Michael Owen Wise in Language and Literacy in Roman Judaea claims it's about ten percent among Jewish men. But, I've only read the abstract of that book. One thing that I've read (and I can't remember where) is that literacy went way up after the destruction of the Temple in 70AD and Judaism became more liturgical. But, that would be too late to be reflected in Josephus. Either way, I should have been more careful here.
Literacy is not such a problem. Josephus in Against Appion says that all male Jews are literate.
Michael Owen Wise in Language and Literacy in Roman Judaea claims it's about ten percent among Jewish men. But, I've only read the abstract of that book. One thing that I've read (and I can't remember where) is that literacy went way up after the destruction of the Temple in 70AD and Judaism became more liturgical. But, that would be too late to be reflected in Josephus. Either way, I should have been more careful here.