Machine ethics via logic programming

Machine ethics is an interdisciplinary field of inquiry that emerges from the need of imbuing autonomous agents with the capacity of moral decision-making. While some approaches provide implementations in Logic Programming (LP) systems, they have not exploited LP-based reasoning features that appear essential for moral reasoning. This PhD thesis aims at investigating further the appropriateness of LP, notably a combination of LP-based reasoning features, including techniques available in LP systems, to machine ethics. Moral facets, as studied in moral philosophy and psychology, that are amenable to computational modeling are identified, and mapped to appropriate LP concepts for representing and reasoning about them. The main contributions of the thesis are twofold. First, novel approaches are proposed for employing tabling in contextual abduction and updating – individually and combined – plus a LP approach of counterfactual reasoning; the latter being implemented on top of the aforementioned combined abduction and updating technique with tabling. They are all important to model various issues of the aforementioned moral facets. Second, a variety of LP-based reasoning features are applied to model the identified moral facets, through moral examples taken off-the-shelf from the morality literature. These applications include: (1) Modeling moral permissibility according to the Doctrines of Double Effect (DDE) and Triple Effect (DTE), demonstrating deontological and utilitarian judgments via integrity constraints (in abduction) and preferences over abductive scenarios; (2) Modeling moral reasoning under uncertainty of actions, via abduction and probabilistic LP; (3) Modeling moral updating (that allows other – possibly overriding – moral rules to be adopted by an agent, on top of those it currently follows) via the integration of tabling in contextual abduction and updating; and (4) Modeling moral permissibility and its justification via counterfactuals, where counterfactuals are used for formulating DDE.Fundação para a Ciência e a Tecnologia (FCT)-grant SFRH/BD/72795/2010 ; CENTRIA and DI/FCT/UNL for the supplementary fundin

Logic Programming and Machine Ethics

Transparency is a key requirement for ethical machines. Verified ethical behavior is not enough to establish justified trust in autonomous intelligent agents: it needs to be supported by the ability to explain decisions. Logic Programming (LP) has a great potential for developing such perspective ethical systems, as in fact logic rules are easily comprehensible by humans. Furthermore, LP is able to model causality, which is crucial for ethical decision making.Comment: In Proceedings ICLP 2020, arXiv:2009.09158. Invited paper for the ICLP2020 Panel on "Machine Ethics". arXiv admin note: text overlap with arXiv:1909.0825

Every normal logic program has a 2-valued semantics: theory, extensions, applications, implementations

Trabalho apresentado no âmbito do Doutoramento em Informática, como requisito parcial para obtenção do grau de Doutor em InformáticaAfter a very brief introduction to the general subject of Knowledge Representation and Reasoning with Logic Programs we analyse the syntactic structure of a logic program and how it can influence the semantics. We outline the important properties of a 2-valued semantics for Normal Logic Programs, proceed to define the new Minimal Hypotheses semantics with those properties and explore how it can be used to benefit some knowledge representation and reasoning mechanisms. The main original contributions of this work, whose connections will be detailed in the sequel, are: • The Layering for generic graphs which we then apply to NLPs yielding the Rule Layering and Atom Layering — a generalization of the stratification notion; • The Full shifting transformation of Disjunctive Logic Programs into (highly nonstratified)NLPs; • The Layer Support — a generalization of the classical notion of support; • The Brave Relevance and Brave Cautious Monotony properties of a 2-valued semantics; • The notions of Relevant Partial Knowledge Answer to a Query and Locally Consistent Relevant Partial Knowledge Answer to a Query; • The Layer-Decomposable Semantics family — the family of semantics that reflect the above mentioned Layerings; • The Approved Models argumentation approach to semantics; • The Minimal Hypotheses 2-valued semantics for NLP — a member of the Layer-Decomposable Semantics family rooted on a minimization of positive hypotheses assumption approach; • The definition and implementation of the Answer Completion mechanism in XSB Prolog — an essential component to ensure XSB’s WAM full compliance with the Well-Founded Semantics; • The definition of the Inspection Points mechanism for Abductive Logic Programs;• An implementation of the Inspection Points workings within the Abdual system [21] We recommend reading the chapters in this thesis in the sequence they appear. However, if the reader is not interested in all the subjects, or is more keen on some topics rather than others, we provide alternative reading paths as shown below. 1-2-3-4-5-6-7-8-9-12 Definition of the Layer-Decomposable Semantics family and the Minimal Hypotheses semantics (1 and 2 are optional) 3-6-7-8-10-11-12 All main contributions – assumes the reader is familiarized with logic programming topics 3-4-5-10-11-12 Focus on abductive reasoning and applications.FCT-MCTES (Fundação para a Ciência e Tecnologia do Ministério da Ciência,Tecnologia e Ensino Superior)- (no. SFRH/BD/28761/2006

Joy Beyond the Walls of the World: How Christianity Ably Explains the Moral Facts

I argue that Christianity ably explains the moral facts of moral goodness, intrinsic human value, moral rationality, and moral transformation. Chapter 1 provides an explanation of the thesis, a historical overview of the moral argument, a defense of the method, a critique of William Lane Craig’s deductive argument, and a response to some challenges to abduction from a Christian worldview. In chapter 2, I explain how Christianity ably explains moral goodness. I first give some reason to think God should be identified with the Good, following Robert Adams. Next, I summarize some of the issues related to moral goodness. Then, I argue that being loving is an important way of being good. The Bible and Christian reflection upon revelation rightly understand God as consistent with the good. Finally, I suggest that given the importance of love to the good, the specifically Christian understanding of God as a single God in three persons powerfully accounts for this. Chapter 3 argues that the Christian worldview strongly affirms the intrinsic value of human beings because they are made in “the image of God.” I offer a functional account over an ontological one, suggesting that the functional account includes the ontological one and offers an even higher view of human value. Second, I show that the incarnation of the Second Person of the Trinity in Jesus of Nazareth implies a high view of intrinsic human value, both because of the function of the incarnation and the ontological implications for human beings. In chapter 4, I argue that Christianity ably explains moral rationality because it provides a plausible account of how morality and self-interest are reconciled and because of the natural connection between morality and rationality on the Christian view. Specifically, I develop the idea that the Great White Throne judgment is not about moral rationality, but about the choice between life and death and that moral rationality is only ensured once one enters into life with God. In the penultimate chapter, I argue that Christianity ably explains why there is a moral gap and how to overcome it. Specifically, Christianity offers a realistic depiction of human incapacity. It also reinforces and heightens the moral demand. Finally, Christianity explains how we can overcome the moral gap by addressing moral guilt through God’s forgiveness and through the sanctifying power of the Holy Spirit, who graciously cooperates with man in his moral transformation. Finally, I consider the practical import of the moral argument on offer, suggesting it has a potentially eternal consequence and transformative power. I also clarify the force of the argument, proposing that it is more suggestive than coercive

From Logic Programming to Human Reasoning:: How to be Artificially Human

Results of psychological experiments have shown that humans make assumptions, which are not necessarily valid, that they are influenced by their background knowledge and that they reason non-monotonically. These observations show that classical logic does not seem to be adequate for modeling human reasoning. Instead of assuming that humans do not reason logically at all, we take the view that humans do not reason classical logically. Our goal is to model episodes of human reasoning and for this purpose we investigate the so-called Weak Completion Semantics. The Weak Completion Semantics is a Logic Programming approach and considers the least model of the weak completion of logic programs under the three-valued Łukasiewicz logic. As the Weak Completion Semantics is relatively new and has not yet been extensively investigated, we first motivate why this approach is interesting for modeling human reasoning. After that, we show the formal correspondence to the already established Stable Model Semantics and Well-founded Semantics. Next, we present an extension with an additional context operator, that allows us to express negation as failure. Finally, we propose a contextual abductive reasoning approach, in which the context of observations is relevant. Some properties do not hold anymore under this extension. Besides discussing the well-known psychological experiments Byrne’s suppression task and Wason’s selection task, we investigate an experiment in spatial reasoning, an experiment in syllogistic reasoning and an experiment that examines the belief-bias effect. We show that the results of these experiments can be adequately modeled under the Weak Completion Semantics. A result which stands out here, is the outcome of modeling the syllogistic reasoning experiment, as we have a higher prediction match with the participants’ answers than any of twelve current cognitive theories. We present an abstract evaluation system for conditionals and discuss well-known examples from the literature. We show that in this system, conditionals can be evaluated in various ways and we put up the hypothesis that humans use a particular evaluation strategy, namely that they prefer abduction to revision. We also discuss how relevance plays a role in the evaluation process of conditionals. For this purpose we propose a semantic definition of relevance and justify why this is preferable to a exclusively syntactic definition. Finally, we show that our system is more general than another system, which has recently been presented in the literature. Altogether, this thesis shows one possible path on bridging the gap between Cognitive Science and Computational Logic. We investigated findings from psychological experiments and modeled their results within one formal approach, the Weak Completion Semantics. Furthermore, we proposed a general evaluation system for conditionals, for which we suggest a specific evaluation strategy. Yet, the outcome cannot be seen as the ultimate solution but delivers a starting point for new open questions in both areas

The Print Page Space as Aesthetic Discourse Art Semiotic in Democracy

[Abstract] Roland Barthes writing, to the zero degree, seemed to put its accent on the differences between art and craft as a question of style, mannerism: writing limits, merges, proportions, isolate, build its own social reality, but is it still a thoughtful shape? Or it is the suit, the envelop, the skin, of a constitutional part of the ‘I’, that revolts this scenery, that renews the pact as agreement of the rights of the person, the individual outside the conveniences as before 1996 were the ground of the usury of any political term? Among linguistic and semiotic we can discover the traits of differences as to perceive its eidetic necessity, the elements and the objects. Since Erik Landowsky, in which the page is structured as a painting of spaces connotations, oblique to the reader or since Giovanni Anceschi where the art of the page it is experience of communication, the occurrence, the author, inference a social space and a collective «I», the subject restrain, closes, exemplify or even models what is expanded, translated, loosened. From the identity body of the newspaper we get to the unreachable public identity of the consumer. The chiastic gesture or the censure one, or the polisemic as it is involved just in the object: it should impress a certain quality of the message and continuity of the communication. A semiotic landscape, in some of the terms of Ruggero Pierantoni, of light phenomenon, while on the newspaper could be seen in its own categories exploited as re-reading a townscape, as the voyageur propose a journey, the compositions aspects may represent some ways to renew the fragmented process, pauses, attitudes to rebuild a reader theory. To Jean Marie Floch, the page is the emergences of the meaning: utters as sudden wriggle, out of the waving envelop. If there is a mania that is to compare the different corporate identity without results, as to forget the composition, the athletic heritage of the development; but here is the challenge: the irony become quotation, through a passionate writer – the pigiama seems only to create the deal, the game, the landscape in a possible recognition of a certain time braking the appearances between words and deeds, knowledge and real objects. Subjectivity is in the semiotic montage: where it disappears, democracy is forgotten. To Giovanni Anceschi the newspaper is a communicational artefact that sculpts, models, our history: its typefaces are still means that signs the melodic registry of counterfeit? We will bring together some pieces of graphic experiences, some deep lecture and irony as vocation, and compare the voices as textual genres and the typefaces as tools for semiotic culture: as in a painting of J.-L. T. Gericault, the relicts of The Raft of The Medusa, to demystify the genres, to rediscover some anthropological calls for cultural objects in visual communication from painting to architecture, from sculpture to print