If they are incapable of applying reason, then surely it is fruitless in hitting them?
I would assume you wouldn't hit a 2 month old baby because it is crying?
What about a 14 year old teenager? Are they incapable of applying reason?
At last we are coming to the core of the problem and where we fundamentally differ. I hold the view that small children do have reason(and this is not unsubstanciated btw). What they don't have is the socialisation to deal with their emotions, and thus get frustrated about it.
Watch this video and tell me that children are not yet developed enough to understand or be able to apply reason:
You can see it on the older one's face as she is coming to grips with her emotions. Simply turning it into a game, where they should cry on demand in turn, then showing them how it is done, made it understandable to them. That is nothing else but reason.