My father loved to tease me with philosophical questions when I was still too young to realize their implications. For example, "If a tree falls in a forest and no one is there to hear it, does it make a sound?"
As a child (maybe ten), I chose what seemed like the obvious opinion of, "Of course it makes a sound; how could it not!?" We'd go back and forth as he would ask, "but how do you know for sure?"

