Talk 1

Title: The Dynamics of Non-belief (with Modesty)

Speaker: Hans Rott (University of Regensburg)

Time: 15:10 -18:00 (Sep. 26th)

Location: Room 108, Buidling of Geometry (地学楼), PKU

Abstract:

“Suspension of judgment” is an ambiguous term that may refer either to a doxastic state (“suspended judgment”) or to a doxastic action (“suspending judgment”). Based on a simple non-belief account, this paper presents a formal study of both aspects of suspension. We first introduce the notion of a suspension set (a set of non-beliefs) and determine its logical structure. Then we present the classical AGM operations of belief revision and belief contraction and give characterizations of them that refer to suspension sets rather than belief sets. Finally, we study the suspension operation, a symmetric cousin of belief contraction, and characterize it both in terms of belief sets and in terms of suspension sets. Belief contraction and belief suspension thereby get reinterpreted as two different forms of the expansion of suspension sets. The project is interesting because in contrast to belief revision and belief contraction, the suspension operation is symmetric with respect to negation: suspending judgment on A is the same as suspending judgment on \neg A. Most of our results are premised on an assumption of modesty: For every person there is always at least one proposition on which she suspends judgment.

Talk 2

Title: Towards Topic-Related Ordering for Belief Suspension: A New Framework

Speaker: 朱薇 (University of Regensburg)

Time: 15:10 -18:00 (Sep. 26th)

Location: Room 108, Buidling of Geometry (地学楼), PKU

Abstract:

In traditional epistemology, the doxastic attitudes towards a proposition ϕ are commonly categorized as belief, disbelief, or indeterminate. Belief suspension, which refers to the absence of any doxastic attitude towards a specific proposition ϕ as well as its negation ¬ϕ, has been discussed in the literature as non-belief. Researchers have proposed various conceptions of belief suspension, including those presented in Quine and Ullian (1978), Rott (2009), Friedman (2013b, 2017), and Zinke (2021). In this study, we build upon Rott's proposal from Rott (2009) by incorporating the threevalued weak Kleene logic (Halld´en 1949; Bochvar and Bergmann 1981; Kleene 1952) and extending the belief, disbelief, and suspension ordering to develop a more complex structure that accounts for the notion of topic. To do this, we combine Parikh (1999)'s syntax splitting idea with a recent off-topic semantics of weak Kleene logic proposed in Joaquin (2022) on the basis of Beall (2016) and Francez (2019)'s discussion about being off-topic. By doing so, we are able to distinguish between off-topic suspension and on-topic suspension, as well as split Rott's ordering on non-beliefs into sub-orderings based on different topics. The proposed approach expands the understanding of belief suspension and its relation to the three-valued weak Kleene logic, offering some insights for further research in the field.