Predicativity beyond Gamma_0
  We reevaluate the claim that predicative reasoning (given the natural numbers) is limited by the Feferman-Schutte ordinal Gamma_0. First we comprehensively criticize the arguments that have been offered in support of this position. Then we analyze predicativism from first principles and develop a general method for accessing ordinals which is predicatively valid according to this analysis. We find that the Veblen ordinal \phi_{\Omega^\omega}(0), and larger ordinals, are predicatively provable. 
Nik Weaver