Your kids will sometimes question your decisions. They may interrogate you about the reasons behind your answers to them. They may demand an explanation for the course of action you have chosen.
You may decide to answer them or you may choose not to. How do you know which questions require answers and which don't? Let me give you a very easy way to make that determination.
If your child asks "Why?", you need to determine if the question is asked in good faith or bad. Fortunately, this determination can be made almost instantly.
Bad faith questions are very easy to identify. They are not legitimate efforts to gather information. Instead, they are designed to wear you down, to erode your resistance so that you will change your mind. Or, they are simply designed to engage you emotionally, upset you, or punish you for making a decision with which your child disagrees.
With bad faith questions, there is typically a good bit of emotion on the part of your child. And there is certainly no attempt made to understand your point of view--they merely wish to verbally batter you with an onslaught of verbiage.
Good faith questions are equally easy to identify. They reflect genuine efforts to understand you. They are asked with little or no emotion. Your children wish to engage you intellectually rather than emotionally. They will accept what you have to say even if it disappoints or frustrates them.
Since bad faith questions are merely hooks to engage you in an unproductive argument, they require no response from you. Simply remain silent and end the conversation. Good faith questions, on the other hand, are those that you will answer all day long.
So keep this distinction in mind. Don't confuse bad faith attempts to emotionally engage you with those of good faith. If your children don't genuniely wish to know why but only want to argue, give them no fodder for their argument.