LSAT Q&A: Ask the Experts Forum

[LSAT Blog]

If you guys had to offer just one piece of advice for the Logical Reasoning section, something that encompasses your entire approach the section, what would it be? I know that's probably a tough question considering people have written whole books on the subject, but I assume these will be on the general side of things. Thanks!

These are all along the same lines, so I'll count them as "one piece of advice":

-Be critical and skeptical of every argument
-Consider potential alternative causes for any result
-Consider potential alternative explanations for any conclusion
-Develop obsessive attention to detail
-Have fun

[wanderlust]

Hey, wanderlust,

Here, notice that the claim about vulnerability is a subsidiary (or intermediate) conclusion. This is the gap the test writers are exposing with (D) - the distance between the lack of education and the vulnerability of the populace. In classic Necessary Assumption fashion, negating (D) ruins that conclusion.

The difference is that here, the conclusion being ruined isn't the main conclusion.

This points out for us the possibility that a weakness may appear anywhere within a passage - any time two ideas are not explicitly linked, we have a flaw; even between evidence and a sub claim based on that evidence.

Thanks so much Dave!

[bp shinners]

Question about 44.2.14:

I have evaluated this question and understand why each of the answers is credited/incorrect. However, I am looking for a little clarification on the difference between inference questions that ask you "Which one of the following must be true/cannot be true" and questions that ask "Which one of the following inferences is most strongly supported by the information above?

For the other experts, how do you approach these two different types of questions?

We call the former Must Be True (MBT) questions, and the latter Soft Must Be True (~MBT) questions.

MBT questions require absolute certainty in the answer choices. You better be willing to bet your life on the answer choice because of how certain you are; no wiggle room.

~MBT questions require a slightly lowered level of certainty (call it 99%). While not always (since some ~MBT answer would be correct in a MBT question as well), you can sometimes explain how the credited response isn't something that must be true. However, that explanation usually defies credulity, or it requires bending over backwards to explain away.

While taking the test, it's probably not going to affect you much in analyzing the answers to think of them requiring this difference in logical certainty. However, it greatly affects how you should approach the stimulus.

MBT questions will be diagrammed ~50% of the time; ~MBT questions will be diagrammed ~10% of the time. That 10% for ~MBT also mostly comes from the ~MBT principle questions ("Which of the following most closely conforms to the principle stated above?").

For MBT questions, I generally like weaker answer choices, but I'll quite often have enough logical force in the stimulus to pick a strong answer choice (especially if I diagram). For ~MBT questions, I almost universally want to pick a weak answer choice.

For ~MBT questions, there will also often be a statement in the stimulus that carried significantly more logical force than the rest of the premises. This strong statement usually plays a role in selecting an answer choice.

Hope that helps!

[Easy-E]

If you guys had to offer just one piece of advice for the Logical Reasoning section, something that encompasses your entire approach the section, what would it be? I know that's probably a tough question considering people have written whole books on the subject, but I assume these will be on the general side of things. Thanks!

These are all along the same lines, so I'll count them as "one piece of advice":

-Be critical and skeptical of every argument
-Consider potential alternative causes for any result
-Consider potential alternative explanations for any conclusion
-Develop obsessive attention to detail
-Have fun

As a retaker who lives at the beach, you're pushing my limits Steve

Thanks for the tips!

[outlookingin]

OK I've got one, and I'm really curious to see how this pans out:

PT 62 S4 Q24 - Arthritis Sufferers and the Weather

I just read over the whole MLSAT thread on this and what I'm gathering from mshermn's remarks is:

The reason (B) is wrong is because the premises do not support the inference that the beliefs of the arthritis sufferers are causing their increased pain intensity.

But I don't follow that.

The stimulus clearly states that the sufferer's beliefs are playing a part in what they feel is a genuine causal relationship. They are "convinced of the existence of such a correlation [between the weather and their pain]" and, thus, they gave accounts of feeling increased pain intensity when the relevant feature of the weather occurred. In my mind, their beliefs are affecting their assessment of the intensity of that pain.

Earlier in that thread it was suggested that the problem was with "assessment of the intensity of that pain" not being equatable to the sufferer's feeling "increased intensity of pain." Could that be it?

Oh no I'm so twisted... HELP!

My problem with answer choice B is that it mixes up what's going on in the heads of the arthritis sufferers.

In their heads, they have an increase in the intensity of pain in their knee. From that, they conclude that it's going to rain in three days. The beliefs about the intensity of their pain is affecting their assessment of what is going to happen in the future, i.e. it's going to rain. Answer choice B creates a situation where they know it's going to rain in 3 days, and therefore that affects how they assess their pain today. It's reversing the causal relationship purported by these people to exist.

On top of that, the study is clearly meant to discredit the belief that arthritis sufferers can predict the weather ("it tried but failed to find any correlation"). For these 'fill in the blank' questions, I'm not trying to jump that far away from the stimulus and make additional deductions. I'm just trying to, more or less, sum up the ideas we've already discussed. Answer choice B seems to feed into the arthritis sufferers' beliefs; answer choice C reflects that the study indicated that they're imagining it. C is completely in line with what the study showed, and it combines my two ideas (we didn't find any proof; arthritis sufferers still believe it), making it the perfect completion to the argument.

Thanks to you (and Timmy, I just don't know how to double quote...) I think I get this now. I especially like the part where I have to take into account the fact that they "tried by failed to find any correlation." Silly me for now seeing that before. Thanks again!

[timmydoeslsat]

From PT 29-4-21, the weaklings, cowards flawed parallel question...how would you diagram "few cowards fail to be fools."

This argument can be seen as:


W some C
C (most/some) F
____________
W some F

When I see the phrase few A fail to be B, I believe I am being told that A most B. The word few can cause issues in terms of logic. By stating few, I believe you are telling me that the majority are not.

In the context of this question, which I have done many times before, the flaw is inferring commonality between quantifying statements that give no justification to believe there is overlap between them. So I am fine with the answer choice of C.

If you do not mind, I would like to give you a statement. This statement, in my opinion can be interpreted in different ways.

Few people take the bus.

P some B

P most ~B


Which would you choose and why.

[Manhattan LSAT Noah]

From PT 29-4-21, the weaklings, cowards flawed parallel question...how would you diagram "few cowards fail to be fools."

This argument can be seen as:


W some C
C (most/some) F
____________
W some F

When I see the phrase few A fail to be B, I believe I am being told that A most B. The word few can cause issues in terms of logic. By stating few, I believe you are telling me that the majority are not.

In the context of this question, which I have done many times before, the flaw is inferring commonality between quantifying statements that give no justification to believe there is overlap between them. So I am fine with the answer choice of C.

If you do not mind, I would like to give you a statement. This statement, in my opinion can be interpreted in different ways.

Few people take the bus.

P some B

P most ~B


Which would you choose and why.

Few people fail to despise that coward question.

In terms of your final question, about the bus, I think you're asking the wrong question -- shouldn't we discuss what "few people fail to take the bus" means? If few people fail to take the bus, then I know for sure that some do. It's tough to say that it definitely means most do since "few" and "a few" are pretty close (and, a few people can be most if the total population is, say, 4). And, most importantly for LSAT prep, inferring "some" is good enough for this question.

In terms of your actual bus question, for the LSAT, I'd go with door #1, but in real life, when I'm hanging with normal people and not trying to be a real jerk-nerd (jerd?), I'd go with door #2.

Here we are again, Timmy, at the fringes of logic and LSAT prep!

[shifty_eyed]

Crossposting this here and in the June LSAT prep thread

Is there a typo in the Cambridge Logic Games by type book (volume 2)?

Page 56 (PT34-S4-G4) says
Edited

The rules at the beginning state that each doctor is at exactly one of two clinics: Souderton or Randsborough.

Perhaps I am just having one of those days, but I don't see how it it is possible to place Onawa in only one place if Longtree is at Souderton.

f you have PT 34 handy and could check the rules on this game, I would appreciate it. Alternately, if you could explain how the set up for those rules would work, please do.

[LSAT Blog]

PT34-S4-G4:

The rules at the beginning state that each doctor is at exactly one of two clinics: Souderton or Randsborough.

Perhaps I am just having one of those days, but I don't see how it it is possible to place Onawa in only one place if Longtree is at Souderton.

f you have PT 34 handy and could check the rules on this game, I would appreciate it. Alternately, if you could explain how the set up for those rules would work, please do.

Not a typo - just a nasty game with a big twist.

Here's what my diagram looks like (at first):




Since Ls requires impossible things (every variable being in both places simultaneously - It even requires itself to be at r), Ls itself must be impossible.

Once you realize that, you can cross out Ls.

Since Pr -> Ks and Os, we can simply say Pr -> Ks because Ks indirectly leads to Os anyway. Because the Pr -> Ks and Os rule is redundant, so is the contrapositive of it, and we can simply say that Kr -> Ps.

(btw, please edit your post to remove the rules themselves - LSAC doesn't want people posting text from questions online without a license.)

[timmydoeslsat]

In terms of your final question, about the bus, I think you're asking the wrong question -- shouldn't we discuss what "few people fail to take the bus" means? If few people fail to take the bus, then I know for sure that some do.
Here we are again, Timmy, at the fringes of logic and LSAT prep!

Few people fail to take the bus

I believe I can infer also that P some ~B
I believe I can infer that P some B

Perhaps if language appears such as few people fail to take the bus...I know that some people do take the bus and some people do not take the bus.

I believe both ways of diagramming are appropriate, however the question of PT 29-4-21 would require you to diagram it as P some B, rather than the P some ~B way.

Thanks for help Noah.

[BlackadderIn]

Thanks to all Gurus for taking your time and thanks MLBrandow for establishing this thread!

I have a question about PT44 S4 Q20. I understand that B is correct, but I don't get why D is wrong.

The research data suggest a correlation between the gene variant and impulsive behavior in children. The conclusion is about a causal relationship between the variant and thrill-seeking behavior (TS) that has been identified as adult behavior in the first sentence. But if the individuals who have thrill-seeking behavior as adults are not the same ones who have impulsive behavior as children, there can be no correlation established between TS and that gene variant, even less a causal relationship??

and I thought a Q20 would require you to read into all the details in wording?

thanks!

[MLBrandow]

8.1.20 - Choose a principle justifying either A's position or B's position.

Matthew Sherman of MLSAT describes this question on the mlsat forum as "an open-ended priniciple question." I think that's a great way to describe it, but I'm curious:

Are there other examples of this particular brand of principle question on the LSAT in more recent tests? I recall seeing this before, but remember it being in another older test.

Is this a type of question I should take special care to practice with, or is it antiquated? It certainly took me a while to get to the answer.

Thanks for your reply!

[bp shinners]

8.1.20 - Choose a principle justifying either A's position or B's position.

Matthew Sherman of MLSAT describes this question on the mlsat forum as "an open-ended priniciple question." I think that's a great way to describe it, but I'm curious:

Are there other examples of this particular brand of principle question on the LSAT in more recent tests? I recall seeing this before, but remember it being in another older test.

Is this a type of question I should take special care to practice with, or is it antiquated? It certainly took me a while to get to the answer.

Thanks for your reply!

I can't think of any recent examples off the top of my head. It also seems to have the air of an older test-type question. Honestly, though, it's the same as a regular Justify question (we call them strengthen principle questions), only you have to keep track of more info. I wouldn't expect to see one on game day, but I also wouldn't panic if I did and had never practiced it - you already have the tools if you could find a principle that justified one of their actions.

[timmydoeslsat]

45-1-24: DNA samples

This stimulus hinges on one's understanding of this sentence, "Although every person's DNA is unique, DNA tests often fail to distinguish among DNA samples taken from distinct individuals."

I would like clarification on this stimulus and how to interpret it.

The way I understand it is that we have DNA tests attributing two samples of different DNA to the same person.

[Jeffort]

Thanks to all Gurus for taking your time and thanks MLBrandow for establishing this thread!

I have a question about PT44 S4 Q20. I understand that B is correct, but I don't get why D is wrong.

The research data suggest a correlation between the gene variant and impulsive behavior in children. The conclusion is about a causal relationship between the variant and thrill-seeking behavior (TS) that has been identified as adult behavior in the first sentence. But if the individuals who have thrill-seeking behavior as adults are not the same ones who have impulsive behavior as children, there can be no correlation established between TS and that gene variant, even less a causal relationship??

and I thought a Q20 would require you to read into all the details in wording?

thanks!

The problem with answer choice (D) is that it does not specify any specific type of behavioral tendencies. It just says 'behavior tendencies' without giving any indication of what type the answer choice is referring to.

The statement is so general that it could be talking about any type of behavioral tendencies many adults have that they did not have as children, such as doing your own laundry, keeping the bedroom and bathrooms clean, keeping fresh food to eat stocked in the refrigerator, etc.

To tether it together with the behavioral tendencies the argument and conclusion specifically focuses on and tries to link together (impulsive as a child to thrill seeking as an adult) because of a common cause, the gene variant, you have to add on the unwarranted assumption that answer choice (D) is talking about thrill seeking behavior and impulsive behavioral tendencies.

Making that assumption is unwarranted due to how vague and general the answer choice is about what it is talking about.

Many tempting trap answers on weaken and strengthen questions temp you to add on an unwarranted/unsupported assumption/inference that is not supported by the material in the stimulus, in the text of the trap answer or by reasonable common sense applied to interpretation of any of the text in context.

It's a common construction tactic used by LSAT question writers to give you an opportunity to attribute more meaning to what an answer choice says and means than it actually does, especially given the short time you have for each question in order to test attention to detail and how well you are actively reading and scrutinizing the meaning and substance of what each statement really means and logically establishes.

With this one, by the time you get to (D) (or have read all 5 answer choices, which you always should unless running out of time), you've read the word 'behavior(al)' multiple times in several different places, and if not being really anal with literal analysis of what it is referring to in each instance, it's really easy for your mind to just assume that (D) is specifically talking about impulsive behavior by children and thrill seeking behavior by adults even though it doesn't.

This question is a good example of how the DH 'load bearing language' strategies to select an answer choice when down to two will likely insure selection of several incorrect answer choices per logical reasoning section that will cause one to score somewhere below 170 or even below 165+

Notice the logical force of the correct answer choice (B), it's 100% rock solid with logical force, 'it is NOT POSSIBLE', whereas the main trap answer (D) uses what he calls 'middle language' with the word 'many'.

Just thought I would point that out for people seriously looking to achieve a ~165+ or even 98-99th percentile score. There are plenty of other examples in the LR sections of every administered test that do not conform to the 'load bearing level' of how the correct answer choices are phrased per question type gimmicks Mr. Hall preaches to use to avoid doing 'analysis'. Use at your own risk if you are shooting for a 90th percentile score or higher.

[Paraflam]

Could someone please explain 45.1.12? I chose (E) since there seemed to be a shift in language from "reproductive abnormalities" to "concentration of hormones." I realize that this doesn't directly address the conclusion (that dioxin is unlikely to be the cause), but I don't see why the rate at which dioxin is carried downstream undermines the conclusion, either. I read (C) and thought "who cares" and moved on. So I'm also interested in someone's thoughts about how this answer choice should've jumped out as the correct answer, so that I'm prepared for a similar type of question in the future. Thanks in advance!

[suspicious android]

Could someone please explain 45.1.12? . . . I read (C) and thought "who cares" and moved on. . . Thanks in advance!

If you google "LSAT dioxin" you'll see that this is one of the most contentious and difficult questions ever. (not suggesting you should have googled first, just pointing out how many people thought this question was ridiculous)

Anyway, it's a great question, really throwing the reader off track with the lots of extraneous detail. But when you boil it down the essentials, you have a very simple argument:

Some fish near the mill are sick getting sick when the mill is operating. But dioxin's probably not making them sick, because dioxin lasts like 1000 years, and the fish actually get better in a day or two when the mill shuts down.

Note that the only evidence in support of the argument is that dioxin lasts a very long time in the environment. So for his argument to have any hope of being valid, that evidence needs to be relevant. And based on just the information in the stimulus, it seems like a plausible defense. If dioxin were the cause, the fish should probably stay sick for a long time, since dioxin lasts so long. Maybe it's more likely to be a poison that only lasts a few days. However, the credited response on this question does a great job at making that single premise irrelevant. If dioxin is carried downstream by currents so that it is only present in the area near the mill for a few hours, then who cares if it lasts 1000 years? That single defense of dioxin is now essentially useless, and there's nothing left to support our conclusion.

tl;dr version: the fish are getting sick but it's not dioxin's fault because the fish get better in like 2 days and dioxin lasts 1000 years. Oh, dioxin is only present in the area for like 2 days? Nevermind, it could be dioxin.

[BlackadderIn]

Thanks to all Gurus for taking your time and thanks MLBrandow for establishing this thread!

I have a question about PT44 S4 Q20. I understand that B is correct, but I don't get why D is wrong.

The research data suggest a correlation between the gene variant and impulsive behavior in children. The conclusion is about a causal relationship between the variant and thrill-seeking behavior (TS) that has been identified as adult behavior in the first sentence. But if the individuals who have thrill-seeking behavior as adults are not the same ones who have impulsive behavior as children, there can be no correlation established between TS and that gene variant, even less a causal relationship??

and I thought a Q20 would require you to read into all the details in wording?

thanks!

The problem with answer choice (D) is that it does not specify any specific type of behavioral tendencies. It just says 'behavior tendencies' without giving any indication of what type the answer choice is referring to.

The statement is so general that it could be talking about any type of behavioral tendencies many adults have that they did not have as children, such as doing your own laundry, keeping the bedroom and bathrooms clean, keeping fresh food to eat stocked in the refrigerator, etc.

To tether it together with the behavioral tendencies the argument and conclusion specifically focuses on and tries to link together (impulsive as a child to thrill seeking as an adult) because of a common cause, the gene variant, you have to add on the unwarranted assumption that answer choice (D) is talking about thrill seeking behavior and impulsive behavioral tendencies.

Making that assumption is unwarranted due to how vague and general the answer choice is about what it is talking about.

Ahhhh! Thanks Jeffort --- I think I got it. D CAN/COULD weaken but far from necessarily so, whereas B weakens for sure! Somehow I didn't understand D correctly and took it as if it would say "ALL childhood tendencies are different from adult behavior". Thanks!

Many tempting trap answers on weaken and strengthen questions temp you to add on an unwarranted/unsupported assumption/inference that is not supported by the material in the stimulus, in the text of the trap answer or by reasonable common sense applied to interpretation of any of the text in context.

It's a common construction tactic used by LSAT question writers to give you an opportunity to attribute more meaning to what an answer choice says and means than it actually does, especially given the short time you have for each question in order to test attention to detail and how well you are actively reading and scrutinizing the meaning and substance of what each statement really means and logically establishes.

If you or anybody else can post some other similar examples here, I would be very grateful! Thanks in advance!

[Paraflam]

Could someone please explain 45.1.12? . . . I read (C) and thought "who cares" and moved on. . . Thanks in advance!

tl;dr version: the fish are getting sick but it's not dioxin's fault because the fish get better in like 2 days and dioxin lasts 1000 years. Oh, dioxin is only present in the area for like 2 days? Nevermind, it could be dioxin.

Ohhh, I see now. Wow, that's a fucking difficult question. I guess what threw me off was the language shift, I was all focused on looking for that as an answer choice. But there's no way I could've anticipated what the actual answer was.

Thanks for your help!

[timmydoeslsat]

I would like to know what the experts think on this issue.

A ---> B
W
_________
~A

Would you consider there being a necessary assumption with this argument?

Do you believe that the W ---> ~B link is necessary? Or do you simply consider it one of several sufficient ways to make this argument valid?

[thestalkmore]

I would like to know what the experts think on this issue.

A ---> B
W
_________
~A

Would you consider there being a necessary assumption with this argument?

Do you believe that the W ---> ~B link is necessary? Or do you simply consider it one of several sufficient ways to make this argument valid?

--ImageRemoved--

[timmydoeslsat]

I kindly ask you to stop these antics in threads that I post in.

It is my opinion that an argument that gives you a conditional statement, A ---> B, and then gives you a situation of W existing, only to conclude that ~A...it seems as if the argument as given necessarily relies on the idea that W leads to ~B.

[thestalkmore]

I kindly ask you to stop these antics in threads that I post in.

[Jeffort]

I kindly ask you to stop these antics in threads that I post in.

It is my opinion that an argument that gives you a conditional statement, A ---> B, and then gives you a situation of W existing, only to conclude that ~A...it seems as if the argument as given necessarily relies on the idea that W leads to ~B.

Timmy,

This topic you seem obsessed with was beaten to death in the other thread you started. Please don't litter this good thread with the same issue you've already asked about over and over that has been answered over and over.

FYI, not all LSAT questions, especially not necessary assumption questions, are based on formal deductive logic. Many of the LR arguments employ inductive logic. The correct answer choice for an LSAT necessary assumption question only needs to be something required so that the proffered conclusion CAN BE true to make a decent inductive argument based on the premises offered and will rarely be something that guarantees the conclusion to deductively must be true when combined with the premises offered in the stimulus.

You keep just focusing on this topic in terms of deductive conditional logic argument structures about conditional premises and proving that the conclusion MUST BE TRUE, which is great for sufficient assumption questions, but not for necessary assumption ones.

Necessary assumption questions are asking for something that, if not true, the conclusion, based on the premises offered, has no chance of being logically supported by them/of it being a good/decent argument with good support and reasoning. Simple analogy, in football you need possession of the ball to score a touchdown, but having possession of the ball does not get you into the end zone for a touchdown.

In many necessary assumption questions, the correct answer choice when negated basically establishes that the evidence offered in support of the conclusion in the stimulus is irrelevant to what the argument is asserting in the conclusion or that it is crappy evidence because the argument left out something related that goes against the point of the argument that is directly relevant/related that has a bearing on the main point, thereby stripping the conclusion of its support so the argument as a whole falls apart and the conclusion is left sitting there naked with proof that it has no support and is wearing no clothes.

Sometimes the correct answer choice when negated will fairly directly contradict the conclusion, those are the low difficulty rated ones. Otherwise, the negated correct answer choice will drive a wedge between the evidence and the conclusion by giving you information that in essence says 'hey dummy, that evidence doesn't support that conclusion, what about this?', leaving you with an unsupported conclusion, hence not a good argument.

PS: Your avatar is really creepy. It reminds me of some of the scary ugly stuff at carnivals, the circus and in weird parades that creeped me out and scared me when I was a kid.

[timmydoeslsat]

Here is my point, although it is true that the conclusion could be true without the W ---> ~B link, that does not make this link unnecessary to the argument (evidence + conclusion).

The evidence of a conditional (A ---> B) and the occurrence of a variable (W).

For an arguer to conclude ~A, it is necessary to the argument that W lead to ~B. As you stated Jeffort, a negated version of the assumption would lead to a conclusion not being able to follow or evidence that has been entered to be irrelevant. Not having the W ---> ~B link would make the evidence irrelevant would it not?

I do not intend to "litter" any thread on this forum, a forum in which I help others and in turn others help me. I am having a serious problem seeing this issue clearly and it was not addressed in a respectable fashion.

I would appreciate your take on this Jeffort or any other instructors' take. I understand that this is not a commonly tested topic on the LSAT, but it is still relevant and I would appreciate help.