I'm a teacher by profession. I've dealt with thousands upon thousands of students, and hundreds of parents. I am very much in favour of corporal punishment.
Whenever I've taught older teenagers, it's never been an issue. With patience and tact, you can get older kids to answer to logic. For younger kids though...
Do not bloody tell me that you've never been in a situation playing a video game and you encounter the noisy, rude, disrespectful little pissant and you wanted to reach an arm through the monitor and crack a fist into their face.
The argument that resorting to physical punishment is a sign of bad parenting is extremely flawed. If physical pain is the first thing you go to every time for most problems that would be true, but for many/most young people, especially these days, a respect for authority needs to be garnered BEFORE logic and reasoning can take firm hold.
As part of the education degree, I've sat through countless classes regarding conflict resolution, intellectual/emotional development, etc. Many of the techniques presented work minimally at best, especially with the calibre of youth who need discipline the most.
As with most things in the world, arguments founded in the extremes of a side will nearly always be wrong. Thinking a rap across the knuckles is child abuse is no less inane than thinking that daily beatings promote character growth. I get to watch, first hand, progressive generations of youth as they filter through schools with increasingly degenerating judgement, respect, and morality. This correlates perfectly with the government's mentality of giving in more and more to the thought that each child must be patted on the head and told they're special. Attitudes continually worsen, even such things as basic literacy skills falter, and teachers' authority is continually undermined.
I work in adult education now. I've been able to do so much more good here than in the youth sector - a place where if a 12 year old tells me to fuck off, the extent of my power is to give them a detention which he will not show up to, or call home to parents who 9 times out of 10 will just tell me to deal with it myself and stop bothering them.