some necessary assumptions are sufficient!!!

lsateagle
Posts: 4
Joined: Sun Oct 20, 2013 8:04 pm

some necessary assumptions are sufficient!!!

Postby lsateagle » Sun Oct 20, 2013 8:24 pm

Question 12 from section 1 in PT 38 has been driving me crazy. It's worded as a necessary assumption question ("... an assumption required by the economist's argument ...) but is actually a sufficient assumption question. The argument is basically as follows:

efficient (E) -> meets short-term needs (STN)
gov't programs (GP) -> not efficient (~E)

The correct choice, D, can be rewritten to say:
gov't program (GP) -> doesn't meet short-term needs (~STN)

So if we take the contrapositive of the premise and add choice D we get (putting the choice first for clarity):

GP -> ~STN
~STN -> ~E
GP -> ~E

The problem there is that this is clearly a sufficient assumption (if it's true there's no way that the conclusion doesn't follow), but not a necessary assumption (it doesn't have to be true for the conclusion to follow). If you negate it you get 'GP and STN', which is perfectly compatible with a scenario where the conclusion is true (just because we have STN doesn't mean that we don't have E, that would be a mistaken reversal). I've actually noticed a bunch of supposed necessary assumption questions where the choice is actually (also?) a sufficient assumption but have combed through my powerscore books and the net and haven't really found anything about how common this is, let alone that the choices aren't actually necessary but sufficient assumptions. I'd appreciate any thoughts or if someone can point out what the problem with my analysis is.

User avatar
PourMeTea
Posts: 6508
Joined: Sun Jun 17, 2012 8:32 am

Post removed.

Postby PourMeTea » Sun Oct 20, 2013 8:33 pm

Post removed.
Last edited by PourMeTea on Fri May 08, 2015 12:20 am, edited 1 time in total.

lsateagle
Posts: 4
Joined: Sun Oct 20, 2013 8:04 pm

Re: some necessary assumptions are sufficient!!!

Postby lsateagle » Sun Oct 20, 2013 8:36 pm

PourMeTea wrote:A condition can be both necessary and sufficient. HTH


Except that this one isn't necessary.

User avatar
drawstring
Posts: 1933
Joined: Tue Apr 09, 2013 4:52 pm

Re: some necessary assumptions are sufficient!!!

Postby drawstring » Sun Oct 20, 2013 9:00 pm

The economist argues: retraining is efficient only if it allows companies to meet own needs SO BECAUSE OF THIS gov programs are not a viable option to retrain workers efficiently.

If D is not true then some large gov retraining programs meet the short-term needs of different individual companies. But if some large government retraining programs meet the short-term needs of these companies, how can the economist say that such gov programs would not be a viable option because they don't allow companies to meet their own needs?
Last edited by drawstring on Sun Oct 20, 2013 9:04 pm, edited 1 time in total.

User avatar
Hotguy
Posts: 382
Joined: Mon Sep 16, 2013 12:33 am

Re: some necessary assumptions are sufficient!!!

Postby Hotguy » Sun Oct 20, 2013 9:01 pm

lsateagle wrote:
PourMeTea wrote:A condition can be both necessary and sufficient. HTH


Except that this one isn't necessary.

It's both. Think about it. If you don't come up with that conclusion, I will explain.

lsateagle
Posts: 4
Joined: Sun Oct 20, 2013 8:04 pm

Re: some necessary assumptions are sufficient!!!

Postby lsateagle » Sun Oct 20, 2013 9:24 pm

drawstring wrote:The economist argues: retraining is efficient only if it allows companies to meet own needs SO BECAUSE OF THIS gov programs are not a viable option to retrain workers efficiently.


It doesn't say 'because of this' it says 'hence', regardless, both are conclusion/premise-indicators and don't indicate sufficiency or necessity. To give you an example:
I'm eating jam, BECAUSE OF THIS I am happy. I don't NEED to eat jam to be happy, but eating it makes me happy.

drawstring wrote:If D is not true then some large gov retraining programs meet the short-term needs of different individual companies. But if some large government retraining programs meet the short-term needs of these companies, how can the economist say that such gov programs would not be a viable option because they don't allow companies to meet their own needs?


I don't understand what you're saying here, can you please explain? The problem is that when you negate the choice you get a situation where GP no longer leads to ~STN. ~STN is sufficient for ~E, which means that something else can also lead to ~E, which means that even if you have a gov't program that does meet the needs of companies you could conceivably have something else that causes them to be inefficient and so the conclusion can still be true. Please take a look at the way I diagrammed it.


Hotguy wrote:It's both. Think about it. If you don't come up with that conclusion, I will explain.

I've thought about it, that's why I'm asking on the forum. Please explain. And not why it's sufficient, that I can see.

User avatar
Hotguy
Posts: 382
Joined: Mon Sep 16, 2013 12:33 am

Re: some necessary assumptions are sufficient!!!

Postby Hotguy » Sun Oct 20, 2013 9:53 pm

I believe the problem with your analysis is that you think that something else could lead to the company being inefficient instead of the assumption marked as D. However, the question is asking about the economist's argument, not just any argument. You can't bring other triggers [of things that could make the company inefficient] that were not introduced/triggered by the economist.
Let me know if that makes sense.
Last edited by Hotguy on Sun Oct 20, 2013 10:38 pm, edited 2 times in total.

User avatar
drawstring
Posts: 1933
Joined: Tue Apr 09, 2013 4:52 pm

Re: some necessary assumptions are sufficient!!!

Postby drawstring » Sun Oct 20, 2013 10:27 pm

It doesn't say 'because of this' it says 'hence', regardless, both are conclusion/premise-indicators and don't indicate sufficiency or necessity. To give you an example:I'm eating jam, BECAUSE OF THIS I am happy. I don't NEED to eat jam to be happy, but eating it makes me happy.


It doesn't say 'because of this', but I put that in to make it very clear that the economist thinks the second point follows from the first point.

I don't understand what you're saying here, can you please explain? The problem is that when you negate the choice you get a situation where GP no longer leads to ~STN. ~STN is sufficient for ~E, which means that something else can also lead to ~E, which means that even if you have a gov't program that does meet the needs of companies you could conceivably have something else that causes them to be inefficient and so the conclusion can still be true. Please take a look at the way I diagrammed it.


You need to focus on what the economist is arguing. They essentially argue that BECAUSE retraining is efficient only if it allows companies to meet their own needs, gov programs won't be able to retrain workers efficiently. But if D is false and these gov programs meet companies own needs, the necessary condition is met; if gov programs do not allow for efficient retraining it WON'T be because they do not meet companies' needs. The economist made an argument that is incompatible with this, so that argument falls apart.

I advise you to post these questions in bpshinners' thread. He's got 180 skills and may be able to explain in a way that you understand.

User avatar
Jeffort
Posts: 1896
Joined: Wed Jun 18, 2008 4:43 pm

Re: some necessary assumptions are sufficient!!!

Postby Jeffort » Sun Oct 20, 2013 11:25 pm

OP, you have to evaluate whether or not the premise in each answer choice is something that is necessary to be able to draw the conclusion FROM THE PREMISE(S) offered in the argument, not whether the answer choice is something required to be able to prove the conclusion itself in any context from any set of premises. You are just looking at whether the answer choice is necessary to the conclusion itself being able to be true in any circumstances, which is not what necessary assumption questions on the LSAT are testing. They are testing you about what is necessary to draw the conclusion from the set of premises offered along with the conclusion in the stimulus.

You have to examine the premise-to-conclusion support relationship within the reasoning of the argument to determine which answer choice states something that is necessary to THAT particular argument as a WHOLE (offered premises + conclusion) for the offered premises to be able to actually provide direct support for the given conclusion, not just examine if it is necessary for the conclusion by itself to be able to be a true statement that can somehow be proven by other evidence. In short, you are looking for the gap BETWEEN the given premise(s) and the stated conclusion that is something that allows the stated evidence to be connected to and able to provide support for what the substance of the conclusion is directly about.

Part of the substance of the conclusion is always an idea that is different than something important the closest relating premise is about. If you notice the shift/difference between something in the conclusion and something similar/related but different that is mentioned in a major premise, the assumption is the gap/unstated connecting idea between those two that links them together as relevant connected ideas . Here, the argument doesn't connect GP with short term needs explicitly. By only giving a premise that talks about efficiency and short term needs and then making the conclusion about GPs, the gap is that the reasoning jumps from the idea ~STN to GP without telling us they are connected/related to each other, thus they are ideas the argument is assuming are connected/related to each other. Otherwise, why would the author offer that premise to form that conclusion if (s)he didn't implicitly believe (assume) GP means ~STN?

Another way to think about it is:
What idea/relationship must the author believe is true in order to correctly think that the premise(s) given for the conclusion actually do directly relate to and support the substance of the conclusion?

Does that make sense?

User avatar
JazzOne
Posts: 2938
Joined: Tue Sep 09, 2008 11:04 am

Re: some necessary assumptions are sufficient!!!

Postby JazzOne » Mon Oct 21, 2013 10:16 am

As usual, I agree with Jeffort. Assumption questions are asking about the validity of the logic, not simply the truth of the conclusion.

lsateagle
Posts: 4
Joined: Sun Oct 20, 2013 8:04 pm

Re: some necessary assumptions are sufficient!!!

Postby lsateagle » Mon Oct 21, 2013 11:03 am

Thanks everyone for the responses, I appreciate your help. I'll take a look at some of the other questions that I had flagged and see if this clears things up.

bp shinners
Posts: 3091
Joined: Wed Mar 16, 2011 7:05 pm

Re: some necessary assumptions are sufficient!!!

Postby bp shinners » Mon Oct 21, 2013 1:53 pm

Jeffort wrote:OP, you have to evaluate whether or not the premise in each answer choice is something that is necessary to be able to draw the conclusion FROM THE PREMISE(S) offered in the argument, not whether the answer choice is something required to be able to prove the conclusion itself in any context from any set of premises.


Quoted because it associates me with Jeffort's awesome answer.




Return to “LSAT Prep and Discussion Forum”

Who is online

Users browsing this forum: Alexandros, Baidu [Spider], beancounter15, Majestic-12 [Bot], mintme, mukol, Pozzo, theGrinch, VMars, Yahoo [Bot] and 13 guests