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John Horty [25]John F. Horty [25]John Francis Horty [1]
  1. Agency and deontic logic.John Horty - 2001 - New York: Oxford University Press.
    John Horty effectively develops deontic logic (the logic of ethical concepts like obligation and permission) against the background of a formal theory of agency. He incorporates certain elements of decision theory to set out a new deontic account of what agents ought to do under various conditions over extended periods of time. Offering a conceptual rather than technical emphasis, Horty's framework allows a number of recent issues from moral theory to be set out clearly and discussed from a uniform point (...)
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  2. Reasons as Defaults.John Horty - 2007 - Philosophers' Imprint 7:1-28.
    The goal of this paper is to frame a theory of reasons--what they are, how they support actions or conclusions--using the tools of default logic. After sketching the basic account of reasons as provided by defaults, I show how it can be elaborated to deal with two more complicated issues: first, situations in which the priority relation among defaults, and so reasons as well, is itself established through default reasoning; second, the treatment of undercutting defeat and exclusionary reasons. Finally, and (...)
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  3. Reasoning with moral conflicts.John F. Horty - 2003 - Noûs 37 (4):557–605.
    Let us say that a normative conflict is a situation in which an agent ought to perform an action A, and also ought to perform an action B, but in which it is impossible for the agent to perform both A and B. Not all normative conflicts are moral conflicts, of course. It may be that the agent ought to perform the action A for reasons of personal generosity, but ought to perform the action B for reasons of prudence: perhaps (...)
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  4.  47
    Reasoning with dimensions and magnitudes.John Horty - 2019 - Artificial Intelligence and Law 27 (3):309-345.
    This paper shows how two models of precedential constraint can be broadened to include legal information represented through dimensions. I begin by describing a standard representation of legal cases based on boolean factors alone, and then reviewing two models of constraint developed within this standard setting. The first is the “result model”, supporting only a fortiori reasoning. The second is the “reason model”, supporting a richer notion of constraint, since it allows the reasons behind a court’s decisions to be taken (...)
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  5.  66
    A sceptical theory of inheritance in nonmonotonic semantic networks.John F. Horty, Richmond H. Thomason & David S. Touretzky - 1990 - Artificial Intelligence 42 (2-3):311-348.
    inheritance reasoning in semantic networks allowing for multiple inheritance with exceptions. The approach leads to a definition of iaheritance that is..
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  6. A factor-based definition of precedential constraint.John F. Horty & Trevor J. M. Bench-Capon - 2012 - Artificial Intelligence and Law 20 (2):181-214.
    This paper describes one way in which a precise reason model of precedent could be developed, based on the general idea that courts are constrained to reach a decision that is consistent with the assessment of the balance of reasons made in relevant earlier decisions. The account provided here has the additional advantage of showing how this reason model can be reconciled with the traditional idea that precedential constraint involves rules, as long as these rules are taken to be defeasible. (...)
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  7. Rules and reasons in the theory of precedent.John F. Horty - 2011 - Legal Theory 17 (1):1-33.
    The doctrine of precedent, as it has evolved within the common law, has at its heart a form of reasoning—broadly speaking, alogic—according to which the decisions of earlier courts in particular cases somehow generalize to constrain the decisions of later courts facing different cases, while still allowing these later courts a degree of freedom in responding to fresh circumstances. Although the techniques for arguing on the basis of precedent are taught early on in law schools, mastered with relative ease, and (...)
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  8. Moral dilemmas and nonmonotonic logic.John Horty - 1994 - Journal of Philosophical Logic 23 (1):35 - 65.
    From a philosophical standpoint, the work presented here is based on van Fraassen [26]. The bulk of that paper is organized around a series of arguments against the assumption, built into standard deontic logic, that moral dilemmas are impossible; and van Fraassen only briefly sketches his alternative approach. His paper ends with the conclusion that “the problem of possibly irresolvable moral conflict reveals serious flaws in the philosophical and semantic foundations of ‘orthodox’ deontic logic, but also suggests a rich set (...)
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  9.  14
    Frege on Definitions: A Case Study of Semantic Content.John Horty - 2007 - , US: Oup Usa.
    In this short monograph, John Horty explores the difficulties presented for Gottlob Frege's semantic theory, as well as its modern descendents, by the treatment of defined expressions. The book begins by focusing on the psychological constraints governing Frege's notion of sense, or meaning, and argues that, given these constraints, even the treatment of simple stipulative definitions led Frege to important difficulties. Horty is able to suggest ways out of these difficulties that are both philosophically and logically plausible and Fregean in (...)
  10.  43
    Action Types in Stit Semantics.John Horty & Eric Pacuit - 2017 - Review of Symbolic Logic 10 (4):617-637.
    Stit semantics grows out of a modal tradition in the logic of action that concentrates on an operator representing the agency of an individual in seeing to it that some state of affairs holds, rather than on the actions the individual performs in doing so. The purpose of this paper is to enrich stit semantics, and especially epistemic stit semantics, by supplementing the overall framework with an explicit treatment of action types. We show how the introduction of these new action (...)
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  11.  29
    Modifying the reason model.John Horty - 2020 - Artificial Intelligence and Law 29 (2):271-285.
    In previous work, I showed how the “reason model” of precedential constraint could naturally be generalized from the standard setting in which it was first developed to a richer setting in which dimensional information is represented as well. Surprisingly, it then turned out that, in this new dimensional setting, the reason model of constraint collapsed into the “result model,” which supports only a fortiori reasoning. The purpose of this note is to suggest a modification of the reason model of constraint (...)
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  12.  47
    A Clash of Intuitions: The Current State of Nonmonotonic Multiple Inheritance Systems.Richmond H. Thomason & John F. Horty - unknown
    Early attempts at combining multiple inheritance with nonmonotonic reasoning were based on straightforward extensions of tree-structured inheritance systems, and were theoretically unsound. In The Mathcmat~'cs of Inheritance Systcrns, or TMOIS, Touretzky described two problems these systems cannot handle: reasoning in the presence of true but redundant assertions, and coping with ambiguity. TMOIS provided a definition and analysis of a theoretically sound multiple inheritance system, accom-.
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  13. Agency and obligation.John F. Horty - 1996 - Synthese 108 (2):269 - 307.
    The purpose of this paper is to explore a new deontic operator for representing what an agent ought to do; the operator is cast against the background of a modal treatment of action developed by Nuel Belnap and Michael Perloff, which itself relies on Arthur Prior's indeterministic tense logic. The analysis developed here of what an agent ought to do is based on a dominance ordering adapted from the decision theoretic study of choice under uncertainty to the present account of (...)
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  14.  19
    (1 other version)Skepticism and floating conclusions.John F. Horty - 2002 - Artificial Intelligence 135 (1-2):55-72.
  15. The Logic of Reasons.Shyam Nair & John Horty - 2018 - In Daniel Star (ed.), The Oxford Handbook of Reasons and Normativity. New York, NY, United States of America: Oxford University Press. pp. 67-84.
    In this chapter, we begin by sketching in the broadest possible strokes the ideas behind two formal systems that have been introduced with to goal of explicating the ways in which reasons interact to support the actions and conclusions they do. The first of these is the theory of defeasible reasoning developed in the seminal work of Pollock; the second is a more recent theory due to Horty, which adapts and develops the default logic introduced by Reiter to provide an (...)
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  16.  62
    Defaults with Priorities.John Horty - 2007 - Journal of Philosophical Logic 36 (4):367-413.
  17. The result model of precedent.John F. Horty - 2004 - Legal Theory 10 (1):19-31.
    The result model of precedent holds that a legal precedent controls a fortiori cases—those cases, that is, that are at least as strong for the winning side of the precedent as the precedent case itself. This paper defends the result model against some objections by Larry Alexander, drawing on ideas from the field of Artificial Intelligence and Law in order to define an appropriate strength ordering for cases.
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  18.  41
    Deontic Modals: Why Abandon the Classical Semantics?John Horty - 2014 - Pacific Philosophical Quarterly 95 (4):424-460.
    I begin by reviewing classical semantics and the problems presented by normative conflicts. After a brief detour through default logic, I establish some connections between the treatment of conflicts in each of these two approaches, classical and default, and then move on to consider some further issues: priorities among norms, or reasons, conditional oughts, and reasons about reasons.
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  19.  47
    Constraint and Freedom in the Common Law.John Horty - 2015 - Philosophers' Imprint 15:1-27.
    This paper contributes to our formal understanding of the common law — especially the nature of the reasoning involved, but also its point, or justification, in terms of social coordination. I present two apparently distinct models of constraint by precedent in the common law, establish their equivalence, and argue for a perspective according to which courts are best thought of, not as creating and modifying rules, but as generating a social priority ordering on reasons through a procedure that is piecemeal, (...)
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  20.  47
    Epistemic Oughts in Stit Semantics.John Horty - 2019 - Ergo: An Open Access Journal of Philosophy 6.
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  21. Reasons and Precedent.John Horty - unknown
    This paper describes one way in which a precise reason model of precedent could be developed, based on Grant Lamond’s general idea that a later court is constrained to reach a decision that is consistent an earlier court’s assessment of the balance of reasons. The account provided here has the additional advantage of showing how this reason model can be reconciled with the traditional idea that precedential constraint involves rules, as long as these rules are taken to be defeasible.
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  22. Argument construction and reinstatement in logics for defeasible reasoning.John F. Horty - 2001 - Artificial Intelligence and Law 9 (1):1-28.
    This paper points out some problems with two recent logical systems – one due to Prakken and Sartor, the other due to Kowalski and Toni – designedfor the representation of defeasible arguments in general, but with a specialemphasis on legal reasoning.
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  23.  78
    An appreciation of John Pollock's work on the computational study of argument.Henry Prakken & John Horty - 2012 - Argument and Computation 3 (1):1 - 19.
    John Pollock (1940?2009) was an influential American philosopher who made important contributions to various fields, including epistemology and cognitive science. In the last 25 years of his life, he also contributed to the computational study of defeasible reasoning and practical cognition in artificial intelligence. He developed one of the first formal systems for argumentation-based inference and he put many issues on the research agenda that are still relevant for the argumentation community today. This paper presents an appreciation of Pollock's work (...)
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  24.  79
    Precedent, Deontic Logic, and Inheritance.John F. Horty - unknown
    The purpose of this paper is to e»tahlish some connections between precedent-based reasoning as it is studied in the field of Artificial Intelligence and Law, particularly in the work of Ashley, and two other fields: deontic logic and nonmonotonic logic. First, a deontic logic is described that allows lor sensible reasoning in the presence of conflicting norms. Second, a simplified version of Ashley's account of precedent-based reasoning is reformulated within the framework of this deontic logic. Finally, some ideas from the (...)
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  25.  90
    Evaluating new options in the context of existing plans.John F. Horty & Martha E. Pollack - unknown - Artificial Intelligence 127 (2):199-220.
    This paper contributes to the foundations of a theory of rational choice for artificial agents in dynamic environments. Our work is developed within a theoretical framework, originally due to Bratman, that models resource-bounded agents as operating against the background of some current set of intentions, which helps to frame their subsequent reasoning. In contrast to the standard theory of rational choice, where options are evaluated in isolation, we therefore provide an analysis of situations in which the options presented to an (...)
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  26.  20
    Nonmonotonic Logic.John F. Horty - 2001 - In Lou Goble (ed.), The Blackwell Guide to Philosophical Logic. Malden, Mass.: Wiley-Blackwell. pp. 336–361.
    The goal of a logic is to define a consequence relation between a set of formulas Γ and, in most cases, an individual formula A. This definition generally takes one of two forms. From a proof theoretic standpoint, A is said to be a consequence of Γ whenever there is a deduction of A from the set Γ, viewed as a set of premises; from a model theoretic standpoint, A is said to be a consequence of Γ whenever A holds (...)
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  27.  60
    Requirements, Oughts, Intentions.John Horty - 2015 - Philosophy and Phenomenological Research 91 (1):220-229.
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  28. Frege on the psychological significance of definitions.John F. Horty - 1993 - Philosophical Studies 72 (2-3):223 - 263.
  29.  89
    Perspectival act utilitarianism.John Horty - unknown
    This paper works within a particular framework for reasoning about actions—sometimes known as the framework of “stit semantics”—originally due to Belnap and Perloff, based ultimately on the theory of indeterminism set out in Prior’s indeterministic tense logic, and developed in full detail by Belnap, Perloff, and Xu [3]. The issues I want to consider arise when certain normative, or decision theoretic, notions are introduced into this framework: here I will focus on the notion of a right action, and so on (...)
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  30. The deliberative stit: A study of action, omission, ability, and obligation. [REVIEW]John F. Horty & Nuel Belnap - 1995 - Journal of Philosophical Logic 24 (6):583 - 644.
  31. Handbook of Deontic Logic and Normative System, Volume 2.Dov Gabbay, , John Horty, Xavier Parent, Ron van der Meyden & Leon van der Torre (eds.) - forthcoming - College Publications.
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  32. Handbook of deontic logic and normative system.Dov Gabbay, John Horty, Xavier Parent, Ron van der Meyden & Leon van der Torre (eds.) - forthcoming - College Publications.
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  33. The Handbook of Deontic Logic (Vol. II).Dov Gabbay, Ron van der Meyden, John Horty, Xavier Parent & Leandert van der Torre (eds.) - forthcoming - College Publications.
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  34.  17
    A skeptical theory of mixed inheritance.John F. Horty - 1990 - In J. Dunn & A. Gupta (eds.), Truth or Consequences: Essays in Honor of Nuel Belnap. Boston, MA, USA: Kluwer Academic Publishers. pp. 267--281.
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  35.  11
    Chapter 1 Overview.John F. Horty - 2001 - In John Horty (ed.), Agency and deontic logic. New York: Oxford University Press.
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  36.  9
    Conditional Oughts.John F. Horty - 2001 - In John Horty (ed.), Agency and deontic logic. New York: Oxford University Press.
    The notion of what an agent ought to do is refined to yield a notion conditional obligation, representing what the agent ought to do under various circumstances. Patterns of reasoning in the conditional deontic logic are explored. In contrast to the dominance account developed earlier, a competing notion of orthodox act utilitarianism is formulated.
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  37. Double Time Reference in the Evaluation of Action.John F. Horty - 2006 - In Henrik Lagerlund, Sten Lindström & Rysiek Sliwinski (eds.), Modality Matters: Twenty-Five Essays in Honour of Krister Segerberg. Uppsala Philosophical Studies 53. pp. 53--205.
     
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  38.  5
    Group Oughts.John F. Horty - 2001 - In John Horty (ed.), Agency and deontic logic. New York: Oxford University Press.
    The notion of what an agent ought to do is generalized to yield a notion of what groups of agents ought to do. Relations among the obligations governing groups and subgroups are explored, as well as the connections among different species of individual act utilitarianism, group act utilitarianism, and rule utilitarianism.
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  39.  45
    Introduction.John Horty & Frank Veltman - 2015 - Journal of Philosophical Logic 44 (6):593-594.
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  40.  8
    Indeterminism and Agency.John F. Horty - 2001 - In John Horty (ed.), Agency and deontic logic. New York: Oxford University Press.
    Develops the formal theory of action, or agency, that forms the background of the book. The account is cast against the background of Prior's theory of branching, or indeterministic, time. Against this background, the chapter develops precise notions of action and ability for both individuals and groups.
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  41.  8
    Ought to Be.John F. Horty - 2001 - In John Horty (ed.), Agency and deontic logic. New York: Oxford University Press.
    Supplements the background theory of indeterministic time with a standard deontic logic, representing what ought to be the case. Taken together with the formal notion of action introduced in the previous chapter, the framework now allows us to speak about what it ought to be that the agent does, and to explore the possibility that this notion should be identified with the notion of what the agent ought to do. Examples are developed to show that the two notions should not (...)
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  42.  7
    Ought to Do.John F. Horty - 2001 - In John Horty (ed.), Agency and deontic logic. New York: Oxford University Press.
    An analogy is developed between action in an indeterministic setting and choice under uncertainty, as it is studied in decision theory. Various dominance relations among actions are explored, and used both to provide a semantic account of what agents ought to do and to formulate a notion of dominance act utilitarianism. The ideas are related to problems involving independence, conditionals, and sure‐thing reasoning.
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  43.  45
    Right actions in perspective.John Horty - 2006 - In Henrik Lagerlund, Sten Lindström & Rysiek Sliwinski (eds.), Modality Matters: Twenty-Five Essays in Honour of Krister Segerberg. Uppsala Philosophical Studies 53. pp. 53.
  44.  31
    Synthese.John F. Horty - unknown
    The purpose of this paper is to explore a new deontic operator for representing what an agent ought to do; the operator is cast against the background of a modal treatment of action developed by Nuel Belnap and Michael Perlo, which itself relies on Arthur Prior's indeterministic tense logic. The analysis developed here of what an agent ought to do is based on a dominance ordering adapted from the decision theoretic study of choice under uncertainty to the present account of (...)
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  45.  7
    Strategic Oughts.John F. Horty - 2001 - In John Horty (ed.), Agency and deontic logic. New York: Oxford University Press.
    The notion of what an agent ought to do at a moment is generalized to yield a notion of what the agent ought to do over extended periods of time. This requires us to develop the notion of a strategy as a function from moments to actions available at those moments and appropriate notions of strategic dominance. A strategic ought operator is introduced and used to analyze the debate between actualists and possibilists concerning the ways in which an agent's obligations (...)
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  46.  5
    The Logic of Precedent: Constraint, Freedom, and Common Law Reasoning.John Horty - 2024 - Cambridge University Press.
    Unlike statutory law, which relies on the explicit formulation of rules, common law is thought to emerge from a complex doctrine of precedential constraint, according to which decisions in earlier cases constrain later courts while still allowing these courts the freedom to address new situations in creative ways. Although this doctrine is applied by legal practitioners on a daily basis, it has proved to be considerably more difficult to develop an adequate theoretical account of the doctrine itself. Drawing on recent (...)
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  47.  33
    The Structure of Values and Norms.John Horty - unknown
    This book provides a unified account of Hansson’s work on values (or preferences), norms, and their interrelations. Although much of the detailed material contained here appears among the numerous articles published by the author over the past decade or so, the book presents this work as a coherent whole. The overall style is formal: definitions are set out, results are established. Readers who do not enjoy formal work in value theory are likely to find little of interest here. But readers (...)
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  48.  24
    Review of Sven ove Hansson, The Structure of Values and Norms[REVIEW]John Horty - 2002 - Notre Dame Philosophical Reviews 2002 (6).
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