence of skin cancer has increased does not tell us whether it is evenly distributed between those who are susceptible to the disease and those who are not. In fact, if the vast majority of cancer patients were people who were susceptible to the disease (and therefore used sunscreen regularly, as this answer choice suggests), this would provide fairly strong evidence that using sunscreen is unlikely to reduce a susceptible person’s risk of developing cancer. Because this would strengthen the conclusion of the argument, this answer choice is incorrect.

[queenbee]

Hi
I didnt pick B because if people started using sunscreens in the last 25 years, the population of the people they should be inspecting are those who started using sunscreen, lets say, in their teens or 20's, and that would mean that 25 years later they are in their late 40's or early 50's, certainly not old. What is the point of tracking a population before 25 years ago if they were not using sunscreen? It seemed to me that B was looking that a population that was not affected by the increase use of sun screen.

Even if we included the population before 25 years ago, the numbers should still go down because people are now using sunscreen. So all the people in there 60's and 70's who are now getting skin cancer and were not using sunscreen are not supplemented with the people in their 40's and 50's

Extreme example:
Before 25 years of sunscreen development, people impacted: 30's, 40's, 50's, 60+, etc
After 25 years of sunscreen development, people impacted: 50's and 60+, etc

The way I looked at this is that the only people who are buying and using sunscreen religiously are the people who have a predisposition. Hence, the number of people predisposed to skin cancer have decreased but not the overall population.

Any chance you can help me with this?
Thank you!

[Adam Tyson]

The answer is right there in your analysis, queenbee! If skin cancer is generally found only among "very old" people who were burned when they were "very young," then 25 years of sunscreen use might not start to show any difference yet. It's too soon to see the rate of skin cancers going down! 50-year-olds don't tend to have skin cancer (yet) regardless of whether they have been using sunscreen or not.

For the sake of argument, let's just say that 80+ is "very old," and anyone younger than 20 is "very young." This means that it takes about 60 years or more for those sunburns to manifest as skin cancer. The relatively recent increase in the use of sunscreens won't make any measurable impact for another 35 years at least! That's what answer B is saying, and that weakens the claim that sunscreens aren't helping. The data we have so far simply isn't relevant because it's too soon to come to any such conclusion!

[PresidentLSAT]

I ruled out E because "those who used it the most" could be an insignificant sample of the research we are concluding from. Also, a person using sunscreens 7 days a week could be categorized as "using it the most" compared to someone who only uses it when they are in the sun. Both adequately use it.

Is my reasoning correct?

Thank you in advance.

[Jeff Wren]

Hi President,

While the points that you make are possible, they are not actually the reason that this answer is wrong.

The real problem with Answer E is that it involves the wrong group of people.

Answer E states that the people who believe that they are most susceptible to skin cancer are the ones to use sunscreen most regularly. Now one possibility is that these people are mistaken and they aren't actually more susceptible to skin cancer than anyone else, in which case this answer has no effect on the argument. The other possibility is that these people are correct in their belief (perhaps they have a family history of skin cancer, for example). In that case, this answer would actually strengthen the argument because the people who should most be using sunscreen to prevent skin cancer are the ones doing so. If that were true, it seems like the skin cancer rates should be going down if the sunscreen was protecting against skin cancer.

On the other hand, if Answer E had said something like "Most of the people using the sunscreen are actually the LEAST susceptible to getting skin cancer" (for whatever reason, genetics, life style, etc.) that would be an acceptable answer because it would explain how the use of sunscreen has increased and the rates of skin cancer have also gone up, not because sunscreen doesn't work (the argument's conclusion) but because the wrong people are using the sunscreen. In other words, the people who really need to use sunscreen to prevent skin cancer aren't the ones who are actually using it.