This paper explores principles governing the rational balance among an agent's beliefs, goals, actions, and intentions. Such principles provide specifications for artificial agents, and approximate a theory of human action (as philosophers use the term). By making explicit the conditions under which an agent can drop his goals, i.e., by specifying how the agent is committed to his goals, the formalism captures a number of important properties of intention. Specifically, the formalism provides analyses for Bratman's three characteristic functional roles played (...) by intentions [7, 9], and shows how agents can avoid intending all the foreseen side-effects of what they actually intend. Finally, the analysis shows how intentions can be adopted relative to a background of relevant beliefs and other intentions or goals. By relativizing one agent's intentions in terms of beliefs about another agent's intentions (or beliefs'), we derive a preliminary account of interpersonal commitments. (shrink)

In H-C interaction, computer supported cooperation andorganisation, computer mediated commerce, intelligentdata bases, teams of robots. etc. there will bepurposively deceiving computers. In particular, withinthe Agent-based paradigm we will have ``deceivingagents''''. Several kinds of deception will be present ininteraction with the user, or among people viacomputer, or among artificial agents not only formalicious reasons (war, commerce, fraud, etc.) butalso for goodwill and in our interest. Social control,trust, and moral aspects in artificial societies willbe the focus of theoretical worm as well as (...) ofimplementation. Is there any special affinity betweenAI and deception? (shrink)

Few moral questions have greater bearing on the conduct of our everyday lives than questions about the morality of lying. These questions are also important for ethical theory. An important test of any theory of right and wrong is whether it gives an adequate account of the morality of lying. Conceptual questions about the nature of lying are prior to questions about the moral status of lying. Any theory about the moral status of lying presupposes an account of what lying (...) is. (shrink)

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)

We extend the ordinary logic of knowledge based on the operator K and the system of axioms S₅ by adding a new operator Uφ, standing for "the agent utters φ", and certain axioms and a rule for U, forming thus a new system KU. The main advantage of KU is that we can express in it intentions of the speaker concerning the truth or falsehood of the claims he utters and analyze them logically. Specifically we can express in the new (...) language various notions of lying, as well as of telling the truth. Consequently, as long as lying or telling the truth about a fact is an intentional mode of the speaker, we can resolve the Liar paradox, or at least some of its variants, turning it into an ordinary (false or true) sentence. Also, using Kripke structures analogous to those employed by S. Kraus and D. Lehmann in [3] for modelling the logic of knowledge and belief, we offer a sound and complete semantics for KU. (shrink)

This article first examines a number of different definitions of lying, from Aldert Vrij, Warren Shibles, Sissela Bok, the Oxford English Dictionary, Linda Coleman and Paul Kay, and Joseph Kupfer. It considers objections to all of them, and then defends Kupfer’s definition, as well as a modified version of his definition, as the best of those so far considered. Next, it examines five other definitions of lying, from Harry G. Frankfurt, Roderick M. Chisholm and Thomas D. Feehan, David Simpson, Thomas (...) Carson, and Don Fallis. It finds reason to reject these definitions, in favor of the two definitions of lying previously defended, namely:(i) To lie (to another person) = df. to make a believed-false statement (to another person) with the intention that that statement be believed to be true (by the other person).(ii) To lie (to another person) = df. to make a believed-false statement (to another person), either with the intention that that statement be believed to be true (by the other person), or with the intention that it be believed (by the other person) that that statement is believed to be true (by the person making the statement), or with both intentions. (shrink)

In this article I consider six definitions of deceiving (that is, other-deceiving, as opposed to self-deceiving) from Lily-Marlene Russow, Sissela Bok, OED/Webster's dictionary, Leonard Linsky, Roderick Chisholm and Thomas Feehan, and Gary Fuller, and reject them all, in favor of a modified version of a rejected definition (Fuller). I also defend this definition from a possible objection from Annette Barnes. According to this new definition, deceiving is necessarily intentional, requires that the deceived person acquires or continues to have a false (...) belief, and must involve the agency of the deceived person; furthermore, the deceiver must know or truly believe that the false belief that the deceived person acquires or continues to have is false. (shrink)

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)

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)