Approach to Nec/Suff Assumption Questions

nosleeptillsuccess
Posts: 89
Joined: Mon Jun 04, 2012 5:03 pm

Approach to Nec/Suff Assumption Questions

Postby nosleeptillsuccess » Sat Nov 10, 2012 4:49 am

I know the diff between suff and nec when diagramming

but what's it really mean when it's in the form of a question stem??

I know the negate technique, but really... what am I really looking for in each of these questions types

What's the REAL difference.. I believe these types of questions confuse test takers the most on LR

natashka85
Posts: 255
Joined: Thu Nov 01, 2012 4:29 pm

Re: Approach to Nec/Suff Assumption Questions

Postby natashka85 » Sat Nov 10, 2012 5:26 am

nosleeptillsuccess wrote:I know the diff between suff and nec when diagramming

but what's it really mean when it's in the form of a question stem??

I know the negate technique, but really... what am I really looking for in each of these questions types

What's the REAL difference.. I believe these types of questions confuse test takers the most on LR

The real difference is that when u have the sufficient u know 100 percent that necc has to happen,but when u have the necc the sufficient doesn`t have to happen,it could happen but doesn`t have to.

CR2012
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Re: Approach to Nec/Suff Assumption Questions

Postby CR2012 » Sat Nov 10, 2012 9:30 am

What I do is I underline the conclusion (This has helped me tremendously). Then I read the conclusion to myself and I ask myself, what in the argument supports this? Then I go back and identify the support. So, at this point I have a pretty good idea of what the argument is saying.

If it is a Necessary question, then you know that something is missing/unstated. The argument has taken some liberties and is not airtight as it is written. So then I scan the ACs and look for the answer would fill a void/unstated element of the passage. Now, this void won't make the argument airtight, but, as you mentioned, if it was false, it would destroy the argument. For example:

This nuclear reactor is old, its almost 50 years old. The nearby town has 50,000 people living in it. If this reactor were to explode, 50,000 people would be subject to extreme radiation.

A correct necessary condition answer could be A) no one in the nearby town would be able to avoid exposure to radiation in the instance of the nuclear reactor exploding.

Notice that the conclusion assumes that everyone in the nearby town would would be exposed to radiation if it exploded, but is that mentioned in the premises? No. The correct answer will address this omission.

----

For Sufficient questions, I look for the answer that will blanket the argument. The way I look at it is that usually the correct sufficient answer goes well beyond what the argument requires. For example:

My Dog is yellow. My dog likes bones and trying to run away. My dog is 84 years old. Therefore, my dog will most certainly develop cancer.

A correct sufficient assumption answer could be A) Anything that is Yellow will most certainly develop cancer.

This answer goes well beyond what the argument requires, but it most definitely justifies the conclusion. A sufficient answer will always justify the argument, but may not touch on all the premises.

Hope this helps a little. Its the way I approach them.

nosleeptillsuccess
Posts: 89
Joined: Mon Jun 04, 2012 5:03 pm

Re: Approach to Nec/Suff Assumption Questions

Postby nosleeptillsuccess » Sat Nov 10, 2012 10:49 am

CR2012 wrote:What I do is I underline the conclusion (This has helped me tremendously). Then I read the conclusion to myself and I ask myself, what in the argument supports this? Then I go back and identify the support. So, at this point I have a pretty good idea of what the argument is saying.

If it is a Necessary question, then you know that something is missing/unstated. The argument has taken some liberties and is not airtight as it is written. So then I scan the ACs and look for the answer would fill a void/unstated element of the passage. Now, this void won't make the argument airtight, but, as you mentioned, if it was false, it would destroy the argument. For example:

This nuclear reactor is old, its almost 50 years old. The nearby town has 50,000 people living in it. If this reactor were to explode, 50,000 people would be subject to extreme radiation.

A correct necessary condition answer could be A) no one in the nearby town would be able to avoid exposure to radiation in the instance of the nuclear reactor exploding.

Notice that the conclusion assumes that everyone in the nearby town would would be exposed to radiation if it exploded, but is that mentioned in the premises? No. The correct answer will address this omission.

----

For Sufficient questions, I look for the answer that will blanket the argument. The way I look at it is that usually the correct sufficient answer goes well beyond what the argument requires. For example:

My Dog is yellow. My dog likes bones and trying to run away. My dog is 84 years old. Therefore, my dog will most certainly develop cancer.

A correct sufficient assumption answer could be A) Anything that is Yellow will most certainly develop cancer.

This answer goes well beyond what the argument requires, but it most definitely justifies the conclusion. A sufficient answer will always justify the argument, but may not touch on all the premises.

Hope this helps a little. Its the way I approach them.


Thanks a lot.. So in the suff assumptions I should find something that definitely has the conclusion in the answer choice right??

The confusing part is they both seem like "necessary questions" because something is necessary for both of them

gspiel1232
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Re: Approach to Nec/Suff Assumption Questions

Postby gspiel1232 » Sat Nov 10, 2012 11:16 am

okay so.

If you add the sufficient assumption into an argument, it 100% GUARANTEES that the conclusion comes true.

a NECESSARY assumption is required for the argument to be valid, but does not guarantee it. For this reason, N.A's are usually extremely small/flimsy (for use of a better word) statements


Go buy Manhattan LR immediately....seriously

M.M.
Posts: 381
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Re: Approach to Nec/Suff Assumption Questions

Postby M.M. » Sat Nov 10, 2012 9:11 pm

gspiel1232 wrote:okay so.

If you add the sufficient assumption into an argument, it 100% GUARANTEES that the conclusion comes true.

a NECESSARY assumption is required for the argument to be valid, but does not guarantee it. For this reason, N.A's are usually extremely small/flimsy (for use of a better word) statements


Go buy Manhattan LR immediately....seriously


This

bp shinners
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Re: Approach to Nec/Suff Assumption Questions

Postby bp shinners » Sun Nov 11, 2012 8:46 pm

gspiel1232 wrote:okay so.

If you add the sufficient assumption into an argument, it 100% GUARANTEES that the conclusion comes true.

a NECESSARY assumption is required for the argument to be valid, but does not guarantee it. For this reason, N.A's are usually extremely small/flimsy (for use of a better word) statements


Go buy Manhattan LR immediately....seriously


Slight change to make there - it doesn't NECESSARILY guarantee it. Sometimes, the correct answer to a necessary assumption question will also be sufficient to draw the argument's conclusion.

gspiel1232
Posts: 61
Joined: Fri Jul 15, 2011 3:37 pm

Re: Approach to Nec/Suff Assumption Questions

Postby gspiel1232 » Sun Nov 11, 2012 9:36 pm

bp shinners wrote:
gspiel1232 wrote:okay so.

If you add the sufficient assumption into an argument, it 100% GUARANTEES that the conclusion comes true.

a NECESSARY assumption is required for the argument to be valid, but does not guarantee it. For this reason, N.A's are usually extremely small/flimsy (for use of a better word) statements


Go buy Manhattan LR immediately....seriously


Slight change to make there - it doesn't NECESSARILY guarantee it. Sometimes, the correct answer to a necessary assumption question will also be sufficient to draw the argument's conclusion.


Ah yes, you are correct! Although they don't show up frequently, occasionally you do run into some nec. Assumptions that also act as sufficient..i wouldn't think much about this until you understand the crux though...good catch BP

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zipehtzin
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Re: Approach to Nec/Suff Assumption Questions

Postby zipehtzin » Mon Nov 12, 2012 3:25 pm

CR2012 wrote:This nuclear reactor is old, its almost 50 years old. The nearby town has 50,000 people living in it. If this reactor were to explode, 50,000 people in the nearby town would be subject to extreme radiation.

A correct necessary condition answer could be A) no one in the nearby town would be able to avoid exposure to radiation in the instance of the nuclear reactor exploding.

Notice that the conclusion assumes that everyone in the nearby town would would be exposed to radiation if it exploded, but is that mentioned in the premises? No. The correct answer will address this omission.


I think it should look like this. Otherwise, one person working at the nuclear facility could be afflicted, whereas only 49,999 people in the town may be afflicted, in which case, "A)" is not necessary.

theycallmefoes
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Re: Approach to Nec/Suff Assumption Questions

Postby theycallmefoes » Mon Nov 12, 2012 10:39 pm

bp shinners wrote:
gspiel1232 wrote:okay so.

If you add the sufficient assumption into an argument, it 100% GUARANTEES that the conclusion comes true.

a NECESSARY assumption is required for the argument to be valid, but does not guarantee it. For this reason, N.A's are usually extremely small/flimsy (for use of a better word) statements


Go buy Manhattan LR immediately....seriously


Slight change to make there - it doesn't NECESSARILY guarantee it. Sometimes, the correct answer to a necessary assumption question will also be sufficient to draw the argument's conclusion.


All of this. (And also the examples above - I meant to quote a bigger chunk of the thread but clicked on the wrong thing and don't want to go through the trouble of fixing it on my phone - but pretty much this entire thread is golden. Great explanations. :D)

Also, with respect to the Manhattan LR guide: if there's one specific reason to get it, it's to solidify your understanding of this distinction. Up until a couple of days ago, I had been a Powerscore purist, but NoodleyOne convinced me that the MLSAT LR guide was worth reading, especially for necessary and sufficient assumptions. I'm currently only about a quarter of the way through the guide, and, although I still love the LRB, I can say that the Manhattan guide has made me 100% confident in my ability to answer these particular questions.

The e-book (I.e, Kindle) version of the guide is only $10. [If you don't have a Kindle (I don't), you can download a free Kindle app for virtually any device - Mac, PC, smartphone, etc.]




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