I guess another reason we don't want to spank our kids, besides the fact that it is cruel and humiliating. A study reported yesterday "found that spanking and other corporal punishment is associated with an increased probability of verbally and physically coercing a dating partner to have sex; risky sex such as premarital sex without using a condom; and masochistic sex such as spanking during sex." Link
I think that it's all pretty obvious. If you're going to have self-respect for yourself and others it's important to develop body integrity early. Spanking can violate that sense of one's body and its integration with the self. Researchers talk about how a few smacks now and then can lead to a much greater frequency of using physical means to rein your kids in, and the more it's done the more problems people have later on. To my mind, it's important to remember that kids will always confound you regardless of what you do. Discipline is a constant, ongoing process.
Last night, in fact, BB broke down over something silly. We'd watched an episode of "Between the Lions," and just as it was about to end it occurred to him that he had wanted to watch something different. When I said no, he kicked a couch cushion toward me. Instead of blowing up as well, I patiently told him to take a time out. He only needed a minute in his room before he was able to turn that emotion around, and he was cheery and chatty the rest of the evening. It works.