Idiot a écrit  merde.

It is necessary for you to get some education, a private schools is
alwsys preferable over a croweded public school in provinsial France
full of immigrants. Possibly, you are one yourself given your arrogant
ignorance.

Now,  given that an implication is true says nothing about the
antecedant, as it is well known to those who studied logic (that
excludes you) that an implication is false only if, and only if, the
consequent is false.

Thus, by showing a formal proof you do nto answer the question. B can
be decuded for a only if a strict logic applies in which the
countefactual, "B can be only if A" is true.

This is what Androcles is trying to teach you. We all know that the
light will go on, only if the switch is turned on. This is a
counterfactual. from A, the fact that the switch is turned on, you can
immediately deduce the light will go on. But unless the counterfactual
is valid, you cannot in general deduce THE TRUTH OF B for the truth of
A. YOU CAN ONLY DEDUCE THE VALIDITY OF A => B.

Thus, you are just another moron you posts very frequently at
alt.morons (check it for yourself, you have a post there just today)
who CONFUSES TRUTH AND VALIDITY, along with your guy cross-dressing
friends. 

mangez merde.

Mike