The professor held out his hand, in which rested a single silver coin.

“Now,” he said, “If I flip this coin one thousand times—flip, flip, flip—and every time I come up tails, what do the rules of probability say my chances of getting heads will be on the next flip?”

A girl raised her hand.
“Still 50/50?”

“Very good!” the professor said, bouncing the coin in his palm. “Who’s to say that the next attempt won’t come up heads; or the next thousand, for that matter?”

A boy raised his hand.
“But what if probability can’t factor in? What if there’s actually something wrong with the coin that makes it keep ending up that way?”

“Ah,” the professor said, closing his palm.  “You never question the coin.  Math can’t fix the coin.”