Is this a flaw?

wjun15
Posts: 105
Joined: Thu Jul 09, 2009 8:09 pm

Is this a flaw?

Postby wjun15 » Thu Sep 16, 2010 12:19 am

in a flaw question one of the choices were:

"infers from the fact that a certain factor is sufficient for a result that the absence of that factor is necessary for the opposite result"

that just means someones making a mistake by considering a contrapositive of a conditional statement right? In other words, that is not a mistake, correct?

Thanks!

dakatz
Posts: 2460
Joined: Sat Mar 29, 2008 4:19 pm

Re: Is this a flaw?

Postby dakatz » Thu Sep 16, 2010 12:25 am

wjun15 wrote:in a flaw question one of the choices were:

"infers from the fact that a certain factor is sufficient for a result that the absence of that factor is necessary for the opposite result"

that just means someones making a mistake by considering a contrapositive of a conditional statement right? In other words, that is not a mistake, correct?

Thanks!


Odd phrasing, but yes. That is a description of the contrapositive, which is obviously never an error.

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suspicious android
Posts: 938
Joined: Tue Feb 09, 2010 4:54 pm

Re: Is this a flaw?

Postby suspicious android » Thu Sep 16, 2010 1:23 am

wjun15 wrote:in a flaw question one of the choices were:

"infers from the fact that a certain factor is sufficient for a result that the absence of that factor is necessary for the opposite result"

that just means someones making a mistake by considering a contrapositive of a conditional statement right? In other words, that is not a mistake, correct?

Thanks!


Wow, I've never seen that. What question was this?

Yeah, like you thought and the other poster said, this would be a contrapositive inference. If X -->Y, then x is a factor that is sufficient for y result, so the absence of X (~X) would be necessary for the opposite result (~Y). ~Y --> ~X

wjun15
Posts: 105
Joined: Thu Jul 09, 2009 8:09 pm

Re: Is this a flaw?

Postby wjun15 » Thu Sep 16, 2010 3:05 am

PT 54
section 2 #19




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