A child’s mind develops in a miraculous, but predictable sequence. The newborn swimming through a world of random sensations eventually becomes a fully rational adult.
And, between those points in time, the child’s mind is a unique place. They live, up until the time of the “9 year old change” (to be discussed another day) in a world where it is easy to imagine princesses and monsters, but it is both difficult and uninteresting to imagine what is going on in someone else’s mind.
They are developing “Theory of Mind”- the ability to predict from context and visible clues what another person is thinking. At first, this theory is patchy and inaccurate, which explains why small children hide so badly. It’s very cute to watch, but it should also remind us that their brains are different than ours. Specifically, they are more concrete (non-abstract) and less connected to what others are thinking.
So, what is my point? If you want a child to stop hitting someone, it is more effective to say “Stop hitting” than it is to say, “Sweetie, don’t you think it would be better to be nicer to your friend?” or “You are making Mommy sad” or “Be a good boy”. The processing involved is so complex. To be guided by the instruction to be a good boy, one has to have a clear idea of what the concept of “good” means, how that is different for a boy, whether or not you are a boy, what your mother expects from good boys, and how your current activities relate to that concept. There is none of this difficulty in responding to a simple concrete instruction.
I think that most parents who avoid simple instructions like this are worried that they will seem like harsh disciplinarians. But it’s all in the tone. It’s perfectly possible to cheerfully tell a child to do something different than what they are doing without being too angry or harsh. You could use positive commands like “quick, hands on head!” instead of “stop hitting” to arrest dangerous behaviour. Your own creativity will help you come up with simple positive instructions for different situations.
To summarize, if you’re not getting the results you want by talking to your child diplomatically, try using short simple statements, repeating more or less the same words in each situation. It’s easier for a child to remember that mom wants “no touching in stores” if those 4 exact words are repeated every time the little hands reach out of the buggy. Remember that their mental world is different than yours, and their failure to obey may actually be a failure to understand your request.