I swore when I was a child that when I grew up I'd never tell my kids “Because I said so!” when they asked me why they had to do something. Good thing I didn't put that in writing or my children would be suing me for breach of contract. Kids invariably will ask why when we tell them to do something (or why not when we tell them not to, that must be in their rulebook.) Unfortunately for us, the "why?" is usually in that annoying whiny voice implying “I don't wanna.” or in that independence asserting voice, yep you know the one. It makes the hairs on your neck bristle because it means that the answer you give will be used as ammunition against you in the ensuing battle. And the why war was on! After all I wanted to be the mother that encouraged her child's curiosity and self expression...hah
I lost count of how many times I said it and of how many times I fought the why war and lost. Finally one day, suffering from battle fatigue my response to why was “I don't know, but as soon as I do, you'll be the first to know!” It wasn't defensive, it was just honest and they knew it. No they didn't tie their tidy whiteys to a stick and surrender. Let's just say it opened the door to negotiations. The rule is this, you do not have to explain why you want them to do something at least not until after they've complied. There just isn't enough time nor energy. Sometimes we really don't know why and that doesn't mean they get to run amok. Just tell them that it's in the Mother's Rule Book , rule #2.
