So, do you like to be slapped? As a human?
One of the issues always faced in any debate of this type, is the type of 'discipline' experienced by people on both sides of the divide (while they were growing up)
Those who experienced good forms of physical discipline, inevitably support it (or don't have anything against it) - for they experienced, and see all around them, the positive results of physical discipline (done properly), and see the negative results of both : a lack of discipline, and 'poor/incorrect discipline'. Regarding the latter part of that last sentence - those who experienced positive physical discipline disagree with beatings, with face slapping, with excessive force, and with discipline without a balancing love
(which isn't saying "I'm only doing this because I love you' - but the actions, support, warmth, time and interest in the person that comes with love). They also tend to disagree with 'discipline' done out of anger...which is not discipline at all.
Those that experienced the negative forms of discipline, in this sort of forum, inevitably (and understandably) associate such with beatings and violence...which is what they experienced under the guise of 'discipline'. In my experience, they inevitably take most of what a person who experienced positive physical discipline has to say, and attach negative labels to such, and use examples which most sane people would find abhorrent/wrong...and tie the example to a 'positive example' (positive to the person who finds positives in correctly done physical discipline)...which view they (people who experienced poor/incorrect discipline) hold of the positive, bears no resemblance at all to the other parties experiences...
...in other words, it's usually an emotional debate based on family history, with two parties talking about related, but in the end, entirely different things.
For my own :
All my siblings bar one (so 3 & 1), experienced positive physical discipline.
All are law abiding, well employed, well mannered. One struggles a bit more than the rest of us. That is to say, our mother (who was the disciplinarian in the family - who as a balance, also put a hell of a lot of time and love into us) made mistakes with one of us, and wasn't perfect.
My history includes : several drags by the ear, one stick, 2 belts, and probably a few whacks on the shoulders (not sure about that last bit). One the balance side, she spent a lot of time explaining right & wrong to us, teaching us about the dangers of the world, teaching us to respect our elders, teaching us about responsibility, spending time with us at playgrounds, to fetes, taking us fishing, coming to school with meals for us, driving us around...etc.
It's not that other ways can't work...but going down that path is a whole topic in itself.