Law School Discussion

"most", "some", "at least one" in LR

sluan

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"most", "some", "at least one" in LR
« on: August 07, 2004, 02:19:22 PM »
continued from previous thread....

sluan:

Would this be a flawed argument?

In Sheldon SOME bicyclists aged 18 and over have lights on their bicycles, whereas SOME bicyclists under the age of 18 do not.  It follows that in Sheldon SOME bicyclists who have lights on their bicycles are at least 18 years old.

I was trying to continue the previous discussion about the distinction between "most", "some", and "at least one".  For me, this proves that "most" is not logically equivalent to "some" or "at least one".


Matthew_24_24:

That is because that particular question is not looking for a deductive answer.  There are two types of arguments used on the LR section: Deductive and Inductive.  That is an inductive use of the word most.  It is not a strict quantifier in the example given from preptest 15, it is asking for an inductive comparison.

This statement would be redundant ***It follows that in Sheldon most bicyclists who have lights on their bicycles are at least 18 years old.*** if it was the deductive use of the word.

However, in a question that is a pure logical statement:

Most women are smart
Most women are healthy
Thus some women are smart and healthy.

This is not correct.  This is a deductive conclusion and does not follow from the premises.

Matt

sluan

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Re: "most", "some", "at least one" in LR
« Reply #1 on: August 07, 2004, 02:20:40 PM »
Matt,

That's interesting.  If possible, can you give me a real LSAT example of "most" in a deductive argument?

Thanks. 

Louder Than Bombs

Re: "most", "some", "at least one" in LR
« Reply #2 on: August 07, 2004, 02:28:10 PM »

However, in a question that is a pure logical statement:

Most women are smart
Most women are healthy
Thus some women are smart and healthy.

This is not correct.  This is a deductive conclusion and does not follow from the premises.

Matt

Actually, that some women are both smart and healthy IS a valid conclusion based on these premises (that is, if the meaning of the word 'most' is taken as 'more than 50%')...

sluan

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Re: "most", "some", "at least one" in LR
« Reply #3 on: August 07, 2004, 02:32:04 PM »
Just to clarify...
Matt's point is that for deductive arguments "most" is logically equivalent to "some".
However, he agrees that for inductive arguments "most" means "more than half".

Re: "most", "some", "at least one" in LR
« Reply #4 on: August 07, 2004, 03:05:15 PM »
Matt's just being pedantic and silly. Let me reiterate: it's called "logical reasoning," not "logical reasoning within the strictly circumscribed bounds of first order predicate calculus." The questions are supposed to look like things you might actually encounter in the real world -- a newspaper article, a politician's speech, argument with a friend, whatever -- not symbolic little contrivances you'd find on a computer science or philosophy exam. Words like "most" and "nearly all" have significance for us in the real world that they don't in formal logic. Because the arguments are real world arguments, you need to use the real world definitions in them. The preoccupation with formal logic is at best a big waste of time, and at worst, something that could actually hurt your score. I challenge anyone to find a LR question that relies on equating "most" with "some" for the correct answer, rather than using the more straightforward definition of the word that we all manage to employ quite handily in everyday reasoning. You won't find one.

sluan

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Re: "most", "some", "at least one" in LR
« Reply #5 on: August 07, 2004, 03:34:54 PM »
That's exactly my challenge.  :)

Louder Than Bombs

Re: "most", "some", "at least one" in LR
« Reply #6 on: August 07, 2004, 05:21:11 PM »
Just to clarify...
Matt's point is that for deductive arguments "most" is logically equivalent to "some".
However, he agrees that for inductive arguments "most" means "more than half".

This assertion is incorrect. 'Some' means 'at least one'...'most' means (at the very least) 'more than half'...

Matthew_24_24

Re: "most", "some", "at least one" in LR
« Reply #7 on: August 08, 2004, 08:37:00 AM »
I made it quite clear in the first post on this that they are VERY unlikely to throw a deductive most at you.  It is just that they will never (also) violate the logical meaning of most in a predicate statement.

So i'm not saying i can find an example where they use a deductive most.  I'm saying you can't find one where it gives you a wrong answer.  And examples where they use an "inductive" most does not count.

The big deal?

Because there ARE deductive questions on the LSAT (though not many) and symbolizing most as 1-100 (or, "at least one but not all") makes that symbolization much easier (even if it never factors into the answer!) than if you start playing with the laymen's definition of the word.

Matt

Re: "most", "some", "at least one" in LR
« Reply #8 on: August 10, 2004, 08:03:44 AM »
Most lecturers who are effective teachers are eccentric, but some noneccentric lecturers are very effective teachers. In addition, every effective teacher is a good communicator.

a). Some good communicators are eccentric.

b). All good communicators are effective teachers.

c). Some lecturers who are not effective teachers are not eccentric.

d). Most lecturers who are good communicators are eccentric.

e). Some noneccentric lecturers are effective teachers but are not good communicators.

Matthew_24_24

Re: "most", "some", "at least one" in LR
« Reply #9 on: August 10, 2004, 08:10:55 AM »
1-10 are eccentric and effective.
1-10 are non-eccentric and very effective.
Every effective is good communicator.

Thus:   1-10 are eccentric, effective, and a good communicator.

Answer is A.

Verified:

All E are GC
1 - 10 GC's are Eccentric.

Easy.

Matt