The volume analyses and develops David Makinson’s efforts to make classical logic useful outside its most obvious application areas. The book contains chapters that analyse, appraise, or reshape Makinson’s work and chapters that develop themes emerging from his contributions. These are grouped into major areas to which Makinsons has made highly influential contributions and the volume in its entirety is divided into four sections, each devoted to a particular area of logic: belief change, uncertain reasoning, normative systems and the resources (...) of classical logic. Among the contributions included in the volume, one chapter focuses on the “inferential preferential method”, i.e. the combined use of classical logic and mechanisms of preference and choice and provides examples from Makinson’s work in non-monotonic and defeasible reasoning and belief revision. One chapter offers a short autobiography by Makinson which details his discovery of modern logic, his travels across continents and reveals his intellectual encounters and inspirations. The chapter also contains an unusually explicit statement on his views on the role of logic in philosophy. (shrink)

This article evaluates the strengths and weaknesses of arguments based on appeals to expertise. The intersection of two areas is explored: (i) the traditional argumentum ad verecundiam (literally, “appeal to modesty,” but characteristically the appeal to the authority of expert judgment) in informal logic, and (ii) the uses of expert systems in artificial intelligence. The article identifies a model of practical reasoning that underlies the logic of expert systems and the model of argument appropriate for the informal logic of the (...) argumentum ad verecundiam. (shrink)

Diagnosis theory reasons about incomplete knowledge and only considers the past. It distinguishes between violations and non-violations. Qualitative decision theory reasons about decision variables and considers the future. It distinguishes between fulfilled goals and unfulfilled goals. In this paper we formalize normative diagnoses and decisions in the special purpose formalism DIO(DE)2 as well as in extensions of the preference-based deontic logic PDL. The DIagnostic and DEcision-theoretic framework for DEontic reasoning DIO(DE)2 formalizes reasoning about violations and fulfillments, and is used to (...) characterize the distinction between normative diagnosis theory and (qualitative) decision theory. The extension of the preference-based deontic logic PDL shows how normative diagnostic and decision-theoretic reasoning — i.e. reasoning about violations and fulfillments — can be formalized as an extension of deontic reasoning. (shrink)

A history of the logic of action is outlined, beginning with St Anselm. Five modern authors are discussed in some detail: von Wright, Fitch, Kanger, Chellas and Pratt.

We shall introduce a set of fundamental legal concepts, providing a definition of each of them. This set will include, besides the usual deontic modalities (obligation, prohibition and permission), the following notions: obligative rights (rights related to other’s obligations), permissive rights, erga-omnes rights, normative conditionals, liability rights, different kinds of legal powers, potestative rights (rights to produce legal results), result-declarations (acts intended to produce legal determinations), and sources of the law.

According to explanatory individualism, every action must be explained in terms of an agent's desire. According to explanatory nonindividualism, we sometimes act on our desires, but it is also possible for us to act on others' desires without acting on desires of our own. While explanatory nonindividualism has guided the thinking of many social scientists, it is considered to be incoherent by most philosophers of mind who insist that actions must be explained ultimately in terms of some desire of the (...) agent. In the first part of the paper, I show that some powerful arguments designed to demonstrate the incoherence of explanatory nonindividualism fail. In the second part of the paper, I offer a nonindividualist explanation of the apparent obviousness of belief-desire psychology. I argue that there are two levels of the intelligibility of our actions. On the more fundamental (explanatory) level, the question "Why did the agent do something?" admits a variety of folk-psychological categories. But there is another (formation-of-self) level, at which the same question admits only of answers that ultimately appeal only to the agent's own desires. Explanatory individualism results from the confusion of the two levels. (shrink)

This paper argues that both technological determinism (the development of technology is uniquely determined by internal laws) and technological voluntarism (technological change can be externally directed and regulated by the wants and free choice of human beings) are one‐sided and partly mistaken. The determinists are right in the sense that technology has a power to influence our values and behaviour, and thereby appear to direct ‘technological imperatives’ to us. However, such commands are always conditional on some value premises; the voluntarists (...) are thus right in pointing out that we need not obey such imperatives. The principle ‘Can implies Ought’ (all technological possibilities should be realized) is therefore invalid. (shrink)

The author discusses a question related to a certain aspect of justification of legal decisions, often so-called internal justification-a legal decision is internally justified if and only if it can be deduced from the norm(s) applicable to the case, and from the statement(s) describing the facts of the case. According to this notion, infinite irrelevant logical consequences are justified. To avoid this counterintuitive conclusion, the author analyzes three notions of relevance: Sperber-Wilson's notion, Anderson-Belnap's notion, and Schurz's notion. The author presents (...) a reconstruction of the notion of relevance very close to Schurz's notion, extended to make it suitable to the particular characteristics of deontic logic. Finally, this notion of relevance is used to discuss some aspects of the concept of normative system, conceived as a deductive system, that is, a system containing all its logical consequences. (shrink)

In his last papers about deontic logic, von Wright sustained that there is no genuine logic of norms. We argue in this paper that this striking statement by the father of deontic logic should not be understood as a death sentence to the subject. Rather, it indicates a profound change in von Wright's understanding about the epistemic and ontological role of logic in the field of norms. Instead of a logical constructivism of deontic systems revealing a necessary structure of prescriptive (...) discourse, which marked his earlier efforts, he adopted the view that such systems should be seem as mere objects of comparison, i.e. as providing practical standards of rationality for normgiving activity. Within such view he proposed an interpretation of standard deontic logic in such a way to free deontic logicians from the philosophical difficulties related to the so-called Jørgensen's dilemma and deontic paradoxes. This effort, as we claim in the present paper, is an application of Wittgenstein's therapeutic method to dissolve philosophical difficulties caused by the use of logical tools to model relations between norms. (shrink)

John Searle has recently developed a theory of reasons for acting that intends to rescue the freedom of the will, endangered by causal determinism, whether physical or psychological. To achieve this purpose, Searle postulates a series of “gaps” that are supposed toendowthe self with free will. Reviewing key steps in Searle's argument, this article shows that such an undertaking cannot be successfully completed because of its solipsist premises. The author argues that reasons for acting do not have a subjective, I-ontology (...) but a first-person plural, Weontology that better accounts for agency and responsibility. (shrink)

John Searle has recently developed a theory of reasons for acting that intends to rescue the freedom of the will, endangered by causal determinism, whether physical or psychological. To achieve this purpose, Searle postulates a series of "gaps" that are supposed toendowthe self with free will. Reviewing key steps in Searle's argument, this article shows that such an undertaking cannot be successfully completed because of its solipsist premises. The author argues that reasons for acting do not have a subjective, I-ontology (...) but a first-person plural, Weontology that better accounts for agency and responsibility. Key Words: free will • agency • reasons for acting • ontology. (shrink)

In a recent paper, Sven Danielsson argued that the ‘original paradoxes' of deontic logic, in particular Ross's paradox and Prior's paradox of derived obligation, can be solved by restricting the modal inheritance rule. I argue that this does not solve the paradoxes.

In this paper, we investigate the ‘ought implies can’ thesis, focusing on explanations and interpretations of OIC, with a view to clarifying its uses and relevance to legal philosophy. We first review various issues concerning the semantics and pragmatics of OIC; then we consider how OIC may be incorporated in Hartian and Kelsenian theories of the law. Along the way we also propose a taxonomy of OIC-related claims.

It is central to standard economic theory that people act on their interests. People are interested in a variety of things, so a range of values should influence market behavior. When engaged in commerce, however, people generally act for personal gain; the influence of other values usually just disappears in the marketplace. What is missing from the standard account is that people often act on proper subsets of their interests. Economics can, however, be extended to capture this insight. Key Words: (...) economic theory • attention • self-interest • social responsibility • discrimination. (shrink)

Pragmatic Ambiguity: The Thetic Function of Modality The aim of this paper is to present an overview of the pragmatic aspects of ambiguity present in deontic sentences, which may have three pragmatic functions: a prescriptive or a descriptive or a constitutive function. This type of ambiguity is investigated on the lexical, phrasal, and sentential level. The discussion focuses on the deontic constructions of the German verb sollen and the English shall as they are used in legal texts. It also includes (...) comments on the thetic function of the Latin imperative mood and the subjunctive mood. (shrink)

L’article cherche à fournir une défense de la théorie discursive de la morale de Habermas contre une critique importante formulée récemment par J. G. Finlayson, lequel soutient que Habermas rejetterait ce qu’il appelle le « cognitivisme métaéthique » et qu’un tel rejet le confronterait au problème de Frege-Geach. L’article démontre en détail que cette critique est non fondée. Il montre de plus que la seule forme de cognitivisme rejetée par Habermas est le descriptivisme moral en ce que cette approche serait (...) contre-intuitive eu égard à l’usage normal de nos expressions morales. L’article cherche finalement à répondre à certaines objections majeures que les philosophes descriptivistes pourraient soulever à l’endroit de la théorie habermassienne de la morale, en particulier contre sa thèse de l’analogie entre vérité propositionnelle et justesse normative.The paper aims at providing a defence of Habermas’s discourse theory of morality against a significant criticism recently levelled by J. G. Finlayson, who maintains that Habermas would reject what he calls “metaethical cognitivism” and that such a rejection would cause him to face what has been known as the Frege-Geach problem. The paper demonstrates in detail that this claim is unfounded. It further shows that the only form of cognitivism rejected by Habermas is moral descriptivism, since this approach would be counter-intuitive as regards the normal use of our moral expressions. The paper finally seeks to respond to major objections descriptivist philosophers might raise against Habermas’s theory of morality, in particular against his analogy thesis between propositional truth and normative rightness. (shrink)

This paper develops the first deontic logic in the context of paraconsistent logics.

Law being a derivative feature of reality, it exists in virtue of more fundamental things, upon which it depends. This raises the question of what is the relation of dependence that holds between law and its more basic determinants. The primary aim of this paper is to argue that grounding is that relation. We first make a positive case for this claim, and then we defend it from the potential objection that the relevant relation is rather rational determination (Greenberg 2004, (...) 2006). Against this challenge, we argue that the apparent objection is really no objection, for on its best understanding, rational determination turns out to actually be grounding. Finally, we clarify the framework for theories on law-determination that results from embracing our view; by way of illustration, we offer a ground-theoretic interpretation of Hartian positivism, and show how it can defuse an influential challenge to simple positivist accounts of law. (shrink)

The crucial feature of obligation sentences to which the puzzles point is that such sentences, and evaluative sentences more generally, are defeasible. They may be warranted, given some information, only to be defeated by further information. A theory that recognizes this no longer needs to see conditional obligation as anything more than a simple combination of unary obligation and the conditional.

Modern belief revision theory is based to a large extent on partial meet contraction that was introduced in the seminal article by Carlos Alchourrón, Peter Gärdenfors, and David Makinson that appeared in 1985. In the same year, Alchourrón and Makinson published a significantly different approach to the same problem, called safe contraction. Since then, safe contraction has received much less attention than partial meet contraction. The present paper summarizes the current state of knowledge on safe contraction, provides some new results (...) and offers a list of unsolved problems that are in need of investigation. (shrink)

The paper discusses ten philosophical problems in deontic logic: how to formally represent norms, when a set of norms may be termed ‘coherent’, how to deal with normative conflicts, how contraryto-duty obligations can be appropriately modeled, how dyadic deontic operators may be redefined to relate to sets of norms instead of preference relations between possible worlds, how various concepts of permission can be accommodated, how meaning postulates and counts-as conditionals can be taken into account, and how sets of norms may (...) be revised and merged. The problems are discussed from the viewpoint of input/output logic as developed by van der Torre & Makinson. We argue that norms, not ideality, should take the central position in deontic semantics, and that a semantics that represents norms, as input/output logic does, provides helpful tools for analyzing, clarifying and solving the problems of deontic logic. (shrink)

In the last papers published by Alchourrón, he attacked non-monotonic logics, which he considered philosophically unsound for the representation of defeasible reasoning. Instead of a non-monotonic consequence relation, he proposed a formal representation of defeasibility based on an AGM-like revision of implicit assumptions connected to the premises. Given that this is a procedure to generate non-monotonic logics, it is not clear, from a mathematical standpoint, why he was so suspicious of such logics. In the present paper we try to answer (...) this question based on Alchourrón' s convictions about epistemology, particularly the epistemology of law. We also propose another revision operator on theories called refinement, which provides a faithful representation of the sort of epistemic change considered by Alchourrón as intrinsic to defeasibility. En sus últimos escritos publicados, Alchourrón desarrolló un ataque contra las lógicas no-monotónicas, que consideraba filosóficamente inadecuadas a la representación del razonamiento derrotable. En vez de una relación de consecuencia no-monotónica, él propuso una representación formal de la derrotabilidad basada en un modelo de revisión de las asunciones implícitas ligadas a las premisas. Dado que éste es un procedimiento para generar lógicas no-monotónicas, no está claro -en el nivel matemático- por qué él era tan desconfiado de tales lógicas. En el presente texto intentamos contestar a esta pregunta basados en las convicciones de Alchourrón sobre epistemología, particularmente la epistemología jurídica. También proponemos otro operador de revisión aplicado a las teorías, llamado refinamiento, que proporciona una representación fiel de la especie de cambio epistémico considerado por Alchourrón como intrínseco a la derrotabilidad. (shrink)

El objeto principal de este trabajo consiste en discutir una propuesta de C. Alchourrón y A. Martino para hacer frente al problema de la fundamentación de la lógica deóntica, planteado por el dilema de Jørgensen. La propuesta criticada se basa en la idea de que no existe obstáculo alguno en compatibilizar la idea de que las normas carecen de valor de verdad con la idea de que poseen una lógica, una vez que se renuncia al "prejuicio filosófico" de que es (...) indispensable caracterizar semánticamente las relaciones y propiedades lógicas y se explica la lógica a partir de la noción abstracta de consecuencia, desligándola de las nociones de verdad y falsedad. Sostienen que el significado de los operadores deónticos, al igual que el de los términos lógicos en la deducción natural, puede quedar totalmente expresado una vez que se explicita su uso mediante reglas de introducción y eliminación. Para ilustrar su propuesta, pretenden ofrecer una fundamentación puramente sintáctica de la lógica deóntica standard. Mis críticas se centran en tres puntos: a) no utilizan auténticas reglas de introducción para los operadores deónticos; b) no derivan la lógica deóntica standard como pretenden haber hecho, y c) no se establecen criterios para relacionar las fórmulas del cálculo con el lenguaje normativo ordinario, con lo que no existen razones para considerar que se trata de una lógica deóntica. Defiendo la idea de que, a los fines de fundamentar semánticamente la lógica deóntica, sólo es necesario que existan interpretaciones admisibles que atribuyan valores de verdad a las normas, y que este requisito es cumplido por la semántica usual de la lógica deóntica standard, con lo que el dilema de Jørgensen resulta ser un seudoproblema. In this paper I discuss a proposal from C. Alchourrón and A. Martino with which they try to face the problem posed to the foundation of deontic logic by Jørgensen' s dilemma. Their proposal is based on the idea that there is no problem at all in compatibilizing the fact that norms lack truth values with their possession of a logic, once it is denied that it is absolutely necessary to offer a semantic characterization of logical properties and relations, and the abstract notion of consequence is taken as primitive. They claim that the meaning of deontic operators, like that of logical terms in natural deduction, is completely expressed through their use, which is explained by means of rules of introduction and elimination. As an illustration, they present a calculus with which they intend to offer a foundation for standard deontic logic. I make three objections: a) They don' t use real rules of introduction for deontic operators; b) They don' t have derived standard deontic logic as they claim; c) There are no criteria for relating the formulas with ordinary normative discourse; so there are no reasons for considering their calculus as a deontic logic. I claim that, in order to give a semantical foundation to deontic logic it is only necessary that there are admissible interpretations that assign truth values to norms, and that this requisite is satisfied by the usual semantic of standard deontic logic. I conclude that Jørgensen' s dilemma is a pseudoproblem. (shrink)