Earlier quoted context omitted.
We don’t allow adults to strike one another in anger or as punishment for a mistake or wrongdoing. We don’t allow children to hit each other — indeed, we actively discourage it. Then why is it okay for an adult to hit a child?
I agree with you, but what alternatives does that leave us with? Economic or "jail" punishments aren't suitable in many cases when it comes to kids.
You might be interested in checking out:
https://en.wikipedia.org/wiki/Reinforcement
It covers the types of operant conditioning with definitions. From this article, you can blast off into tons of reading. Read carefully - these are holy topics to some writers and they will carefully shape their message to support their viewpoints.