How many angels can dance on the head of a pin?
What can go up a chimney down but can't go down a chimney up?
What can go up a chimney down but can't go down a chimney up?
It's not the least charm of a theory that it is refutable. The hundred-times-refuted theory of "free will" owes its persistence to this charm alone; some one is always appearing who feels himself strong enough to refute it - Friedrich Nietzsche