Successful parenting happens when you take what the child offers you and turn it around to the child.  Take the martial arts practice Aikido for example.  When someone comes toward you, fighting, you don't confront the atatcker head-on.  Nope.  Instead, you use your center of balance to move quickly, turning the person to catch them off balance, with you in control.

When your child asks you, "why?" you smile sweetly and reply with excitement, "That's a great question!  Let me give you a sheet of paper so you can write out three possible answers for me.  Then pick up the one answer you think is best and come back and show me."

Some families ahve a "why" notebook so whenever anyone in the family says, "why", point them to the why notebook.