Imagine that God and the Devil are once again caught up in that peculiar spirit of jocularity and contentiousness that once led them to harass poor Job, but that this time they’ve decided to play a game with you. They arrive by your bedside late at night and tell you what they propose to do.
GOD: The Devil tells me that there is not a creature on the face of the earth who deserves to be described as created in my own image. He maintains, and I agree with him about this, that any being created in my own image must be a thinking being, a being capable of reasoning. What I am appalled by is a further contention of his, and I intend to use you to prove him wrong. His further contention is that there is not a soul on earth that can think its way out of a paper bag.
SATAN: That’s what I say, and I must say, too, that seeing this poor wretch makes me wonder why you should think I could conceivably be wrong.
YOU: But my God! Why me?
GOD: You’re just a good representative human being. Your name was picked in a drawing we held last night. Now here’s the deal. You’re going to have to match wits with the Devil. You’re going to have to play a little game. It’ll be a round a night, for as long as you keep on winning. If you lose, Satan here will immediately possess your soul, and I, to say the least, will be disappointed. Why, I’ll be humiliated. I’ll have to start all over in this business of creating something in my own image. There’s a nice piece of property near Alpha Centauri. Maybe I’ll try there. I’ve often wondered whether the dust I used here on earth wasn’t pretty low-grade stuff.
SATAN: Come on now. Snap out of the daydream and explain the game.
GOD: Oh, yeah. Right. Well, here it is. Since Satan’s claim was that you folks are deficient in reasoning, the game is one that involves reasoning. Well, I promised not to say more than that about what it involves. I’m just supposed to explain the rules.
SATAN: It’s quite a devilish little game. I thought it up.
GOD: Each night, the Devil will appear at your bedside and will make a set of remarks. He might make one remark or two or three, or even more. He might even make zero remarks—that’s making a set of remarks, you know. Then you must make a remark. If even one of the remarks he makes is false, then you may make any remark you please. However, if he makes no false remarks at all, then the remark you make must be true. If you screw up and say something that’s false when he has said nothing that’s false, you lose. That’s it. That’s all there is to it.
YOU: How do I win?
GOD: You can’t win with the Devil. You can only keep from losing.
YOU: But really, how can I lose? So long as I stick with things I believe, I’ll be O.K. Whatever I believe is true for me.
GOD: Where on earth did you get that hogwash? It won’t matter whether what you say is “true for you” or not—whatever that might mean. The rule is that it’s got to be just plain true.
YOU: But who’s to say what’s really true?
GOD: Oh. Didn’t I tell you? I’m the referee.
SATAN: And he’s omniscient, you know.
GOD: Any questions?
YOU: Is there any way I can get out of this?
GOD: ’Fraid not. Best of luck. I’m counting on you.
A real nightmare situation, wouldn’t you say? What can you do? You’re certainly not going to be able to fake your way out of this one. The fact that God’s the referee makes that plain. Satan’s likely to come in the first night off and say something like “2 + 2 = 4”, and then where’ll you be? You’ll have to say something true, unless, of course, “2 + 2 = 4” just happens to be false. And what if he comes in and says “The moon is made of green cheese”? Will that be grounds for a sigh of relief and great jubilation? Are you really sure the moon’s not make of green cheese? If the sentence “The moon is made of green cheese” is false, you can say anything you like and the resulting sequence—first, the Devil’s set of remarks, and then your remark—will be a sequence that’s O.K. so far as the rules are concerned, and you’ll have gotten through the first night. But if it isn’t false (and God only knows for sure about that), the heat is on. The sequence resulting from the remark you make will be O.K. if and only if the remark you make is true. What can you do? God said something about reasoning. Maybe there’s some trick that can be figured out....
What do you think? Is there anything you can do—any strategy that you can adopt—that will ensure that for as long as you live and avoid sinking into the depths of senile dementia,* you will never, never lose?
*If you suffer the misfortune of losing your mind, then God forbid that you shouldn’t be off the hook.