On the Logic of Lying

  • Hans van Ditmarsch
  • Jan van Eijck
  • Floor Sietsma
  • Yanjing Wang
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7010)


We model lying as a communicative act changing the beliefs of the agents in a multi-agent system. With Augustine, we see lying as an utterance believed to be false by the speaker and uttered with the intent to deceive the addressee. The deceit is successful if the lie is believed after the utterance by the addressee. This is our perspective. Also, as common in dynamic epistemic logics, we model the agents addressed by the lie, but we do not (necessarily) model the speaker as one of those agents. This further simplifies the picture: we do not need to model the intention of the speaker, nor do we need to distinguish between knowledge and belief of the speaker: he is the observer of the system and his beliefs are taken to be the truth by the listeners. We provide a sketch of what goes on logically when a lie is communicated. We present a complete logic of manipulative updating, to analyse the effects of lying in public discourse. Next, we turn to the study of lying in games. First, a game-theoretical analysis is used to explain how the possibility of lying makes games such as Liar’s Dice interesting, and how lying is put to use in optimal strategies for playing the game. This is the opposite of the logical manipulative update: instead of always believing the utterance, now, it is never believed. We also give a matching logical analysis for the games perspective, and implement that in the model checker DEMO. Our running example of lying in games is the game of Liar’s Dice.


Nash Equilibrium Action Model Actual World True Belief Belief Revision 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Hans van Ditmarsch
    • 1
    • 2
  • Jan van Eijck
    • 3
  • Floor Sietsma
    • 4
  • Yanjing Wang
    • 5
  1. 1.University of SevillaSpain
  2. 2.Institute of Mathematical Sciences (IMSc)ChennaiIndia
  3. 3.Centrum Wiskunde & Informatica (CWI) and ILLCAmsterdamThe Netherlands
  4. 4.Centrum Wiskunde & Informatica (CWI)AmsterdamThe Netherlands
  5. 5.Peking UniversityBeijingChina

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