Default Logic Seminar: Exploring Reasons with Prioritized Default Logic - Prof. John Horty, Papers of Introduction to Philosophy

Download Default Logic Seminar: Exploring Reasons with Prioritized Default Logic - Prof. John Horty and more Papers Introduction to Philosophy in PDF only on Docsity! Spring Semester, 2007 Instructor: Jeff Horty Syllabus Version 1.0 January 23, 2007 PHIL 858B: Defaults and Reasons Description This is an experimental seminar, organized around an idea, or a hope. The idea is that default logic can be used to develop a formally precise theory of reasons—what they are, how they interact— and that this theory can then be applied to other areas of philosophy in which talk of reasons is common, such as ethics or epistemology. In order to explore this idea, we will have to spend some time understanding default logic—more particularly, prioritized default logic, and more particularly still, prioritized default logics in which it is also possible to reason, by default, about the priorities among defaults. I will try to guide you through this work as gently as possible, but there is no question that some of it is complicated and technical; students enrolled in the seminar should be prepared to read papers in logic. They should also be prepared to read papers that are not in logic, but in ethics or epistemology, and in this case I hope they will be willing to explain to me what is going on. I mean that. Given the experimental nature of the seminar, I’m not exactly sure how things will develop, but I do have the first part of the course pretty well mapped out. We’ll begin by looking at (A) Raymond Reiter’s classic paper on default logic, along with bits of nonmonotonic inheritance reasoning. Then, to illustrate the applicability of default reasoning, we’ll look at (B) some of the literature on normative conflicts (“moral dilemmas”), the problems they create for deontic logic, and how defaults can help. After that, we’ll turn to (C) a careful study of prioritized default logics, as well as, possibly, (D) the alternative fomalism of argument systems, although this latter topic may be skipped entirely. At this point, we’ll move on to applications, beginning with (E) moral particularism, Jonathan Dancy’s argument from “reason holism” to particularism, and a suggestion, based on our study of default logic, about how we might allow for reason holism without being forced into particularism. We may then turn to (F) some comparisons between the account of default reasoning developed in this course and John Pollock’s theory of defeasible reasoning in epistemology. This is as far as I’ve got; after this, I’m not sure where to go. We can decide as a class what to look at next, but some options include: (G) some recent literature on the significance of disagreement among peers in epistemology and its relation to multiple extension in default logic; (H) the epistemic significance of “floating conclusions” in nonmonotonic reasoning; (I) constructivism as a metaethical position; and (J) legal rules, case law, and precedent. Time and place Thursdays, time not yet determined, Skinner 1116. 1 Office, phone, etc. Office: Skinner Building, Rm. 1101. Office phone: I don’t use my office phone. Home phone: 301-585-4586. You are welcome to call me at home. Email: horty@umiacs.umd.edu. I’ll let you know my exact office hours once they’ve sorted themselves out, but I’m generally available for appointments. Course materials Most of the more recent things are available on the web, other papers for copying will be in the Philosophy Lounge. I’ll let you know where to find various things as we get to them. Course work Students who want credit for the course must do two things: 1. Turn in assigned problem sets, which will be nuts and bolts, nothing tricky. Their main function, in fact, is to show me how well you’re understanding the material. 2. Complete a final project, which can have one of two forms: (a) an original paper, prepared as if for submission to a journal, and possibly submitted to a journal; or (b) a final, more extensive problem set. If it’s at all possible, I’d encourage students to take option (a), and I’ll work with you on that. The course will be run as a seminar, and everyone attending, students and auditors, will have to help present some of the material. For the most part, I’ll try to present the technical work myself and then hope to rely on others to present the non-technical work, though this may shift around a bit. Course topics Here is a tentative, initial list. The list of readings may still be revised, and further topics will be added as we decide where we want to go in the second part of the course. A. Default reasoning. 1. Default logic. Readings: Reiter [43]. Background and related material: Horty [27], Reiter and Criscuolo [44]. 2. Nonmonotonic inheritance reasoning. Readings: Horty [24], Touretzky et al. [46]. Background and related material: Fahlman [17], Horty et al. [31], Touretzky [45]. B. Normative conflicts 1. Orientation. Readings: Gowans [19]. 2 [13] James Delgrande, Torsten Schaub, Hans Tompits, and Kewen Wang. A classification and sur- vey of preference handling approaches in nonmonotonic reasoning. Computational Intelligence, 20:308–334, 2004. [14] Alan Donagan. Consistency in rationalist moral systems. The Journal of Philosophy, 81:291– 309, 1984. [15] Alan Donagan. Moral dilemmas, genuine and spurious: a comparative anatomy. Ethics, 104:7–21, 1993. [16] P. M. Dung. On the acceptability of arguments and its fundamental role in nonmonotonic reason, logic programming, and n-person games. Artificial Intelligence, 77:321–357, 1995. [17] Scott Fahlman. NETL: A System for Representing and Using Real-world Knowledge. The MIT Press, 1979. [18] Lou Goble. Normative conflicts and the logic of ‘ought’. Unpublished manuscript, 2006. [19] Christopher Gowans. Introduction: the debate on moral dilemmas. In Christopher Gowans, editor, Moral Dilemmas, pages 3–33. Oxford University Press, 1987. [20] Jörg Hansen. Deontic logic for prioritized imperatives. Artificial Intelligence and Law, 2006. [21] Jörg Hansen. Prioritized conditional imperatives: problems and a new proposal. Unpublished manuscript, 2007. [22] Brad Hooker and Margaret Little. Moral Particularism. Oxford University Press, 2000. [23] John Horty. Moral dilemmas and nonmonotonic logic. Journal of Philosophical Logic, 23:35–65, 1994. [24] John Horty. Some direct theories of nonmonotonic inheritance. In D. Gabbay, C. Hogger, and J. Robinson, editors, Handbook of Logic in Artificial Intelligence and Logic Programming, Vol- ume 3: Nonmonotonic Reasoning and Uncertain Reasoning, pages 111–187. Oxford University Press, 1994. [25] John Horty. Nonmonotonic foundations for deontic logic. In Donald Nute, editor, Defeasible Deontic Logic, pages 17–44. Kluwer Academic Publishers, 1997. [26] John Horty. Argument construction and reinstatement in logics for defeasible reasoning. Ar- tificial Intelligence and Law, 9:1–28, 2001. [27] John Horty. Nonmonotonic logic. In Lou Goble, editor, The Blackwell Guide to Philosophical Logic, pages 336–361. Basil Blackwell Publisher, 2001. [28] John Horty. Reasoning with moral conflicts. Nous, 37:557–605, 2003. [29] John Horty. Defaults with priorities. Forthcoming in Journal of Philosophical Logic, 2007+. [30] John Horty. Reasons as defaults. Forthcoming in Philosophers’ Imprint, 2007+. [31] John Horty, Richmond Thomason, and David Touretzky. A skeptical theory of inheritance in nonmonotonic semantic networks. Artificial Intelligence, 42:311–348, 1990. [32] E. J. Lemmon. Moral dilemmas. Philosophical Review, 70:139–158, 1962. 5 [33] Ruth Barcan Marcus. Moral dilemmas and consistency. Journal of Philosophy, 77:121–136, 1980. [34] Paul Pietroski. Prima facie obligations, ceteris paribus laws in moral theory. Ethics, 103:489– 515, 1993. [35] John Pollock. Cognitive Carpentry: A Blueprint for How to Build a Person. The MIT Press, 1995. [36] John Pollock. Defeasible reasoning. Unpublished manuscript, 2007+. [37] John Pollock and Joseph Cruz. Contemporary Theories of Knowledge. Rowman and Littlefield Publishers, Inc., 1999. [38] Henry Prakken. Intuitions and the modelling of defeasible reasoning: some case studies. In Salem Benferhat and Enrico Giunchiglia, editors, Proceedings of the Ninth International Workshop on Nonmonotonic Reasoning, 2002. [39] Henry Prakken and Giovanni Sartor. A dialectical model of assessing conflicting arguments in legal reasoning. Artificial Intelligence and Law, 4:331–368, 1996. [40] Henry Prakken and Giovanni Sartor. Argument-based extended logic programming with de- feasible priorities. Journal of Applied Non-classical Logics, 7:25–75, 1997. [41] Henry Prakken and Gerard Vreeswijk. Logical systems for defeasible argumentation. In Dov Gabbay and F. Guethner, editors, Handbook of Philosophical Logic (Second Edition), pages 219–318. Kluwer Academic Publishers, 2002. [42] Joseph Raz. Practical Reasoning and Norms. Hutchinson and Company, 1975. Reprinted by Oxford University Press, 2002. [43] Raymond Reiter. A logic for default reasoning. Artificial Intelligence, 13:81–132, 1980. [44] Raymond Reiter and Giovanni Criscuolo. On interacting defaults. In Proceedings of the Seventh International Joint Conference on Artificial Intelligence (IJCAI-81), pages 270–276, 1981. [45] David Touretzky. The Mathematics of Inheritance Systems. Morgan Kaufmann, 1986. [46] David Touretzky, John Horty, and Richmond Thomason. A clash of intuitions: the current state of nonmonotonic multiple inheritance systems. In Proceedings of the Tenth International Joint Conference on Artificial Intelligence (IJCAI-87), pages 476–482. Morgan Kaufmann, 1987. [47] Bas van Fraassen. Values and the heart’s command. The Journal of Philosophy, 70:5–19, 1973. [48] Quoc Bao Vo, Norman Foo, and Joe Thurbon. Semantics for a theory of defeasible reasoning. Annals of Mathematics and Artificial Intelligence, 44:87–119, 2005. [49] Bernard Williams. Ethical consistency. Proceedings of the Aristotelian Society, 39 (supplemental):103–124, 1965. A revised version appears in Problems of the Self: Philosophical Papers 1956–1972, Cambridge University Press, 1973, pages 166–186. 6