Is this a flaw? Forum

[wjun15]

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]

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.

[suspicious android]

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]

PT 54
section 2 #19