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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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