[FOM] EFA/PA correspondence

Nik Weaver nweaver at math.wustl.edu
Thu Oct 7 14:09:04 EDT 2010

Harvey Friedman quotes Richard Borcherds as asking

> (1) We have a hierarchy of stronger and stronger systems, starting
> at EFA and passing through PRA, PA, second order arithmetics, set
> theory, various large cardinal axioms, and so on. Why does almost
> all mathematics seem to need just the very lowest level of this?

Answer: because almost all mathematics is predicative.

Nik Weaver
Math Dept.
Washington University
St. Louis, MO 63130
nweaver at math.wustl.edu

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