I really don't understand in what sense it can be said that "the world is 15 billion years old" and "the world was created by God in six days" can both be literally true.
Where did you get young earth creationism from above? Where did you get "6 day creation is literally true given earth days"? If this is how you are parsing Aumann why are you even talking about this?
If we are sufficiently broad-minded, then we can simultaneously entertain different ideas of truth, different models, different views of the world.
And a "different way is with the six days of creation."
Now he doesn't strictly say that he holds both simultaneously, but I think that can be implied.
Just came across this interview with Robert Aumann. On pgs. 20-27 he describes why and how he believes in Orthodox Judaism. I don't really understand what he's saying. Key quote (I think):
Anybody have a clue what he means by all this? Do you think this is a valid way of looking at the world and/or religion? If not, how confident are you in your assertion? If you are very confident, on what basis do you think you have greatly out-thought Robert Aumann?
Please read the source (all 7 pages I referenced, rather than just the above quote), and think about it carefully before you answer. Robert Aumann is an absolutely brilliant man, a confirmed Bayesian, author of Aumann's Agreement Theorem, Nobel Prize winner, and founder / head of Hebrew University's Center for the Study of Rationality. Please don't strawman his arguments or simply dismiss them!