In the good (bad) old days, many parent disciplined their children with a belt or rod. But true discipline is not simply physical punishment for a perceived wrong; it is training a child how to behave using love and kindness rather than harsh physical pain to accomplish your goals.
No one would smack or belt a little puppy that chewed a slipper or left its calling card on the floor, so why do this to a child? Children should be taught first by example, then by showing them how to do a thing and encouraging them to do it – even doing it with them can work well. Rewards can be given for good behaviour, but little children are so eager to copy and to please their parents that a simple hug is often reward enough.
When a small child misbehaves, it is usually caused by them being overtired or upset about something rather than them making a conscious decision to do something bad. It is the parents responsibility to find out what the problem is and fix it for them, until they learn how to cope with such problems on their own. The parent has the duty of care to protect their child and keep them out of mischief as well as out of danger. Sadly, this does not always happen.
Part of the reason for this is that parents often reflect their own upbringing in how they discipline their children. If they were abused by their parents, they may easily have anger issues they find difficult to control. The end result is they take their own anger and pain out on their children, hitting them for minor infractions, instead of nurturing them in love and kindness.
If you hit your child to make them do as you say, they will soon begin to rebel against the injustice and lack of love that such a trauma causes. As they grow older they will copy you and use force to try and get their own way. That is not to say a little smack on the leg from a loving parent is wrong. Sometimes it is the only way to make a child take notice, especially if they have done something that has harmed someone else, or put themselves in danger.
For instance, if a toddler consistently fiddles with the knobs on your gas stove, it is essential that they learn not to, or they may gas the whole household. A quick, light smack after a few warnings will give them a fright and make them think twice about doing it again.
An older child deserves an explanation of what the right thing to do is and why, rather than just getting a smack. They may not even know why they were punished, otherwise. Of course, different children have different natures and while some may be easy to train and tractable, others seem to be born rebels. But even rebels don’t deserve to be abused.