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 KelseyWoods
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#83399
Hi jdavidwik!

Glad you now see that "sage advice" haha! And it's certainly always good to remember not to panic! Basically, whenever you have a conditional chain, everything going forward along that chain must be true. So if we have a chain that goes like this:

A :arrow: B :arrow: C :arrow: D

That means that all of the following statements must be true:

A :arrow: B      A :most: B      A :some: B
A :arrow: C      A :most: C      A :some: C
A :arrow: D      A :most: D      A :some: D
B :arrow: C      B :most: C      B :some: C
B :arrow: D      B :most: D      B :some: D
C :arrow: D      C :most: D      C :some: D

So that means that any answer choice that denies one of those above relationships cannot be true. So it cannot be true that:

A :arrow: B      A :most: B      A :some: B
A :arrow: C      A :most: C      A :some: C
A :arrow: D      A :most: D      A :some: D
B :arrow: C      B :most: C      B :some: C
B :arrow: D      B :most: D      B :some: D
C :arrow: D      C :most: D      C :some: D

Hope this helps!

Best,
Kelsey
 jdavidwik
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#83427
Thank you Kelsey!

What was giving me the willies was the presence of the "some"s and "most"s. I have to calm down, decrease my heart rate and parse the sequence of arrows for what each one indicates. Apologies to anyone named Willie ;)
 jdavidwik
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#83443
I do not understand the third column, the "some" bidirectional arrows under Kelsey's Must Be True grouping. Namely, how can some B, C and D in this schema lead to A, likewise for the next three backward arrow relationships in that column. I am missing something.
 Adam Tyson
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#83690
Not "leads to," jdavidwik - that's causal language, not conditional language. Nitpicky of me, perhaps, but it's important to think about those two as distinct from each other, and using the right language helps you do that.

Conditionally, if all A's are B's, then it must be the case that some B's are A's. For example, if every pizza has mozzarella cheese on it, then some things with mozzarella cheese must be pizzas. We can do a "some" arrow that goes in both directions, even though we cannot do a conditional reversal of "if mozzarella, then pizza," as that would be a Mistaken Negation.

So let's build a chain here:

If pizza, then mozzarella
If mozzarella, then dairy
If dairy, then fattening

(Not that any of these must be true in the real world, mind you. Let's just accept these as true for our purposes here.)

Putting this together, we get:

pizza :arrow: mozzarella :arrow: dairy :arrow: fattening

We could now conclude that every pizza has something fattening on it. But we can also conclude that SOME things that are fattening are found on pizza! Not everything fattening - no ice cream on pizza, thank goodness - but at least some things that are fattening are dairy products, and some of those are mozzarella, and some of that is on pizza.

For the last examples in Kelsey's post, if all A's are B's, then it cannot be true that some A's are not B's, and it cannot be true that some things that are not B's are A's (because the A's all have to be B's). However, it could be true that some B's are not A's.

"Some" is a two-way street, while "all" and "most" only go one way. I hope that clears things up!
 jdavidwik
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#83824
That totally clears things up. That was exactly what I was doing, i.e. thinking "causal" instead of "conditional". This has been a thorn in my LSAT-study side and you just honed in on that. I appreciate the thorough explanation and hope that others will also benefit from it.
 jdavidwik
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#84452
In addition to the "some" relationships I believe "many" statements are reversible. Is it possible to replace the "some"s in this schema with "many"s and still have a correct series of relationships?
 Rachael Wilkenfeld
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#84500
Be careful jdavid. Many means more than one, and while it's nebulous the exact numbers, you can't necessarily reverse it.

For example, many Sumatran Rhinos have horns. Many animals with horns are not Sumatran Rhinos because there are only a handful left in the world. We can't reverse that term many because it would be applying to different sized populations.

I would say that you could reverse "many" into "some." You know that there's at least one animal with horns that is a Sumatran Rhino based on the above, so it would be fair to say you know that some horned animals are Sumatran Rhinos.

Hope that helps!
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 cornflakes
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#87640
More of general approach question here - wondering if this is a type of question that you could even get if you didn't diagram it? Usually by this part of the exam, I am low on time and seeing which questions will take the least amount of time. When looking at this one on first glance, I knew it was some type of conditional logic maze, but knew that I would likely have to diagram it in order to have a shot (because I'm not too great at holding and maneuvering 3-4 conditional chains in my head and cross analyzing them with answer choices).

Unfortunately, once I did diagram it, the answer was fairly easy to find, just not one I would have seen had I not diagrammed. Do you have any advice on attacking these in the future?
 Adam Tyson
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#87837
For complex arguments with a lot of conditional statements like this one, cornflakes, it might be possible to do it without diagramming, but in my experience it's faster, easier, and more accurate to do the diagram. That's what I would do with something like this every single time, and if I was so short on time that I thought doing it that way would prevent me from getting two other questions done right, I would guess and move on to those others.

The thing is, seeing this I just know that I WILL get it right if I do the diagram, whereas the next question could be a lot harder, so I would probably still forge ahead with the diagram and take the easy point. I feel the same way about every Parallel Reasoning question: they may take a little longer, but done correctly they pretty much guarantee correct answers, and I would rather take the sure thing than gamble on being able to answer two additional questions correctly in exchange for skipping that one. Just my opinion, perhaps, but I like a sure thing!
 jdavidwik
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#88156
I was advised to review past questions which proved troublesome for me in LR. Writing out the conditional statements, their contrapositives, and the two conditional chains here was essential for me and I finally understand all the comments made my James, Brook, Jeremy, Kelsey and Adam.

My mistakes were manifold. I eliminated C and E but for the wrong reasons. I had not read James & Brook's addenda to the "some" meaning "some statement of probability or possibility" in the initial explanation. Fortuitously, before doing that I had erased "some" and rightfully replaced it with "may", which along with James F's explanation, which I finally understood, explained why the "respect" term fell out of the conditional chain, which is key to this question. Given that "may", C and E both CBT.

For A and D, I initially had trouble eliminating. Brook paid me a compliment by assuming I performed Mistaken Negation on both, and pointed to following the techniques (re. "some" and a conditional chain). For A, I had formed the contrapositive and then a Mistaken Reversal. A corollary issue is whether "like" equals "~ dislike". For D, I had performed a Mistaken Reversal and also not looked to the correct conditional chain of the two for guidance, which I will call the lesser chain: ~WP > ~K > DL > ~FC. I had looked at the greater FC > ~DL > K > WP. For these reasons, A and D seemed to be MBF candidates. In effect, it looked like I had performed a Mistaken Negation on both, which would have been a cleaner way to get the question wrong. We had to quickly infer those two conditional chains and know how to apply the some relationships, and "as we have an A > D chain...be on the lookout for one of the following possibilities as the Prephrase for this question and others like it" re. those relationships.

As Brook and James F, then later Kelsey, explained, the technique of seeing the "some" relationships in the chain solves the question by helping to eliminate A and D. Early LSAT enthusiasts may misdirect themselves by seeing the "Some" at the beginning of each answer choice and recalling that in conditional logic, "some" can include "all", and leave things at that. As well, it may not seem important in early days given such "some" wording to make sure to determine which is the sufficient condition and which part of the sentence is the necessary condition. At least it didn't to me.

However, as Brook first mentioned, then James F. elaborated in regard to this question, the technique of knowing the "some" relationships in the chain is instrumental. For choice A, "Some people who like each other are not fully content in each other's presence." Looking at the necessary condition, "not fully content in each other's presence", since "dislike" is the sufficient condition in the chain, and other states such as "like" can be sufficient and result in the necessary condition in our chain, choice A then CBT. It CBT that some D's are not C's in that lesser chain. Thanks Adam. Likewise for choice D, "Some people who want each other to prosper dislike each other." Looking at the necessary condition, "dislike each other", since "do not want each other to prosper" is the sufficient condition in the chain, and other states such as "do WP" can be sufficient and result in the necessary condition in our chain, choice D then CBT. It CBT that some C's are not A's in that lesser chain.

The granddaddy of them all is choice B, which MBF. This contradicts the greater conditional chain of FC > ~DL > K > WP. We are given A <some> ~D in choice B, but we have A <some> D in our chain. Kelsey warned us., and James F. had as well, in regard to the technique of being on the lookout for the standard MBT and MBF relationships in such a conditional chain.

While I previously saw most of the above, the logic glue holding all the pieces together had eluded me, but thanks to the great questions and answers here, voila!

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