We discuss similarities and residual differences, within the general semantic framework of minimality, between defeasible inference, belief revision, counterfactual conditionals, updating — and also conditional obligation in deontic logic. Our purpose is not to establish new results, but to bring together existing material to form a clear overall picture.

This paper provides a computational framework, based on defeasible logic, to capture some aspects of institutional agency. Our background is Kanger-Lindahl-Pörn account of organised interaction, which describes this interaction within a multi-modal logical setting. This work focuses in particular on the notions of counts-as link and on those of attempt and of personal and direct action to realise states of affairs. We show how standard defeasible logic (DL) can be extended to represent these concepts: the resulting system preserves some basic (...) properties commonly attributed to them. In addition, the framework enjoys nice computational properties, as it turns out that the extension of any theory can be computed in time linear to the size of the theory itself. (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.

Information about the powers and abilities of acting entities is used to coordinate their actions in societies, either physical or digital. Yet, the commonsensical meaning of an acting entity being deemed able to do something is still missing from the existing specification languages for the web or for multi-agent systems. We advance a general purpose abstract logical account of evidence-based ability. A basic model can be thought of as the ongoing trace of a multi-agent system. Every state records systemic confirmations (...) and disconfirmations of whether an acting entity is able to bring about something. Qualitative inductive reasoning is then used in order to infer what acting entities are deemed able to bring about in the multi-agent system. A temporalised modal language is used to talk about deemed ability, actual agency, and confirmation and disconfirmation of deemed ability. What constitutes a confirmation and a disconfirmation is left to the modeller as in general it depends on the application at hand. So to illustrate the methodology we propose two extended examples, one in practical philosophy, the other in system engineering. We first use a logic of agency and ability to obtain a version of Mele’s general practical abilities. Then, we look at the management of abilities in a supervised system. (shrink)

Wesley Newcomb Hohfeld's account of legal rights is now 100 years old. It has been much discussed, and remains very influential with philosophers and lawyers alike. Yet it is still sometimes misunderstood in crucial respects. This article offers a rigorous exposition of Hohfeld's framework; discusses its claims to comprehensiveness and fundamentality, reviewing recent work on the topic; and highlights the argumentative uses of Hohfeld's most important distinction.

¿Cómo justificar la validez jurídica de aquellas normas cuya creación no puede ser evaluada como regular o irregular por apelación a ninguna otra norma jurídica? Entre las respuestas más ilustres a este problema se cuentan la norma fundante kelseniana y la regla de reconocimiento de Hart, pero cada una de esas ideas ha sido objeto de serias críticas. Eugenio Bulygin ha efectuado aportes decisivos en esta discusión: ha advertido que cuando se examina el fundamento último de la validez de las (...) normas jurídicas es preciso discriminar un sentido prescriptivo y uno descriptivo de validez, y que la norma fundante de Kelsen no es sino el producto de una confusión entre ambos; ha resaltado que la regla de reconocimiento debe interpretarse como una regla conceptual que especifica los criterios de identificación de las normas jurídicas, y ha señalado que las normas de competencia no pueden reconstruirse como normas de conducta. Si bien con tales aportes ha sentado las bases para ofrecer una solución, su reconstrucción requiere de ciertas precisiones para poder ser considerada una respuesta enteramente satisfactoria a la pregunta respecto del fundamento último de la validez jurídica. How is it possible to ground the legal validity of those rules whose creation cannot be assessed as regular or irregular by reference to any other legal rule? Kelsen's basic norm and Hart's rule of recognition are among the most famous answers to this question, but both ideas have been seriously challenged. Eugenio Bulygin has made decisive contributions to this discussion. He has shown that in the analysis of the ultimate ground of validity of legal rules, two different senses of validity should be distinguished: a prescriptive and a descriptive sense, and that the Kelsenian basic norm is nothing but the product of confusion between these two different senses. He has also claimed that the rule of recognition has to be understood as a conceptual rule specifying the criteria of identification of legal rules, and those power-conferring rules cannot be interpreted as prescriptive norms of conduct. Although these contributions have provided a basic framework for a possible solution, Bulygin's ideas need a refinement in order to be considered as a satisfactory answer to the question concerning the ultimate ground of legal validity. (shrink)

Does Duncan Kennedy successfully cannibalize jurisprudence? He attempts to do it by demonstrating the inexistence of rightness in legal argumentation. If there is no right legal argument, then there is no right answer in adjudication, adjudication is not a rational enterprise and legal doctrine cannot be said to be a science. It can be shown that skepticism is self-defeating. Duncan Kennedy can avoid self defeat only because he actually believes in a lot of legal arguments. His thesis that judges decide (...) questions of policy without any methodology that distinguishes them from legislators does not hold. Judicial reasoning is subject to constraints that do not affect legislators. It must be based on the sources of law and is limited by rules of procedure. Even when the judges have ‘interstitial’ legislative powers they are, unlike the legislator, bound to fit the system and their decisions are considered in procedure from the perspective of the right answer doctrine. The only work that can convincingly refute the skeptic argument against legal science is the reconstruction of jurisprudence as a scientific enterprise. Such work is beyond the scope of any single paper. The article aims to give some inspirations for such a task. (shrink)

El ensayo que presento intenta establecer la unidad conceptual entre las llamadas normas regulatorias y las normas de competencia. Para ello se hace una construcción conceptual de la norma jurídica y del orden jurídico, cuando existe una pluralidad de normas. Con base en ello se ofrece un esquema del orden jurídico que comprende tanto a las normas regulatorias como a las de competencia, estableciendo la unidad entre ambas clases de normas, considerando que las normas regulatorias son una parte de las (...) normas de competencia, en tanto determinan el contenido de las normas inferiores creadas en el ejercicio de facultades jurídicas. The essay here presented tries to establish the conceptual unity between regulatory and empowerment norms. To that effect the path taken must be to carry out a conceptual construction of the legal norm and the legal order, when there exists a plurality of norms. Thereafter, one offers an outline of the legal order that encloses both regulatory and empowerment norms, thus establishing the unity between the latter two. Furthermore, one considers that regulatory norms are a subset of empowerment norms, so far as they determine the content of inferior norms created in the exercise of legal faculties. (shrink)

The paper intends to show, that W. N. Hohfeld's theory of fundamental jural relations is relevant to economic theory, and that Hohfeld's system can be reconstructed by the concepts of 'liberty space' and 'ability space', understood as an agent's Spielraum for action. The first half of the paper is devoted to an exposition of Hohfeld's system and to the question of its relation to the economic analysis of property rights. The second half concerns Spielraum theory and the reformulation of Hohfeldian (...) distinctions in terms of liberty spaces and ability spaces. It is argued that the reformulation is useful, inter alia, for describing exchange of property rights by contract. El artículo intenta mostrar: que la teoría de las relaciones jurídicas fundamentales de W. N. Hohfeld es relevante para la teoría económica y que el sistema de Hohfeld puede ser reconstruido mediante los conceptos de "espacio de libertad" y "espacio de capacidad", entendidos como el Spielraum para la acción del agente. La primera mitad del artículo está dedicada a la exposición del sistema de Hohfeld y al problema de su relación con el análisis económico de los derechos reales. La segunda mitad se refiere a la teoría del Spielraum y a la reformulación de las distinciones hohfeldianas en términos de espacio de libertad y espacio de capacidad. Se argumenta que esta reformulación es útil, inter alia, para describir el cambio de los derechos reales mediante contratos. (shrink)