Noddyholder, you sound like you've missed the point of my argument. The point is that as adults we react against smacking as an act of 'force' or physical violence because we lump it together with punching, kicking, guns and knives - in other words, when we take an extremist point of view on the matter. You can do exactly the same thing with any type of punishment - I could claim that by telling your children off you're emotionally abusing them, or that by sending them to the naughty step you're illegally incarcerating them. But I wouldn't, because that would be silly.
Madame Platypus - I agree with you, it is incredibly difficult to get a young child to understand the difference between who is and isn't allowed to smack each other, but is that really your main reason for being anti-smacking? There are lots of things that parents do their children don't understand - can any parent on this discussion honestly say that they have NEVER had to repeat themselves time and again because their child forgets/ doesn't get it/ for some other reason? Unfortunately that's life, there are no easy answers, but on the issue of discipline, I believe that by using a range of punishments combined with unconditional love, the best we can hope for is that we will eventually have the desired impact on our children as they grow and increase in their understanding of the world.
Voluptua - thank you, and what a fabulous name.