Some arguments include imperative clauses. For example: ‘Buy me a drink; you can’t buy me that drink unless you go to the bar; so, go to the bar!’ How should we build a logic that predicts which of these arguments are good? Because imperatives aren’t truth apt and so don’t stand in relations of truth preservation, this technical question gives rise to a foundational one: What would be the subject matter of this logic? I argue that declaratives are used to (...) produce beliefs, imperatives are used to produce intentions, and beliefs and intentions are subject to rational requirements. An argument will strike us as valid when anyone whose mental state satisfies the premises is rationally required to satisfy the conclusion. For example, the above argument reflects the principle that it is irrational not to intend what one takes to be the necessary means to one’s intended ends. I argue that all intuitively good patterns of imperative inference can be explained using off-the-shelf formulations of our rational requirements. I then develop a formal-semantic theory embodying this view that predicts a range of data, including free-choice effects and Ross’s paradox. The resulting theory shows one way that our aspirations to rational agency can be discerned in the patterns of our speech, and is a case study in how the philosophy of language and the philosophy of action can be mutually illuminating. (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 present a Gentzen system for reasoning with contrary-to-duty obligations. The intuition behind the system is that a contrary-to-duty is a special kind of normative exception. The logical machinery to formalise this idea is taken from substructural logics and it is based on the definition of a new non-classical connective capturing the notion of reparational obligation. Then the system is tested against well-known contrary-to-duty 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.

I present a novel account of unconditional obligation and of its relationship to conditional obligation and bring this account to bear upon Chisholm's puzzle concerning contrary-to duty obligation.

The importance of potential intentions has been demonstrated both in the construction of agent systems and in the formalisation of teamwork behaviour. However, there still lacks an adequate semantics for the notion of potential intentions as introduced by Grosz and Kraus in their SharedPlans framework. In this paper, we give a formal semantics to intentions and potential intentions, drawing upon both the representationalist approach and the accessibility-based approach. The model captures the dynamic relationship among intentions and potential intentions by providing (...) semantic rules and conditions. Also, the model treats norms as a special class of intentional context, and it is shown that norms play a critical role in the dynamics of intentions in multiagent systems. The formal semantics allows us to validate some properties that are widely-accepted for intention attitudes. (shrink)

Enjoying great popularity in decision theory, epistemology, and philosophy of science, Bayesianism as understood here is fundamentally concerned with epistemically ideal rationality. It assumes a tight connection between evidential probability and ideally rational credence, and usually interprets evidential probability in terms of such credence. Timothy Williamson challenges Bayesianism by arguing that evidential probabilities cannot be adequately interpreted as the credences of an ideal agent. From this and his assumption that evidential probabilities cannot be interpreted as the actual credences of human (...) agents either, he concludes that no interpretation of evidential probabilities in terms of credence is adequate. I argue to the contrary. My overarching aim is to show on behalf of Bayesians how one can still interpret evidential probabilities in terms of ideally rational credence and how one can maintain a tight connection between evidential probabilities and ideally rational credence even if the former cannot be interpreted in terms of the latter. By achieving this aim I illuminate the limits and prospects of Bayesianism. (shrink)

Amie Thomasson's Norms and Necessity offers a non-factualist theory of the language of metaphysical necessity, centering on the idea that statements of necessity express semantic norms. This article identifies a potential problem for the view by distinguishing two kinds of conditional necessity, investigates a solution derived from a well-known parallel pair of conditional necessities in deontic logic, but finds it is not up to the job. The last part of the paper suggests a different route, largely in keeping with the (...) underlying ideas behind Thomasson's approach. (shrink)

Seth Yalcin has pointed out some puzzling facts about the behaviour of epistemic modals in certain embedded contexts. For example, conditionals that begin ‘If it is raining and it might not be raining, … ’ sound unacceptable, unlike conditionals that begin ‘If it is raining and I don’t know it, … ’. These facts pose a prima facie problem for an orthodox treatment of epistemic modals as expressing propositions about the knowledge of some contextually specified individual or group. This paper (...) develops an explanation of the puzzling facts about embedding within an orthodox framework. (shrink)

Actions are usually grouped into one of several moral categories. Familiar ones include the morally required, the morally permitted, and the morally prohibited. These categories have been expanded and/or refined to include the supererogatory and the “suberogatory”. Some eschew deontic categories such as the above, but nevertheless allow the existence of two comparative moral categories, i.e., the morally better or morally worse. At the risk of adding to the clutter, I want to explore the possibility of yet a further category, (...) viz., amoral action, or actions that, strictly speaking, lack any moral status whatsoever. I think admitting the existence of amoral actions is not only plausible in its own right, but has consequences for our understanding the nature of moral obligation. (shrink)

The Fallibility Norm—the claim that we ought to take our fallibility into account when managing our beliefs—appears to conflict with several other compelling epistemic norms. To shed light on these apparent conflicts, I distinguish two kinds of norms: norms of perfection and norms of compensation. Roughly, norms of perfection tell us how agents ought to behave if they’re to be perfect; norms of compensation tell us how imperfect agents ought to behave in order to compensate for their imperfections. I argue (...) that the Fallibility Norm is a norm of compensation, and that thinking of it like this helps us make progress in debates surrounding disagreement, higher-order evidence, and coherence. (shrink)

The “Evidentialist Dictum” says we must believe what our evidence supports, and the “Fallibility Norm” says we must take our fallibility into account when managing our beliefs. This paper presents a problem for the Evidentialist Dictum based in the Fallibility Norm and a particular conception of evidential support. It then addresses two novel Evidentialist responses to this problem. The first response solves the problem by claiming that fallibility information causes “evidence-loss.” In addition to solving the problem, this response appears to (...) explain what’s wrong with certain illegitimate dismissals of misleading evidence. However, this explanation opens it up to objections. Next, I consider and pose challenges to an Evidentialist strategy that attempts to solve the problem by converting accounts of fallibility’s epistemic significance for rational belief into principles of evidential support. I conclude by sketching a solution that allows us to capture what’s true in the Evidentialist Dictum and the Fallibility Norm. (shrink)

This paper offers a two dimensional variation of Standard Deontic Logic SDL, which we call 2SDL. Using 2SDL we can show that we can overcome many of the difficulties that SDL has in representing linguistic sets of Contrary-to-Duties (known as paradoxes) including the Chisholm, Ross, Good Samaritan and Forrester paradoxes. We note that many dimensional logics have been around since 1947, and so 2SDL could have been presented already in the 1970s. Better late than never! As a detailed case study (...) illustrating the power of 2SDL, we examine the system DL of Deontic Logic of Andrew Jones and Ingmar Pörn offered in 1985 to solve the Chisholm paradox of Contrary to Duties. The critical examination is done using logics and methods available in 1985 and solutions are proposed using what was available in 1985. (shrink)

James Wm. Forrester, Being Good and Being Logical. Philosophical Groundwork for a New Deontic Logic. Armonk and London, M.E. Sharpe, 1996. Pp.x+332.

It is argued that Ross's Paradox in deontic logic is a problem which should be taken seriously, and which can be given a solution which also solves some other wellknown paradoxes and the traditional problems with conditional obligation.

I argue that normative requirements should be interpreted as the conditional obligations of dyadic deontic logic. Semantically, normative requirements are conditionals understood as restrictors, the prevailing view of conditionals in linguistics. This means that Modus Ponens is invalid, even when the premises are known.

This article surveys a range of current views on the semantics of imperatives, presenting them as more or less conservative with respect to the Truth-Conditional Paradigm in semantics. It describes and critiques views at either extreme of this spectrum: accounts on which the meaning of an imperative is a modal truth-condition, as well as various accounts that attempt to explain imperative meaning without making use of truth-conditions. It briefly describes and encourages further work on a family of views lying somewhere (...) in the middle. On such views, an imperative will semantically determine, without having as its meaning, a modal truth-condition, which figures centrally in accounting for various aspects of its meaning. (shrink)

The paper discusses the potential value of a deontic approach to database specification. More specifically, some different types of integrity constraints are considered and a distinction is drawn between necessary (hard) and deontic (soft) constraints.Databases are compared with other normative systems. A deontic logic for database specification is proposed and the problems of how to react to, and of how to correct, or repair, a situation which arises through norm violation are discussed in the context of this logic. The limitations (...) of the proposed logic and possible modifications and extensions of it are analysed. (shrink)

Conditionals that contain a modality in the consequent give rise to a particular semantic phenomenon whereby the antecedent of the conditional blocks possibilities when interpreting the modality in the consequent. This explains the puzzling logical behaviour of constructions like "If you don't buy a lottery ticket, you can't win", "If you eat that poison, it is unlikely that you will survive the day" and "If you kill Harry, you ought to kill him gently". In this paper it is argued that (...) a semantic version of the Ramsey Test provides a key in the analysis of such constructions. The logic for this semantics is axiomatized and some examples are studied, among them a well-known puzzle for contrary-to-duty obligations. (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.

This paper offers a two dimensional variation of Standard Deontic Logic SDL, which we call 2SDL. Using 2SDL we can show that we can overcome many of the difficulties that SDL has in representing linguistic sets of Contrary-to-Duties (known as paradoxes) including the Chisholm, Ross, Good Samaritan and Forrester paradoxes. We note that many dimensional logics have been around since 1947, and so 2SDL could have been presented already in the 1970s. Better late than never! As a detailed case study (...) illustrating the power of 2SDL, we examine the system DL of Deontic Logic of Andrew Jones and Ingmar Pörn offered in 1985 to solve the Chisholm paradox of Contrary to Duties. The critical examination is done using logics and methods available in 1985 and solutions are proposed using what was available in 1985. (shrink)

A new deontic logic, Action Type Deontic Logic, is presented. To motivate this logic, a number of benchmark cases are shown, representing inferences a deontic logic should validate. Some of the benchmark cases are singled out for further comments and some formal approaches to deontic reasoning are evaluated with respect to the benchmark cases. After that follows an informal introduction to the ideas behind the formal semantics, focussing on the distinction between action types and action tokens. Then the syntax and (...) semantics of Action Type Deontic Logic is presented and it is shown to meet the benchmarks. Finally, possibilities for further research are indicated. In the appendix, decidability of the satisfiability of formulas is proved via a technique known from monadic First Order Logic. (shrink)

We provide a retrospective of 25 years of the International Conference on AI and Law, which was first held in 1987. Fifty papers have been selected from the thirteen conferences and each of them is described in a short subsection individually written by one of the 24 authors. These subsections attempt to place the paper discussed in the context of the development of AI and Law, while often offering some personal reactions and reflections. As a whole, the subsections build into (...) a history of the last quarter century of the field, and provide some insights into where it has come from, where it is now, and where it might go. (shrink)

In this article I respond to the eight critical essays in this issue that evaluate the claims in my book with Gerhard Øverland, Responding to Global Poverty: Harm, Responsibility, and Agency.

In this article I respond to the eight critical essays in this issue that evaluate the claims in my book with Gerhard Øverland, Responding to Global Poverty: Harm, Responsibility, and Agency.

This paper presents a nonmonotonic deontic logic based on commonsense entailment. It establishes criteria a successful account of obligation should satisfy, and develops a theory that satisfies them. The theory includes two conditional notions of prima facie obligation. One is constitutive; the other is epistemic, and follows nonmonotonically from the constitutive notion. The paper defines unconditional notions of prima facie obligation in terms of the conditional notions.

This paper investigates some aspects of the semantics of deontic should-conditionals. The main objective is to understand which actual world facts make deontic statements true. The starting point for the investigation is a famous puzzle known as Chisholm’s Paradox. It is important because making sense of the data in Chisholm-style examples involves arriving at some conclusion regarding the interaction between what we consider ideal and what is actually true. I give an account of how facts affect the evaluation of should (...) formulated in a way that does not predict that the divergence between ideals and facts leads to contradictions. The proposed semantics for should and should-conditionals allows for factual detachment without giving rise to paradoxes. The proposal has several parts: a situation-based semantics for the modal should, a view of the propositions embedded under should that allows aspect to play a crucial role in anchoring propositions to the context set, and a proposal for if-clauses that distinguishes between epistemic if-clauses and if-clauses in the scope of should, treating the latter as restrictors on the quantificational domain of the modal. (shrink)

The article argues for a parallelism between the interpretation of deontic modals and the interpretation of counterfactuals. The main claim is that dependencies between facts play a role in the resolution of both types of modality: in both cases, facts ‘stand and fall’ together. The article provides two types of evidence supporting this claim: (i) evidence that comes from the interaction between primary and secondary duties (as presented in contrary-to-duty imperatives) and (ii) evidence that comes from the possibility of reproducing (...) well-known counterfactual puzzles in the domain of deontic statements. The article argues that the semantics of deontic modals needs to be stated in a way that pays attention to dependencies between facts and illustrates this with a proposal building on work on counterfactuals by Kratzer and Veltman. (shrink)

In Meyer’s promising account [7] deontic logic is reduced to a dynamic logic. Meyer claims that with his account “we get rid of most (if not all) of the nasty paradoxes that have plagued traditional deontic logic.” But as was shown by van der Meyden in [4], Meyer’s logic also contains a paradoxical formula. In this paper we will show that another paradox can be proven, one which also effects Meyer’s “solution” to contrary to duty obligations and his logic in (...) general. (shrink)

In this article I defend that Floridi’s Theory of Strongly Semantic Information – TSSI – is correct while encompassing the Veracity Thesis, which guides the semantic information definition as “p is information if and only if p is constituted by meaningful, truth well-formed data”. I argue that the theory is not arbitrary because it deals with important philosophical conundrums, mainly by avoiding the Bar-Hillel and Carnap paradox (1953) generated from the classical theory of semantic information. First, one of the classic (...) theory’s main result is discussed: the production of “too much informative sentences to be true”. Then the motivations to elaborate a “logic of being informed” are summarized and it is shown how the KTB-IL system is built and modelled keeping the veracity axiom among its axioms – K or A4. Finally the TSSI is examined and defended by showing that it aletically restricts the extension of the classic concept of information, avoiding problems with tautologies and contradictions. The TSSI offers an original solution by capturing our modal intuitions concerning informativeness as a basic notion. (shrink)

Normative systems have been advocated as an effective tool to regulate interaction in multi-agent systems. The use of deontic operators and the ability to represent defeasible information are known to be two fundamental ingredients to represent and reason about normative systems. In this paper, after introducing a framework that combines standard deontic logic and non-monotonic logic programming, deontic logic programs (DLP), we tackle the fundamental problem of equivalence between normative systems using a deontic extension of David Pearce’s Equilibrium Logic and (...) its monotonic basis, the logic of Here-and-There. We also show how deontic logic programs can be used to represent and reason about normative systems, and establish a strong connection with input-output logic. (shrink)

An internalist slogan says that justification depends on internal factors. But which factors are those? This paper examines some common motivations favoring internalism over externalism, and says they are compatible with including dispositional and even past mental states in the internal.

We formally introduce a novel, yet ubiquitous, category of norms: norms of instrumentality. Norms of this category describe which actions are obligatory, or prohibited, as instruments for certain purposes. We propose the Logic of Agency and Norms (LAN) that enables reasoning about actions, instrumentality, and normative principles in a multi-agent setting. Leveraging LAN , we formalize norms of instrumentality and compare them to two prevalent norm categories: norms to be and norms to do. Last, we pose principles relating the three (...) categories and evaluate their validity vis-à-vis notions of deliberative acting. On a technical note, the logic will be shown decidable via the finite model property. (shrink)

In this paper, I apply the "conceptual role semantics" approach that I have proposed elsewhere (according to which the meaning of normative terms is given by their role in practical reasoning or deliberation) to the meaning of the term 'ought'. I argue that this approach can do three things: It can give an adequate explanation of the special connection that normative judgments have to practical reasoning and motivation for action. It can give an adequate account of why the central principles (...) of deontic logic are correct. It can give an explanation of the precise ways in which the term 'ought' is systematically context-sensitive, so that the term expresses different (but systematically related) concepts in different contexts. (shrink)

Define teleology as the view that requirements hold in virtue of facts about value or goodness. Teleological views are quite popular, and in fact some philosophers (e.g. Dreier, Smith) argue that all (plausible) moral theories can be understood teleologically. I argue, however, that certain well-known cases show that the teleologist must at minimum assume that there are certain facts that an agent ought to know, and that this means that requirements can't, in general, hold in virtue of facts about value (...) or goodness. I then show that even if we grant those 'ought's teleology still runs into problems. A positive justification of teleology looks like it will require an argument of this form: O(X); if X, then O(Y); therefore O(Y). But this form of argument isn't in general valid. I conclude by offering two positive suggestions for those attracted to a teleological outlook. (shrink)

This paper argues for contrastivism about the deontic modals, 'ought', 'must', and 'may'. A simple contrastivist semantics that predicts the desired entailment relations among these modals is offered.

(See also the separate entry for the volume itself.) This introduction has three parts. The first providing an overview of some main lines of research in deontic logic: the emergence of SDL, Chisholm's paradox and the development of dyadic deontic logics, various other puzzles/challenges and areas of development, along with philosophical applications. The second part focus on some actual and potential fruitful interactions between deontic logic, computer science and artificial intelligence. These include applications of deontic logic to AI knowledge representation (...) in legal systems, to modelling computer systems where it is expected that sub-ideal states will emerge and require countermeasures, to norm-governed human interactions with computer systems, and to the representation of some features of multi-agent systems where different agent-like computer systems interact with one another. The third and final part briefly groups and previews the papers in the anthology. (shrink)