Cette thèse vise à mieux définir ainsi qu'à mieux évaluer les stratégies de tromperie et de manipulation de l'information. Des ressources conceptuelles, formelles et expérimentales sont combinées en vue d'analyser des cas standards de tromperie, tels que le mensonge, mais aussi non-standards, tels que les inférences trompeuses et l'omission stratégique. Les aspects définitionnels sont traités en premier. J'analyse la définition traditionnelle du mensonge en présentant des résultats empiriques en faveur de cette définition classique (dite 'définition subjective'), contre certains arguments visant à défendre une 'définition objective' par l'ajout d'une condition de fausseté. J'examine ensuite une énigme logique issue de R. Smullyan, et qui porte sur un cas limite de tromperie basé sur une règle d'inférence par défaut pour tromper un agent par omission. Je traite ensuite des aspects évaluatifs. Je pars du cadre existant pour l'évaluation du renseignement et propose une typologie des messages fondée sur les dimensions descriptives de vérité (pour leur contenu) et d'honnêteté (pour leur source). Je présente ensuite une procédure numérique pour l'évaluation des messages basée sur les dimensions évaluatives de crédibilité (pour la vérité) et de fiabilité (pour l'honnêteté). Des modèles numériques de plausibilité servent à capturer la crédibilité a priori des messages puis des règles numériques sont proposées pour actualiser ces degrés selon la fiabilité de la source. / This thesis aims at improving the definition and evaluation of deceptive strategies that can manipulate information. Using conceptual, formal and experimental resources, I analyze three deceptive strategies, some of which are standard cases of deception, in particular lies, and others non-standard cases of deception, in particular misleading inferences and strategic omissions. Firstly, I consider definitional aspects. I deal with the definition of lying, and present new empirical data supporting the traditional account of the notion (called the ‘subjective definition’), contradicting recent claims in favour of a falsity clause (leading to an ‘objective definition’). Next, I analyze non-standard cases of deception through the categories of misleading defaults and omissions of information. I use qualitative belief revision to examine a puzzle due to R. Smullyan about the possibility of triggering a default inference to deceive an addressee by omission. Secondly, I consider evaluative aspects. I take the perspective of military intelligence data processing to offer a typology of informational messages based on the descriptive dimensions of truth (for message contents) and honesty (for message sources). I also propose a numerical procedure to evaluate these messages based on the evaluative dimensions of credibility (for truth) and reliability (for honesty). Quantitative plausibility models are used to capture degrees of prior credibility of messages, and dynamic rules are defined to update these degrees depending on the reliability of the source.

The quest for epistemic liberation remains an important project in the post-colonial era of Zambia, and entails challenging the existing inequalities in knowledge representation at the epistemic front in the country. At the core of this quest is the position that the continued dominance of Western knowledge and the corresponding marginalisation of indigenous knowledges amount to an epistemic injustice that affects the contemporary existence of the peoples in the country. This study critically examines the problem of epistemic injustice in Zambia while reflecting on the country’s uncompleted project of decolonisation. It traces the problem from the theoretical assumption of modernity that Western knowledge is universal and that it should, therefore, be applied to all societies in the world. It is submitted that the current education system in Zambia is based on this assumption, and, consequently, favours Western knowledge to the exclusion of indigenous knowledges. This practice is identified as a conduit for accelerating epistemic injustice and its intensity in the country. The study approaches this problem from an African philosophical standpoint, and draws its current from the history of the political struggle against domination on the continent. To adequately confront the problem of epistemic injustice in Zambia, the study suggests parity and equilibrium in representation between indigenous knowledges and Western knowledge in the country. / Philosophy, Practical and Systematic Theology / M.A. (Philosophy)

In this thesis, a particular class of agent is singled out for examination. In order to provide a guiding metaphor, we speak of control room agents. Our focus is on rational decision- making by such agents, where the circumstances obtaining are such that rationality is bounded. Control room agents, whether human or non-human, need to reason and act in a changing environment with only limited information available to them. Determining the current state of the environment is a central concern for control room agents if they are to reason and act sensibly. A control room agent cannot plan its actions without having an internal representation (epistemic state) of its environment, and cannot make rational decisions unless this representation, to some level of accuracy, reflects the state of its environment. The focus of this thesis is on three aspects regarding the epistemic functioning of a control room agent: 1. How should the epistemic state of a control room agent be represented in order to facilitate logical analysis? 2. How should a control room agent change its epistemic state upon receiving new information? 3. How should a control room agent combine available information from different sources? In describing the class of control room agents as first-order intentional systems hav- ing both informational and motivational attitudes, an agent-oriented view is adopted. The central construct used in the information-theoretic approach, which is qualitative in nature, is the concept of a templated ordering. Representing the epistemic state of a control room agent by a (special form of) tem- plated ordering signals a departure from the many approaches in which only the beliefs of an agent are represented. Templated orderings allow for the representation of both knowledge and belief. A control room agent changes its epistemic state according to a proposed epistemic change algorithm, which allows the agent to select between two well-established forms of belief change operations, namely, belief revision and belief update. The combination of (possibly conflicting) information from different sources has re- ceived a lot of attention in recent years. Using templated orderings for the semantic representation of information, a new family of purely qualitative merging operations is developed. / School of Computing / Ph. D. (Computer Science)

In this thesis, a particular class of agent is singled out for examination. In order to provide a guiding metaphor, we speak of control room agents. Our focus is on rational decision- making by such agents, where the circumstances obtaining are such that rationality is bounded. Control room agents, whether human or non-human, need to reason and act in a changing environment with only limited information available to them. Determining the current state of the environment is a central concern for control room agents if they are to reason and act sensibly. A control room agent cannot plan its actions without having an internal representation (epistemic state) of its environment, and cannot make rational decisions unless this representation, to some level of accuracy, reflects the state of its environment. The focus of this thesis is on three aspects regarding the epistemic functioning of a control room agent: 1. How should the epistemic state of a control room agent be represented in order to facilitate logical analysis? 2. How should a control room agent change its epistemic state upon receiving new information? 3. How should a control room agent combine available information from different sources? In describing the class of control room agents as first-order intentional systems hav- ing both informational and motivational attitudes, an agent-oriented view is adopted. The central construct used in the information-theoretic approach, which is qualitative in nature, is the concept of a templated ordering. Representing the epistemic state of a control room agent by a (special form of) tem- plated ordering signals a departure from the many approaches in which only the beliefs of an agent are represented. Templated orderings allow for the representation of both knowledge and belief. A control room agent changes its epistemic state according to a proposed epistemic change algorithm, which allows the agent to select between two well-established forms of belief change operations, namely, belief revision and belief update. The combination of (possibly conflicting) information from different sources has re- ceived a lot of attention in recent years. Using templated orderings for the semantic representation of information, a new family of purely qualitative merging operations is developed. / School of Computing / Ph. D. (Computer Science)