In this dissertation we present proof systems for several modal logics. These proof systems are based on analytic (or semantic) tableaux. -/- Modal logics are logics for reasoning about possibility, knowledge, beliefs, preferences, and other modalities. Their semantics are almost always based on Saul Kripke’s possible world semantics. In Kripke semantics, models are represented by relational structures or, equivalently, labeled graphs. Syntactic formulas that express statements about knowledge and other modalities are evaluated in terms of such models. -/- This dissertation (...) focuses on modal logics with dynamic operators for public announcements, belief revision, preference upgrades, and so on. These operators are defined in terms of mathematical operations on Kripke models. Thus, for example, a belief revision operator in the syntax would correspond to a belief revision operation on models. -/- The ‘dynamic’ semantics of dynamic modal logics are a clever way of extending languages without compromising on intuitiveness. We present ‘dynamic’ tableau proof systems for these dynamic semantics, with the express aim to make them conceptually simple, easy to use, modular, and extensible. This we do by reflecting the semantics as closely as possible in the components of our tableau system. For instance, dynamic operations on Kripke models have counterpart dynamic relations between tableaux. -/- Soundness, completeness, and decidability are three of the most important properties that a proof system may have. A proof system is sound if and only if any formula for which a proof exists, is true in every model. A proof system is complete if and only if for any formula that is true in all models, a proof exists. A proof system is decidable if and only if any formula can be proved to be a theorem or not a theorem in a finite number of steps. All proof systems in this dissertation are sound, complete, and decidable. -/- Part of our strategy to create modular tableau systems is to delay concerns over decidability until after soundness and completeness have been established. Decidability is attained through the operations of folding and through operations on ‘tableau cascades’, which are graphs of tableaux. -/- Finally, we provide a proof-of-concept implementation of our dynamic tableau system for public announcement logic in the Clojure programming language. (shrink)

This paper is an original attempt to understand the foundations of economic reasoning. It endeavors to rigorously define the relationship between subjective interpretations and objective valuations of such interpretations in the context of theoretical economics. This analysis is substantially expanded through a dynamic approach, where the truth of a valuation results in an updated interpretation or changes in the agent's subjective belief regarding the effectiveness of the selected action as well as the objective reality of the effectiveness of all (...) other possible actions (i.e. consequence realization). Complications arise when the economic agent is presented with a set of actions that render ambiguous preference, or when the effectiveness of an action cannot be perceived upon its selection, thereby necessitating a different theory of choice and consequence realization. (shrink)

In New Essays on Human Understanding, book II, chapter xxi Leibniz presents an interesting picture of the human mind as not only populated by perceptions, volitions and appetitions, but also by endeavours. The endeavours in question can be divided to entelechy and effort; Leibniz calls entelechy as primitive active forces and efforts as derivative forces. The entelechy, understood as primitive active force is to be equated with a substantial form, as Leibniz says: “When an entelechy – i.e. a primary or (...) substantial endeavour – is accompanied by perception, it is a soul” (NE II, xxi, §1; RB, 170). What about efforts, then? One is certainly the will. In NE, II, xxi, §5 Leibniz argues that volition is the effort (conatus) to move towards what one finds good and away from what one finds bad and that this endeavor arises from the perceptions we are aware of. As an endeavour results in action unless it is prevented, from will (which is always directed to the good) and power together follows action. However, this is not so simple. Leibniz argues that there is also a second class of efforts: “There are other efforts, arising from insensible perceptions, which we are not aware of; I prefer to call these ‘appetitions’ rather than volitions” (NE II, xxi, §5; RB, 173). Although there are appetitions of which one can be aware, usually these appetitions arise from the insensible petite perceptions and are consequently affecting us subconsciously. Now, although all minute perceptions are confused perceptions, they are always related to pleasure and displeasure and also to perfection and imperfection. From this follows that there can be different efforts present in the soul at the same time: the will which is directed to apperceived good and several separate appetitions which lead to different goals, both to those which bring about perfection and pleasure of the mind (joy) and those which bring about displeasure and imperfection (sorrow). These efforts are not only in conflict with each other but may also be in conflict with entelechy. A typical case is perceiving a sensual pleasure. Our entelechy which is always directed to final causes (perfection) may be in conflict with several different appetitions which are related in different ways to the sensual pleasure in question. If our understanding is developed enough, our will resists the temptation posed by the pleasure (agreeing with entelechy), but if the temptation is too strong, the appetitions outweigh the will and the resulting action bring about imperfection and sorrow as it is related to imperfection. In this paper I will argue that deliberation in the human soul is a battle of different endeavors described above: the entelechy in the soul strives according to its law-of-the-series towards its telos (perfection) and the will accompanies it by being automatically directed to the good. This thrust towards the apparent good is aided or hindered by the appetitions which can be thought as derivative forces in the Leibnizian dynamics. Depending on whether the predominant appetitions are related to good or bad desires, the deliberation succeeds or fails in achieving the real good which is the goal of human deliberation. The successs can be facilitated beforehand by developing our understanding so that we are less easily swept away by the derivative forces (NE II, xxi, §19). A central role in this task is played by strong willing. As Martha Bolton has noted in her recent paper, an essential feature of the basic, standing endeavors is that they are continuous – although the power balance in the soul changes from moment to moment, something lingers from our previous volitions. That is why Leibniz argues that we pave way for the future deliberations by our previous voluntary actions (NE II, xxi, §23). In contrast, the appetitions are temporary, fliegende Gedanken as Leibniz says in NE II, xxi, §12. Therefore there is a constant, always changing power balance between two kinds of endeavors in the soul: primitive active force versus derivative forces. I will argue that the behavior of the forces in the soul can be understood with a vectorial model which is related to Leibniz’s early ideas of calculus of variations and which was anticipated by Arnauld and Nicole’s Port-Royal Logic. The central idea in the model is that the options are in tension towards each other and the ratio between them at each moment determines the consequent outcome. The proper relationship between the endeavors is not a simple balance, two options which exhaust each other, but a case where different efforts complement each other: “Since the final result is determined by how things weigh against one another, I should think it could happen that he most pressing disquiet did not prevail; for even If it prevailed over each of the contrary endeavours taken singly, it may be outweighed by all of them together.” Leibniz continues : “Everything which then impinges on us weighs in the balance and contributes to determining a resultant direction, almost as in mechanics” (NE II, xxi, §40; RB, 193). The different endeavors can be understood as vectors leading to different directions and the end result is a certain direction that deliberation takes. The dynamical tension between the different endeavors presents a situation where everything affects everything and the following direction, the resulting volition follows more or less automatically. In Theodicy, §325 Leibniz describes the deliberation as follows: “One might, instead of the balance, compare the soul with a force that puts forth an effort on various sides simultaneously, but which acts only at the spot where action is easiest or there is least resistance” (Huggard, 322) This kind of dynamical tension can be understood in terms of the calculus of variations where there are several possible variations available but where the dynamics of the situation results in the decision taking the “easiest” route which is more or less objectively good depending on the level of the deliberator’s understanding. In his comments to Bayle’s note L of “Rorarius” Leibniz says: “The soul, even though it has no parts, has within it, because of the multitude of representations of external things, or rather because of the representation of the universe lodged within it by the creator, a great number, or rather an infinite number, of variations (Woolhouse & Francks (ed.), ‘New System’ and Associated Texts, 101). This kind of deliberation is comparable to God’s choice of the best world with the difference that God’s understanding is infinite which again results in the fact that the choice is the best possible. Whereas in nature the easiest route taken is always optimal as nature is God’s creation, in men the goodness or badness of men’s actions is dependent on their state of wisdom, that is, how developed their understanding is. The more wise men are, the more metaphysical goodness or perfection follows from their actions. (shrink)

In New Essays on Human Understanding, book II, chapter xxi Leibniz presents an interesting picture of the human mind as not only populated by perceptions, volitions and appetitions, but also by endeavours. The endeavours in question can be divided to entelechy and effort; Leibniz calls entelechy as primitive active forces and efforts as derivative forces. The entelechy, understood as primitive active force is to be equated with a substantial form, as Leibniz says: “When an entelechy – i.e. a primary or (...) substantial endeavour – is accompanied by perception, it is a soul” (NE II, xxi, §1; RB, 170). What about efforts, then? One is certainly the will. In NE, II, xxi, §5 Leibniz argues that volition is the effort (conatus) to move towards what one finds good and away from what one finds bad and that this endeavor arises from the perceptions we are aware of. As an endeavour results in action unless it is prevented, from will (which is always directed to the good) and power together follows action. However, this is not so simple. Leibniz argues that there is also a second class of efforts: “There are other efforts, arising from insensible perceptions, which we are not aware of; I prefer to call these ‘appetitions’ rather than volitions” (NE II, xxi, §5; RB, 173). Although there are appetitions of which one can be aware, usually these appetitions arise from the insensible petite perceptions and are consequently affecting us subconsciously. Now, although all minute perceptions are confused perceptions, they are always related to pleasure and displeasure and also to perfection and imperfection. From this follows that there can be different efforts present in the soul at the same time: the will which is directed to apperceived good and several separate appetitions which lead to different goals, both to those which bring about perfection and pleasure of the mind (joy) and those which bring about displeasure and imperfection (sorrow). These efforts are not only in conflict with each other but may also be in conflict with entelechy. A typical case is perceiving a sensual pleasure. Our entelechy which is always directed to final causes (perfection) may be in conflict with several different appetitions which are related in different ways to the sensual pleasure in question. If our understanding is developed enough, our will resists the temptation posed by the pleasure (agreeing with entelechy), but if the temptation is too strong, the appetitions outweigh the will and the resulting action bring about imperfection and sorrow as it is related to imperfection. In this paper I will argue that deliberation in the human soul is a battle of different endeavors described above: the entelechy in the soul strives according to its law-of-the-series towards its telos (perfection) and the will accompanies it by being automatically directed to the good. This thrust towards the apparent good is aided or hindered by the appetitions which can be thought as derivative forces in the Leibnizian dynamics. Depending on whether the predominant appetitions are related to good or bad desires, the deliberation succeeds or fails in achieving the real good which is the goal of human deliberation. The successs can be facilitated beforehand by developing our understanding so that we are less easily swept away by the derivative forces (NE II, xxi, §19). A central role in this task is played by strong willing. As Martha Bolton has noted in her recent paper, an essential feature of the basic, standing endeavors is that they are continuous – although the power balance in the soul changes from moment to moment, something lingers from our previous volitions. That is why Leibniz argues that we pave way for the future deliberations by our previous voluntary actions (NE II, xxi, §23). In contrast, the appetitions are temporary, fliegende Gedanken as Leibniz says in NE II, xxi, §12. Therefore there is a constant, always changing power balance between two kinds of endeavors in the soul: primitive active force versus derivative forces. I will argue that the behavior of the forces in the soul can be understood with a vectorial model which is related to Leibniz’s early ideas of calculus of variations and which was anticipated by Arnauld and Nicole’s Port-Royal Logic. The central idea in the model is that the options are in tension towards each other and the ratio between them at each moment determines the consequent outcome. The proper relationship between the endeavors is not a simple balance, two options which exhaust each other, but a case where different efforts complement each other: “Since the final result is determined by how things weigh against one another, I should think it could happen that he most pressing disquiet did not prevail; for even If it prevailed over each of the contrary endeavours taken singly, it may be outweighed by all of them together.” Leibniz continues : “Everything which then impinges on us weighs in the balance and contributes to determining a resultant direction, almost as in mechanics” (NE II, xxi, §40; RB, 193). The different endeavors can be understood as vectors leading to different directions and the end result is a certain direction that deliberation takes. The dynamical tension between the different endeavors presents a situation where everything affects everything and the following direction, the resulting volition follows more or less automatically. In Theodicy, §325 Leibniz describes the deliberation as follows: “One might, instead of the balance, compare the soul with a force that puts forth an effort on various sides simultaneously, but which acts only at the spot where action is easiest or there is least resistance” (Huggard, 322) This kind of dynamical tension can be understood in terms of the calculus of variations where there are several possible variations available but where the dynamics of the situation results in the decision taking the “easiest” route which is more or less objectively good depending on the level of the deliberator’s understanding. In his comments to Bayle’s note L of “Rorarius” Leibniz says: “The soul, even though it has no parts, has within it, because of the multitude of representations of external things, or rather because of the representation of the universe lodged within it by the creator, a great number, or rather an infinite number, of variations (Woolhouse & Francks (ed.), ‘New System’ and Associated Texts, 101). This kind of deliberation is comparable to God’s choice of the best world with the difference that God’s understanding is infinite which again results in the fact that the choice is the best possible. Whereas in nature the easiest route taken is always optimal as nature is God’s creation, in men the goodness or badness of men’s actions is dependent on their state of wisdom, that is, how developed their understanding is. The more wise men are, the more metaphysical goodness or perfection follows from their actions. (shrink)

Epistemic logics based on the possible worlds semantics suffer from the problem of logical omniscience, whereby agents are described as knowing all logical consequences of what they know, including all tautologies. This problem is doubly challenging: on the one hand, agents should be treated as logically non-omniscient, and on the other hand, as moderately logically competent. Many responses to logical omniscience fail to meet this double challenge because the concepts of knowledge and reasoning are not properly separated. In this paper, (...) I present a dynamic logic of knowledge that models an agent’s epistemic state as it evolves over the course of reasoning. I show that the logic does not sacrifice logical competence on the altar of logical non- omniscience. (shrink)

Combinatory logic (Curry and Feys 1958) is a “variable-free” alternative to the lambda calculus. The two have the same expressive power but build their expressions differently. “Variable-free” semantics is, more precisely, “free of variable binding”: it has no operation like abstraction that turns a free variable into a bound one; it uses combinators—operations on functions—instead. For the general linguistic motivation of this approach, see the works of Steedman, Szabolcsi, and Jacobson, among others. The standard view in linguistics is that (...) reflexive and personal pronouns are free variables that get bound by an antecedent through some coindexing mechanism. In variable free semantics the same task is performed by some combinator that identifies two arguments of the function it operates on (a duplicator). This combinator may be built into the lexical semantics of the pronoun, into that of the antecedent, or it may be a free-floating operation applicable to predicates or larger chunks of texts, i.e. a typeshifter. This note is concerned with the case of cross-sentential anaphora. It adopts Hepple’s and Jacobson’s interpretation of pronouns as identity maps and asks how this can be extended to the cross-sentential case, assuming the dynamic semantic view of anaphora. It first outlines the possibility of interpreting indefinites that antecede non-ccommanded pronouns as existential quantifiers enriched with a duplicator. Then it argues that it is preferable to use the duplicator as a type-shifter that applies “on the fly”. The proposal has consequences for two central ingredients of the classical dynamic semantic treatment: it does away with abstraction over assignments and with treating indefinites as inherently existentially quantified. However, cross-sentential anaphora remains a matter of binding, and the idea of propositions as context change potentials is retained. (shrink)

A dynamic epistemic logic is presented in which the single agent can reason about his knowledge stages before and after announcements. The logic is generated by reinterpreting multi agent private announcements in a single agent environment. It is shown that a knowability principle is valid for such logic: any initially true ϕ can be known after a certain number of announcements.

The theories of belief change developed within the AGM-tradition are not logics in the proper sense, but rather informal axiomatic theories of belief change. Instead of characterizing the models of belief and belief change in a formalized object language, the AGM-approach uses a natural language — ordinary mathematical English — to characterize the mathematical structures that are under study. Recently, however, various authors such as Johan van Benthem and Maarten de Rijke have suggested representing doxastic change within a formal logical (...) language: a dynamic modal logic. Inspired by these suggestions Krister Segerberg has developed a very general logical framework for reasoning about doxastic change: dynamic doxastic logic (DDL). This framework may be seen as an extension of standard Hintikka-style doxastic logic with dynamic operators representing various kinds of transformations of the agent's doxastic state. Basic DDL describes an agent that has opinions about the external world and an ability to change these opinions in the light of new information. Such an agent is non-introspective in the sense that he lacks opinions about his own belief states. Here we are going to discuss various possibilities for developing a dynamic doxastic logic for introspective agents: full DDL or DDL unlimited. The project of constructing such a logic is faced with difficulties due to the fact that the agent’s own doxastic state now becomes a part of the reality that he is trying to explore: when an introspective agent learns more about the world, then the reality he holds beliefs about undergoes a change. But then his introspective (higher-order) beliefs have to be adjusted accordingly. In the paper we shall consider various ways of solving this problem. (shrink)

The paper analyzes dynamic epistemic logic from a topological perspective. The main contribution consists of a framework in which dynamic epistemic logic satisfies the requirements for being a topological dynamical system thus interfacing discrete dynamic logics with continuous mappings of dynamical systems. The setting is based on a notion of logical convergence, demonstratively equivalent with convergence in Stone topology. Presented is a flexible, parametrized family of metrics inducing the latter, used as an analytical aid. We (...) show maps induced by action model transformations continuous with respect to the Stone topology and present results on the recurrent behavior of said maps. (shrink)

In this paper we distinguish between various kinds of doxastic theories. One distinction is between informal and formal doxastic theories. AGM-type theories of belief change are of the former kind, while Hintikka’s logic of knowledge and belief is of the latter. Then we distinguish between static theories that study the unchanging beliefs of a certain agent and dynamic theories that investigate not only the constraints that can reasonably be imposed on the doxastic states of a rational agent but (...) also rationality constraints on the changes of doxastic state that may occur in such agents. An additional distinction is that between non-introspective theories and introspective ones. Non-introspective theories investigate agents that have opinions about the external world but no higher-order opinions about their own doxasticnstates. Standard AGM-type theories as well as the currently existing versions of Segerberg’s dynamic doxastic logic (DDL) are non-introspective. Hintikka-style doxastic logic is of course introspective but it is a static theory. Thus, the challenge remains to devise doxastic theories that are both dynamic and introspective. We outline the semantics for truly introspective dynamic doxastic logic, i.e., a dynamic doxastic logic that allows us to describe agents who have both the ability to form higher-order beliefs and to reflect upon and change their minds about their own (higher-order) beliefs. This extension of DDL demands that we give up the Preservation condition on revision. We make some suggestions as to how such a non-preservative revision operation can be constructed. We also consider extending DDL with conditionals satisfying the Ramsey test and show that Gärdenfors’ well-known impossibility result applies to such a framework. Also in this case, Preservation has to be given up. (shrink)

The dominant approach to the study of dynamic preference is to generate preference change by manipulating aspects of decision-problem presentation (problem description, task procedure, contextual options). The predisposing approach instead manipulates the decision maker’s mental state while holding problem presentation constant. Three illustrative studies are outlined here. The first modified preferences for ambitious consumption by manipulating subjects’ consumption energy. The second modified preferences for immediate consumption by manipulating subjects’ hedonic resources. The third modified preferences for consumption itself (...) by manipulating subjects’ desire proneness. Whereas framing is thought to affect perception, predisposing apparently can affect tastes and so involves a special kind of preference dynamism. (shrink)

C.S. Peirce's and Isaac Levi's accounts of the belief-doubt-belief model are discussed and evaluated. It is argued that the contemporary study of belief change has metamorphosed into a branch of philosophical logic where empirical considerations have become obsolete. A case is made for reformulations of belief change systems that do allow for empirical tests. Last, a belief change system is presented that (1) uses finite representations of information, (2) can adequately deal with inconsistencies, (3) has finite operations of change, (...) (4) can do without extra-logical elements, and (5) only licenses consistent beliefs. (shrink)

In lieu of an abstract, here is a brief excerpt of the content: There is an abundance of scholarship on John Dewey. Dewey's writings are vast, so scholars try to find the crux that connects their many themes into a distinctive vision for philosophy and life. Many claim that the democratic way of life is the center of Dewey's philosophical vision. Others claim that Dewey's response to Darwin was the impetus for a philosophical experimentalism that could envision a better life (...) by responding to the needs in an age of modern industry. Some claim that the crux is a dynamic and non-mechanistic naturalism that Dewey develops to critically undo the dualisms of tradition, most especially the distinction between nature and culture. There has even been an effort to interpret each of these themes within Dewey's theory about the conditions for aesthetics in life, the life of art within an experience, and an experience of life as art. Arguably, no strategy is more preferable than another because each is plausible. Each plausibly selects a crux that connects the many themes across an array of writings, since Dewey's philosophy is multimodal by design and shuns reductionism for pluralism. Even amidst plurality, through many modes of activity and existence, each of these themes and all of Dewey's writings have a concern for meaning in life and how life is a process of meaning-making. And yet, meaning, for Dewey, is irreducible to verbal or written language and is made by more than propositions, but extends beyond the divide of nature and culture to potentially encompass all of life and life's processes. This expansive conception of meaning has more in common with semiotics, especially those of Charles Sanders Peirce, than any philosophy of language. And yet almost no scholar has sought to semiotically interpret Dewey's philosophy as a whole. Perhaps, though, Dewey's multimodal and pluralistic vision for philosophy and life also has a semiotic crux that intersects with the others in ways that are fundamentally important. There are scholars who have dealt with semiotic themes or insights with implications for semiotics in Dewey's writings. None have sought to semiotically interpret Dewey's philosophy as a whole, or, as a consequence, to chronologically survey Dewey's writings to determine if there is a conceivably Deweyan approach to semiotics that might contrast with or contribute to the more dominant approaches. There is a reason scholars may not have sought a Deweyan approach to semiotics. Dewey did not have an explicit theory of semiotics. There is no attempt to devise a doctrine of signs in Dewey's writings. Never did Dewey try to classify the fundamental types of sign, analyze the relations of signification by which they differ, or methodically explain how the logic of signification works. This contrasts sharply with Charles Sanders Peirce. Peirce has an explicit theory of semiotics that divides the fundamental types of sign into icons, indices, and symbols by their distinct relations of signification that are at work in the logic of inference by the categories. During his second year at Johns Hopkins, Dewey was actually Peirce's student in a class on logic. This already suggests the possibility of influence. Dewey's writings around 1883 even espouse the central thesis of Peirce's semiotics. All signs, however else their significations may differ, are triadic relations for both Peirce and Dewey. Whether and how far Peirce's logic was an influence on Dewey at Johns... (shrink)

In the paper, certain rational postulates for protocols describing real communicating are introduced.These rational postulates, on the one hand, allow assigning a certain typology of real systems of interactions, which is consistent with the reality of epistemic argumentation in systems of communicating, and on the other one – defining rules of using argumentation in real situations. Moreover, the presented postulates for protocols characterize information networks and administering knowledge in real interactivity systems. Due to the epistemic character of the considerations, the (...) problem undertaken in the paper concerns working out fundamental assumptions that refer to building of epistemic logics. They allow establishing the correctness of the discourse defined by rational postulates of protocols of real communication. In the context of the presented problem there are the following two research questions distinguished: 1) How do we determine the rule of building of real dynamic epistemic logics? and 2) How should we define semantics for these logics? Within the framework of considerations relating to the research questions asked, certain epistemic operators, relativized to types of communicating, are introduced. Basic logical relations between using these operators are established for these operators. The relations are presented by a diagram called the square of epis temic operators. On the basis of these logical relations some axioms for real dynamic epistemic logics are presented. The semantics of real dynamic epistem ic logics is extended by the methods of lower and upper approximation of formula evaluating. This allows defining ‘approximation Kripke models’. The results of conceptualization of knowledge on real premises of epistemic argum entation presented in this paper can be applied to rhetoric in real systems of interaction. (shrink)

Most formalisms for representing common-sense knowledge allow incomplete and potentially inconsistent information. When strong negation is also allowed, contradictory conclusions can arise. A criterion for deciding between them is needed. The aim of this paper is to investigate an inherent and autonomous comparison criterion, based on specificity as defined in [POO 85, SIM 92]. In contrast to other approaches, we consider not only defeasible, but also strict knowledge. Our criterion is context-sensitive, i. e., preference among defeasible rules is determined (...) dynamically during the dialectical analysis.We show how specificity can be defined in terms of two different approaches: activation sets and derivation trees. This allows us to get a syntactic criterion that can be implemented in a computationally attractive way. The resulting definitions may be applied in general rulebased formalisms. We present theorems linking both characterizations. Finally we discuss other frameworks for defeasible reasoning in which preference handling is considered explicitly. (shrink)

We propose a dynamic hyperintensional logic of belief revision for non-omniscient agents, reducing the logical omniscience phenomena affecting standard doxastic/epistemic logic as well as AGM belief revision theory. Our agents don’t know all a priori truths; their belief states are not closed under classical logical consequence; and their belief update policies are such that logically or necessarily equivalent contents can lead to different revisions. We model both plain and conditional belief, then focus on dynamic belief revision. (...) The key idea we exploit to achieve non-omniscience focuses on topic- or subject matter-sensitivity: a feature of belief states which is gaining growing attention in the recent literature. (shrink)

The traditional possible-worlds model of belief describes agents as ‘logically omniscient’ in the sense that they believe all logical consequences of what they believe, including all logical truths. This is widely considered a problem if we want to reason about the epistemic lives of non-ideal agents who—much like ordinary human beings—are logically competent, but not logically omniscient. A popular strategy for avoiding logical omniscience centers around the use of impossible worlds: worlds that, in one way or another, violate the laws (...) of logic. In this paper, we argue that existing impossible-worlds models of belief fail to describe agents who are both logically non-omniscient and logically competent. To model such agents, we argue, we need to ‘dynamize’ the impossible-worlds framework in a way that allows us to capture not only what agents believe, but also what they are able to infer from what they believe. In light of this diagnosis, we go on to develop the formal details of a dynamic impossible-worlds framework, and show that it successfully models agents who are both logically non-omniscient and logically competent. (shrink)

This essay advances and develops a dynamic conception of inference rules and uses it to reexamine a long-standing problem about logical inference raised by Lewis Carroll’s regress.

In researching presuppositions dealing with logic and dynamic of belief we distinguish two related parts. The first part refers to presuppositions and logic, which is not necessarily involved with intentional operators. We are primarily concerned with classical, free and presuppositonal logic. Here, we practice a well known Strawson’s approach to the problem of presupposition in relation to classical logic. Further on in this work, free logic is used, especially Van Fraassen’s research of the role (...) of presupposition in supervaluations logical systems. At the end of the first part, presuppositional logic, advocated by S.K. Thomason, is taken into consideration. The second part refers to the presuppositions in relation to the logic of the dynamics of belief. Here the logic of belief change is taken into consideration and other epistemic notions with immanent mechanism for the presentation of the dynamics. Three representative and dominant approaches are evaluated. First, we deal with new, less classical, situation semantics. Besides Strawson’s theory, the second theory is the theory of the belief change, developed by Alchourron, Gärdenfors, and Makinson (AGM theory). At the end, the oldest, universal, and dominant approach is used, recognized as Hintikka’s approach to the analysis of epistemic notions. (shrink)

Narrativity is basically linked to the dynamics of the events and actions which are told and it depends on the pragmatic context, mainly on the narrator and his audience, i.e. on the discursive setting. These dynamics ask for an adequate theoretical frame, e.g. in the format of dynamical system theory or vector analysis. Furthermore, narrativity can be manifested in different modalities. We shall present some specimens of analysis in the linguistic modality (spontaneous oral tales, folktales), in the visual modality (painting (...) by Leonardo da Vinci, action movie in the series of Bond films), and in the musical modality (Blues music). The static analyses in the tradition of structuralism are replaced by morphodynamic schemes, by gesture and glance vectors, paths of pursuit and scenarios of conflict in action movies and eventually by harmonic sequences in the Blues. In this dynamic perspective, the notion of narrativity gains a different profile and it is freed from the preference for linguistic or logical categories. (shrink)

The theory of imperatives is philosophically relevant since in building it — some of the long standing problems need to be addressed, and presumably some new ones are waiting to be discovered. The relevance of the theory of imperatives for philosophical research is remarkable, but usually recognized only within the field of practical philosophy. Nevertheless, the emphasis can be put on problems of theoretical philosophy. Proper understanding of imperatives is likely to raise doubts about some of our deeply entrenched and (...) tacit presumptions. In philosophy of language it is the presumption that declaratives provide the paradigm for sentence form; in philosophy of science it is the belief that theory construction is independent from the language practice, in logic it is the conviction that logical meaning relations are constituted out of logical terminology, in ontology it is the view that language use is free from ontological commitments. The list is not exhaustive; it includes only those presumptions that this paper concerns. (shrink)

In this work we present NERVOUS, an intelligent recommender system exploiting a probabilistic extension of a Description Logic of typicality to dynamically generate novel contents in AllMusic, a comprehensive and in-depth resource about music, providing data about albums, bands, musicians and songs. The tool can be used for both the generation of novel music genres and styles, described by a set of typical properties characterizing them, and the reclassification of the available songs within such new genres.

Although it seems intuitively clear that acts of requesting are different from acts of commanding, it is not very easy to sate their differences precisely in dynamic terms. In this paper we show that it becomes possible to characterize, at least partially, the effects of acts of requesting and compare them with the effects of acts of commanding by combining dynamified deontic logic with epistemic logic. One interesting result is the following: each act of requesting is appropriately (...) differentiated from an act of commanding with the same content, but for each act of requesting, there is another act of commanding with much more complex content which updates models in exactly the same way as it does. We will also consider an application of our characterization of acts of requesting to acts of asking yes-no questions. It yields a straightforward formalization of the view of acts of asking questions as requests for information. (shrink)

It has been an open question whether or not we can define a belief revision operation that is distinct from simple belief expansion using paraconsistent logic. In this paper, we investigate the possibility of meeting the challenge of defining a belief revision operation using the resources made available by the study of dynamic epistemic logic in the presence of paraconsistent logic. We will show that it is possible to define dynamic operations of belief revision in (...) a paraconsistent setting. (shrink)

The aim of this paper is to introduce a system of dynamic deontic logic in which the main problems related to the de finition of deontic concepts, especially those emerging from a standard analysis of permission in terms of possibility of doing an action without incurring in a violation of the law, are solved. The basic idea is to introduce two crucial distinctions allowing us to differentiate (i) what is ideal with respect to a given code, which fixes (...) the types of action that are abstractly prescribed, and what is ideal with respect to the specific situation in which the agent acts, and (ii) the transitions associated with actions and the results of actions, which can obtain even without the action being performed. (shrink)

We present a framework for epistemic logic, modeling the logical aspects of System 1 and System 2 cognitive processes, as per dual process theories of reasoning. The framework combines non-normal worlds semantics with the techniques of Dynamic Epistemic Logic. It models non-logically-omniscient, but moderately rational agents: their System 1 makes fast sense of incoming information by integrating it on the basis of their background knowledge and beliefs. Their System 2 allows them to slowly, step-wise unpack some of (...) the logical consequences of such knowledge and beliefs, by paying a cognitive cost. The framework is applied to three instances of limited rationality, widely discussed in cognitive psychology: Stereotypical Thinking, the Framing Effect, and the Anchoring Effect. (shrink)

Cases of inexact observations have been used extensively in the recent literature on higher-order evidence and higher-order knowledge. I argue that the received understanding of inexact observations is mistaken. Although it is convenient to assume that such cases can be modeled statically, they should be analyzed as dynamic cases that involve change of knowledge. Consequently, the underlying logic should be dynamic epistemic logic, not its static counterpart. When reasoning about inexact knowledge, it is easy to confuse (...) the initial situation, the observation process, and the result of the observation; I analyze the three separately. This dynamic approach has far reaching implications: Williamson’s influential argument against the KK principle loses its force, and new insights can be gained regarding synchronic and diachronic introspection principles. (shrink)

The rationality of future bias figures crucially in various metaphysical and ethical arguments (Prior 1959; Parfit 1984; Fischer 2019). Recently, however, philosophers have raised several arguments to the effect that future bias is irrational (Dougherty 2011; Suhler and Callender 2012; Greene and Sullivan 2015). Particularly, Greene and Sullivan (2015) claim that future bias is irrational because future bias leads to two kinds of irrational planning behaviors in agents who also seek to avoid regret. In this paper, I join others who (...) have objected to Greene and Sullivan’s argument (Dorsey 2016; Tarsney 2017), but for significantly different reasons that put into question an unchallenged premise in the debate. These reasons are based on the relationship between the alleged irrational planning behaviors and certain features of regret that regret shares with future bias. First, regret is dynamic, involving preferences that change over time and in inconsistent ways. Second, regret comes in degrees, meaning that we can rank our potential regrets. Because regret has these features, I show that the future-biased agents in Greene and Sullivan’s cases do not need to act in irrational ways to rationally avoid regret. (shrink)

The aim of this paper is to provide a dynamic interpretation of Kant’s logical hylomorphism. Firstly, various types of the logical hylomorphism will be illustrated. Secondly, I propose to reevaluate Kant’s constitutivity thesis about logic. Finally, I focus on the design of logical norms as specific kinds of artefacts.

The goal of the present paper is to construct a formal explication of the pluralistic ignorance explanation of the bystander effect. The social dynamics leading to inaction is presented, decomposed, and modeled using dynamic epistemic logic augmented with ‘transition rules’ able to characterize agent behavior. Three agent types are defined: First Responders who intervene given belief of accident; City Dwellers, capturing ‘apathetic urban residents’ and Hesitators, who observe others when in doubt, basing subsequent decision on social proof. It (...) is shown how groups of the latter may end in a state of pluralistic ignorance leading to inaction. Sequential models for each agent type are specified, and their results compared to empirical studies. It is concluded that only the Hesitator model produces reasonable results. (shrink)

In Groenendijk & Stokhof [1989] a system of dynamic predicate logic (DPL) was developed, as a compositional alternative for classical discourse representation theory (DRT ). DPL shares with DRT the restriction of being a first-order system. In the present paper, we are mainly concerned with overcoming this limitation. We shall define a dynamic semantics for a typed language with λ-abstraction which is compatible with the semantics DPL specifies for the language of first-order predicate logic. We shall (...) propose to use this new logical system as the semantic component of a Montague-style grammar (referred to as dynamic Montague grammar, DMG), which will enable us to extend the compositionality of DPL to the subsentential level. Furthermore, we shall extend this analysis also in this sense that we shall add new, dynamic interpretations for logical constants which in DPL were treated in a static fashion. This will substantially increase the descriptive coverage of DMG. (shrink)

Some common explanations of issue polarization and echo chambers rely on social or cognitive mechanisms of exclusion. Accordingly, suggested interventions like “be more open-minded” target these mechanisms: avoid epistemic bubbles and don’t discount contrary information. Contrary to such explanations, we show how a much weaker mechanism—the preference for belief—can produce issue polarization in epistemic communities with little to no mechanisms of exclusion. We present a network model that demonstrates how a dynamic interaction between the preference for belief (...) and common structures of epistemic communities can turn very small unequal distributions of initial beliefs into full-blown polarization. This points to a different class of explanations, one that emphasizes the importance of the initial spread of information. We also show how our model complements extant explanations by including a version of biased assimilation and motivated reasoning—cognitive mechanisms of exclusion. We find that mechanisms of exclusion can exacerbate issue polarization, but may not be the ultimate root of it. Hence, the recommended interventions suggested by extant literature is expected to be limited and the problem of issue polarization to be even more intractable. (shrink)

I show that standard dynamic approaches to the semantics of epistemic modals invalidate the classical laws of excluded middle and non-contradiction, as well as the law of epistemic non-contradiction. I argue that these facts pose a serious challenge.

I argue that taking the Practical Conditionals Thesis seriously demands a new understanding of the semantics of such conditionals. Practical Conditionals Thesis: A practical conditional [if A][ought] expresses B’s conditional preferability given A Paul Weirich has argued that the conditional utility of a state of affairs B on A is to be identified as the degree to which it is desired under indicative supposition that A. Similarly, exploiting the PCT, I will argue that the proper analysis of indicative practical conditionals (...) is in terms of what is planned, desired, or preferred, given suppositional changes to an agent’s information. Implementing such a conception of conditional preference in a semantic analysis of indicative practical conditionals turns out to be incompatible with any approach which treats the indicative conditional as expressing non-vacuous universal quantification over some domain of relevant antecedent-possibilities. Such analyses, I argue, encode a fundamental misunderstanding of what it is to be best, given some condition. The analysis that does the best vis-à-vis the PCT is, instead, one that blends a Context-Shifty account of indicative antecedents with an Expressivistic, or non-propositional, treatment of their practical consequents. (shrink)

Deontic logic is standardly conceived as the logic of true statements about the existence of obligations and permissions. In his last writings on the subject, G. H. von Wright criticized this view of deontic logic, stressing the rationality of norm imposition as the proper foundation of deontic logic. The present paper is an attempt to advance such an account of deontic logic using the formal apparatus of update semantics and dynamic logic. That is, (...) we first define norm systems and a semantics of norm performatives as transformations of the norm system. Then a static modal logic for norm propositions is defined on that basis. In the course of this exposition we stress the performative nature of (i) free choice permission, (ii) the sealing legal principle and (iii) the social nature of permission. That is, (i) granting a disjunctive permission means granting permission for both disjuncts; (ii) non-prohibition does not entail permission, but the authority can declare that whatever he does not forbid is thereby permitted; and (iii) granting permission to one person means that all others are committed to not prevent the invocation of that permission. (shrink)

Noun phrases with overt determiners, such as <i>some apples</i> or <i>a quantity of milk</i>, differ from bare noun phrases like <i>apples</i> or <i>milk</i> in their contribution to aspectual composition. While this has been attributed to syntactic or algebraic properties of these noun phrases, such accounts have explanatory shortcomings. We suggest instead that the relevant property that distinguishes between the two classes of noun phrases derives from two modes of existential quantification, one of which holds the values of a variable fixed (...) throughout a quantificational context while the other allows them to vary. Inspired by Dynamic Plural Logic and Dependence Logic, we propose Plural Predicate Logic as an extension of Predicate Logic to formalize this difference. We suggest that temporal <i>for</i>-adverbials are sensitive to aspect because of the way they manipulate quantificational contexts, and that analogous manipulations occur with spatial <i>for</i>-adverbials, habituals, and the quantifier <i>all</i>. (shrink)

Traditionally, consistency is the only criterion for the quality of a theory in logic-based approaches to reasoning about actions. This work goes beyond that and contributes to the meta-theory of actions by investigating what other properties a good domain de- scription should satisfy. Having Propositional Dynamic Logic (PDL) as background, we state some meta-theoretical postulates concerning this sore spot. When all pos- tulates are satisfied, we call the action theory modular. We point out the problems that arise (...) when the postulates about modularity are violated, and propose algorith- mic checks that can help the designer of an action theory to overcome them. Besides being easier to understand and more elaboration tolerant in McCarthy’s sense, mod- ular theories have interesting computational properties. Moreover, we also propose a framework for updating domain descriptions and show the importance modularity has in action theory change. (shrink)

In the dynamic choice literature, temptations are usually understood as temporary shifts in an agent’s preferences. What has been puzzling about these cases is that, on the one hand, an agent seems to do better by her own lights if she does not give into the temptation, and does so without engaging in costly commitment strategies. This seems to indicate that it is instrumentally irrational for her to give into temptation. On the other hand, resisting temptation also requires her (...) to act contrary to the preferences she has at the time of temptation. But that seems to be instrumentally irrational as well. I here consider the two most prominent types of argument why resisting temptation could nevertheless be instrumentally rational, namely two-tier and intra-personal cooperation arguments. I establish that the arguments either fail or are redundant. In particular, the arguments fail under the pervasive assumption in both decision theory and the wider literature on practical rationality that the agent’s preferences over the objects of choice are themselves the standard of instrumental rationality. And they either still fail or they become redundant when we give up that assumption. (shrink)

This article proposes a general strategy to overcome normative conflicts, namely, paradoxes represented in Standard Deontic Logic. This solution is based on preference relations between norms that circumvent situations of conflict. Pragmatic justifications of the proposed method are also given.

According to Fine’s famous take on the infamous McTaggartian paradox, realism about tensed facts is incompatible with the joint acceptence of three very general and seemingly plausible theses about reality. However, Correia and Rosenkranz have recently objected that Fine’s argument depends on a crucial assumption about the nature of tensed facts; once that assumption is given up, they claim, realists can endorse the theses in question without further ado. They also argue that their novel version of tense realism, called (...) class='Hi'>dynamic absolutism, is to be preferred over its rivals. I argue in this paper that dynamic absolutism does not constitute a genuine alternative for realists about tense. (shrink)

We propose a solution to the problem of logical omniscience in what we take to be its fundamental version: as concerning arbitrary agents and the knowledge attitude per se. Our logic of knowledge is a spin-off from a general theory of thick content, whereby the content of a sentence has two components: an intension, taking care of truth conditions; and a topic, taking care of subject matter. We present a list of plausible logical validities and invalidities for the (...) class='Hi'>logic of knowledge per se for arbitrary agents, and isolate three explanatory factors for them: the topic-sensitivity of content; the fragmentation of knowledge states; the defeasibility of knowledge acquisition. We then present a novel dynamic epistemic logic that yields precisely the desired validities and invalidities, for which we provide expressivity and completeness results. We contrast this with related systems and address possible objections. (shrink)

I distinguish two ways of developing anti-exceptionalist approaches to logical revision. The first emphasizes comparing the theoretical virtuousness of developed bodies of logical theories, such as classical and intuitionistic logic. I'll call this whole theory comparison. The second attempts local repairs to problematic bits of our logical theories, such as dropping excluded middle to deal with intuitions about vagueness. I'll call this the piecemeal approach. I then briefly discuss a problem I've developed elsewhere for comparisons of logical theories. Essentially, (...) the problem is that a pair of logics may each evaluate the alternative as superior to themselves, resulting in oscillation between logical options. The piecemeal approach offers a way out of this problem andthereby might seem a preferable to whole theory comparisons. I go on to show that reflective equilibrium, the best known piecemeal method, has deep problems of its own when applied to logic. (shrink)

Vector models of language are based on the contextual aspects of language, the distributions of words and how they co-occur in text. Truth conditional models focus on the logical aspects of language, compositional properties of words and how they compose to form sentences. In the truth conditional approach, the denotation of a sentence determines its truth conditions, which can be taken to be a truth value, a set of possible worlds, a context change potential, or similar. In the vector models, (...) the degree of co-occurrence of words in context determines how similar the meanings of words are. In this paper, we put these two models together and develop a vector semantics for language based on the simply typed lambda calculus models of natural language. We provide two types of vector semantics: a static one that uses techniques familiar from the truth conditional tradition and a dynamic one based on a form of dynamic interpretation inspired by Heim’s context change potentials. We show how the dynamic model can be applied to entailment between a corpus and a sentence and provide examples. (shrink)

Imperatives are linguistic devices used by an authority (speaker) to express wishes, requests, commands, orders, instructions, and suggestions to a subject (addressee). This essay's goal is to tentatively address some of the following questions about the imperative. -/- METASEMANTIC. What is the menu of options for understanding fundamental semantic notions like satisfaction, truth-conditions, validity, and entailment in the context of imperatives? Are there good imperative arguments, and, if so, how are they to be characterized? What are the options for understanding (...) the property that an account of good imperative arguments is supposed to track? What constraints on a semantic analysis of the imperative do different positions on the metasemantic issues impose? -/- SEMANTIC. How might we implement metasemantic postures in a rigorous formal system? How much can we do using familiar tools from deontic modal logic? How much leverage over semantic questions can we gain by introducing tools from natural language semantics—ordering sources, dyadic modal operators, salient alternatives, and the like—into a formal semantics for an imperative object language? How much leverage can we gain by introducing tools from rather less-utilized areas of modal logic—devices for representing actions and planning in time, modal operators constructed from action-terms, and the like—into the analysis? -/- DYNAMIC. How do imperatives succeed in performing the speech acts they are used to perform? How do imperatives update discourses? How can we leverage an account of imperative discourse update in giving a dynamic semantics for the imperative? Is there anything about the imperative that demands a dynamic semantic treatment? (shrink)

Future Logic is an original, and wide-ranging treatise of formal logic. It deals with deduction and induction, of categorical and conditional propositions, involving the natural, temporal, extensional, and logical modalities. Traditional and Modern logic have covered in detail only formal deduction from actual categoricals, or from logical conditionals (conjunctives, hypotheticals, and disjunctives). Deduction from modal categoricals has also been considered, though very vaguely and roughly; whereas deduction from natural, temporal and extensional forms of conditioning has been all (...) but totally ignored. As for induction, apart from the elucidation of adductive processes (the scientific method), almost no formal work has been done. This is the first work ever to strictly formalize the inductive processes of generalization and particularization, through the novel methods of factorial analysis, factor selection and formula revision. This is the first work ever to develop a formal logic of the natural, temporal and extensional types of conditioning (as distinct from logical conditioning), including their production from modal categorical premises. Future Logic contains a great many other new discoveries, organized into a unified, consistent and empirical system, with precise definitions of the various categories and types of modality (including logical modality), and full awareness of the epistemological and ontological issues involved. Though strictly formal, it uses ordinary language, wherever symbols can be avoided. Among its other contributions: a full list of the valid modal syllogisms (which is more restrictive than previous lists); the main formalities of the logic of change (which introduces a dynamic instead of merely static approach to classification); the first formal definitions of the modal types of causality; a new theory of class logic, free of the Russell Paradox; as well as a critical review of modern metalogic. But it is impossible to list briefly all the innovations in logical science — and therefore, epistemology and ontology — this book presents; it has to be read for its scope to be appreciated. (shrink)

Arguments have always played a central role within logic and philosophy. But little attention has been paid to arguments as a distinctive kind of discourse, with its own semantics and pragmatics. The goal of this essay is to study the mechanisms by means of which we make arguments in discourse, starting from the semantics of argument connectives such as `therefore'. While some proposals have been made in the literature, they fail to account for the distinctive anaphoric behavior of `therefore', (...) as well as uses of argument connectives in complex arguments, suppositional arguments, arguments with non-declarative conclusions, as well as arguments with parenthetical remarks. A comprehensive account of arguments requires imposing a distinctive tree-like structure on contexts. We show how to extend our account to accommodate modal subordination and and di fferent flavors of `therefore'. (shrink)

Experts in Artificial Intelligence (AI) development predict that advances in the dvelopment of intelligent systems and agents will reshape vital areas in our society. Nevertheless, if such an advance isn't done with prudence, it can result in negative outcomes for humanity. For this reason, several researchers in the area are trying to develop a robust, beneficial, and safe concept of artificial intelligence. Currently, several of the open problems in the field of AI research arise from the difficulty of avoiding unwanted (...) behaviors of intelligent agents, and at the same time specifying what we want such systems to do. It is of utmost importance that artificial intelligent agents have their values aligned with human values, given the fact that we cannot expect an AI to develop our moral preferences simply because of its intelligence, as discussed in the Orthogonality Thesis. Perhaps this difficulty comes from the way we are addressing the problem of expressing objectives, values, and ends, using representational cognitive methods. A solution to this problem would be the dynamic cognitive approach proposed by Dreyfus, whose phenomenological philosophy defends that the human experience of being-in-the-world cannot be represented by the symbolic or connectionist cognitive methods. A possible approach to this problem would be to use theoretical models such as SED (situated embodied dynamics) to address the values learning problem in AI. (shrink)

This paper examines three accounts of the sleeping beauty case: an account proposed by Adam Elga, an account proposed by David Lewis, and a third account defended in this paper. It provides two reasons for preferring the third account. First, this account does a good job of capturing the temporal continuity of our beliefs, while the accounts favored by Elga and Lewis do not. Second, Elga’s and Lewis’ treatments of the sleeping beauty case lead to highly counterintuitive consequences. The proposed (...) account also leads to counterintuitive consequences, but they’re not as bad as those of Elga’s account, and no worse than those of Lewis’ account. (shrink)

When discussing the general inertia in climate change mitigation, it is common to approach the analysis either in terms of epistemic obstacles (climate change is too scientifically complex to be fully understood by all in its dramatic nature and/or to find space in the media) and/or moral obstacles (the causal link between polluting actions and social damage is too loose, both geographically and temporally, to allow individuals to understand the consequences of their emissions). In this chapter I maintain that both (...) categories of obstacles now play a secondary role: many people have a clear understanding of the physical and social dynamics involved in climate change. The main reason why so few manage to reduce their ecological footprint is an ethical short-circuit that does not allow most people to reveal their “true” climate-related preferences in their daily choices. This short-circuit manifests itself in two phenomena that can be analysed through the lens of moral psychology. First, as the possibility of anticipated utility approaches, individuals further discount expected future utility and may even reverse their preferences (due to the so-called immediacy multiplier, in addition to the better known and discussed future utility discounting). Second, individuals struggle to order their preferences transitively when presented with the opportunity to obtain small net marginal utilities in the short run. The intertemporal and collective structure of the climate problem creates fertile ground for both phenomena, which means that even those who are sincerely convinced of the need to contribute to climate change mitigation end up trapped in loops of procrastination, both first and second level. If, however, we can understand the origin of these phenomena, then we will be able to devise counteracting solutions that will speed up individual mitigation efforts. I will therefore briefly propose three ethical/public strategies to break the procrastination loop: pre-commitment; increasing the costs of marginal postponements; reducing the disutility of action that is likely to be postponed. (shrink)