Necessary Assumption issue Forum

[timmydoeslsat]

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[timmydoeslsat]

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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[BlackadderIn]

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)

now please notice
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]

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?

[princeR]

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]

GO TAKE A PT. THIS IS USELESS FUCKERY.

[Paraflam]

GO TAKE A PT. THIS IS USELESS NEUROTIC FUCKERY.

[thestalkmore]

GO TAKE A PT. USE LESS FUCKERY.