An "Occamian" prior that weights computable hypotheses according to the fraction of computer-program-space occupied by programs that compute their consequences provably performs -- in an admittedly somewhat artificial sense -- at least as well in the long run as any other prior, provided the observations you see really are generated by something computable.
Yes and any prior that doesn't assign things zero probability has this property. Why that one in particular?
any prior that doesn't assign things zero probability has this property
Oh yes, so it does. Let me therefore be both more precise and more accurate.
Let p be an Occamian prior in this sense and q any computable prior. Then as cousin_it remarks "a computable human cannot beat Solomonoff in accumulated log scores by more than a constant, even if the universe is uncomputable and loves the human"; in other words, whatever q is -- however much information about the world is built into it in advance -- it can't do much better than p, even though p enc...
In two posts, Bayesian stats guru Andrew Gelman argues against parsimony, though it seems to be favored 'round these parts, in particular Solomonoff Induction and BIC as imperfect formalizations of Occam's Razor.
Gelman says: