2017 Logical Reasoning Bible Question 2 Page 287

[johnawysham]

The question reads as follows: "Most antidepressant drugs cause weight gain. While dieting can help reduce the amount of weight gained while taking such antidepressants, some weight gain is unlikely to be preventable."

If you turn to page 290, the 2017 LRB states "Answer choice (C): This is the correct answer. Some individuals taking antidepressants that cause weight gain will gain weight even though dieting can reduce the amount of the gain."

But answer C as given on page 287 reads "(C) At least some patients taking antidepressant drugs gain weight as a result of taking them."

And here problems arise. Note carefully that the answer on page 287 characterizes the antidepressant drugs in general terms thus --- "antidepressant drugs" --- while the answer given on page 289 narrows the antidepressant drugs to "antidepressants that cause weight gain". Obviously the version on page 289 is not a faithful copy of the answer we students see on page 287, which is problem number 1. And problem number 2 is that given the premise in the first sentence of the question, there must exist antidepressant drugs that DO NOT cause weight gain (since "most" but not all antidepressant drugs cause weight gain). And, should patients take antidepressant drugs that do not cause weight gain, therefore the conclusion " at least some patients taking antidepressant drugs gain weight as a result of taking them" would not be true.

Why, firstly, is the answer as shown on page 289 a narrower description of antidepressant drugs than the answer we read on page 287 and, secondly, since only most antidepressant drugs cause weight gain and therefore some do not, why is it true to claim that "at least some patients taking antidepressant drugs gain weight" when the antidepressant drugs patients take could be the type that DO NOT cause weight gain and so the patients would not gain weight?


Canada John

[Dave Killoran]

Hi John,

Thanks for the questions! Let's look at both of them and see if I can't help make you feel more comfortable with this question. I'll quote your questions below to make it easy to see what point I'm addressing in each case.


1. "Why, firstly, is the answer as shown on page 289 a narrower description of antidepressant drugs than the answer we read on page 287?"

This is a question that has come up before, and so first I'm going to quote the response of one of my PowerScore colleagues, Jonathan Evans, and then I'll add some thoughts as well. In the quote below, the first paragraph is an explanation of why the answer is correct, and the second paragraph contains an explanation of the specific wording you reference and thus is the part you should focus on for this discussion:

• "The only way to know that most antidepressant drugs cause weight gain is if such weight gain has been observed more than once among patients taking them. According to the stimulus, such weight gain might be mitigated by dieting but is unlikely to be eliminated entirely. These statements provide ample evidence to know definitively: "At least some patients taking antidepressant drugs gain weight as a result of taking them." Answer choice C with its weak language and direct evidence is a classic credited response for a Must Be True question, irrespective of the particularities of the wording of the question stem.
  
  The answer explanation does not misquote the answer choice but rather elaborates upon the logical connections that lead (C) to be the credited response. As noted above, the fact that we know that "most antidepressant drugs cause weight gain" along with the fact that "some weight gain is unlikely to be preventable" ipso facto gives us proof that "some patients taking antidepressant drugs gain weight as a result of taking them!" There were at least some patients who took these drugs and gained weight."

What I've done here is simply reword the concept, not change it entirely or narrow in an unreasonable fashion. Here's what we know from the stimulus: "Most antidepressant drugs cause weight gain." If that's the case, that means there are "antidepressants that cause weight gain," and consequently someone who takes those particular antidepressants will gain weight. Answer choice (C) states that, "At least some patients taking antidepressant drugs gain weight as a result of taking them." Yes, this has to be the case because some of those antidepressants cause weight gain (most of them do, actually), so when a patient takes them, they gain weight.

Consequently, when I say that "Some individuals taking antidepressants that cause weight gain will gain weight," it adds the element that explains why they gain weight. Basically, all I've done is take what they told us and stated in slightly different terms, but those terms are the same in meaning; I've just added the part that makes it why the weight is gained.

Now, there are two things that follow here that I believe are useful for you as a test taker. First, the LSAT constantly rewords and rephrases ideas, so this is something you will see multiple times on every single exam. You are clearly tuned into that idea already (even though in this case it's something I wrote, it shows that you are tracking this issue already) and so keep focusing on this idea and watching how they rephrase ideas—it will pay dividends over time. Second, it's good that you are tracking details at this level already. It's really hard to do in general, but these are the details that can make a difference. Just watch out for what is something truly different or new vs something that falls under the umbrella of the idea or sates a piece that exists but wasn't previously stated. the former situations would cause an answer in a Must question to be wrong, but the latter wouldn't.


2. "Since only most antidepressant drugs cause weight gain and therefore some do not, why is it true to claim that "at least some patients taking antidepressant drugs gain weight" when the antidepressant drugs patients take could be the type that DO NOT cause weight gain and so the patients would not gain weight?"

A very detailed discussion of "some" and "most" is coming in Chapter 13 (amazingly enough, even though we all use those words daily, their meaning on the LSAT is different from how most of us use those words), and so for now I'm going to refer you to a few sections of that chapter so you can see how the word "most" doesn't automatically imply "just a portion":

• A. Please take a look at page 402, at the bottom in the section "Relationships involving Some"
  
  Note the definition there: "The word “some” can be defined as at least one, possibly all."
  
  B. Please take a look at page 404, at the top in the section "Relationships involving Most"
  
  Note that definition as well: The word “most” can be defined as a majority, possibly all." I've added bolding here to emphasize a key point, because I believe you are saying that because "most" do, then automatically some do not. That is not known to be the case for certain simply form the "most" because "most" could mean "all."

Now, interestingly, that's not really key to (C) here, so I'm only mentioning it to you as a matter of general interest. Instead, the key point is that we are talking about all patients taking antidepressants, and what we know is that most of those antidepressants cause weight gain, so inevitably there are cases out there where someone took an antidepressant and gained weight (because they took one of the antidepressants that cause weight gain. In other words, there's no way in this circumstance to avoid some weight gain cases because (C) references "patients taking antidepressant drugs," and in that group most are taking antidepressants that cause weight gain. Unfortunately, I'm running out of time this evening or I'd create an analogous case to make this clearer, but I'll leave this here for now, and then if it still doesn't make sense, I'll add more to the explanation tomorrow.

One helpful point is that you know (C) is right, so you can look at it and try to figure out what the test makers were thinking. In other words, how do they justify (C) being the correct answer? If we can learn that, we can become better at figuring our other correct and incorrect answers, and so that what my explanations attempt to do, explain what the test makers are thinking.

Please let me know if this helps, thanks!

[johnawysham]

I accept the explanation you offer, Dave. Thank you for your time and patience and encouraging language. Shortly after posting my question I saw the 'error of my ways'. The error is that I, for some reason, thought of a situation where some patients took the type of antidepressant drugs that DO NOT cause weight gain (such drugs exist) and then, focusing on just this narrow type of patients, concluded that in this case it would not be true that 'at least some patients taking antidepressant drugs gain weight'. My mistake, clearly, is in reducing the body of patients to a special body of patients that took only this type of antidepressant. I should have properly considered the patient body to be all patients taking antidepressants. Doing so, I would have immediately agreed that some patients taking antidepressant drugs gain weight. My question, before I thought further about it, probably resulted from not knowing the "language" of the LSAT stem properly and, further, from over analyzing the situation. I have already had a second career and believe my greatest challenge in preparing for the LSAT is going to be learning not to lean on old habits but rather to approach learning the LSAT lingo with an open mind, a tabula rasa. Again, thank you for your patience and encouragement. I am really enjoying your book and learning much along with way. Best, John

[Dave Killoran]

Hi John,

Thanks for the reply—I really appreciate it, and I'm also glad I was able to help out here!

I really like what you said about not leaning on old habits. A lot of people preparing for this test don't think about points like that, and so the fact that you are actively doing so is a great sign! I kind of addressed that idea in an article I wrote a while back, and you might find it interesting since it talks about the way to think about these questions: http://blog.powerscore.com/lsat/you-can ... h-the-lsat (by the way, I didn't see you as so much arguing with the test but more taking issue with how I worded something and then wondering about their answer justification; but the article contains ideas that I think you will find interesting based on what you said in your last message).

Thanks again, and I get the feeling I may see a few more questions from you as you work through the books. I look forward to it!