Logic List Mailing Archive

Meeting in Internal Categoricity, Helsinki (Finland) & Virtual

21-22 May 2022

Meeting on Internal Categoricity at the University of Helsinki

May 21-22 (CET+1)


In person and by zoom.


Tim Button, Walter Dean, Martin Fischer, Toby Meadows, Beau Mount, Lavinia 
Piccolo, Jouko Väänänen, Dan Waxman

Zoom link:

Meeting ID: 863 0047 0746
Passcode: 218917

Contact person: Juliette Kennedy juliette.kennedy@helsinki.fi 

The categoricity of an axiom system means that its non-logical symbols 
have, up to isomorphism, only one possible interpretation. The first 
axiomatizations of mathematical theories such as number theory and 
analysis by Dedekind, Hilbert, Huntington, Peano and Veblen were indeed 
categorical. These were all second order axiomatisations, suffering from 
what many consider a weakness, namely dependence on a strong metatheory, 
casting a shadow over these celebrated categoricity results. In finer 
analysis a new form of categoricity has emerged. It is called internal 
categoricity because it is perfectly meaningful without any reference to a 
metatheory, and it is now known that the classical theories, surprisingly 
even in their first order formulation, can be shown to be internally 

In this workshop various aspects of and approaches to internal 
categoricity are presented and the following questions, among others, are 
discussed: What is the philosophical import/advantage of internal 
categoricity over ordinary categoricity? Is internal categoricity the 
“right” concept of categoricity? Does internal categoricity play a role 
also in first order theories?

The conference is meant for philosophers of logic and philosophers of 
mathematics, and logicians generally. There is limited funding available 
for junior participants. Please write to juliette.kennedy@helsinki.fi 
<mailto:juliette.kennedy@helsinki.fi> to inquire.

See you there!

Department of Mathematics and Statistics
P.O. Box 68 (Gustaf Hällströmin katu 2b)
FI-00014 University of Helsinki, Finland
tel. (+358-9)-191-51446, fax (+358-9)-191-51400
mobile: +358-50-371-4576
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