Editors van Ditmarsch, Hendriks and Verbrugge of this special issue of topiCS on lying describe some recent trends in research on lying from a multidisciplinary perspective, including logic, philosophy, linguistics, psychology, cognitive science, behavioral economics, and artificial intelligence. Furthermore, they outline the seven contributions to this special issue.

Editors van Ditmarsch, Hendriks and Verbrugge of this special issue of topiCS on lying describe some recent trends in research on lying from a multidisciplinary perspective, including logic, philosophy, linguistics, psychology, cognitive science, behavioral economics, and artificial intelligence. Furthermore, they outline the seven contributions to this special issue.

Presents a theory of bullshit, how it differs from lying, how those who engage in it change the rules of conversation, and how indulgence in bullshit can alter a person's ability to tell the truth.

Lavoie and Talwar examine the phenomenon of prosocial lie telling: lying with the intention to benefit others. They investigate how well children aged 4 to 11 are able to conceal information about a surprise gift from their parents based on these children’s responses to their parents’ questions. Lavoie and Talwar conclude that, as children’s theory of mind abilities and working memory improve, their ability to conceal information from others also develops.

This handbook brings together past and current research on all aspects of lying and deception, with chapters contributed by leading international experts in the field. We are confronted daily with cases of lying, deception, bullshitting, and 'fake news', making it imperative to understand how lying works, how it can be defined, and whether it can be detected. A further important issue is whether lying should always be considered a bad thing or if, in some cases, it is simply a useful (...) instrument of human cognition. This volume is the first to offer a comprehensive and up-to-date exploration of these and other issues from the combined perspectives of linguistics, philosophy, and psychology. Chapters offer precise definitions of lying and its subtypes, and outline the range of fields in which lying and deception play a role, from empirical lie detection and the acquisition of lying to its role in fiction, metaphor, and humour. They also describe the tools and approaches that are used by scholars researching lying and deception, such as questionnaire studies, EEG, neuroimaging, and the polygraph. The volume will be an essential reference for students and researchers in a range of fields who are looking to deepen their understanding of all aspects of lying and deception, and will contribute to establishing the vibrant new field of interdisciplinary lying research. (shrink)

The lack of consensus on how to characterize humans’ capacity for belief reasoning has been brought into sharp focus by recent research. Children fail critical tests of belief reasoning before 3 to 4 years (Wellman, Cross, & Watson, 2001; Wimmer & Perner, 1983), yet infants apparently pass false belief tasks at 13 or 15 months (Onishi & Baillargeon, 2005; Surian, Caldi, & Sperber, 2007). Non-human animals also fail critical tests of belief reasoning but can show very complex social behaviour (e.g., (...) Call & Tomasello, 2005). Fluent social interaction in adult humans implies efficient processing of beliefs, yet direct tests suggest that belief reasoning is cognitively demanding, even for adults (e.g., Apperly, Samson & Humphreys, 2005). We interpret these findings by drawing an analogy with the domain of number cognition, where similarly contrasting results have been observed. We propose that the success of infants and non-human animals on some belief reasoning tasks may be best explained by a cognitively efficient but inflexible capacity for tracking belief-like states. In humans this capacity persists in parallel with later-developing, more flexible but more cognitively demanding theory of mind abilities. (shrink)

Many social situations require a mental model of the knowledge, beliefs, goals, and intentions of others: a Theory of Mind (ToM). If a person can reason about other people’s beliefs about his own beliefs or intentions, he is demonstrating second-order ToM reasoning. A standard task to test second-order ToM reasoning is the second-order false belief task. A different approach to investigating ToM reasoning is through its application in a strategic game. Another task that is believed to involve the application of (...) second-order ToM is the comprehension of sentences that the hearer can only understand by considering the speaker’s alternatives. In this study we tested 40 children between 8 and 10 years old and 27 adult controls on (adaptations of) the three tasks mentioned above: the false belief task, a strategic game, and a sentence comprehension task. The results show interesting differences between adults and children, between the three tasks, and between this study and previous research. (shrink)

In this paper we introduce Dynamic Epistemic Logic, which is alogic for reasoning about information change in a multi-agent system. Theinformation structures we use are based on non-well-founded sets, and canbe conceived as bisimulation classes of Kripke models. On these structures,we define a notion of information change that is inspired by UpdateSemantics (Veltman, 1996). We give a sound and complete axiomatization ofthe resulting logic, and we discuss applications to the puzzle of the dirtychildren, and to knowledge programs.

In order to lie, you have to say something that you believe to be false. But lying is not simply saying what you believe to be false. Philosophers have made several suggestions for what the additional condition might be. For example, it has been suggested that the liar has to intend to deceive (Augustine 395, Bok 1978, Mahon 2006), that she has to believe that she will deceive (Chisholm and Feehan 1977), or that she has to warrant the truth of (...) what she says (Carson 2006). In this paper, I argue that none of the existing definitions of lying identify a necessary condition on lying. I claim that lying is saying what you believe to be false when you believe that the following norm of conversation is in effect: "Do not say what you believe to be false" (Grice 1989, 27). And I argue that this definition handles all of the counter-examples to the existing definitions. (shrink)

This paper aims to distil the essence of deception performed by means of withholding information, a topic hitherto largely neglected in the psychological, linguistic, and philosophical research on deception. First, the key conditions for deceptively withholding information are specified. Second, several notions related to deceptively withholding information are critically addressed with a view to teasing out the main forms of withholding information. Third, it is argued that deceptively withholding information can be conceptualized in pragmatic-philosophical terms as being based on the (...) violation of Grice's first maxim of Quantity, which is conducive to covertly untruthful meaning, specifically hearer-inferred what is said that presents the violation of the first maxim of Quality. In order to meet this goal, Gricean and neo-Gricean scholarship on the first maxim of Quantity and its consequences is revisited. Fourth, a number of linguistic realizations of withholding information are examined. It is argued that some of the examples found in the relevant scholarship, namely those that involve scalar expressions, qualify rather as lies. (shrink)

Bereby‐Meyer, Hayakawa, Shalvi, Corey, Costa and Keysar investigate lying for self‐serving reasons. Participants in their experiments had to report the outcome of rolling a die only known to them. They inflated their outcomes less, and thus lied less, when using a foreign language than when using their native language. The authors suggest that lying for self‐serving reasons is an automatic tendency that can be overcome by speaking in a foreign language. [71].

We present Arrow Update Logic, a theory of epistemic access elimination that can be used to reason about multi-agent belief change. While the belief-changing of Arrow Update Logic can be transformed into equivalent belief-changing from the popular Dynamic Epistemic Logic approach, we prove that arrow updates are sometimes exponentially more succinct than action models. Further, since many examples of belief change are naturally thought of from Arrow Update Logicrelativized” common knowledge familiar from the Dynamic Epistemic Logic literature.

A true lie is a lie that becomes true when announced. In a logic of announcements, where the announcing agent is not modelled, a true lie is a formula that becomes true when announced. We investigate true lies and other types of interaction between announced formulas, their preconditions and their postconditions, in the setting of Gerbrandy’s logic of believed announcements, wherein agents may have or obtain incorrect beliefs. Our results are on the satisfiability and validity of instantiations of these semantically (...) defined categories, on iterated announcements, including arbitrarily often iterated announcements, and on syntactic characterization. We close with results for iterated announcements in the logic of knowledge, and for lying as private announcements to different agents. Detailed examples illustrate our lying concepts. (shrink)

Survey of different definitions of lying and deceiving, with an emphasis on the contemporary debate between Thomas Carson, Roy Sorensen, Don Fallis, Jennifer Saul, Paul Faulkner, Jennifer Lackey, David Simpson, Andreas Stokke, Jorg Meibauer, Seana Shiffrin, and James Mahon, among others, over whether lies always aim to deceive. Related questions include whether lies must be assertions, whether lies always breach trust, whether it is possible to lie without using spoken or written language, whether lies must always be false, whether lies (...) that are unsuccessful are still lies, and whether deception must aim at creating false beliefs as opposed to preventing people from acquiring true beliefs. (shrink)

Braüner, Blackburn and Polyanskaya relate children’s being deceived to their theory of mind skills. Second‐order false‐belief tasks are often used to test children’s second‐order theory of mind development. The article gives a logical analysis of the reasoning needed to solve four types of second‐order false belief tasks, distinguished on whether a story character is deceived, and on whether the story hinges on facts in the world changing. The principle of inertia plays an important role. [74].

I begin by discussing views about the permissibility of lying by political leaders. Sections II and III address historically important lies and lies about history and the historical record. These two categories overlap - some lies about the historical record were historically important events. In section IV, I discuss the related notion of half-truths and give examples of misleading/deceptive half-truths about history. In the final section of this chapter, I briefly discuss the obligations of historians to give truthful accounts of (...) historical events. (shrink)

Franke, Dulcinati and Pouscoulous also examine a form of covert lying, by considering to what extent speakers use implicatures to deceive their addressee. The participants in their online signaling game had to describe a card, which a virtual coplayer then had to select. When the goal was to deceive rather than help the coplayer, participants produced more false descriptions (overt lies), but also more uninformative descriptions (covert lies by means of an implicature). [73].

We want to keep hackers in the dark about our passwords and our credit card numbers. We want to keep potential eavesdroppers in the dark about our private communications with friends and business associates. This need for secrecy raises important questions in epistemology (how do we do it?) and in ethics (should we do it?). In order to answer these questions, it would be useful to have a good understanding of the concept of keeping someone in the dark. Several philosophers (...) (e.g., Bok, 1983; Carson, 2010; Mahon, 2009; Scheppele, 1988) have analyzed this concept (or, equivalently, the concept of keeping secrets) in terms of concealing and/or withholding information. However, their analyses incorrectly exclude clear instances of keeping someone in the dark. And more important, they incorrectly focus on possible means of keeping someone in the dark rather than on what it is to keep someone in the dark. In this paper, I argue that you keep X in the dark about a proposition P if and only if you intentionally cause X not to have a true belief that P. In addition, I show how this analysis of keeping someone in the dark can be extended from a categorical belief model of epistemic states to a credence (or degree of belief) model. (shrink)

Geven, Ben‐Shakhar, Kindt and Verschuere point out that research on deception detection usually employs instructed cheating. They experimentally demonstrate that participants show slower reaction times for concealed information than for other information, regardless of whether they are explicitly instructed to cheat or whether they can freely choose to cheat or not. Finding this ‘cognitive signature of lying’ with self‐initiated cheating too is argued by the authors to strengthen the external validity of deception detection research. [75].

We propose a dynamic logic of lying, wherein a ‘lie that $\varphi $ ’ (where $\varphi $ is a formula in the logic) is an action in the sense of dynamic modal logic, that is interpreted as a state transformer relative to the formula $\varphi $ . The states that are being transformed are pointed Kripke models encoding the uncertainty of agents about their beliefs. Lies can be about factual propositions but also about modal formulas, such as the beliefs of (...) other agents or the belief consequences of the lies of other agents. We distinguish two speaker perspectives: (Obs) an outside observer who is lying to an agent that is modelled in the system, and (Ag) an agent who is lying to another agent, and where both are modelled in the system. We distinguish three addressee perspectives: (Cred) the credulous agent who believes everything that it is told (even at the price of inconsistency), (Skep) the skeptical agent who only believes what it is told if that is consistent with its current beliefs, and (Rev) the belief revising agent who believes everything that it is told by consistently revising its current, possibly conflicting, beliefs. The logics have complete axiomatizations, which can most elegantly be shown by way of their embedding in what is known as action model logic or in the extension of that logic to belief revision. (shrink)

In this paper, we first propose a simple formal language to specify types of agents in terms of necessary conditions for their announcements. Based on this language, types of agents are treated as ‘first-class citizens’ and studied extensively in various dynamic epistemic frameworks which are suitable for reasoning about knowledge and agent types via announcements and questions. To demonstrate our approach, we discuss various versions of Smullyan’s Knights and Knaves puzzles, including the Hardest Logic Puzzle Ever (HLPE) proposed by Boolos (...) (in Harv Rev Philos 6:62–65, 1996). In particular, we formalize HLPE and verify a classic solution to it. Moreover, we propose a spectrum of new puzzles based on HLPE by considering subjective (knowledge-based) agent types and relaxing the implicit epistemic assumptions in the original puzzle. The new puzzles are harder than the previously proposed ones in the literature, in the sense that they require deeper epistemic reasoning. Surprisingly, we also show that a version of HLPE in which the agents do not know the others’ types does not have a solution at all. Our formalism paves the way for studying these new puzzles using automatic model checking techniques. (shrink)

We propose a dynamic logic of lying, wherein a ‘lie that $$\varphi $$ ’ is an action in the sense of dynamic modal logic, that is interpreted as a state transformer relative to the formula $$\varphi $$. The states that are being transformed are pointed Kripke models encoding the uncertainty of agents about their beliefs. Lies can be about factual propositions but also about modal formulas, such as the beliefs of other agents or the belief consequences of the lies of (...) other agents. We distinguish two speaker perspectives: an outside observer who is lying to an agent that is modelled in the system, and an agent who is lying to another agent, and where both are modelled in the system. We distinguish three addressee perspectives: the credulous agent who believes everything that it is told, the skeptical agent who only believes what it is told if that is consistent with its current beliefs, and the belief revising agent who believes everything that it is told by consistently revising its current, possibly conflicting, beliefs. The logics have complete axiomatizations, which can most elegantly be shown by way of their embedding in what is known as action model logic or in the extension of that logic to belief revision. (shrink)