Argument Completion Drill Question?

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LSAT_Padawan
Posts: 45
Joined: Thu Feb 18, 2010 10:17 pm

Argument Completion Drill Question?

Postby LSAT_Padawan » Mon Mar 22, 2010 6:32 pm

Can someone explain how you come up with the conclusion "U"?

P: W or X ---> Y and Z
P: Not U ---> X
P: Not T
__________________________
C: U

Thank you for your enlightenment!

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FreeGuy
Posts: 133
Joined: Sun Dec 21, 2008 4:42 pm

Re: Argument Completion Drill Question?

Postby FreeGuy » Mon Mar 22, 2010 6:39 pm

Here are a few sufficient assumptions for this argument:

Not Y
Not Z
Not X


Because:

Not U ---> X ---> Y and Z

so, the contrapositive is:

Not Y or Not Z ---> Not X ---> U


The Not T is irrelevant.
The W in the first premise is irrelevant.

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LSAT_Padawan
Posts: 45
Joined: Thu Feb 18, 2010 10:17 pm

Re: Argument Completion Drill Question?

Postby LSAT_Padawan » Mon Mar 22, 2010 6:51 pm

FreeGuy, thank you for your input. I understand your explanation and how you came to conclude "U" but how did you know that "W" and the 3rd premise "not T" were irrelevant? That's where I struggle because I'm trying to incorporate all the elements.

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FreeGuy
Posts: 133
Joined: Sun Dec 21, 2008 4:42 pm

Re: Argument Completion Drill Question?

Postby FreeGuy » Mon Mar 22, 2010 6:55 pm

X is the only variable repeated in the premises.

It connects "Not U," "Y," and "Z" together.

"Not T" and "W" are not connected by X.

Sometimes, certain elements in the premises won't matter. Stimuli can contain useless info.




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