John:

You're right, of course, paper could cover scissors, and that's probably the way it was when the game was first invented. But, very soon, scissors began to recognize paper as a potential threat to it's existence and so it began launching preemptive attacks against paper saying, "I need to fight paper over there so I won't have to fight it over here." And ever since that time paper could not cover scissors and they all lived happily ever after.

Bev and Jerry