I have had some very odd conversations with people on this. I did smack my children occasionally when a relatively new father but I thought about it, worked out I was being a dick so stopped. I can't understand why so many still feel it's not just acceptable but a reasonable way to moderate behaviour. You have to stop sometime and find another way so why not from day 1?
Not that long ago a friend said to me that a lack of smacking is why kids are so bad today. I had a heated conversation with her as the ignorance and logical fallacies spewing out of her mouth infuriated me. She still didn't get it, accusing me of not respecting others' right to raise their kids as they see fit. I told her society's historical deference to the seemingly unassailable right of parents to do what they like with their kids is why child abuse has gone on for so long.