[FOM] nonplatonistic impredicativity

Gabriel Stolzenberg gstolzen at math.bu.edu
Thu Feb 16 18:09:17 EST 2006

   In "predicative foundations," February 15, Nik Weaver asks,

> Can [Harvey Friedman] give a compelling justification for any
> impredicative system that does not assume a platonistic conception
> of sets?

   I can't speak for Harvey but, on my block, impredicative definitions
are O.K. constructively, even for the logical constants.

   However, I admit that this is mainly a matter of wishing to explore
some of the very interesting and computationally powerful consequences
of admitting such definitions.

      Gabriel Stolzenberg

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