I think we're talking about authoritarian parenting vs.cooperative parenting. Sure, there's a difference between a smack and a beating, but for a small child even harsh words can be debilitating. I was brought up in an authoritarian home and I didn't know how to say no when I grew up and was conditioned to be compliant. I didn't even know how to make a decision.
I wanted a different relationship with my children. I learned that they, that all of us, have a good reason for their behavior. We have choices in conflict with children and adults. Children are, by nature, dependent--they cannot fulfill their own needs. When a child "misbehaves," it may be that she is simply frustrated by a legitimate need. She may be tired, hungry, or overwhelmed by a disruption of her routine; she may be feeling jealous, frustrated, confused, or afraid; or she may be simply too young to understand or to express her emotions. When we eliminate the symptoms of the problem by punishing, the problem does not go away.
Your child's behavior can teach you something about his needs, if you take the time to listen. Almost all acting out is a cry for help. Your child may be jealous, afraid, lonely, or in a situation that is out of his control. Often the child who is acting most unlovable is the most in need of love.
Young children are naturally impatient, forgetful, stubborn, loud, messy, and demanding. They are childish. It is unrealistic to expect them to act in socially acceptable ways until they have the maturity to do so. Most youngsters under five do not have the language or cognitive skills needed to share or work our disagreements, so they fight or cry instead.
Even in the case of real danger--as when a child runs out into the road--you can grab him, sit him down, look him in the eyes, and tell him why he must never do that again. The panic in your voice will communicate your message much more effectively than any spanking. You can be dramatic without being abusive.
And, I find it illuminating that while we talk of some states outlawing spanking, 32 countries outlaw spanking! Sweden did so in 1979. Kenya in 2010. Republic of Congo in 2010. Sudan in 2011. I don't think it's any coincidence that we are such a violent and aggressive society when we condone spanking.