Argument Completion Drill Question?

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

Argument Completion Drill Question?

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

FreeGuy

Posts: 130
Joined: Sun Dec 21, 2008 4:42 pm

Re: Argument Completion Drill Question?

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.

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

Re: Argument Completion Drill Question?

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.

FreeGuy

Posts: 130
Joined: Sun Dec 21, 2008 4:42 pm

Re: Argument Completion Drill Question?

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.