Dear all,

tomorrow we will have a LIRa session with Benjamin Icard and Markus Pfundstein. Everyone is cordially invited!

Date and Time: Friday, May 20th 2016, 13:00-15:00

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

First Speaker: Benjamin Icard (Institut Jean Nicod, Paris)

Title: The ‘Surprise Deception Paradox’: a conceptual and logical insight into veridical deception.

Abstract. Epistemologists have devoted efforts to the analysis of deception (i.e. causing someone to hold a false belief through a false piece of information) by offering epistemic accounts of this pervasive attitude. They have used both conceptual methods [e.g. Chisholm & Feehan 1977; Adler 1997; Mahon 2008] and more formal ones [e.g. Sakama et al. 2010a, 2010b; van Ditmarsch et al. 2012, 2014]. In doing so, however, they have focused on deception caused by false information. But a more subtle form of deception can also happen with the dissemination of true information. We may call veridical deception the method of causing someone to hold a false belief through a true piece of information. Veridical deception has aroused strong interest as well, particularly for those working at the interface with pragmatics on double bluff strategies [e.g. Fallis 2014], presupposition failures [e.g. Harder & Kock 1976; Vincent & Castelfranchi 1981] and false implicatures [e.g. Adler 1997; Fallis 2014]. In this talk, I will focus on one aspect of veridical deception which, as far as I know, has not yet been examined in the literature: the ability for someone to deceive while telling the truth about their deceitful attitude, that is to say the capacity for them to deceive after having publicly announced that they would do so. Following Baltag and Smets’ treatment of the “Surprise Exam Paradox” [Baltag & Smets, Forthcoming], I will show that a paradox about deception I identified in Smullyan [1978] raises similar issues. Moreover, I will argue that it can be simply formalized in Dynamic Belief Revision Theory and receive a solution using adequate plausibility orders over a set of possible states. In this paradox, a sly speaker makes the truthful announcement that he will deceive a vulnerable addressee, but the addressee cannot consistently believe the announcement since it is pragmatically misleading. Indeed, the speaker falsely implicates that he will deceive the addressee by doing a particular action (commission) but he deceives him by not doing any action (omission). Nevertheless, the addressee can consistently believe something after the announcement, namely that the deceiver is ‘unreliable’ because he explicitly states that he is deceitful, thus either truthful or untruthful (or both), therefore absolutely unpredictable. In a nutshell, I aim to show by model-theoretical means that the paradox can be solved if the addressee adopts successive “belief upgrades” regarding the deceiver’s announcement and implicature.

Second Speaker: Markus Pfundstein

Title: A Framework for modelling knowledge about Wireless Sensor Networks using Dynamic Epistemic Logic.

Hope to see you there!

The LIRa team