[Iris] ONLINE TALK: Sean Walsh (UCLA) on "Model completions, model theory, and ideal elements", May 19, 5-7pm (CET)

Dear All, The Philosophy Department of the Central European University, the Institute Vienna Circle and the Unit for Applied Philosophy of Science and Epistemology (of the Department of Philosophy of the University of Vienna) are jointly organizing a series of talks this term. On Thursday, May the 19th, 5-7pm (CET) Prof. Sean Walsh (University of California, Los Angeles) will speak about Model completions, model theory, and ideal elements (abstract below) The meeting will be online via ZOOM: https://univienna.zoom.us/j/61475205762?pwd=akFBUW5sWktDZmNsQVN4cjVFR3lWZz09 Upcoming talks: 2 June 3-5 PM: Eric Nelson 9 June 3-5 PM: Anna Bellomo 23 June 3-5 PM: Hanne Andersen 30 June 3-5 PM: Georg Schiemer Abstract: Manders (1989) suggested that the model-theoretic notion of model completion could help conceptualize the rationale behind the choice of ideal elements in mathematics. Bellomo (2021) usefully compares and contrasts this to the idea of 'domain expansion' that one finds in the principle of permanence, which has many connections to the Hilbert program (cf. Detlefsen 2005). The Hilbert program has given rise to much within mathematical logic, and can be viewed through the lens of reverse mathematics (Simpson 1988, Simpson 1999). In this talk, we look at Manders' preferred method of domain extension in the framework of reverse mathematics. It is one way of trying to understand how hard it is to find the types of models at issue in model completions when they exist. Bellomo, Anna. 2021. "Domain Extension and Ideal Elements in Mathematics." Philosophia Mathematica. Series III 29 (3): 366-91. Detlefsen, Michael. 2005. "Formalism." In The Oxford Handbook of Philosophy of Mathematics and Logic, edited by Stewart Shapiro. Oxford University Press. Manders, Kenneth. 1989. "Domain Extension and the Philosophy of Mathematics." The Journal of Philosophy 86 (10): 553-62. S. G. Simpson. Subsystems of Second Order Arithmetic. Perspectives in Mathematical Logic. Springer- Verlag, Berlin, 1999. S. G. Simpson. Partial realizations of Hilbert's program. J. Symbolic Logic, 53(2):349-363, 1988. On behalf of the organizers, Iulian Toader