This work adopts H. Kelsen’s concept of legal system, proposes a formal definition for such notion, and introduces an operational semantical framework for legal systems that are situated in agent societies. Agent societies are defined. Relevant formal properties of situated legal systems are discussed; the way they are exposed in the operational semantical framework is explained, and their truth formally proved. Also, for the sake of a better understanding of the legal-theoretic assumptions of the paper, recurring issues regarding Kelsen’s theory (...) of law are briefly reviewed. They are put in confrontation with the points of view of R. Dworkin, H. Hart, and J. Raz, and an attempt is made to clarify them from the perspective of the provided formalization. A brief case study in agent-based modeling and simulation of public policy processes is presented, as an illustration of the way of using situated legal systems, and the proposed operational semantical framework, in a practical application. (shrink)

The goal of this paper is to provide an accurate grounding-based formulation of positivism in the philosophy of law. I start off by discussing some simple formulations, based on the ideas that social facts are always either full or partial grounds of legal facts. I then raise a number of objections against these definitions: the full grounding proposal rules out possibilities that are compatible with positivism; the partial grounding proposal fails, on its own, to vindicate the distinctive role that is (...) played by social facts within positivist accounts of law. Then, I present a more adequate and insightful formulation capable of solving their problems, which crucially relies on a robust notion of a social enabler. Finally, I model inclusive and exclusive positivism on the resulting template, and set out the advantages of the ground-enablers proposal. (shrink)

The necessity to model the mental ingredients of norm compliance is a controversial issue within the study of norms. So far, the simulation-based study of norm emergence has shown a prevailing tendency to model norm conformity as a thoughtless behavior, emerging from social learning and imitation rather than from specific, norm-related mental representations. In this paper, the opposite stance—namely, a view of norms as hybrid, two-faceted phenomena, including a behavioral/social and an internal/mental side—is taken. Such a view is aimed at (...) accounting for the difference between norms, on one hand, and either behavioral regularities (conventions) on the other. This paper, in particular, is addressed to find out the internal ingredients required for the former distinction, i.e., to model norms as distinct from mere conventions, and defined as behaviors spreading to the extent that and because the corresponding commands and beliefs do spread as well. After a brief presentation of a normative agent architecture, the results of agent-based simulations testing the impact of norm recognition and the role of normative beliefs in the emergence and innovation of social norms are presented and discussed. More specifically, the present work will endeavour to show that a sudden external constraint (e.g. a barrier preventing agents from moving among social settings) facilitates norm innovation: under such a condition, agents provided with a module for telling what a norm is can generate new (social) norms by forming new normative beliefs, irrespective of the most frequent actions. (shrink)

Some important ideas in Kelsen's Pure Theory of Law can be traced back to Kantian tradition, which has been very influential in Kelsen's thought, particularly in his early period. Among them we find the distinction between two radically different worlds (the world of facts and the world of norms), the normativity of legal science and the idea of validity as a binding force, based on the famous doctrine of the basic norm. These tenets and, especially, the use of a normative (...) concept of validity prove to be incompatible with Kelsen's positivistic programme of a value‐free legal science. The science of law cannot state that legal norms are obligatory or binding without trespassing the limits of Kelsen's ideal of a legal science; on the other hand, it is possible to define the concept of a legal system without resorting to the basic norm. So, if Kelsen is to be regarded as a consequent positivist, the Kantian ingredients of his theory must be rejected and the descriptive concept of validity as membership must be substituted for the normative notion of validity as a binding force. (shrink)

Selon une thèse largement partagée, le droit et une pratique sociale et les contributions des participants sont complémentaires les unes des autres. Dans ces conditions, le raisonnement juridique consiste d’abord en une interprétation de ces pratiques et présuppose un point de vue interne de la part de celui qui souhaite en rendre compte. Le raisonnement juridique est ainsi conçu comme une argumentation pratique, subordonnée aux exigences de la rationalité car ceux qui participent à la pratique juridique sont contraints de donner (...) des raisons à leur action et ces raisons tissent un réseau de contraintes. Très séduisante, cette thèse qui doit beaucoup à la critique des réalistes par Hart, n’en demeure pas moins justiciable de quelque critique. (shrink)

In this article we describe two core ontologies of law that specify knowledge that is common to all domains of law. The first one, FOLaw describes and explains dependencies between types of knowledge in legal reasoning; the second one, LRI-Core ontology, captures the main concepts in legal information processing. Although FOLaw has shown to be of high practical value in various applied European ICT projects, its reuse is rather limited as it is rather concerned with the structure of legal reasoning (...) than with legal knowledge itself: as many other “legal core ontologies”, FOLaw is therefore rather an epistemological framework than an ontology. Therefore, we also developed LRI-Core. As we argue here that legal knowledge is based to a large extend on common-sense knowledge, LRI-Core is particularly inspired by research on abstract common-sense concepts. The main categories of LRI-Core are: physical, mental and abstract concepts. Roles cover in particular social worlds. Another special category are occurrences; terms that denote events and situations. We illustrate the use of LRI-Core with an ontology for Dutch criminal law, developed in the e-Court European project. (shrink)

This paper generalises classical revision theory of the AGM brand to sets of norms. This is achieved substituting input/output logic for classical logic and tracking the changes. Operations of derogation and amendment—analogues of contraction and revision—are defined and characterised, and the precise relationship between contraction and derogation, on the one hand, and derogation and amendment on the other, is established. It is argued that the notion of derogation, in particular, is a very important analytical tool, and that even core deontic (...) concepts such as that of permission resists a satisfactory analysis without it. By way of illustration the last section of the paper analyses the much debated concept of positive permission, of which there turns out to be more than one kind. (shrink)

I shall compare two views of legal concepts: as nodes in inferential nets and as categories in an ontology (a conceptual architecture). Firstly, I shall introduce the inferential approach, consider its implications, and distinguish the mere possession of an inferentially defined concept from the belief in the concept’s applicability, which also involves the acceptance of the concept’s constitutive inferences. For making this distinction, the inferential and eliminative analysis of legal concepts proposed by Alf Ross will be connected to the views (...) on theoretical concepts in science advanced by Frank Ramsey and Rudolf Carnap. Consequently, the mere comprehension of a legal concept will be distinguished from the application of the concept to a particular legal system, since application presupposes a doctrinal commitment, namely, the belief that the inferences constituting the concept hold in that system. Then, I shall consider how concepts can be characterised by defining the corresponding terms and placing them within an ontology. Finally, I shall argue that there is a tension between the inferential and the ontological approach, but that both need to be taken into account, to capture the meaning and the cognitive function of legal concepts. (shrink)

The main stream of legal theory tends to incorporate unwritten principles into the law. Weighing of principles plays a great role in legal argumentation, inter alia in statutory interpretation. A weighing and balancing of principles and other prima facie reasons is a jump. The inference is not conclusive.To deal with defeasibility and weighing, a jurist needs both the belief-revision logic and the nonmonotonic logic. The systems of nonmonotonic logic included in the present volume provide logical tools enabling one to speak (...) precisely about various kinds of rules about rules, dealing with such things as applicability of rules, what is assumed by rules, priority between rules and the burden of proof. Nonmonotonic logic is an example of an extension of the domain of logic. But the more far-reaching the extension is, the greater problems it meets. It seems impossible to make logical reconstruction of the totality of legal argumentation. (shrink)

The semantics for a deontic action logic based on Boolean algebra is extended with an interpretation of action expressions in terms of sets of alternative actions, intended as a way to model choice. This results in a non-classical interpretation of action expressions, while sentences not in the scope of deontic operators are kept classical. A deontic structure based on Simons’ supercover semantics is used to interpret permission and obligation. It is argued that these constructions provide ways to handle various problems (...) related to free choice permission. The main result is a sound and complete axiomatization of the semantics. (shrink)

En esta contribución intentaré mostrar que el criterio lex superior derogat legi inferiori conduce a una consecuencia que, al menos en lo que conozco, no ha sido todavía advertida. Si las normas de la máxima jerarquía de un sistema jurídico, verbigracia, normas constitucionales constituyen un conjunto consistente, entonces necesariamente el sistema jurídico es consistente. Dicho de otra manera, lex superior preserva necesariamente la consistencia. Si las normas del nivel más alto son miembros de un conjunto consistente, los niveles inferiores de (...) la jerarquía no podrían admitir normas contradictorias con las superiores. Más aún, habida cuenta que de una contradicción se sigue cualquier norma, en virtud del principio lógico ex falso quodlibet, de dos normas contradictorias que pertenecen a algún nivel inferior se derivan algunas normas en contradicción con normas del nivel superior; así normas contradictorias no podrían ser admitidas en los niveles inferiores. In this contribution, I shall intend to show that the criterion lex superior derogat legi inferiori has a consequence which, as far as I know, has not been noted yet: if the higherlevel norms in a legal system, i.e. constitutional norms, configure a consistent set, then necessarily the legal system is consistent. Lex superior preserves necessarily the consistency, as it were. If higher-level norms are members of a consistent set, then the lower-levels could admit no norm in contradiction with the higher-level norms. Moreover, given that from a contradiction follows anything, in virtue of the logical principle ex falso quodlibet, from two contradictory lower-level norms follow some norms in contradiction with norms of the higher-level, thus contradictory norms could never be admit in the lower-levels. (shrink)

La question posée est celle des interfaces entre le système juridique et la société. Le contexte social du droit n’est pas pris ici comme surdéterminant, le droit se développant de manière autoréférentielle, dans une mesure, certes limitée, limites qu’il convient précisément d’analyser. Il y a entre le système social et le système juridique une circulation constante d’informations, qui passent par ce que nous appelons les figures juridiques. Celles-ci—le législateur, le juge ou le sujet de droit—sont en situation de choisir dans (...) le contexte social ce qu’elles décident d’y prendre pour lui donner statut de norme. En cela, la figure juridique fait acte politique: elle ne prend pas le contexte auquel elle fait face comme un donné «naturel» qui s’imposerait à elle univoquement, mais elle choisit dans la complexité de ce contexte ce qui lui semble correspondre à l’univers juridique auquel elle appartient. Cela est possible de par sa position même dans chacun des deux univers—c’est sa véritable situation—d’un côté comme fonction juridique et de l’autre, mais en même temps, comme acteur social: elle a à dire ce qui peut passer de l’un à l’autre, elle ne répète pas ce que l’un ou l’autre dit; elle se trouve en situation parce qu’elle est le lieu de passage entre deux mondes non concomitants dans leur existence propre, mais entre lesquels elle a à faire correspondre un discours qui donne et prenne sens. (shrink)

We discuss five kinds of representations of rationales and provide a formal account of how they can alter disputation. The formal model of disputation is derived from recent work in argument. The five kinds of rationales are compilation rationales, which can be represented without assuming domain-knowledge (such as utilities) beyond that normally required for argument. The principal thesis is that such rationales can be analyzed in a framework of argument not too different from what AI already has. The result is (...) a formal understanding of rationales, a partial taxonomy, and a foundation for computer programs that represent and reason with rationales.The five kinds of rationales are as follows: (c)ompression and (s)pecialization, which yield rules, and (d)isputation, which yields a decision. These are modeled as potentially changing the focus of the dispute. Then there are (f)it, a rationale for rules, and (r)esolution, a rationale for decisions. These cannot be modeled as simply; they force disputation to a meta-level, at least temporarily. (shrink)

Legal terms, such as “ownership,”“contract,”“validity,”“negligence,” are used as middle terms in legal deduction. The paper distinguishes two problems regarding this use. One is the logical function of terms for deduction within a normative system. Specific problems dealt with in this connection are meaning, definition, and economy of expression. The other problem connected with middle terms is the “moulding” and possible manipulation of the meaning of legal terms, for arriving at desired conclusions in a given scheme of inference. It is indicated (...) how the moulding of contested legal concepts, if not restricted, will obscure the ratio of legal rules. This problem is relevant, inter alia, to arguments ex analogia in the law. (shrink)

In 1880, when Oliver Wendell Holmes (later to be a Justice of the U.S. Supreme Court) criticized the logical theology of law articulated by Christopher Columbus Langdell (the first Dean of Harvard Law School), neither Holmes nor Langdell was aware of the revolution in logic that had begun, the year before, with Frege's Begriffsschrift. But there is an important element of truth in Holmes's insistence that a legal system cannot be adequately understood as a system of axioms and corollaries; and (...) this element of truth is not obviated by the more powerful logical techniques that are now available. (shrink)

Abstract.According to the normative theory of legal science, juristic ought‐sentences describe rules, since legal science just deals with rules, and rules cannot be described but by means of ought‐sentences. The author challenges this view. Two different constructions of “describing rules” are proposed: Namely, either interpreting or stating the validity of rules. “Interpreting rules,” in its turn, can be understood in three different senses: listing all the possible meanings of rule‐formulations, reporting the different interpretations a rule‐formulation has in fact received by (...) courts, or ascribing meaning to rule‐formulations. However, the author argues that ought‐sentences are not the proper tools to accomplish such tasks. At the same time, juristic ought‐sentences cannot be understood as validity statements, since they neither mention any rule whatsoever, nor include the term “valid.” Further, if validity‐statements were ought‐sentences, their logical behaviour would reflect the logic of rules themselves. However, as the late Kelsen argued, things do not run this way, since two inconsistent ought‐sentences, if understood as validity statements, can paradoxically both be true, as well as both false. Hence, validity‐statements cannot be reduced to ought‐sentences iterating the rules which they (are supposed to) refer to. (shrink)

The article develops and justifies, on the basis of the epistemological argumentation theory, two central pieces of the theory of evaluative argumentation interpretation: 1. criteria for recognizing argument types and 2. rules for adding reasons to create ideal arguments. Ad 1: The criteria for identifying argument types are a selection of essential elements from the definitions of the respective argument types. Ad 2: After presenting the general principles for adding reasons (benevolence, authenticity, immanence, optimization), heuristics are proposed for finding missing (...) reasons, for deductive arguments, e.g., semantic tableaux are suggested. (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)

Responsibility has entered the academic discourse of logicians hardly more than few decades ago. I suggest a logical concept of responsibility which employs ideas both from a number of theories belonging to different branches of logic as well from other academic areas. As a comment to this concept, I suggest five steps narrative scenario in order to show how the logical dimension of responsibility emerges from diverse tendencies in logic and other sciences. Here are the five steps briefly stated: Step (...) 1. Developing modal formalisms capable of evaluative analysis of situations (deontic, epistemic and etc.). Step 2. Drawing a conceptual borderline between normal and non-normal (weak) logical systems. Step 3. Using different kinds of models. Step 4. Agent- and action- friendly turn in logic. Step 5. Creating formalisms for modeling different types of agency. An idea advocated here within 5-Steps route to responsibility is that this concept is a complex causal and evaluative (axiological) relation. A logical account may be given for causal and normative aspects of this relation. Unfolding the responsibility back and forth through 5 Steps will result in different concepts. The technicalities are minimized for the sake of keeping the philosophical scope of the paper. For the same reason I also refrain from discussing legal and juridical ramifications of the issue. (shrink)