#19 - Doctor: Medical researchers recently examined a large

[Administrator]

Complete Question Explanation

Flaw in the Reasoning, CE. The correct answer choice is (B)

The stimulus indicates that medical researchers examined a group of people who never experienced back pain. Surprisingly, half of them had bulging or slipped disks in their spines, conditions often blamed for serious back pain. When confronted with this apparent discrepancy, the doctor concluded that bulging or slipped disks could not cause serious back pain.
The argument, when reordered, is structured as follows:

PT62 - LR2 #19 diagram 1.png

Because this is a Flaw question, it is important to examine closely the relationship between premises and conclusion in order to understand the logical flaw before proceeding to the answer choices. At first glance, the conclusion seems somewhat reasonable. After all, the study establishes that there are instances in which the cause occurs (slipped disks) without the effect (back pain), which is a common way to weaken arguments based on causal reasoning. However, the introduction of evidence against a position only weakens the position; it does not necessarily prove the position false. It is still possible that slipped disks do occasionally cause back pain, just not always.

It is worth noting that the study disproves the conditional relationship between slipped disks and back pain (“if pain, then slipped or bulging disk”), not the causal relationship between the two (“slipped or bulging disk causes pain”). If we find evidence suggesting that the sufficient condition can occur without the necessary condition (slipped disks occur in the absence of back pain), we can conclude that having a slipped disk is not a sufficient condition for back pain. However, this does not disprove the hypothesis that one causes the other. Had the conclusion been phrased in a less definitive way (“these conditions do not necessarily lead to serious back pain”), the argument would have been valid.

Answer choice (A): This answer choice describes the possibility that having a slipped disk need not be present in order for someone to experience back pain, but may be sufficient to cause back pain. There is no evidence, however, that having a slipped disk is a sufficient condition for back pain. In fact, the study shows instances in which a slipped disk did not cause back pain, suggesting that a slipped disk is not a sufficient condition for back pain. Because this answer choice fails the Fact Test, it is incorrect.

Answer choice (B): This is the correct answer choice. Even though a slipped disk is not in itself sufficient to cause back pain, it may nonetheless be partly responsible for back pain in some instances. This answer choice correctly points out that having a slipped disk is not a sufficient condition for back pain (if it were, then all instances of slipped disk would lead to back pain, which is not the case). In that sense, the author undermined the idea that slipped disks always cause back pain. However, because a slipped disk can still occasionally cause back pain, the causal link between the two is still possible.

Note that there are multiple ways to describe the same error in the use of evidence. Compare the following examples, all of which describe to the same error:

• The author fails to consider the possibility that even though slipped disks do not always cause back, they sometimes can.
  
  The author confuses undermining an argument in support of a given conclusion with showing that the conclusion itself is false.
  
  The author takes for granted that just because slipped disks do not always cause back pain, they never do.
  
  The author presumes, without justification, that just because a certain factor is not in itself sufficient to produce a certain effect, it is never responsible for that effect.

Because there are many ways to describe a Flaw in the reasoning, it is important to prephrase an answer describing the error you notice, but keep an open mind.

Answer choice (C): This answer choice fails the Fact Test because the study does not describe an effect (back pain) that occurs in the absence of a particular phenomenon (slipped disk). Rather, it describes a phenomenon (slipped disk) that occurs in the absence of a particular effect (back pain).

Answer choice (D): This answer choice describes an Overgeneralization. It fails the Fact Test, because the author never suggested that half of the entire population without back pain have slipped disks. Do not be misled by the attractive language used in this answer choice. Just because it is easier to associate the wording of the answer with the description of the study (“half a given sample of the population”) does not mean that the answer is correct.

Answer choice (E): This answer choice describes the possibility that even though slipped disks do not cause back pain, they are more likely to be present when the pain occurs than when the pain does not occur. However, the correlation between the slipped disks and back pain would not by itself weaken the author’s conclusion, as it is still possible that slipped disks do not cause back pain even though the two are correlated. In fact, since this answer choice concedes that slipped disks do not cause back pain, it describes a possibility that is consistent with the author’s argument.

[moshei24]

Is the reason the answer is (B) because if the slipped disks were sufficient to cause the back pain, they always would, so in this case they aren't, but even though they aren't sufficient that doesn't mean that the slipped disks along with let's say old age together couldn't lead to the back pain. So then if the slipped disks are partly responsible, then in a case where someone is old, the slipped disks could lead to the back pain, which the conclusion claims isn't possible.

Correct?

Thanks!

[Steve Stein]

Hey Moshe,

That's correct--even if a slipped disc is not enough on its own to cause back issues, that doesn't mean that it can't contribute to back issues.

Nice work!

~Steve

[moshei24]

Thank you!

[ddion8206]

Powerscore,

Could some explain the answer for DEC 2010 LR2 19 for me? It seems that the harder questions appear later in the section which is hurting my LR Score, any strategies to deal with the harder problems? Any help will be greatly appreciated! Please! Thank you!

Best,
Daniel Dion

[Laura Carrier]

Hi Daniel,

The doctor here relies on a single piece of evidence:

Researchers examined a large group of people who said they had never experienced serious back pain and found that half of them had bulging or slipped disks in their spines.

We are also told that these two conditions are often blamed for serious back pain.

The doctor goes on to conclude that, because the people in the examined group who exhibited these conditions did not feel pain, these conditions could not ever be the cause of serious back pain in people who do feel it.

This conclusion is not properly drawn because it goes much further than what we know from the premises. From the examined group, we do know that a bulging or slipped disk in the spine can occur without the presence of back pain, so the two are not always linked. Thus, we could correctly conclude that a bulging or slipped disk is not sufficient to indicate that there will be back pain, since there are cases of these conditions in the absence of pain. But that doesn’t give us any basis for concluding that the conditions could never cause pain. In themselves, in the examined cases, they were not enough to produce pain; however, what we know about this group of pain-free people doesn’t allow us to conclude anything about the entirely different group of people with serious pain and the role that bulging or slipped disks might play in their pain. Even if they are not sufficient to cause pain every time they occur, this does not tell us that they can never contribute to pain when it occurs.

Thus, answer choice (B) correctly describes what the doctor’s argument overlooks, by saying that “A factor that is not in itself sufficient to produce a certain effect may nonetheless be partly responsible for that effect in some instances.”

I hope this is helpful.
Laura

[bli2016]

Hello, could someone explain why A is wrong? I understood the flaw to be that the doctor was overgeneralizing from the observation that half of the group did not feel pain from their bulging/slipped disks. I thought perhaps for other people, the bulging/slipped disks would be sufficient for them to feel pain. Any help understanding why B is correct and A is wrong would be greatly appreciated. Thanks!

[Alexandra Ruby]

Hi bli2016,

The reason answer choice (A) is incorrect is because the first part of the answer choice does not apply to the Doctor's argument.

More specifically, the Doctor's conclusion is that bulging and slipped disks cannot lead to back pain because those studied who had bulging or slipped disks did not have back pain. Nothing is said about those who did not have bulging or slipped disks.

Answer choice (A) states that the Doctor failed to consider that bulging and slipped discs need not be present in order for back pain to arise but these conditions may still produce back pain. This is out of the scope of the stimulus as it does not mention situations where bulging and slipped disks are not present.

Answer choice (B) provides that the Doctor failed to consider the fact that although bulging and slipped disks are not themselves sufficient to produce back pain these conditions may nonetheless be partly responsible for back pain in some instances which is the flaw.

Hope this helps!

[Kristintrapp]

Hi,

Could you please explain why E. is incorrect?

I'm reading this as:

Just because bulging/slipped disks doesn't bring about back pain, doesn't mean they don't cause back pain more often than not.

To me that seems to work? The author is saying that slipped disks can't induce back pain in people, but this answer choice would argue that actually, just because they didn't, doesn't mean it's not true that actually, more often, they do.

[AthenaDalton]

Hi Kristin,

Thanks for your question!

I read answer choice (E) a bit differently. When answer choice (E) says that the factor "does not bring about a certain effect," I interpreted that to mean that "slipped discs do not cause back pain." Answer choice (E) refers to a factor (slipped discs) being present more often than not when the effect (back pain) occurs, but doesn't claim that the slipped discs actually cause back pain. For example, they could be a frequently-appearing symptom of some third factor which is the true cause of the back pain.

In any case, since answer choice (E) states that slipped discs do not cause back pain, it is consistent with the doctor's argument that slipped discs are not a cause of back pain.

I hope that makes sense. Good luck studying!

Athena