Blueprint LSAT Prep's ongoing ask-an-instructor extravaganza Forum

[BPlaura]

Hi all! I hope those of you who got scores yesterday got good news. For those who are still studying, I'm here til 5 to answer any questions!

[alecks]

I have another question from PT 46- section 2 #23
I choose D bc all of the other ones didn't match, but I saw the assumption as

Love someone -----> love anyone

But didnt know that the contrapositive of those both are no one? Or am I completely off the mark on this???

Thanks!!!!

[BPlaura]

I have another question from PT 46- section 2 #23
I choose D bc all of the other ones didn't match, but I saw the assumption as

Love someone -----> love anyone

But didnt know that the contrapositive of those both are no one? Or am I completely off the mark on this???

Thanks!!!!

You're very close here, but the assumption is actually:

loved by someone -------> love anyone

The contrapositive would be "if you don't love anyone, you aren't loved by anyone," which is what D gives us. This is a fairly common LSAT trick, where they try to get you to treat being loved BY someone and loving someone as the same thing, when in fact they're slightly different.

[BPlaura]

Greetings from chilly Boston! I'm holding Wednesday office hours a little earlier than normal today - taking questions til 5!

[BPlaura]

Hey y'all - hanging out til 4!

[mymrh1]

PT34, Section 2, Q2
PT33, Section 3, Q21

How to diagram these two questions? Thanks!

[BPlaura]

PT34, Section 2, Q2

I would actually recommend against diagramming this question - it's only going to slow you down, and the argument is easy to understand without diagramming. However, if you're curious about how it would be done...

efficient subway ----> good economic sense
good economic sense---> city should do
Therefore,
new subway cars are necessary

So, we can conclude from the stimulus that if it makes the subway efficient and attractive, the city should do it. The conclusion jumps to saying that new cars are necessary, so that must mean that new cars are necessary in order for the subway to be efficient/attractive.

PT33, Section 3, Q21

Another tricky one to diagram

international trade affects prices and wages
Therefore,
prosper ----> look beyond borders (can be rephrased as "look at international trade")

So we know that trade impacts the economy, but we haven't established that it's *necessary* to examine trade in order to be prosperous. The correct answer says that examining every significant influence is necessary for prosperity; since we know that international trade is a significant influence, A proves that examining international trade is necessary for prosperity.

[mymrh1]

Thanks for your explanations!

I have another question: PT39, S4, Q20. The problem I have with this question is answer choice B and E seem correct answers to me.

[BPlaura]

Sure thing. So the stimulus acknowledges that there is a correlation between good health and high education levels; the argument tries to conclude that informed lifestyle choices CAUSE good health. So it's clearly a correlation-to-causation fallacy; the answer choices are where it gets tricky.

We know that for this type of fallacy, it might be possible to reverse cause and effect, or it might be possible that something else causes both things. That's what (D) gives us. But you wanted to know why (B) and (E) are wrong.

The conclusion just says that good health is LARGELY a result of informed choices, so the conclusion already acknowledges that there are other potential contributing factors. B and E both try to act like the conclusion says that informed choices are the only cause of good health.

B says the argument has overlooked the people with inherited diseases, but that's not true - it doesn't explicitly talk about inherited diseases, but the argument never says or assumes that everyone who makes informed choices will have good health, so B is not a flaw that occurs in this argument. Same deal with E - the argument says that good health is mostly a result of informed choices, but it doesn't assume that everyone with good health has made informed choices, so E doesn't happen in the argument.

[jmjm]

Pt-71 LR2 Q21

Doesn't A weaken because chemicals don't reproduce scents perfectly; Is B wrong only because it weakens by not ruling out the alternate possibility that sulfur fumes may be damaging smell sense only temporarily and not permanently?

[BPlaura]

Doesn't A weaken because chemicals don't reproduce scents perfectly?

The problem with A is that even if the chemicals aren't a perfect reproduction, the control group still tested significantly better than the sulfur factory group. In order to weaken the argument, we would need to "explain away" that difference, which A doesn't do.

Is B wrong only because it weakens by not ruling out the alternate possibility that sulfur fumes may be damaging smell sense only temporarily and not permanently?

Yup. If you're testing the factory workers in their sulfur-emitting factory, you're introducing an environmental difference that might explain why they did worse than the control group. Maybe the sulfur fumes damage smell temporarily rather than permanently - maybe the smell of the fumes overpowers the scents being tested - either way, it's an alternate cause for the results of the study, so it weakens the argument.

[jmjm]

Doesn't A weaken because chemicals don't reproduce scents perfectly?

In order to weaken the argument, we would need to "explain away" that difference, which A doesn't do.

This question seems confusing to me as A does seem to weaken the study as "closely not perfectly" still carries the logical force of "no success" in replicating the natural scent. There are many weakness questions that don't fully explain away the difference. If an answer choice weakens the argument even slightly it's supposed to the right choice as the four other choices wouldn't weaken the argument at all. If A does explain away the difference in study results a bit, then doesn't it weaken the argument?

[BPlaura]

No, A doesn't weaken the argument at all. Even if the chemicals replicate natural smells "closely but not perfectly," the control group was still able to identify 50% of the scents, whereas the sulfur group was only able to identify 10% of the scents. Both groups were smelling the same scents, so even if the chemicals aren't an exact match to natural smells, to weaken the argument A would need to provide an alternate explanation for why the sulfur group performed significantly worse than the control group. If both groups are smelling the same chemicals that are close matches to natural scents, but one group identifies far fewer of the scents, it still seems pretty likely that that group's sense of smell is damaged.

"closely not perfectly" still carries the logical force of "no success" in replicating the natural scent.

I'm not sure I understand what you mean by this - "closely but not perfectly" is not logically equivalent to "no success." It means just what it says - that the chemicals are close but not a perfect match.

Also, there are very few answer choices that only weaken the argument a little bit - usually, when a student thinks an answer choice weakens the argument just a little bit, it's because they're making unwarranted assumptions based on that answer choice. An answer choice that weakens the argument will do so to a pretty significant extent.

Let me know whether that helps!

[BPlaura]

Here til 5:30 today if you have any questions!

[jmjm]

No, A doesn't weaken the argument at all. Even if the chemicals replicate natural smells "closely but not perfectly," the control group was still able to identify 50% of the scents, whereas the sulfur group was only able to identify 10% of the scents. Both groups were smelling the same scents, so even if the chemicals aren't an exact match to natural smells, to weaken the argument A would need to provide an alternate explanation for why the sulfur group performed significantly worse than the control group. If both groups are smelling the same chemicals that are close matches to natural scents, but one group identifies far fewer of the scents, it still seems pretty likely that that group's sense of smell is damaged.

"closely not perfectly" still carries the logical force of "no success" in replicating the natural scent.

I'm not sure I understand what you mean by this - "closely but not perfectly" is not logically equivalent to "no success." It means just what it says - that the chemicals are close but not a perfect match.

Also, there are very few answer choices that only weaken the argument a little bit - usually, when a student thinks an answer choice weakens the argument just a little bit, it's because they're making unwarranted assumptions based on that answer choice. An answer choice that weakens the argument will do so to a pretty significant extent.

Let me know whether that helps!

"Closely not perfectly" signifies that the chemical reproduction of scents doesn't match the actual scents fully. So it exposes a clear weakness in the conducted study and therefore the results deduced on its basis. Here is the way I saw this question. An analogous argument could be,
Study S uses M for evaluating a group X.
N reproduces M.
Study S based on M shows that a group X performed worse than the control group in doing task T.
Therefore, group X is bad at T.

If N does not fully reproduce M, which is critical in affecting the results of S, then it shows a flaw in the study. This weakens the study S and its results that were based on M. Any answer choice hinting at N not fully reproducing M will weaken the argument. This seems to be exactly what the answer choice A does in the question and so it seems to weaken the argument.

[BPlaura]

Okay. So I see what you're saying, but I think you're focusing too much on the "but not perfect" part when the most relevant detail is that the chemicals are a "close match." Sure, a perfect match would be ideal, but a close match implies that the chemicals smell very similar to the real thing. If the chemicals smelled nothing like the real thing, then the study would be severely weakened - but the fact that the chemicals are a close match actually supports the study because it means the chemicals are a pretty good reproduction.

[jmjm]

Okay. So I see what you're saying, but I think you're focusing too much on the "but not perfect" part when the most relevant detail is that the chemicals are a "close match."

It seems to depend on how close "close" is. Lsac inserted 'not perfect' to specifically rule out a full reproduction. "Close" can mean the logical force of "most" but not "all" in which case we know that the reproduction of scents at worst is just over 50% and at best 99%. Still, it introduces a flaw in the study. Lsat weaken questions ask us to attack such flaws so only one answer choice will weaken to any extent the argument. For weaken-except, only one choice will not to any extent weaken the argument. It just seems like a bad question to me.

[BPlaura]

Yeah, I definitely understand where you're coming from, although I don't fully agree. (I'm glad we're having this discussion, though, since it's made my afternoon much more interesting!) My counter-argument would be that knowing that it's "close" is good enough to know that the chemicals are substantially representative of the natural scents.

One other nit-picky thing...

"Close" can mean the logical force of "most" but not "all" in which case we know that the reproduction of scents at worst is just over 50%.

I disagree that this is how you should understand "close" - it's not exactly equivalent to "most." Since "close" is relative, it's hard to pin an exact definition to it, but most people would agree that, say, 51% is not "close" to perfect. You have to take "close" at face value here, meaning very similar but not exact.

[alecks]

I have some questions about PT 63, June 2011, the first LR Section.

14) I chose B, can you explain why this is wrong? I had it narrowed down to B & D but I still chose B.

15) I had a hard time with this question, and also had to narrowed down to E & D (chose E)

18) I misread this stem / for some reason was confused by it, but I was trying to strengthen the fact that it was misrepresented... Can you explain the question stem?

25) can you explain why C is wrong?


Thank you!!!!

[BPlaura]

Hey, gang - I'm taking questions til 5ish today!

I have some questions about PT 63, June 2011, the first LR Section.

14: B is wrong because Waller never actually says whether something can be proven to all skeptics. He says that ESP would be accepted by the general public but he doesn't say whether everyone will accept it, so he doesn't express an opinion on that point.

15: So D says:
capable of sincerely apologizing to someone ----> owes that person an apology.

The problem is that although Hagerle sincerely apologized to the doctor, we don't know whether she's capable of sincerely apologizing to the counselor, so D doesn't actually affect the counselor's conclusion.

E says:
can't sincerely apologize to all others ----> shouldn't apologize

That doesn't help because the counselor isn't trying to prove that Hagerle shouldn't apologize. Let's see if the contrapositive is any more helpful:
should apologize ---> can sincerely apologize to all others

But the counselor is trying to prove that Hagerle should apologize to her. This answer choice says IF you should apologize, THEN you can also do something else, but it still hasn't helped us establish that she should apologize!

Contrast that with C, the right answer:
already apologized to someone else ----> someone is owed an apology

Our argument has already told us that the sufficient condition (apologizing to someone else) has been met. This means that it's necessary that someone else is owed an apology, which would mean that the counselor is right.

18: This is a strengthen question - it asks you to "justify the application of the principle," so you're trying to make it seem like it was correct to use the principle in that specific application. The application says that the vase was misrepresented, so we are trying to strengthen that conclusion. It sounds like you interpreted the question stem correctly, actually. Let's take a look at the rest of the question:

The principle is:
tries to mislead ---> guilty of misrepresentation

The application says that the vase was misrepresented because it was described as being old when it was actually a modern reproduction. However, in order to prove that the auction house was guilty of misrepresentation, we need to know that they were actively trying to mislead customers. E supplies that information - they wrote the description of the vase with the sole goal of increasing the price.

25:
The counselor's argument says:

change --> motive
unpleasant criticism --> motive
harsh criticism --> unpleasant criticism (--> motive)

therefore, change --> harsh criticism

His flaw is that he's established that harsh criticism is one way to meet the necessary condition for change, but there could certainly be other ways to supply a motive, so he hasn't established that harsh criticism is NECESSARY for change - just that it can lead there.

So C says he assumes that everyone who is motivated to change will change, but notice that the argument is only ever talking about what is NECESSARY for change - he never assumes that meeting the necessary condition will lead to change.

Let me know if you have additional questions about any of these!

[BPlaura]

Holding down the fort til 5:30 or so!

[mymrh1]

Pt71 Section 1 Q12

Not sure why (C) and (D) are incorrect in view of (B). I guess all three strengthen, but in different degrees?

Pt71 Section 3 Q20

Not sure why (A) is not a correct answer. A good friend or family member seems to be a small sample size. I know (B) is a good answer choice.

[BPlaura]

Pt71 Section 1 Q12

Not sure why (C) and (D) are incorrect in view of (B). I guess all three strengthen, but in different degrees?

The argument itself is pretty straightforward here: global warming will cause warmer temps, which will lead to more rain. Therefore,
(1) the snowpack will melt earlier, leading to
(2) more spring flooding, and
(3) less storable water.

Notice that this is a causal conclusion. As a reminder, a causal conclusion can be strengthened with same cause/same effect, no cause/no effect, or by eliminating alternate causes.

There is one BIG problem with both (C) and (D) - they both just describe correlations. (C) says that, in other areas of the Rockies, warmer temps are correlated with less storable water - but that does nothing to establish that the warmer temps are actually causing the water shortage. Similarly, (D) says mild winters are correlated with less storable water and with flooding, but again, we have no way of knowing whether the warmer temps are CAUSING those two things. We can't use correlations to support a causal argument, so (C) and (D) do nothing.

Let's contrast those with (B). First of all, whereas (C) only mentions storable water and (D) only mentions storable water and flooding, (B) talks about all three of the things that are mentioned in the conclusion of the stimulus. That should catch your eye right away. But more importantly, (B) says that the melting of the snowpack has LED TO flooding/less storable water, so it's establishing the causality that is lacking in the stimulus. It's same cause/same effect, which is why it strengthens the argument.

So I understand why (C) and (D) are tempting, but because they're just discussing correlations, they actually don't strengthen the argument at all. ( B), on the other hand, is same cause/same effect, which we know is a good way to strengthen a causal argument.

[BPlaura]

Pt71 Section 3 Q20

Not sure why (A) is not a correct answer. A good friend or family member seems to be a small sample size. I know (B) is a good answer choice.

I'd be willing to bet that a ton of people had the same thought process as you on this one.

Taylor sez that friends and family know what one is thinking so often that it can't just be coincidence. Therefore, telepathy is possible between people with close psychic ties.

Notice that we actually have no idea how big her sample size is. She doesn't give any indication of how many people she's observed, and she doesn't even say that she's talking about her own friends and family - she just says "From observing close friends and relatives, it is clear to me...," which means it's possible that she's been observing other people with their close friends and relatives. For all we know, she's a big-shot researcher who has done a huge study on this.

(B), on the other hand, addresses a problem with her argument that is true no matter how many people she's observed. (It's not these close friends/relatives are reading each other's minds; it's that they know each other well enough to be able to interpret and understand the other's nonverbal cues. This is true for all instances, as the answer choice says, and is also a huge problem with her argument whether she's studied ten people or ten thousand.)

HTH - let me know if you have any additional Qs. I haven't looked at PT 71 too closely yet so it's fun to delve into it with you guys!

[BPlaura]

Coming to you live from a Bolt Bus (technology, eh?). Here til 5!