"Spanking" can mean anything from soft (zero-pain) swats to belt-whipping. When AndyFromMonday compares it to "cutting your child," I'm certain that even though we're using the same word, we're not talking about the same thing.
So let me define "spanking" as I will use it here:
"Spanking": The use of minimal physical force to inflict surprise (milder form) or pain (stronger form), without any lasting physical injury, by using the hand, or an appropriate tool, on the rear end (where fat tissue helps cushion against injury).
A child recently spanked may suffer a sore bottom for, say, half an hour, if that. Anything more lasting (can't sit down for 24 hours, blisters, scarring, etc.) would fall under "whipping" or "beating", neither of which I advocate for parental discipline. Spanking, as I use the term, falls far short of physical abuse.
If, despite that definition, you still think there's no distinction between "spanking" and "cutting", then I wonder how well you fare with other scales that differ by magnitude. Is a "breeze" as destructive as a "hurricane"? Are "mild government regulations" as invasive as "tyranny"? Slippery Slope much?
But anyway.
In 32 years, I've never thought spanking unjustified, but I've adjusted my view on WHEN it is justified. In general, if the kid still responds to discussion, reason, and logic, if he submits to basic commands and discipline such as "go to your room," then there's absolutely no reason to spank. I don't care if you told him not to play ball in the house and he did and broke the front window AND your mother's favorite Ming vase: There are other ways to handle this. Scold him, send him to time-out, take away privileges, hand him more chores, sit him down and discuss his feelings... whatever works. If he's still talking, or just being sullen for a while, then physical pain is not necessary; spanking, for me, is not a punishment.
But consider a child who has gotten into a downward spiral of rage or rebellion, forsaking reason and resorting to tactics based on "Give in to me OR ELSE!" Younger children have temper tantrums; others may start destroying things, or disrupt the family and outright refuse to stop ("I'm not moving out of the way/letting go of this thing come hell or high water"). When talking doesn't get you anywhere, and they won't follow basic orders, what then?
Ayn Rand posits that if a person has left the world of People (who can be reasoned with) and chosen to act like an Animal (who cannot), the tactics have to change. In my view, the aim of appropriate discipline is to bring the child back into the world of reasonable People again as efficiently as possible, preferably with long-term benefits such as avoiding similar situations in the future. (The same reason you don't ever give in to the kid screaming for candy at the check-out line. Even if you have to give up your groceries and leave the store.)
So, basically, if the kid is in a downward spiral right now, and isn't kicked out of it by a simple command, then here comes spanking: The last resort for very specific circumstances in which other tactics will not help. It's a Reset Button for the will. It snaps them out of it and lets them choose a better path; this is especially important with younger children, who may not understand how to get out of the spiral on their own. (I think letting a four-year-old throw an hour-long temper tantrum is abuse in and of itself.)
Spanking gets the attention fast. It reminds the kid of who's in charge, forces them out of the negative spiral, and moves them back toward a positive relationship with the family.
This is already pretty long, so here's my final thought:
When we were ready to start church today, my 7-year-old nephew was lying under the piano bench (he does that now and then). Mom told him to move; he refused. She bade me deal with it. I gave him one command, and when he refused, I said "We are leaving this room NOW," took him by the arm, and pulled him across the floor. It took him two seconds to decide he could get up and walk, and we exited together. After we got to the Sunday School room, I talked with him a bit and determined that he was just very tired, so I let him sleep through the whole service.
That minimal amount of force, in pulling his arm, gave him the clear message that I was prepared to go all the way. It made him reconsider his options and choose to act differently. He turned back to a fairly reasonable kid almost immediately; our conversation got him the help he needed, and church was not disrupted more than absolutely necessary.
There's no way I would have sat there trying to bargain with the kid as the church service waited for us. It would have been rude to everyone there, and my own embarrassment would have made me harder on my nephew than I had to be. By forcing him to comply at first, I was able to get us to a place where we could hold a reasonable discussion, pin down the reason for his unreasonableness earlier, and find an appropriate solution.
My niece (12) knows that I'm willing and able to drag her down a hallway if I need to enforce discipline (did that once when she refused to stop antagonizing her brother, and then refused to go to her room). Because of that, I no longer need to drag; if it gets near that stage, I only need to mention "You know I'm willing to drag you" and surprise, she chooses to go by herself. It's the same with spanking: If you're doing it right, the kid will only need three or four in his entire life (and they don't even need to be all that painful).
