I don't remember very clearly, but I think I was spanked a couple of times, maybe.
The behavioral psychologists will say that by punishment, you will discourage that particular behavior but you don't know where the alternative behavior may go.
I say: Okay, forty years of Dr. Spock and we have John Walker and suicide 15-year olds. Maybe smacking them a good one when they were six years old would not have been a solution, but the laisse faire philosophy of "whatever" isn't exactly the answer, either. We don't want to beat the kid, but judicious use of a paddle might be better than swearing it off completely.
Having a parent tell a kid "Oh go ahead, explore whatever" was not what John Walker wanted. From the reports, he "wanted to be told precisely how to dress, to eat, to think, to pray. He wanted a value system of absolutes, and he was willing to go to extreme lengths to find it." (MSNBC.com) If he'd been given some direction at home when he needed/wanted it, perhaps he'd not be where he is today.