Q14 - Overexposure to certain wavelengths

[timmydoeslsat]

I would like to express my thought process on this question and have feedback or suggestions for improvement. It was down to (A) and (D) for me.

The stimulus gives a cause and effect. Overexposure to certain wavelengths of strong sunlight causes melanoma.

The conclusion (recommendation in this case) is that doctors urge everyone to put on sufficient sunblock on the skin that exposed to strong sunlight.

Why is that? The evidence is two parts that work together.

1) The cause and effect mentioned above: overexposure to strong sunlight causes melanoma.

2) Sufficient sunblock protects skin from sunburn during periods of strong sunlight.

I would like to go through the answer choices.

A) This answer choice appears to hit on an assumption that is made: that the same wavelengths of sunlight that cause sunburn, also cause melanoma. What I do not like about this answer choice is that even though those certain wavelengths are the main cause of melanoma, there could be lots of other causes of melanoma from perhaps other wavelengths of sunlight that the sunblock protects from. So I suppose it is not a destroying weakener, but does not go as far as I would expect.

B) Is of no consequence. Those people can find other sunblocks. Also, this is about melanoma and stopping it, allergic reactions or not.

C) It does not matter if many sunblocks need reapplication. You can either find other ones that do not.

D) I found this one tempting. The reason for sunblock in this recommendation is to prevent skin from being overexposed to certain wavelengths. The doctors are doing this to prevent melanoma in people. However, if toxins in certain chemical compounds, presumably sunblocks fit this subject matter, then this would seem to weaken the recommendation to use it.

It is like telling someone to do (A) because (A) can prevent (B), but (A) can cause (B). Seems to weaken the recommendation as well.

E) Out of scope. The time frame of sunburn/melanoma development has no bearing on this recommendation.


So help on (A) and (D) please!

[bbirdwell]

Sounds like a great process -- you just made an error in your evaluation of (D). (E) is by far the "craftiest" wrong answer, so good on you for eliminating that one with confidence!

even though those certain wavelengths are the main cause of melanoma, there could be lots of other causes of melanoma from perhaps other wavelengths of sunlight that the sunblock protects from. So I suppose it is not a destroying weakener, but does not go as far as I would expect.

By taking away the MAIN CAUSE, the *causal* argument is severely weakened. Superlative words like "main, primary, best, etc." are red flags on the test. They don't often appear; in fact, I believe they appear most often on incorrect answer choices to inference questions.

D) I found this one tempting. The reason for sunblock in this recommendation is to prevent skin from being overexposed to certain wavelengths. The doctors are doing this to prevent melanoma in people. However, if toxins in certain chemical compounds, presumably sunblocks fit this subject matter, then this would seem to weaken the recommendation to use it.

Absolutely not!! You can NEVER presume that the vague "some chemicals" is synonymous to "chemicals in sunblock"! These kinds of errors are made all over the test.

Note that the word "presumes" = "assumes." If you have to make an assumption like that in order to justify an answer choice, chances are 99% that it's not correct.

[shirando21]

Sounds like a great process -- you just made an error in your evaluation of (D). (E) is by far the "craftiest" wrong answer, so good on you for eliminating that one with confidence!

even though those certain wavelengths are the main cause of melanoma, there could be lots of other causes of melanoma from perhaps other wavelengths of sunlight that the sunblock protects from. So I suppose it is not a destroying weakener, but does not go as far as I would expect.

By taking away the MAIN CAUSE, the *causal* argument is severely weakened. Superlative words like "main, primary, best, etc." are red flags on the test. They don't often appear; in fact, I believe they appear most often on incorrect answer choices to inference questions.

D) I found this one tempting. The reason for sunblock in this recommendation is to prevent skin from being overexposed to certain wavelengths. The doctors are doing this to prevent melanoma in people. However, if toxins in certain chemical compounds, presumably sunblocks fit this subject matter, then this would seem to weaken the recommendation to use it.

Absolutely not!! You can NEVER presume that the vague "some chemicals" is synonymous to "chemicals in sunblock"! These kinds of errors are made all over the test.

Note that the word "presumes" = "assumes." If you have to make an assumption like that in order to justify an answer choice, chances are 99% that it's not correct.

I also found D tempting, because it provides alternative causes that can cause melanoma. So even if you put on sunblock, there's possibility that you will still get melanoma. Don't we use alternative explanation to weaken an argument?

[boy5237]

Hello Matt
So as far as I am concerned,
this argument is flawed because the argument actually equivocates "sunburn" with "melanoma," right?

That's why the recommendation attempts to trick people into thinking that Adequate sunblock -> ~sunburn -> (Tricky) ~melanoma?

[patrice.antoine]

I also found D tempting, because it provides alternative causes that can cause melanoma. So even if you put on sunblock, there's possibility that you will still get melanoma. Don't we use alternative explanation to weaken an argument?

Answer choice (D) actually does not provide an alternative cause but an additional cause by stating "ALSO cause melanoma". As a result, it does nothing to weaken the reason provided by in the stimulus.

Irrespective of this, it does nothing to attack the reasoning of the argument which is:

Since main cause of melanoma is overexposure to sunlight ---> adequate sunblock is urged for skin exposed to strong sunlight

Answer choice (A) weakens the reasoning of the argument by stating there is no evidence of causation between sunlight and melanoma (sunburn, too, though I treated this as additional information not relevant to the argument structure as we cannot assume that skin exposed to strong sunlight = sunburn).

Hope this helps!

[sukim764]

I also found D tempting, because it provides alternative causes that can cause melanoma. So even if you put on sunblock, there's possibility that you will still get melanoma. Don't we use alternative explanation to weaken an argument?

Answer choice (D) actually does not provide an alternative cause but an additional cause by stating "ALSO cause melanoma". As a result, it does nothing to weaken the reason provided by in the stimulus.

Irrespective of this, it does nothing to attack the reasoning of the argument which is:

Since main cause of melanoma is overexposure to sunlight ---> adequate sunblock is urged for skin exposed to strong sunlight

Answer choice (A) weakens the reasoning of the argument by stating there is no evidence of causation between sunlight and melanoma (sunburn, too, though I treated this as additional information not relevant to the argument structure as we cannot assume that skin exposed to strong sunlight = sunburn).

Hope this helps!

With regards to choice D, I agree with the above poster's explanation.
shirando21 wrote:
I also found D tempting, because it provides alternative causes that can cause melanoma. So even if you put on sunblock, there's possibility that you will still get melanoma. Don't we use alternative explanation to weaken an argument?

I'm not sure whether you're making the same assumption that Timmy makes, but regardless, an alternate cause does not necessarily invalidate the other cause in question. Perhaps there's two, three, or four causes to melanoma. Therefore, the possibility of another cause (Toxins) does not weaken the argument's suggestion in addressing another cause (Sunburn). Now choice A, on the other hand, addresses the recommendation of the assumed relation between sunburn and melanoma. I hope this was helpful

[shirando21]

Right, I agree. D does not matter to the relationship btw premise and conclusion, thus, not weaken

[griffin.811]

This was difficult because I didnt read this as saying "the wavelengths that cause sunburn are the same ones that cause melanoma." I instead interpreted it to mean that any sunblock that was strong enough to prevent sunburn (caused by wavelength A) is also strong enough to prevent the effects of the harmful rays that cause melanoma (wavelength B).

(Like a doc telling a patient "you have symptoms that could be caused by either disease A or disease B, but we are not sure exactly which you have. So why dont you take this medicine for disease A. The medicine for disease A is strong enough to cure both, while the meds for B will only cure that disease.")

Reading it this way, I went with D.

[matthew.mainen]

I think there is a far simpler way to look at this (if someone has already touched on this as such, please disregard, I only skimmed through the posts).

Answer choice A makes it possible that there are sunblocks meeting the definition of adequate sunblock that protect against NO waves known to cause melanoma. This is because a bare minimum adequate sunblock would only protect against the waves that cause sunburn but none of the waves that cause melanoma. In other words, using adequate sunblock as defined by the doctors is entirely irrelevant to melanoma. Some may black the other waves, some may not.

[tommywallach]

Hey Matthew,

You're absolutely right! That said, the main argument going on in this thread is why people were tempted by (D), not really why (A) is overall correct.

On a side note, I wish everyone in this thread (including you, Timmy, and my fellow MPrepper) would discuss this weaken question in the traditional (and BEST!) way, by isolating the core and then using that to discuss the assumption:

Premises: Sunlight causes melanoma + Sunblock protects against sunburn
Conclusion: Everyone should wear sunblock

The assumption here is that sunburns are related to melanoma. Some people have been discussing this as if the assumption is between sunlight and melanoma, but that's not an assumption (it's directly stated in the passage!).

Hope that helps!

-t

[timsportschuetz]

Thank god you posted the above Tommy! I was getting a tiny bit frustrated reading the many posts (including those of experienced instructors) and NOT seeing the right elimination process being used (CORE IS KEY!). As far as (D) is concerned, you should eliminate this IMMEDIATELY since you would have to make additional unwarranted assumptions in order to support YOUR side of the argument! Firstly, you do not know if the toxins are in the sunblock. Secondly, you cannot assume that there are or aren't toxins in sunblock. What if I said, in response to your answer (D), "OK, well, the sunblock we are recommending doesn't have those chemicals." -OR- "OK, the sunblock DOES have those chemicals." As illustrated above, answer (D) COULD GO EITHER WAY! HENCE, IT MUST BE WRONG and should be confidently eliminated!

[twu]

I'm still a bit confused about how answer choice A necessarily weakens the recommendation. As I see the stimulus, the doctor's recommendation is based on two premises:

1. Overexposure cause melanoma
2. Sunblock prevents sunburn

It seems to me that there's no real correlation given in the stimulus on the relationship between sunblock and melanoma. But the recommendation can still stand even if the first premise is irrelevant. Doctors can still recommend everyone to put on sunblock because it prevents sunburn. And answer choice A does nothing to weaken the recommendation in this regards.

[bernard.agrest]

This is a weaken question.

Stimulus: Overexposure to strong sunlight is the main cause of melanoma. Because of this, doctors now urge everyone to put on enough sunblock. Enough sunblock - according to doctors - is any preparation that prevents sunburn even if the person is exposed to strong sunlight for a significant length of time.

*I narrowed it down to A and D, and chose wrong, so this is my explanation*

A) Tricky. The assumption here is specific type of sunlight --> melanoma. By putting in enough sunblock --> no melanoma. But that assumes that THAT sunlight also leads to sunburn. If you take away that assumption, then you could be just putting on massive amounts of sunblock for no reason.

I didn't actually have a reason for eliminating this answer, I just liked D better for some reason.... even though I KNEW it was a bad answer choice.

B) That doesn't weaken it, "people" can literally be 2 people out of a 6 billion. Most people, could possibly have been a better answer choice.

C) That doesn't weaken it, if anything it just reiterates what the doctor's say... you need to apply it for how ever long it takes to prevent exposure.

D) This was my A/C. I chose it, while thinking to myself, that I didn't like the way "chemical compounds." looked. But chemical compound's ARE NOT THE SAME THING as sunblock.

E) This is just easy to eliminate.

[deedubbew]

How do we eliminate the possibility that any preparation that prevents sunburn does not also contain something that prevents melanoma? If this is the case, the it is possible that there are waves of sunlight that lead to melanoma but do not cause sunburn.

[christine.defenbaugh]

There are some interesting thoughts here I'd love to weigh in on!

But the recommendation can still stand even if the first premise is irrelevant. Doctors can still recommend everyone to put on sunblock because it prevents sunburn.

You have a point, twu, that the recommendation could stand if it really were doctors just saying "Yo, wear sunblock!" in a vacuum. But the first three words of the second sentence contain a powerful punch: "For this reason...." These doctors aren't just recommending sunblock for any old reason - they are recommending it "for THIS reason", the one mentioned in the sentence immediately beforehand - melanoma!

The recommendation is actually that you should wear sunblock because of melanoma. The implication is that sunblock actually prevents melanoma.

Our premises only tell us that sunblock prevents sunburn though. So the missing link, the assumption, must be that if something prevents sunburn, it also prevents melanoma!

How do we eliminate the possibility that any preparation that prevents sunburn does not also contain something that prevents melanoma? If this is the case, the it is possible that there are waves of sunlight that lead to melanoma but do not cause sunburn.

We don't! It's absolutely possible that every 'sunburn-preventing preparation' in the universe also just so happens to have another ingredient that just so happens to prevent melanoma.

But remember, deedubbew that a valid Weaken answer does not necessarily utterly destroy any possibility of the conclusion being true. The correct answer simply has to make that conclusion a bit less likely to be true.

This argument is assuming that if something prevents sunburn, it also prevents melanoma. If these were caused by the exact same wavelengths of light, then it would be pretty reasonable to believe that assumption - anything blocking the wavelengths for sunburn would necessarily be blocking those same wavelengths from causing melanoma. Taking that away just makes it less likely that sunblock will necessarily prevent melanoma.

Please let me know if this helps clear up a few things!