Since the livejournal link is defunct, here's an archive link: https://web.archive.org/web/20180101160950/http://squid314.livejournal.com/324957.html
I was hoping this would end with Jesus saying "Oh yeah? And how many mental patients hallucinate the Devil telling them to use Bayesian reasoning to conclude that they aren't actually Jesus?"
But on second thought, that's not much evidence at all, comparatively.
If anything, it's strong evidence the other way. If, in the process of trying to figure out whether you're really Jesus, you find yourself using a statistical formula not discovered until the eighteenth century CE, you should probably err on the side of "no."
I don't think the mental-asylum Jesuses believe that they live in Jesus' time, so no contradiction with 18th century math arises.
Well, if you believe some versions of Christianity, Jesus possesses a whole stack of supernatural powers. He can apparently duplicate bread and fish, convert water to wine, manipulate the surface tension of water, coax aquatic life to concentrate on a particular side of a boat, and heal most any form of sickness or injury he feels like. Oh, and if he calls it in upstairs he can resurrect the dead.
Anyways, it seems that the obvious thing would be to attempt to perform a sampling of these miracles and observe the results. Simple theorem :
If this man can perform the miracles of Jesus, then he is Jesus
He can perform miracles
He is Jesus
Modus Ponens FTW.
Course, it isn't that simple. It's always possible that those supernatural powers are getting spread around like Halloween candy, so being able to perform miracles doesn't actually prove anything. (weren't his Disciples able to heal the sick as well, allegedly?) And "knowing" you did something is difficult if you are hallucinating all the time.
The scientific method applied to God was not looked upon favorably in those times (or many thereafter). The specific reason in the Bible that Jesus did not throw himself down from the cliff or turn stones into bread was to not "test God." Therefore any miraculous evidence would probably constitute a test. The situation is like Omega appearing and offering tantalizing amounts of utility if only a complicated (but tractable) hypothetical situation is correctly solved, with the additional condition that using rational thought processes causes immediate failure.
In fact, I should probably post a detailed description of FBDT (Faith-Based Decision Theory) that beats the pants off of TDT and other rational decision theories.
And "knowing" you did something is difficult if you are hallucinating all the time.
OTOH, I never hallucinate. I might be that sick, that in fact I hallucinate all the time and not knowing this, be cause I am never sane enough to even recognize I have hallucinations sometimes.
I feel like you could make a pretty good rationalist children's book, consisting only of a series of stories in which a protagonist is forced to draw an increasingly unpalatable conclusion, under increasingly hard circumstances. Show the pain of the struggle, and make a virtue out of the triumph.
And then children get the lesson that changing your mind is always a good thing. The new idea is always right.
You can throw in some alternative cases as well. But, as it stands, I don't think a strong bias towards discarding deeply held beliefs is a big problem in humans. We can meander quite a distance in that direction before it begins to become a problem.
Yvain isn't a big enough self-promoter to link to this, but I liked it a lot and I think you will too.