Agent's Beliefs Research Articles

HOW TO BE A REDUNDANT REALIST

AbstractIn Group Agency, List and Pettit (L&P) defend ‘non-redundant realism’ about group agency, a view on which (A) facts about group agents are not ‘readily reducible’ to facts about individuals, and (B) the dependence of group agents on individuals is so holistic that one cannot predict facts about group agents on the basis of facts about their members. This paper undermines L&P's case in three stages. §1 shows that L&P's core argument is invalid. L&P infer (A) and (B) from two facts: (1) that group agents must often believe what few members personally believe, and (2) that a group agent's beliefs in certain propositions must often ‘depend on’ member attitudes to distinct propositions. I note that (2) is ambiguous, and that the only true reading of it is irrelevant to the status of (A). I argue further that (1) cannot support (A), since a group agent's belief in P may neatly constitutively depend on member attitudes to P that are weaker than personal belief. §2 makes this idea concrete with a plausible toy theory of group belief that implies it. While this kind of theory is popular in the literature on joint belief, L&P never discuss it – a striking fact, since it explains why (1) is true. Having made these points, I turn to argue in §3 that (B) is either false or uncontroversial.

What are impossible worlds?

In this paper, I argue for a particular conception of impossible worlds. Possible worlds, as traditionally understood, can be used in the analysis of propositions, the content of belief, the truth of counterfactuals, and so on. Yet possible worlds are not capable of differentiating propositions that are necessarily equivalent, making sense of the beliefs of agents who are not ideally rational, or giving truth values to counterfactuals with necessarily false antecedents. The addition of impossible worlds addresses these issues. The kinds of impossible worlds capable of performing this task are not mysterious sui generis entities, but sets of structured propositions that are themselves constructed out of possible worlds and relations. I also respond to a worry that these impossible worlds are unable to represent claims about the shape of modal space itself.

MODELING BELIEF CHANGE IN A POPULATION USING EXPLANATORY COHERENCE

A simulation model that represents belief change within a population of agents who are connected by a social network is presented based on Thagard's theory of explanatory coherence. In this model there are a fixed number of represented beliefs, each of which are either held or not by each agent. These are conceived of existing against a background of a large set of (unrepresented) shared beliefs. These beliefs are to different extents coherent with each other — this is modeled using a coherence function from possible sets of core beliefs to [-1, 1]. The social influence is achieved through gaining of a belief across a social link. Beliefs can be lost by being dropped from an agent's store. Both of these processes happen with a probability related to the change in coherence that would result in an agent's belief store. A resulting measured "opinion" can be retrieved in a number of ways, here as a weighted sum of a pattern of the core beliefs — opinion is thus an outcome and not directly processed by agents. This model suggests hypotheses about group opinion dynamics that differ from that of many established models.

Optimal Hedging of a Contingent Claim with Ambiguity Aversion

We propose a model of hedging and investment with ambiguity aversion in an incomplete financial market. We show that the agent's worst-case belief depends upon the payoff of the derivative to be hedged. Thus, we identify situations where one can distinguish ambiguity averse agents from probabilistically sophisticated agents. Further, we generate the hypothesis: an ambiguity averse agent chooses higher volatility when hedging a derivative position whose payoff function is convex than when hedging a position whose payoff function is concave. Our model can be extended to accommodate non-iid uncertainty and jumps in the continuous time limit of the model.

Exploring the Existential Function of Religion and Supernatural Agent Beliefs Among Christians, Muslims, Atheists, and Agnostics

Building on research suggesting one primary function of religion is the management of death awareness, the present research explored how supernatural beliefs are influenced by the awareness of death, for whom, and how individuals' extant beliefs determine which god(s), if any, are eligible to fulfill that function. In Study 1, death reminders had no effect among Atheists, but enhanced Christians' religiosity, belief in a higher power, and belief in God/Jesus and enhanced denial of Allah and Buddha. Similarly, death reminders increased Muslims' religiosity and belief in a higher power, and led to greater belief in Allah and denial of God/Jesus and Buddha (Study 2). Finally, in Study 3, death reminders motivated Agnostics to increase their religiosity, belief in a higher power, and their faith in God/Jesus, Buddha, and Allah. The studies tested three potential theoretical explanations and were consistent with terror management theory's worldview defense hypothesis. Theoretical implications are discussed.

Modelling collective decision making in groups and crowds: Integrating social contagion and interacting emotions, beliefs and intentions

Collective decision making involves on the one hand individual mental states such as beliefs, emotions and intentions, and on the other hand interaction with others with possibly different mental states. Achieving a satisfactory common group decision on which all agree requires that such mental states are adapted to each other by social interaction. Recent developments in social neuroscience have revealed neural mechanisms by which such mutual adaptation can be realised. These mechanisms not only enable intentions to converge to an emerging common decision, but at the same time enable to achieve shared underlying individual beliefs and emotions. This paper presents a computational model for such processes. As an application of the model, an agent-based analysis was made of patterns in crowd behaviour, in particular to simulate a real-life incident that took place on May 4, 2010 in Amsterdam. From available video material and witness reports, useful empirical data were extracted. Similar patterns were achieved in simulations, whereby some of the parameters of the model were tuned to the case addressed, and most parameters were assigned default values. The results show the inclusion of contagion of belief, emotion, and intention states of agents results in better reproduction of the incident than non-inclusion.

Asymmetric Information and Financial Markets

This paper aims to explore the relevance of the Asymmetric Information and the Theory of Argumentation TA in the complex area of financial crises. Specifically, we investigated the scope of the phenomenon of persuasion in advertising. It examines advertisements in publications notable economic movement in Colombia. The financial communication is important to distinguish how to run the models of behavior based on beliefs of agents. Consequently, investors' beliefs can also change systematically with changes in market prices

The role of preferences in disagreements over scientific hypothesis: Evidence on cognitive bias in formation of beliefs

Have you ever heard the joke that if you ask three economists for an economic policy advice, you will get at least four different answers? This study takes the joke seriously by investigating whether an agent's wish for a scientific hypothesis to be true affects the agent's belief that the hypothesis is true. Using theories in psychology of cognitive bias we argue that, given certain circumstances, a positive preference–expectation relationship is actually expected, and we test the theoretical prediction using a sample of students in economics and science. The scientific hypothesis used in our empirical inquiry is the highly debated Porter hypothesis. The Porter hypothesis suggests that environmental regulations, such as those restricting firms to reduce pollution, stimulate innovations and create a win-win situation for the environment and for firms. Our results show that the students in economics who care more about the environment are more likely to believe in the Porter hypothesis. The results are in line with Fuchs et al. (1998) and Mayer (2001) who found that there is a correlation between economists’ policy positions and their ideological values.

The Equivalence of Strict Liability and Negligence Rule: A Trompe L'oeil Perspective

This paper analyzes the difficulties of comparing the respective effectiveness of two among the most important liability regimes in tort law: rule of negligence and strict liability. Starting from the standard Shavellian unilateral accident scheme, I show that matching up liability regime on their capacity to provide the highest level of safety is ineffective. This demonstration lies on two components. The first one gathers some results drawn from literature that introduces uncertainty. The second one takes into consideration the beliefs of agents and their aversion to ambiguity. The model applies uncertainty to the level of maximum damage. This demonstration reinforces the previous result. Hence, both regimes apply on specific tort question and comparing their individual efficiency needs to call for other components as the transaction costs associated to the burden of evidence, the fairness between victims and injurers, etc.

THE DESIGN OF A PROACTIVE PERSONAL AGENT FOR TASK MANAGEMENT

Personal assistant agents capable of proactively offering assistance can be more helpful to their users through their ability to perform tasks that otherwise would require user involvement. This article characterizes the properties desired of proactive behavior by a personal assistant agent in the realm of task management and develops an operational framework to implement such capabilities. We present an extended agent architectural model that features a meta-level layer charged with identifying potentially helpful actions and determining when it is appropriate to perform them. The reasoning that answers these questions draws on a theory of proactivity that describes user desires and a model of helpfulness. Operationally, assistance patterns represent a compiled form of this knowledge, instantiating meta-reasoning over the agent's beliefs about its user's activities as well as over world state. The resulting generic framework for proactive goal generation and deliberation has been implemented as part of a personal assistant agent in the computer desktop domain.

Igualdade em educação, uniformidade escolar e desafios da diferenciação

Th e organization of the school to ensure equality is based on a decision model that promotes the bureaucratic reception of many measures intended to promote differentiated instruction, insofar as these measures are designed on the central administration to be executed in schools. This organization is also conditioned by the entrenched beliefs of educators and educational agents socialized in a transmissive pedagogy that supports the “traditional school” thus effectively removing any device for differentiation of instruction.

Scanlon on Permissibility and Double Effect

In his book Moral Dimensions. Permissibility, Meaning, Blame, T.M. Scanlon proposes a new account of permissibility, and argues, against the doctrine of double effect (DDE), that intentions do not matter for permissibility. I argue that Scanlon's account of permissibility as based on what the agent should have known at the time of action does not sufficiently take into account Scanlon's own emphasis on permissibility as a question for the deliberating agent. A proper account of permissibility, based on the agent's actual beliefs, will allow us to revise the principle Scanlon proposes for regulating the use of violence in war, and to show that, while the DDE as such might be invalid, its focus on intentions does point toward an important element which Scanlon's proposal lacks, viz. the requirement that the agent believes that her actions will have certain consequences and can be justified for that reason.

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Exogenous control of DeGroot belief learning

Belief learning in social networks is thought to occur through an update process that aggregates dispersed information on the beliefs of connected neighbors through social influences. We explore mechanisms to apply persuasive biases to beliefs at the individual and group level, using the popular DeGroot update as the basic network-learning scheme, to achieve purposeful control on belief learning. We show that linear control of belief learning results in the possibility of shaping the beliefs of individual agents. We prove convergence of the control and show that external persuasive biases, which are our linear control parameters, are not only learnt by the agents just as they learn beliefs, but they can even swamp out the original beliefs. We establish the theoretical foundation for linear dynamic control of belief learning in this paper and illustrate the key results with examples of small networks which show how emerging consensus can be amplified or even destroyed.

An analytic tableau calculus for a temporalised belief logic

A tableau is a refutation-based decision procedure for a related logic, and is among the most popular proof procedures for modal logics. In this paper, we present a labelled tableau calculus for a temporalised belief logic called TML +, which is obtained by adding a linear-time temporal logic onto a belief logic by the temporalisation method of Finger and Gabbay. We first establish the soundness and the completeness of the labelled tableau calculus based on the soundness and completeness results of its constituent logics. We then sketch a resolution-type proof procedure that complements the tableau calculus and also propose a model checking algorithm for TML + based on the recent results for model checking procedures for temporalised logics. TML + is suitable for formalising trust and agent beliefs and reasoning about their evolution for agent-based systems. Based on the logic TML +, the proposed labelled tableau calculus could be used for analysis, design and verification of agent-based systems operating in dynamic environments.

COORDINATION DIAGNOSTIC ALGORITHMS FOR TEAMS OF SITUATED AGENTS: SCALING UP

Agents in a team should be in agreement. Unfortunately, they may come to disagree due to sensor uncertainty, intermittent communication failures, etc. Once a disagreement occurs, the agents should detect and diagnose the disagreement. Current diagnostic techniques do not scale well with the number of agents, as they have high communication and computation complexity. We present novel techniques that enable scalability in three ways. First, we use communications early in the diagnostic process to stave off unneeded reasoning, which ultimately leads to unneeded communications. Second, we use light‐weight (and inaccurate) behavior recognition to focus the diagnostic reasoning on beliefs of agents that might be in conflict. Finally, we propose diagnosing only to a limited number of representative agents (instead of all the agents). We examine these techniques in large‐scale teams of situated agents in two domains and show that combining the techniques produces a diagnostic process that is highly scalable in both communication and computation.

BRIDGING JEFFREY'S RULE, AGM REVISION AND DEMPSTER CONDITIONING IN THE THEORY OF EVIDENCE

Belief revision characterizes the process of revising an agent's beliefs when receiving new evidence. In the field of artificial intelligence, revision strategies have been extensively studied in the context of logic-based formalisms and probability kinematics. However, so far there is not much literature on this topic in evidence theory. In contrast, combination rules proposed so far in the theory of evidence, especially Dempster rule, are symmetric. They rely on a basic assumption, that is, pieces of evidence being combined are considered to be on a par, i.e. play the same role. When one source of evidence is less reliable than another, it is possible to discount it and then a symmetric combination operation is still used. In the case of revision, the idea is to let prior knowledge of an agent be altered by some input information. The change problem is thus intrinsically asymmetric. Assuming the input information is reliable, it should be retained whilst the prior information should be changed minimally to that effect. To deal with this issue, this paper defines the notion of revision for the theory of evidence in such a way as to bring together probabilistic and logical views. Several revision rules previously proposed are reviewed and we advocate one of them as better corresponding to the idea of revision. It is extended to cope with inconsistency between prior and input information. It reduces to Dempster rule of combination, just like revision in the sense of Alchourrón, Gärdenfors, and Makinson (AGM) reduces to expansion, when the input is strongly consistent with the prior belief function. Properties of this revision rule are also investigated and it is shown to generalize Jeffrey's rule of updating, Dempster rule of conditioning and a form of AGM revision.

BETWEEN DE DICTO AND DE RE: DE OBJECTO ATTITUDES

Hintikka's second generation epistemic logic introduces a syntactic device allowing to express independence relations between certain logical constants. De re knowledge attributions can be reformulated in terms of quantifier independence, but the reformulation does not extend to non‐factive attitudes like belief. There, formulae with independent quantifiers serve to express a new type of attitude, intermediate between de dicto and de re, called ‘de objecto’: in each possible world compatible with the agent's belief, there is an individual with the specified property – in each world the same individual, which or who need not exist actually. The philosophical benefits of our analysis of propositional attitudes include a refined account of the behaviour of proper names as well as of indefinite and definite descriptions in attitude reports. Some remarks about perception and about the hallucination argument are also presented.

Iterated Belief Change Due to Actions and Observations

In action domains where agents may have erroneous beliefs, reasoning about the effects of actions involves reasoning about belief change. In this paper, we use a transition system approach to reason about the evolution of an agent's beliefs as actions are executed. Some actions cause an agent to perform belief revision while others cause an agent to perform belief update, but the interaction between revision and update can be non-elementary. We present a set of rationality properties describing the interaction between revision and update, and we introduce a new class of belief change operators for reasoning about alternating sequences of revisions and updates. Our belief change operators can be characterized in terms of a natural shifting operation on total pre-orderings over interpretations. We compare our approach with related work on iterated belief change due to action, and we conclude with some directions for future research.

Financial Crises, Asymmetric Information and Argumentation

This paper aims to explore the relevance of the Asymmetric Information and the Theory of Argumentation TA in the complex area of financial crises. Specifically, we investigated the scope of the phenomenon of persuasion in advertising. It examines advertisements in publications notable economic movement in Colombia. The financial communication is important to distinguish how to run the models of behavior based on beliefs of agents. Consequently, investors' beliefs can also change systematically with changes in market prices