LIRa Session: Alessandro Giordani

Speaker: Alessandro Giordani (Catholic University of Milan)

Date and Time: Thursday, February 15th 2018, 16:30-18:00

Venue: KdVI Seminar Room F3.20, Science Park 107.

Title: Contrastive Epistemic Logic.

Abstract. In standard epistemic logic we assume that knowledge at a world w can be represented as a set E(w) of epistemic scenarios, the ones that are indistinguishable by virtue of the agent’s body of evidence, and that a proposition is known at w provided that all the scenarios in this set are worlds in which that proposition holds, that is E(w) ⊆ [p], where [p] is the set of scenarios where p holds. This immediately implies that knowledge is closed under logical implication, so that it is impossible for an agent to know that p without knowing all the logical consequences of p. Both the basic semantic idea and the closure principle are put into question in contemporary epistemology since, if knowledge is defined along these lines, we can hardly know something, being typically unable to rule out all the epistemic scenarios in which a proposition is false. As a consequence, within the current epistemological debate the idea is explored that an agent can know a proposition even if her evidence set E(w) is not included in [p]. One of the prominent standpoints in this debate is Contrastivism: the position according to which to know that p coincides with knowing that this proposition is the correct answer to a certain question against a set of alternative answers, so that to know is to know the answer to a context-defining question. In the present talk I propose a coherent system of contrastive epistemic logic and show how it can be used to assess the main contrastivist thesis concerning the essence of knowledge.