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It is either section 4 or 5 depending upon whether yours includes an experimental section.

Either way, it is the last LR section of the test.

I am struggling with #19, with the doctor and his flawed reasoning.

I understand the concept of the stimulus. I felt he made two errors in the argument.

1) Just because somebody has a response of (X) to a stimulus (Y) does not mean that a different person would necessarily have the same response to the same stimulus.

In conjunction with the passage, just because these certain people did not feel pain with these conditions does not mean that other people would not experience pain. This could be a pain tolerance issue. I understand that it is a large group, but the stimulus does not rule out that a common trait among these people is that they have a high pain tolerance and do not feel pain.

2) The conclusion is very strong in stating that the conditions mentioned prior could not lead to serious back pain in people who do experience such pain. I see the doctor said "could not lead to..." which is definitely a red flag because we do not know what may or may not lead to something.

I chose answer choice (A) A factor that need not be present in order for a certain effect to arise may nonetheless be sufficient to produce that effect.

In other words, a factor (bulging or slipped disks) that need not be present in order for a certain effect to arise (serious back pain) may nonetheless be sufficient to produce that effect (serious back pain).

How is that not right?

PS: How stupid are the LSAT writers in #19??? Slipped DISKS? It's DISCS!!! Almost should throw the question out because I chuckled at their stupidity.

My first reaction to that conclusion was that the doctor concluded something about a group of people based on a different group of people. The people who were examined

Bump.

The problem with A is that in the sample none of the people experienced back pain and they did have slipped disks. A states that a factor (slipped disks) not be present for a certain effect to arise (back pain). For this to be correct we would have had to see people without slipped disks and experiencing back pain, and then conclude since you can get back pain without a slipped disk, clearly slipped disks can't cause back pain. So the second half of the answer is correct, but the first half is backwards from the sample.

---Sorry, edited. Needed more coffee.

I don't understand your first sentence, "The problem with A is that in the sample none of the people experienced back pain and they did have back pain."

The people in the sample did not have back pain yet you are saying they did. The first line in the stimulus establishes the lack of serious back pain.

And also, I read answer choice A like this now after studying it more.

A factor (slipped discs) that need not be present in order for a certain effect (serious back pain) to arise may nonetheless be sufficient to produce that effect (serious back pain).

I still can't discard this answer!

Please fix my reasoning on this: We have a doctor that is looking at people who have never had serious back pain. Half of these people have bulging or slipped discs in their spines! Ouch! I know I would experience pain! Well, the doctor concludes that since those people do not experience pain from those conditions, those conditions could not lead to serious back pain in people who do experience such pain.

Other people in the world would probably experience pain from that factor of slipped discs. So the doctor's argument is vulnerable due to a factor being able to sufficiently cause pain in other people. He is not viewing the people who have experienced serious back pain.

The flaw in the argument isn't that the doctor fails to consider people without a slipped disc. That's what A indicates, that the doctor's flaw is that he failed to consider that just because a slipped disc is not necessary to having back pain (need not be present), a slipped disc may still be sufficient to causing back pain. A slipped disc is clearly not sufficient, as indicated by the members of Group X.

The argument goes like this: Group X has condition Y and feels no pain. Therefore, condition Y can NEVER lead to pain.

That's why the correct flaw is B - just because condition Y may not cause pain in and of itself, that does not mean that condition Y cannot be partly responsible for the pain.

Bottom line: You can eliminate A on the words "factor that need not be present" as both the evidence in the argument and the conclusion drawn from that evidence concern those WITH that factor.

How sad is it that I actually pulled my LSAT status back up just to make sure I got this right back when I took the test? Anyway, I did! Yay!

Anyhow, the problem here is that A -could- be correct, but isn't proven correct by the text. None of the patients had back-pain and several had bulging "disks". So the passage says nothing about the possibility of bulging discs to be sufficient to produce back pain.

Now look at B. The passage says that these people with slipped discs do not have back pain, but does say that the condition is often blamed for serious back pain. Therefore we have proven that slipped discs alone do not necessarily cause severe back pain, which suggests that in these other cases they are working in tandem with another cause.

B states 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." First the passage proves that slipped discs are not necessarily sufficient to produce server back pain, then references that it is sometimes responsible for back pain. The issue that you are having is that you are using outside knowledge. The passage does nothing to speak of the veracity of the mentioned blame. It never states that it is a fact that slipped discs are sufficient alone to produce the effect of severe back pain. It only suggests that slipped discs are believed to be a factor in some cases. Because of this, you have to ditch A and go with B.

Seriously, forget everything you know regarding anything scientific when taking the LSAT. They love to try to trip you up by including passages that are obvious if you just look at the logic but really muddy if you inject outside information. The only facts that matter are the ones stated in the passage.