[I know Pascal's Wager isn't a hard logical problem for a Bayesian to tackle. However, please read the following account of how it helped me become more rational.]
I was a Christian when I was a boy. I believed in the miraculous birth and resurrection of Christ, heaven and hell, God on high answering prayers, and so on and so forth. I also believed in Santa Claus. When I stopped believing in Santa Claus when I was 9, my faith in the other stuff I'd been told was somewhat shaken, but I got over it, as I was told that everyone did.
When I was 15, I went to a summer program for weird kids (i.e. nerds) called Governor's School. Each week at Governor's School, the entire group of us was addressed by a pencil-necked, jaded philosophy professor called Dr. Bob. (Full disclosure: I am a jaded and pencil-necked person myself.) One week late in the summer, after he'd gotten our trust with other Astounding Insights, he told us about Pascal's Wager, concluding that we should all be Christians. And he left it at that.
We all found this very strange, as Dr. Bob had seemed rather unfriendly to religion before without ever having said anything outright irreligious. In fact, I didn't like him very much because I believed in the Lord Jesus Christ, and I didn't entirely like being forced to think about that belief too much. But Pascal's Wager was too much: I had always just believed because I'd been told by trustworthy people to believe, and here was this guy I didn't like saying I had to believe.
So, I couldn't get it out of my mind. You all know Pascal's Wager (and even have Yudkowski's Pascal's Mugging to boot), but I'm going to take it apart the way 15-year-old Scott did:
I thought: "If Heaven and Hell are real, then it would be best for me if I believed in them. If they aren't real, it wouldn't hurt for me to believe in them, because we're all just dead anyway, in the end. That's straightforward enough."
I objected: "But God doesn't just want our belief in Heaven or Hell, I thought. He wants our love and devotion. Heaven and Hell are just ways of getting Kohlberg 3's and lower to go to church and learn the right way of believing (Another thing we'd all learned by that point was the Kohlberg stages.) Like using Santa Claus giving gifts at Christmas to keep little kids good."
I recalled my 10th Christmas: Ohhhhhh.
I stopped believing in God.
Truth is the thing we need to know to plan, so that we may live better lives. Trust is valuable for reducing our mental workloads in determining the truth, but it can be used as a weapon. The purpose of lying is to control other people, to make them behave the way you want when the truth would cause them to behave differently, or perhaps just have a greater chance of behaving differently. Pascal's Wager laid bare the promise of Heaven and Hell: It is an attempt to control other people. If these people, who always say I should trust them, already want to control me, they'd probably be willing to lie to me. Once I saw that, the lie was plain.