## Necessary Assumption issue

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timmydoeslsat

Posts: 148
Joined: Wed Aug 03, 2011 2:07 pm

### Re: Necessary Assumption issue

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timmydoeslsat

Posts: 148
Joined: Wed Aug 03, 2011 2:07 pm

### Re: Necessary Assumption issue

Am I correct in stating that this argument construct has the same issue as the first?

A ---> B
W
__________
~A

Before I created this thread, I would have stated that W ---> ~B was necessary for the argument, in other words, the way the conclusion is reached from the evidence given.

However since it could be true that W ---> ~A then the prior conditional assumption is not a necessary one. Is this correct?

jas1503

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### Re: Necessary Assumption issue

timmydoeslsat wrote:Your image is not showing up. Try it again.

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### Re: Necessary Assumption issue

timmydoeslsat wrote:In the context of a necessary assumption, sometimes it is true that a necessary assumption will also be sufficient for an argument to be valid. Such as this instance:

P ---> T
_____________
P ---> ~H

The necessary assumption here would be [T---> ~H] which is also sufficient in this case.

However, I would like to discuss this construct:

P ---> T ---> ~C
______________
P ---> ~H

Here we could have two different sufficient assumptions.
(1) [T ---> ~H]
(2) [~C ---> ~H]

Since we have two different ways of making this argument valid, my question would be what is the necessary assumption in this argument.

I will repeat myself as it seems that a majority of my threads do not answer the question posited: What is the necessary assumption of the second argument.

To me, I believe that the [T --->~H] connection is necessary given the evidence presented. Either you go from ~T --->~H or you go from ~C --->~H....either case will have T being led to ~H.

Timmy: not sure if I understand you right, but I don't think T --> ~H is necessary. Actually, neither T --> ~H nor ~C---->~H is necessary, because both require further assumption from what you really need, which is only P---> ~H.

an example completely according to your formal:

premise:
i live in Munich (P) ----> I live in Germany (T) ----> I do not live in US (~C)

the "want-to-have" conclusion:
i live in Munich (P) -----> i do not live in Berlin (~H)

I live in Germany (T) does NOT ----> i do not live in Berlin (~H)
also, of course, I do not live in US (~C) does NOT ----> i do not live in Berlin (~H)

As to what the necessary assumption would be, I would say a typical LSAT necessary assumption would be

at least sometimes T overlaps with ~H
or
~C does not exclude ~H

Again, not sure if I understand you right (I suck in RC), but these would be my two cents.

thestalkmore

Posts: 96
Joined: Sun Feb 28, 2010 5:11 am

### Re: Necessary Assumption issue

The following question is an entirely serious question:

Why are you guys bothering with this? There isn't a single question on any LSAT ever that requires this level of abstraction or this precise of an understanding. Is this just an intellectual circle-jerk or has everyone that has seriously participated in this discussion completely misunderstood the scope of what the LSAT is testing?
Last edited by thestalkmore on Sun May 13, 2012 5:26 pm, edited 1 time in total.

princeR

Posts: 291
Joined: Mon Dec 05, 2011 4:10 pm

### Re: Necessary Assumption issue

thestalkmore wrote:The following question is an entirely serious question:

Why are you guys bothering with this? There isn't a single question on any LSAT ever that requires this level of abstraction or this precise of an understanding. Is this just an intellectual circle-jerk or has everyone that is seriously participated in this discussion completely misunderstood the scope of what the LSAT is testing?

Take out the intellectual part and I'm in. Wait wut?

Mal Reynolds

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Joined: Mon Oct 03, 2011 12:16 am

### Re: Necessary Assumption issue

GO TAKE A PT. THIS IS USELESS FUCKERY.

Paraflam

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Joined: Wed Jan 14, 2009 3:09 pm

### Re: Necessary Assumption issue

Mal Reynolds wrote:GO TAKE A PT. THIS IS USELESS NEUROTIC FUCKERY.

thestalkmore

Posts: 96
Joined: Sun Feb 28, 2010 5:11 am

### Re: Necessary Assumption issue

Mal Reynolds wrote:GO TAKE A PT. USE LESS FUCKERY.