> Don Kresch <email@example.com> wrote in > news:firstname.lastname@example.org: > >>>3. My favorite: "If your God exists you say He >>>incarnated Himself as a man and walked on water. >>>Since we know men can't walk on water, that proves >>>your God can't exist." It assumes God exists and >>>doesn't exist in the same sentence. Not logical. >> >> You've never heard of proof by contradiction/reductio ad >> absurdam? Wow. Just wow. > > Since I teach logic at university, yes, I've heard of it. > The above is not an example of it. It is, rather, an > example of denying the antecedent. So now, if we > need an example of an atheist doing bad logic: we have > you. Wow. Just wow.
To deny the antecedent is to argue thus: if P, then Q; not(P) therefore not(Q). What are the P and Q that make this argument fit that form? I can't see it, but you may have introduced some other assumptions without making them explicit (your remark about what the quoted argument assumes certainly suggests that).