[FOM] acceptable enumerations

[Vaughan Pratt]

One might say that the difference between set-theoretic and 
category-theoretic foundations is that the former has everything to do 
with cartesian closed categories, extended with 1+1 as the subobject 
classifier (for the sake of the Axiom of Power Set).  The latter has 
everything to do with the Duality Principle, extended with adjunctions.

Vaughan Pratt

On 12/25/2011 5:46 PM, T.Forster at dpmms.cam.ac.uk wrote:
> Many thanks to my Cambridge colleague Peter Smith, who has shown me a
> passage in Odifreddi where all this is explained perfectly. As i
> suspected, it has something to do with cartesian-closed categories...