Machine Ethics Via Logic Programming
Total Page:16
File Type:pdf, Size:1020Kb
Ari Saptawijaya Master in Computer Science Machine Ethics via Logic Programming Dissertação para obtenção do Grau de Doutor em Informática Orientador: Luís Moniz Pereira, Professor Catedrático, Universidade Nova de Lisboa Júri: Presidente: Prof. José Augusto Legatheaux Martins Arguentes: Assistant Prof. Alexandre Miguel dos Santos Martins Pinto Dr. Terrance Lee Swift Vogais: Associate Prof. João Alexandre Carvalho Pinheiro Leite Senior Lecturer, Dr. Fariba Sadri July, 2015 Machine Ethics via Logic Programming Copyright c Ari Saptawijaya, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa A Faculdade de Ciências e Tecnologia e a Universidade Nova de Lisboa têm o direito, perpétuo e sem limites geográficos, de arquivar e publicar esta dissertação através de exemplares impressos reproduzidos em papel ou de forma digital, ou por qualquer outro meio conhecido ou que venha a ser inventado, e de a divulgar através de repositórios científicos e de admitir a sua cópia e distribuição com objectivos educacionais ou de investigação, não comerciais, desde que seja dado crédito ao autor e editor. For Ananda ACKNOWLEDGEMENTS I would like to express my sincerest gratitude to my supervisor, Prof. Luís Moniz Pereira, who has introduced me to this challenging topic and provided me the guidance in ex- ploring this terra incognita, whilst also giving me the freedom to explore it on my own. I am really grateful to have Luís as my supervisor for his willingness to help at any time. Luís always encouraged me, with his patience, to go through my difficult situations, which kept me on track, and to eventually finish this thesis. I have learned a lot from his abundant knowledge in this interdisciplinary field (including, of course, his expertise in Logic Programming), absorbed his endless original ideas, and enjoyed many good times, where he shared his adventurous experiences. One is not always so lucky to have such a friendly and helpful supervisor. I am thankful to Dr. João Alexandre Leite, Dr. Fariba Sadri, and Dr. Terrance Swift as the members of my thesis advisory committee, for their suggestions and advices during the discussion of my thesis proposal. I also thank them and Dr. Alexandre Miguel Pinto that have accepted to be the jury members of my thesis defence. I am grateful to Prof. David S. Warren and Dr. Terrance Swift for their expertise in helping me with XSB Prolog, as well as for their specific suggestions in the development of tabling in abduction (TABDUAL) and updating (EVOLP/R) . I am also grateful to have an opportunity to discuss with Prof. Robert Kowalski about the idea of contextual abduction and rule name fluent mechanism in EVOLP/R. I would like to acknowledge Emmanuelle Dietz for our discussion on counterfactuals and other topics during her visit to Portugal, Gonçalo Lopes for explaining the idea of and how to use ACORDA for the work in this thesis, and Dr. Miguel Calejo for a number of suggestions to improve QUALM in future. Prof. Nuno Correia, as the coordinator of the PhD Program in Computer Science, and the secretariat of the Department of Informatics (DI/FCT/UNL), particularly Mrs. Sandra Rainha and Mrs. Susana Pereira, have provided me with their responsive and kind assistance to deal with bureaucratic stuffs, and for all that I am greatly thankful to them. I am indebted to Han The Anh and Martin Slota for their generous help during my first days in Portugal. The Anh has provided me with essential and practical information about doing a doctoral study in Portugal, and has kindly hosted me for several days in his shared apartment with Martin as soon as I arrived in Portugal. It is my pleasure to have a joint work with him on probabilistic moral reasoning, which becomes part of this thesis. Davide D’Alimonte and Tamito Kajiyama (and his lovely family) have particularly spent good times with me and my family with fun activities together, and I greatly value vii our cheerful friendship. Our joint research work in ocean color remote sensing was not less fun either. I am also grateful to have an opportunity, in various occasions, to establish warm friendship with Luís Mota Ferreira & Maria Freitas Casimiro, Jan Cederquist & Ana Almeida Matos, and several people in the department during my doctoral study: Ankica Bariši´c,Jorge Costa, Sinan Egilmez, Sofia Gomes, Ricardo Gonçalves, Cédric Grueau, Matthias Knorr, Fábio Madeira, João Moura, Nguyen Van Hau, and Filipa Peleja. I have also been blessed for knowing an Indonesian community in Lisbon, with whom I never felt being far away from my homeland. I acknowledge the support from Fundação para a Ciência e a Tecnologia (FCT) that has funded my doctoral study through grant SFRH/BD/72795/2010, as well as CENTRIA and DI/FCT/UNL for the supplementary funding that allowed me to attend a number of conferences. I am also grateful to the Faculty of Computer Science at my home university, Universitas Indonesia, for permitting me to take a leave of absence to pursue my doctoral study. The completion of my study would have been impossible without the love and patience of my family, to whom I would like to express my heart-felt gratitude. My parents have always been supportive of me, even though from a long distance, with their unconditional love, all these years. Last but not least, my wife – Meiriana – and my (now not so little anymore) son – Ananda – have been the constant source of encouragement and happiness throughout this endeavour. To all of you, this thesis is dedicated. viii ABSTRACT 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 reason- ing; 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 utili- tarian 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. Keywords: abduction, counterfactual, logic programming, machine ethics, morality, non- monotonic reasoning, tabling. ix RESUMO A ética da máquina é um campo interdisciplinar de investigação que emerge da neces- sidade de embeber os agentes autónomos com a capacidade de decisão moral. Embora certas abordagens providenciem implementações que usam sistemas de Programação em Lógica (PL), elas não têm explorado as facetas do raciocínio baseado em PL que parecem ser essenciais ao raciocínio moral. Esta tese de doutoramento almeja investigar mais longe a pertinência da PL para a ética da máquina, em especial por uma combinação de características para raciocínio da PL, inclusive técnicas já disponíveis em sistemas de PL. As facetas morais, tal como são estudadas na filosofia moral e na psicologia, são por nós identificadas, e mapeadas nos conceitos de PL apropriados para as representar e raciocinar sobre elas. As principais contribuições desta tese são de dois tipos. Em primeiro lugar, são propostas abordagens novas para o emprego de tabulação na abdução contextual e na actualização – quer individualmente quer em combinação – e ainda uma abordagem em PL ao raciocínio contrafactual; esta última é implementada sobre a supramencionada técnica de tabulação combinando a abdução e a actualização. Todas estas abordagens são importantes para modelar várias questões das já referidas facetas morais. Em segundo lugar, diversas características do raciocínio em PL são utilizadas para modelar as facetas morais, através de exemplos de prateleira da literatura da morali- dade. Tais aplicações incluem: (1) Modelação da permissibilidade segundo as Doutrinas do Duplo Efeito (DDE) e Triplo Efeito (DTE), demonstrando os juízos deontológicos e utilitários por via de condições de integridade (na abdução) e de preferências sobre os cenários abdutivos; (2) Modelação do raciocínio moral sujeito a incerteza de acções, via abdução e PL probabilística; (3) Modelação da actualização moral (permitindo que out- ras regras morais – possivelmente