## Jo Walton Is Smart

She is driven round the bend by Robert Heinlein's failure to understand the Law of the Reverend Thomas Bayes:

Jo Walton: A self-aware computer and a revolution on the moon: Having said that, I have two problems with Mike. One is the figuring the odds for the revolution. I’d have bought it if he did it once. It’s the complex refiguring and odds changing and--no. People complain about the Dust hypothesis in

Permutation City,that you can’t calculate things out of order, and this is worse. You can’t work out odds of 7 to 1 against and then say they will keep getting worse until they get better. It makes no sense...

She is right. It makes no sense at all. It shows a deep fundamental confusion about probability at a core level.

Indeed, if I believed in franchise restrictions (which I don't) I would be *much* more eager to exclude people who fail to understand probability at this level from the franchise than--Heinlein's favorite hobbyhorse--to exclude people who cannot do a quadratic equation. A book in which (a) things are going better than expected but (b) the odds of success are going down is an intellectual atrocity.