[FOM] Yablo, Mirimanoff, and Negative Types

Roger Bishop Jones rbj at rbjones.com
Tue Sep 17 15:50:04 EDT 2002

On Tuesday 17 September 2002  2:14 pm, A.P. Hazen wrote:

>    If I'm right, Yablo has given us the proof of a theorem in the
> metatheory of negative type theory: it's language can't express
> well-foundedness.

And hence cannot have the "standard semantics"
for a higher order logic, i.e. some of the power sets must be

So though the theory is consistent when formulated as
a many-sorted first order theory, it is semantically inconsistent
(i.e. has no models) when formulated as a type theory
with "standard semantics".

Roger Jones

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