LIRa Session: Sanjay Modgil

Speaker: Sanjay Modgil

Date and Time: Thursday, November 1st 2018, 17:00-18:30

Venue: ILLC Seminar Room F1.15, Science Park 107.

Title: The Dynamic Turn in Logic: Argument and Dialectic.


“The lonesome thinker in an armchair is as marginal as he looks: most of our logical skills are displayed in interaction.” ­- Johan van Benthem.

This talk reviews research on argumentative characterisations of non-monotonic logics, emphasizing the extent to which the above quotation serves as a leitmotif for developments within the field. I will first describe how a given theory’s non-monotonic inferences can be decided via the dialectical exchange of arguments and counter-arguments constructed from the given theory. I will then review development of argument game proof theories, and their generalization to formal models of dialogue that enable multiple agents to interactively engage in distributed non-monotonic reasoning. In these dialogues, the inferences are defined with respect to the contents of agents’ locutions that are incrementally submitted during a dialogue, rather than with respect to a given theory. In the second half of the talk, I will review recent collaborative work1 on a novel formulation of dialectical models of inference that address a key limitation of existing models; namely that rationality is guaranteed under the assumption that agents are logically omniscient. Specifically, I will illustrate how our novel formulation formalises real world modes of dialectical reasoning, and in so doing preserves rationality under the assumption that agents are resource bounded.

1Collaborative work with Professor Marcello D’Agostino, Department of Philosophy, University of Milan (M. D’Agostino and S. Modgil Classical Logic, Argument and Dialectic. In Artificial Intelligence (AIJ), 262, 15 – 51,2018.)