Math,
I cannot be bothered with responding to every detail of your post, partly because I have already done so and partly because you are comparing apples with chocolate in your critique of my understanding of my children and my risk assessment.
However, my presence was clearly a part of the risk assessment. I think that, with reference to risk that most parents feel are clearly within the normal spectrum, that you are overprotective. Maybe you have your reasons, maybe you have had some unfortunate experiences that have skewed you that way. Just about every toy for any age beyond a baby can cause injury by misuse or shear bad luck. The corner of a lego brick in the eye can be as damaging as the horn of a plastic dinosaur, a toy wendyhouse if picked up and used as a weapon could be severely injurious. I do not believe in 100% safety proving my house, I believe in teaching my children. What actually occurred was a teaching experience and no one got hurt.
"smacked because the boy was hurting his brother then how is hurting him in turn going to teach him anything except that when he gets older he doesn't have to abide by the same rules children apparently must follow?"
This logic, used so often on these threads, is plain wrong. Every parent who uses any form of punishment teaches the child that the punishment is a response to the child's action and not vice versa, and they totally understand it. Would you expect your teenager when he is big enough to put YOU on the naughty step (to think about what you did)? No, because you would expect him to observe a power structure with you at the top. And if you talk about him learning reason blah blah blah, what if he honestly believed you had been naughty and deserved it? Fair enough then? And if not, why not? And I will not teach my child not to hit, I will teach him not to hit first or start a fight. If someone hurts him or anyone smaller, I would be very proud of him if he defended himself or that person.
"In the first place, how does hurting a child teach him anything about hurting his brother?
Second, the answer 'neither' is not as much optimistic as revealing -- this was a child who did not understand why a punishment might have been necessary or what was unacceptable about hurting a brother.
Third, even after the smack on the hand, the child still did not apparently feel remorse -- was interested primarily in the prospect of chocolate."
Haha, re revealing. This was a version of the "marshmallow" test. A lot of children when asked if they wanted one marshmallow now or two in 5 minutes first tried it on with wanting two now. And I am pleased he had got over what was a small misdemeanour and a small punishment. I am glad it was all about the chocolate. I don't want to impose some sort of catholic guilt on him. There are many situations in life where you have to make a choice between two negative outcomes and it is still better to have a choice than none. Think speeding and an education course or 3 points on your licence.