Guys, you may have missed my point. Both punishment and positive re-inforcement are required. They go hand in hand. Spanking a child should be used in extreme conditions, but not on a day to day basis. My kids get a "Swat on the butt", which is a swift, sharp smack, just once, on the bottom, only after all other avenues have been exhausted, ie, time out, sent to room...then they get the swat. Without some form of physical punishment as an ends to a mean,you're just asking for more problems down the road. YOU must set the standard. If you don't the childs unwanted behavior WILL set the standard for you. However, as much as physical response is needed in unwanted behavior, positive re-inforcement is a MUST to PREVENT that behavior. Take the time to tell your child how proud you are of them for behaving so well at times such as, going out to a restaurant when they behave well, or sharing toys with a sibling, etc. Its like positive/negative current with electricity, one does not exist without the other. Its my opinion that spanking is okay, as a last resort to unwanted behavior. Its also my experience that one does not have to resort to spanking IF they use enough positive re-inforcement...but to say you'll never spank your kids is just inviting them to dictate to you what type of behavior you will have to put up with.
Again, beyond a certain age, say, 5, spanking is non-value added, and as mickey said, there are more effective options.