Organisers: Jeffrey Ketland and Jean-Louis Hudry (University of Edinburgh)


Truth and Proof:

Kurt Gödel and the Foundations of Mathematics.


University of Edinburgh, Department of Philosophy

25-26 March 2006

VENUE: Lecture Theatre, Room F21, Psychology Building, 7 George Square (map).

The year 2006 marks the centenary of Kurt Gödel's birth, which is the reason why the Philosophy Department at the University of Edinburgh is organising a two-day conference that aims to reflect on the foundations of mathematics, particularly in the light of Gödel's work.

 

PROGRAMME WITH ABSTRACTS

 

SATURDAY 25 MARCH
 

12.00 - 1.00pm    Registration

1.00 - 2.30pm     John Dawson (Pennsylvania State University)
                              "Taking Truth Seriously"

ABSTRACT: The distinction between syntactic and semantic methods is fundamental to modern logical studies, but it was not always so. Indeed, until surprisingly recently, the idea of formulating an objective notion of truth was regarded with widespread suspicion. This talk will trace the evolution of the notion of truth in propositional and predicate logic, and the eventual acceptance of the legitimacy of model-theoretic methods, through examination of the works of Post, Bernays, Gödel, Tarski, Mal'cev, Robinson and others.

 

3.00 - 4.30pm     Hannes Leitgeb (University of Bristol)
                              "Type-Free Necessity, Truth, and Informal Provability"

ABSTRACT: We suggest a possible worlds semantics of type-free necessity predicates for sentences, where potentially paradoxical instances of modal axiom schemes or rules are excluded by a principle of groundedness. While the same approach yields a plausible semantics of type-free truth predicates as a special case, it is not so clear whether the corresponding semantics for type-free informal provability predicates is satisfying or whether the latter needs a different semantic treatment.

 

5.00 - 6.30pm     Richard Zach (University of Calgary)
                              "Gödel’s First Incompleteness Theorem and Mathematical Instrumentalism"

ABSTRACT: According to instrumentalist views of mathematics, only certain mathematical propositions are straightforwardly meaningful, whereas much of mathematics is only a useful tool which is not, strictly speaking, meaningful. David Hilbert’s foundational program of the 1920s is often read as involving such a brand of instrumentalism: only the finitary part of mathematics is meaningful, the rest—“ideal” mathematics—is not, and its use was supposed to be legitimated by a finitary consistency proof. Gödel’s second incompleteness theorem is generally considered to show that this particular version of instrumentalism cannot be carried out. Consensus on this question is not complete, however, and variants of Hilbert’s Program have been proposed (in particular, by Detlefsen) which avoid this conclusion. I will discuss an argument based on Gödel’s first incompleteness theorem, which, I argue, is a stronger argument against Hilbert’s Program than the usual argument invoking the second theorem, and which also raises difficult issues about Detlefsen’s instrumentalism.
 

 

SUNDAY 26 MARCH
(British Summer Time -- Clocks go forward one hour)

 

11.00am - 12.30pm     Philip Welch (University of Bristol)
                              
 
        "Games for supervaluation and dependency fixed points"

ABSTRACT: We consider an epistemic variation on the construction of fixed points à la Kripke, for finding possible partial extensions for a truth predicate. These involve winning strategies for two person perfect information open games. Now this has been done before by D.A. Martin for Kripkean fixed points using Strong Kleene truth tables, but our aim is to show how this can be effected for fixed points arising from supervaluations, and thus to characterise Hannes Leitgeb’s notion of dependency.
 

                                           Lunch
 

2.00 - 3.30pm     Stewart Shapiro (Ohio State University / University of St Andrews)
                              "We hold these truths to be self-evident: But what do we mean by that?
                              The rationalism of Frege and Zermelo."

ABSTRACT: At the beginning of Die Grundlagen der Arithmetik (§2) [1844], Frege observes that “it is in the nature of mathematics to prefer proof, where proof is possible”. This, of course, is true, but thinkers differ on why it is that mathematicians prefer proof. And what of propositions for which no proof is possible? What of axioms? This talk explores various notions of self-evidence, and the role they play in various foundational systems.

 

4.00 - 5.30pm     Panu Raatikainen (University of Helsinki)
                              "Indefinite extensibility of mathematics and the powers of human mind"

ABSTRACT: Several alleged philosophical consequences of Gödel’s incompleteness theorems are critically evaluated. These include anti-mechanist conclusions of Lucas and Penrose, Benacerraf’s argument about the limits of self-knowledge, Gödel’s own “disjunctive conclusion” on anti-mechanism and Platonism, and Dummett’s and Wright’s views on indefinite extensibility, provability and proof. These claims are discussed in light of relevant logical facts. Feferman’s important work on progressions and reflective closures of theories is also reviewed.

 

Please complete the registration form (click on the link):

Registration Form + Postgraduate Bursary Application (MS Word file)

Suggestions for accommodation (HTML file)

Registration fee: £15 (£5 student / unwaged)
(Postgraduate Bursaries up to £50 are available to offset travel costs.)

For further information, contact Jean-Louis Hudry: jl.hudry@ed.ac.uk

 

The conference has been generously supported by:

Mind Association
London Mathematical Society (LMS)
British Society for the Philosophy of Science (BSPS)
British Logic Colloquium (BLC)
Scots Philosophical Club (SPC)
Analysis Trust