Anne

Generally speaking, a firm tone should be enough. It usually is for me.

First of all, often times discipline hurts the person getting disciplined regardless of whether it is grounding, a timeout, or a spanking. The very nature of disciplining a child is to teach them (through punishment) that doing something wrong 1. is bad 2. results in unpleasant consequences. You know why some toddlers chronically hit, pinch, and bite? Its because it when they perform that action, they always get a specific response from the receiver of their action, making them feel like they have control over the environment. Do you know what most psychologists say to do in those circumstances? Bite/pinch/hit the child back (not as hard as you can of course, just enough to hurt the toddler). Because in most cases, the toddler was 1. to some extent unaware how much his actions were hurting the receiver 2. testing the limits of what is/isn't acceptable behavior. Biting back lets the kid know that if they cross that boundary, there are unpleasant consequences as well as that they hurt other people when they do it.

Of course there is a difference between spanking and beating. Beating a child is wrong. Period. Spanking when done right, is can be a loving/good way to discipline a child. For children, immediate, memorable consequences rather than prolonged ones are more effective at molding behavior. If a kid is grounded, it presents the child with an opportunity to excercise control over the parent, another medium in which to try to challenge the parent's authority. If a parent gives in, which in circumstances will inevitably happen (5 year olds are stubborn by nature) it encourages
1. more of the behavior that warranted the punishment to begin with and 2. the idea that the parent is not the final authority figure

Spanking when done correctly, in the right circumstances tells the child 1. I am the adult (bigger than you). I can hurt you if I want, but I love you and do not want to. I am the authority figure.
2. I love you enough to correct your behavior, even if it means hurting you temporarily.
3. I set the boundaries of acceptable behavior and you as the child need to respect those boundaries. For a child, learning to behave correctly comes first and learning the reasons why certain behaviors are appropriate/inappropriate comes later.

By correctly, I mean
1. Spanking should not be done in anger. If you punish any child in anger, you risk disproportionately punishing the child and with spanking, you risk spanking too hard and hurting the child. If you regularly resort to spanking in anger, you are telling the child that he/she can control you on some level by pushing you to lose your temper. Kids pick up on these patterns quickly. You are also reinforcing the idea that when you lose your temper it is ok to resort to physical violence.
2. Tell the child the reasons for the punishment and why such actions warrant the punishment. For example, if the child is hitting other people, take the child aside and say "Hitting other children is wrong, because you cannot use violence to solve an argument. Even if you are mad, you can not hit other people." Note that if you are angry when you do this, you as the parent are creating an interesting incongruancy for the child. In the truth of the matter you are being a hypocrite.
3. Tell the child after the punishment that you still love them. Its important after any punishment to reinforce the fact that as their parent, you will always love them, even if they make a mistake. It also reinforces the idea that the punishment was performed out of love and concern for the child and his proper development/welfare.

To the woman with the child who hits, I would tell her to control her temper during her child's bouts of violence. When you lose your temper you lose control of the situation. By losing your temper, you are giving him a victory in this contest of wills. It sounds that what the child is doing is similar to my explanation of the toddlers who chronically bite. Your son has learned how to control you and the situation (the cycle of hitting, you punishing him, his continued hitting, you getting angry, and then you spanking). If you don't think that he has learned the pattern to this cycle, you're wrong. He knows what he is doing and he is probably doing it on purpose to some extent.

You have already dug yourself a hole here because as of right now, the child has the upper hand. He knows how to push your buttons and escalate the situation. The trick now is to turn the tables and let your son know that he can NOT control you, even with his bad behavior.

What you need to do is make a preemptive strike. Take the child aside and let him know why hitting is wrong. Then, outline a punishment that he will get when he hits, an appropriate punishment that you see fit. In the end, the most important thing is that you stick to the punishment no matter what! If the child is hitting in the midst of a rage induced temper tantrum, and you need to spank him in order to get his attention and stop the tantrum, do so, but do it BEFORE you reach the point of being angry and before the tantrum escalates. If you are not comfortable with this, another method is to isolate the child, (forcibly if necessary) until their temper tantrum subsides. Depending on the child's age, a temper tantrum or two every once in awhile is natural and part of growing up. Once the child has calmed down, enforce the earlier outlined punishment.

But above all, do not let the child dictate the mood of the encounter and take control out of your hands. You are the adult. If you feel yourself about to lose control of your temper, isolate the child (in his room) until you have both calmed down, and then enforce your punishment.

Seriously, ever tried to talk about why he did something or "are you angry?" with a toddler?

A light slap on the hand gets their attention and stops the behavior. And like all discipline, it need constant repetition and regularity with whatever actions you are trying to curb. Clearly – don't every beat a child. But some form of corporal punishment can be necessary in certain situations.