Sufficient vs Necessary

Walrus
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Sufficient vs Necessary

Postby Walrus » Tue Dec 17, 2013 4:21 pm

I am having trouble to prove myself that this is SA question:

Which one of the following, if assumed, enables the argument's conclusion to be properly inferred?

The trouble lays in interpretation of "enables". When I say "Getting 180 on LSAT enables you to enter one of the best law schools in USA" I don't mean that 180 score will guarantee it.

In my mind "enables" is equal to "makes possible". "Makes possible" is closer to NA but...
Winning 1 million dollars on lottery enables (makes possible) you to pay law school loan. But not necessary...

Is my interpretation flawed? Does LSAT authors have special meaning for "enables"?

Help please!!!

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objection_your_honor
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Re: Sufficient vs Necessary

Postby objection_your_honor » Tue Dec 17, 2013 4:27 pm

You're incorrectly assuming that a sufficient assumption is also a necessary assumption. This is almost never the case.

A sufficient assumption should "enable" (or "make possible") the conclusion 100%, but it doesn't have to be necessary.

Walrus wrote:Winning 1 million dollars on lottery enables (makes possible) you to pay law school loan. But not necessary...


Winning one million dollars would be sufficient, but not necessary, for paying off your loan.

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Nova
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Re: Sufficient vs Necessary

Postby Nova » Tue Dec 17, 2013 4:30 pm

which ENABLES the arguments conclusion to be properly inferred
=
which LETS the arguments conclusion to be properly inferred
=
Which ALLOWS the arguments conclusion to be properly inferred

do any of those words sound better in your head?
Last edited by Nova on Tue Dec 17, 2013 4:44 pm, edited 1 time in total.

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SecondWind
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Re: Sufficient vs Necessary

Postby SecondWind » Tue Dec 17, 2013 4:35 pm

objection_your_honor wrote:You're incorrectly assuming that a sufficient assumption is also a necessary assumption. This is almost never the case.

A sufficient assumption should "enable" (or "make possible") the conclusion 100%, but it doesn't have to be necessary.

Walrus wrote:Winning 1 million dollars on lottery enables (makes possible) you to pay law school loan. But not necessary...


Winning one million dollars would be sufficient, but not necessary, for paying off your loan.


+1

Another way to look at it:

Enable= allows

If the president allows you to urinate in the White House Rose Garden, it's not necessary that you do it.

Walrus
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Re: Sufficient vs Necessary

Postby Walrus » Tue Dec 17, 2013 5:28 pm

Thank you for clarification!
Enables = allows = 100% possible
This works for me.

Can you also check my explanations on Hypothetical vs Holistic Q's?
English isn't my first language so I see troubles where other people don't:)
- PT42 Game 4.
Which one of the following could be an accurate and complete list of the students who review only Sunset?
Which one of the following could be an accurate and complete list of students who review Tamerlane?
These questions are asking about HYPOTHETICAL list within one of the possible worlds. “could be” indicates hypothetical bias in question stem
- PT35 Game 4. Which one of the following is a complete and accurate list of professors who could have been hired in the year 1989 through 1991?
This question asks about HOLISTIC list of professors who could have been hired within 89-91 period. Question stem “what IS a complete and accurate list” indicates that we are asked about EVERY possible world where professors could have been hired in 89-91 period.

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Christine (MLSAT)
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Re: Sufficient vs Necessary

Postby Christine (MLSAT) » Wed Dec 18, 2013 4:11 am

Walrus wrote:Thank you for clarification!
Can you also check my explanations on Hypothetical vs Holistic Q's?
English isn't my first language so I see troubles where other people don't:)
- PT42 Game 4.
Which one of the following could be an accurate and complete list of the students who review only Sunset?
Which one of the following could be an accurate and complete list of students who review Tamerlane?
These questions are asking about HYPOTHETICAL list within one of the possible worlds. “could be” indicates hypothetical bias in question stem
- PT35 Game 4. Which one of the following is a complete and accurate list of professors who could have been hired in the year 1989 through 1991?
This question asks about HOLISTIC list of professors who could have been hired within 89-91 period. Question stem “what IS a complete and accurate list” indicates that we are asked about EVERY possible world where professors could have been hired in 89-91 period.


You got it.

One way to think about these is by asking yourself where the definite language and where the maybe language is.

Which is the list of all the blahblah who could be blahblah? = the only list there is, all the possibilities on it
Which could be the list of all the blahblah who are blahblah? = one possible list that works



Walrus wrote:I am having trouble to prove myself that this is SA question:
Which one of the following, if assumed, enables the argument's conclusion to be properly inferred?

The trouble lays in interpretation of "enables". When I say "Getting 180 on LSAT enables you to enter one of the best law schools in USA" I don't mean that 180 score will guarantee it.

In my mind "enables" is equal to "makes possible". "Makes possible" is closer to NA but...
Winning 1 million dollars on lottery enables (makes possible) you to pay law school loan. But not necessary...

Is my interpretation flawed? Does LSAT authors have special meaning for "enables"?

Help please!!!


I think you're looking at 'enables' in a vacuum. What does the sufficient assumption enable? It enables us to properly infer the conclusion.

Let's say Jack only wears boots when it rains. Seeing Jack wearing boots would enable me to properly conclude that it is raining. Now, I might not actually conclude that - maybe I forgot the rule, or I was so fascinated by the zebra print of the boots that I couldn't think past it. But the fact that Jack was wearing boots does enable me to properly, or correctly, make that conclusion.

In other words, the sufficient assumption guarantees the validity of the conclusion, even if it does not guarantee that any particular person will actually make that conclusion.

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Clearly
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Re: Sufficient vs Necessary

Postby Clearly » Wed Dec 18, 2013 5:07 am

Christine (MLSAT) wrote:
Walrus wrote:Thank you for clarification!
Can you also check my explanations on Hypothetical vs Holistic Q's?
English isn't my first language so I see troubles where other people don't:)
- PT42 Game 4.
Which one of the following could be an accurate and complete list of the students who review only Sunset?
Which one of the following could be an accurate and complete list of students who review Tamerlane?
These questions are asking about HYPOTHETICAL list within one of the possible worlds. “could be” indicates hypothetical bias in question stem
- PT35 Game 4. Which one of the following is a complete and accurate list of professors who could have been hired in the year 1989 through 1991?
This question asks about HOLISTIC list of professors who could have been hired within 89-91 period. Question stem “what IS a complete and accurate list” indicates that we are asked about EVERY possible world where professors could have been hired in 89-91 period.


You got it.

One way to think about these is by asking yourself where the definite language and where the maybe language is.

Which is the list of all the blahblah who could be blahblah? = the only list there is, all the possibilities on it
Which could be the list of all the blahblah who are blahblah? = one possible list that works



Walrus wrote:I am having trouble to prove myself that this is SA question:
Which one of the following, if assumed, enables the argument's conclusion to be properly inferred?

The trouble lays in interpretation of "enables". When I say "Getting 180 on LSAT enables you to enter one of the best law schools in USA" I don't mean that 180 score will guarantee it.

In my mind "enables" is equal to "makes possible". "Makes possible" is closer to NA but...
Winning 1 million dollars on lottery enables (makes possible) you to pay law school loan. But not necessary...

Is my interpretation flawed? Does LSAT authors have special meaning for "enables"?

Help please!!!


I think you're looking at 'enables' in a vacuum. What does the sufficient assumption enable? It enables us to properly infer the conclusion.

Let's say Jack only wears boots when it rains. Seeing Jack wearing boots would enable me to properly conclude that it is raining. Now, I might not actually conclude that - maybe I forgot the rule, or I was so fascinated by the zebra print of the boots that I couldn't think past it. But the fact that Jack was wearing boots does enable me to properly, or correctly, make that conclusion.

In other words, the sufficient assumption guarantees the validity of the conclusion, even if it does not guarantee that any particular person will actually make that conclusion.

Welcome to TLS Christine! ~Stef
Don't quote because name :D

Walrus
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Re: Sufficient vs Necessary

Postby Walrus » Thu Dec 19, 2013 1:22 am

Thank you Christine!
One way to think about these is by asking yourself where the definite language and where the maybe language is.

Now I can use this approach with more confidence.
In other words, the sufficient assumption guarantees the validity of the conclusion, even if it does not guarantee that any particular person will actually make that conclusion.

Got it 8) You pinpointed my trouble

Is it OK to post multiple questions in one topic? I have so many of them...

About NA and Inference questions:

"If the sentence above are true, which one of the following must be true"
"The information above provides the most support for which of the following"
"Which of the following is most strongly supported by the xxx statement"

Do we need to assume on every Inference question that argument in stimulus is VALID?
If yes, then do we need also to assume that all necessary assumptions within original argument are true?

For example:

P: A-->B
C:A-->D

Necessary assumption: B Some D

If the sentences above are true, which one of the following must be true

Correct answer: B some D

Thank you!

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Christine (MLSAT)
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Re: Sufficient vs Necessary

Postby Christine (MLSAT) » Thu Dec 19, 2013 9:46 am

Walrus, you've exactly right! The only thing is, you aren't *assuming* the argument is valid - the question stem *tells* you that the argument must be valid.

Inference questions often just have a laundry list of factoids with no particular structure to them, and you have to accept the whole business as true. But occasionally an inference question does actually contain an argument. In that case, since you must accept every piece of the stimulus as true (the question stem tells you that you must), then you have accept that the argument works. If you accept that the argument works, then any assumptions that are necessary in order to make the argument work must ALSO be true.

Inference questions are not the only questions, in fact, where this nasty little 'nested argument' bit can crop up. The same drama could unfold in an 'Identify the Disagreement question'!

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Christine (MLSAT)
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Re: Sufficient vs Necessary

Postby Christine (MLSAT) » Thu Dec 19, 2013 9:48 am

Clearly wrote:Welcome to TLS Christine!


Thanks!! It's been a long time since I haunted these boards as a student! It's fun to be back. :p

KDLMaj
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Re: Sufficient vs Necessary

Postby KDLMaj » Fri Dec 20, 2013 1:30 am

My slightly different two cents:

You're vastly overthinking "enables" and are missing the point of the question. People gave some great definitions of sufficient and necessary, but if you want a more LSAT-specific practical distinction between the two, here're the real-world implications on the exam::

First, it's less helpful to think about "Necessary Assumptions" and "Sufficient Assumptions" than it is to think about "Necessary Assumption QUESTIONS" and "Sufficient Assumption QUESTIONS". The question type just refers to the format of the answer choice. The "assumption" of a stimulus isn't dependent on the question type- just the way the answer will be written. (i.e. assigning a stimulus to a flaw question and then to a necessary assumption question doesn't actually change what's wrong with the stimulus)

The actual patterns of the answers are based on the argument type of the stimulus. There are fundamentally two types of arguments on the LSAT: shifts in scope (apples and oranges) and overlooked possibilities (conclusion too strong- author assumes things didn't happen). (There are a rare few that don't fit these molds, but they virtually never show up in assumption questions) The LSAT is incredibly patterned about the way it writes its answer choices, and they almost always follow these rules:

Stimulus Contains A Shift in Scope (Apples vs Oranges):
Necessary Assumption: The answer will link the mismatched concepts together but only within the scope of the argument. (i.e. at least once)
Sufficient Assumption: (Virtually all of them are shifts in scope) The answer will link the two mismatched concepts together, but they'll be broader in scope: applying to more situations than just that of the stimulus. Often in the format of "If <evidence> then <conclusion>" (i.e. all the time)

i.e. Mark is an important film critic because he has wide readership.
Necessary Assumption: Having a wide readership makes a film critic important. (applies just to the scope of this argument: film critics)
Sufficient Assumption: Having a wide readership makes one's criticisms important. OR If someone enjoys wide readership, then their opinions are important. (applies to lots of situations beyond film critics)

Stimulus Contains a Problem of Overlooked Possibilities:
Necessary Assumption: Will rule out at least one overlooked possibility (may rule out more- a necessary assumption answer in these cases CAN rule out ALL overlooked possibilities- though it doesn't happen often)
Sufficient Assumption: (VERY rare) Will rule out ALL overlooked possibilities in one statement. (Be on the lookout for answer choices that rule out only one possibility and not all of them- there are almost always going to be one or two)

i.e.
I can't find my wallet. Therefore it must have been stolen.
Necessary Assumption: I did not lose my wallet
Sufficient Assumption: If a wallet is lost, it must have been stolen. OR The only way a wallet can be missing is if it was stolen.

There you go. This is how the LSAT specifically deals with nec vs suff answer choices.

Walrus
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Re: Sufficient vs Necessary

Postby Walrus » Sat Dec 21, 2013 1:20 am

Thank you Christine!
Thank you KDLMaj!


PT 61 S2 Q24

Argument goes like this:
P1: ~[Clear MB and Unambiguous MB] --> [49.9% that someone would see history as the working out of moral themes]
P2: Knowledge of history ↑ --> Inclination to morally judge ↓
C: Knowledge of history ↑ --> likelihood of seeing history as the working out of moral themes ↓

Q stem asks:
“The conclusion is properly drawn if which one of the following is assumed”
1) We are asked about SA
2) SA should make our argument VALID

“B” is correct answer and it says:

Inclination to morally judge ↓ --> likelihood of holding Clear MB and Unambiguous MB ↓

I have troubles with chaining everything up :

1)My concern is a jump from [likelihood of holding Clear MB and Unambiguous MB↓] to ~[Clear MB and Unambiguous MB]
The part [likelihood of holding Clear MB and Unambiguous MB ↓] does not necessary mean ~[Clear MB and Unambiguous MB]

2)My concern is a jump from [49.9% that someone would see history as the working out of moral themes] to [likelihood of seeing history as the working out of moral themes ↓]

It can be true that 49.9% chances that someone would see history as the working out of moral themes is an increase in likelihood of seeing history as the working out of moral themes. We don’t have a clue about what average/normal chances are.

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iamgeorgebush
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Re: Sufficient vs Necessary

Postby iamgeorgebush » Sat Dec 21, 2013 11:06 pm

Which one of the following, if assumed, enables the argument's conclusion to be properly inferred?

The trouble lays in interpretation of "enables". When I say "Getting 180 on LSAT enables you to enter one of the best law schools in USA" I don't mean that 180 score will guarantee it.


NOOOOO

It's not "enables X to be true" (which means "makes X possible")

It's "enables X to be PROPERLY INFERRED" (which means "guarantees X")

See the difference?

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Christine (MLSAT)
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Re: Sufficient vs Necessary

Postby Christine (MLSAT) » Tue Dec 24, 2013 9:06 am

Walrus wrote:PT 61 S2 Q24

Argument goes like this:
P1: ~[Clear MB and Unambiguous MB] --> [49.9% that someone would see history as the working out of moral themes]
P2: Knowledge of history ↑ --> Inclination to morally judge ↓
C: Knowledge of history ↑ --> likelihood of seeing history as the working out of moral themes ↓

Q stem asks:
“The conclusion is properly drawn if which one of the following is assumed”
1) We are asked about SA
2) SA should make our argument VALID

“B” is correct answer and it says:

Inclination to morally judge ↓ --> likelihood of holding Clear MB and Unambiguous MB ↓

I have troubles with chaining everything up :

1)My concern is a jump from [likelihood of holding Clear MB and Unambiguous MB↓] to ~[Clear MB and Unambiguous MB]
The part [likelihood of holding Clear MB and Unambiguous MB ↓] does not necessary mean ~[Clear MB and Unambiguous MB]

2)My concern is a jump from [49.9% that someone would see history as the working out of moral themes] to [likelihood of seeing history as the working out of moral themes ↓]

It can be true that 49.9% chances that someone would see history as the working out of moral themes is an increase in likelihood of seeing history as the working out of moral themes. We don’t have a clue about what average/normal chances are.


You bring up some interesting questions, Walrus, and there are a few ways to answer you. The shortest, simplest answer is that you honestly do not need to perfectly understand the elements you are struggling with right now in order to get through the question. So here's the strategic treatment:

Since we are in a Sufficient Assumption question, we want to make the conclusion work. The conclusion tries to leap from 'knowledge' to 'seeing history as moral themes'. We can link from 'knowledge' to 'judging' and we can link from 'clear moral belief' to 'seeing history as moral themes'. What would be sweet is a connector from 'judging' to 'clear moral belief'.

The only answer that even gets in the galaxy of that connection is (B). Everything else is terrible. This is the extent of the thought process you ought to be going through during a timed exam. You simply do not need anything more sophisticated - that high level gloss is all you need to zero in on the correct answer. All the other answers are wildly wrong in very clear and specific ways. Get in, get out, get the point.

Now, that's not to say your question isn't interesting, as an academic matter. There's some fun weirdness when you mix statements of likelihood with conditionals (in your P1), and that could take us down quite the rabbit hole. But I just want to stress that *none* of that is required, or even really helpful, for answering this particular question. And I don't think the LSAT would ever actively test the logical weirdness it plays with here (say, on a MBT question).

Walrus
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Re: Sufficient vs Necessary

Postby Walrus » Wed Dec 25, 2013 1:39 am

Thank you again Christine!
I understand that my goal on LSAT is to get as many questions right as possible and use any strategy that helps to achieve my goal but It makes me nervous when I don't understand what is the purpose of LSAT authors when they put ambiguous AC when question stem presumably doesn't allow any ambiguity :?

I want to express gratitude to everyone in this topic; your responses are very helpful to me :)

I have more questions:

1) Is NA is always the best choice on Inference questions?

2) Is there distinction between NA on Inference questions and NA on Identify NA questions?


I wrote fake argument to illustrate what I mean so excuse me if it sounds horrible :)

People who read books are generally more creative than people who don’t. Since reading is determinant factor in developing of imagination, no activity can develop imagination to the extent comparable with reading. Abstract thinking is heavily correlated with ability to transcend what is directly available to one’s perception and without abstract thinking creativity is unlikely to occur.

A) The statements above, if true, most strongly support which one of the following?

Answer: Drawing is not determinant factor in developing of imagination
Negation
Drawing is determinant factor in developing of imagination

According to question stem we must assume that ALL statements are true. Therefore statement “no activity can develop imagination to the extent comparable with reading” is also true and RESTRICTS to what extent drawing can play role in developing of imagination:
Not MORE than reading.
So negated answer doesn't challenge validity of the argument.
Therefore “Drawing is not determinant factor in developing of imagination” is not NA

B) Which one of the following is an assumption on which the argument depends for its conclusion to be properly drawn?

Answer: Drawing is not determinant factor in developing of imagination

Negated version “Drawing is determinant factor in developing of imagination” will attack intermediate conclusion by blurring distinction between reading and drawing. If reading and drawing can be equal in their contribution to the development of imagination, conclusion doesn't follow from premises anymore.
Therefore “Drawing is not determinant factor in developing of imagination” is NA

So the same answer may be NA or may not be NA depending on question stem, right?

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iamgeorgebush
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Re: Sufficient vs Necessary

Postby iamgeorgebush » Wed Dec 25, 2013 12:52 pm

Are you writing in red because it's Christmas?

Walrus
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Re: Sufficient vs Necessary

Postby Walrus » Wed Dec 25, 2013 1:34 pm

I can't disprove your suggested cause completely:)
But I can weaken it by suggesting alternative cause: It seems to me that color coding helps to organize structure of my questions and to underline points that I want to stress.




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