On the note of different kinds of discipline, I find that a lot of people immediately feel that corporeal punishment is abuse. However, they forget that other kinds of discipline can just as easily stray into abuse and do worse and more long lasting damage than being hit as a result of being disobedient or ill-mannered.
My parents used a combination of physical, psychological, and emotional discipline. Physical discipline is reactive and falls into the categories that are easily definable: hitting, spanking, belting. Emotional discipline is also reactive involves and uses the removal of something pleasant in response to bad behavior: taking away toys, taking away allowance, denying a child attention when they throw a tantrum to get your attention. Psychological discipline often involves non-physical, proactive approach: teaching a child what's appropriate by modeling it for them, informing a child when their behavior is inappropriate, shaming the child when it has done something inappropriate, and rewarding good behavior.
What people forget is that emotional and psychological discipline VERY easily slip into abusive territories without leaving a visible mark and without seeming extreme. A spanking, if the kid's parents are like mine involves telling the kid what they are getting the spanking for and how many times they will be struck for the offense and why. It's very concrete, requires no thought. It's simple. When you stray outside of the parameters you set for spanking and start doing it in anger, beating welts onto the child or bruising them, it breaks a psychological contract and causes psychological damage.
Emotional discipline becomes abusive when its accompanied with name-calling, verbal abuse, destroying the items that should have just been taken away, confining the child, or ignoring the child without ever explaining to them why its being done and not giving them a discernible limit. It also involves the idea of not disciplining your child until they are embarrassing to YOU. Then it's a violation of a psychological contract and it tells them that their suffering is your pleasure.
Psychological discipline becomes abusive when the teaching protocol is accompanied with an implied or overt idea that the moment they fall outside of your parameters they become useless, when rewards and affection are only given in response to actions...and when shaming goes to the level that many parents see as trendy today...when the whole world joins in the dialogue about how bad a child the child is. This kind of discipline creates a negative psychological contract that affects the kid's self-esteem, self-worth, and causes anxiety. It's also caused kids to kill themselves.
I feel that all three discipline styles should be combined in a way that doesn't ignore the situation or the child's needs at that moment. It's up to the parent or whoever is there to gauge what that is because not every situation and not every child will respond to the same kind of discipline. I currently work in health care and I can tell you, that the prescribed, "No. Stop. Don't harm others or yourself." doesn't work. Sometimes the "If you rip out your IV and your catheter, even if it is uncomfortable, you will hurt yourself, bleed, and probably get sepsis of the blood." doesn't work. Sometimes putting your hands on someone and MAKING them stop is the only way to actually get them to stop.