We take a logical approach to threshold models, used to study the diffusion of opinions, new technologies, infections, or behaviors in social networks. Threshold models consist of a network graph of agents connected by a social relationship and a threshold value which regulates the diffusion process. Agents adopt a new behavior/product/opinion when the proportion of their neighbors who have already adopted it meets the threshold. Under this diffusion policy, threshold models develop dynamically towards a guaranteed fixed point. We construct a (...) minimal dynamic propositional logic to describe the threshold dynamics and show that the logic is sound and complete. We then extend this framework with an epistemic dimension and investigate how information about more distant neighbors’ behavior allows agents to anticipate changes in behavior of their closer neighbors. Overall, our logical formalism captures the interplay between the epistemic and social dimensions in social networks. (shrink)

We address the old question whether a logical understanding of Quantum Mechanics requires abandoning some of the principles of classical logic. Against Putnam and others (Among whom we may count or not E. W. Beth, depending on how we interpret some of his statements), our answer is a clear "no". Philosophically, our argument is based on combining a formal semantic approach, in the spirit of E. W. Beth's proposal of applying Tarski's semantical methods to the analysis of physical theories, with (...) an empirical-experimental approach to Logic, as advocated by both Beth and Putnam, but understood by us in the view of the operationalrealistic tradition of Jauch and Piron, i. e. as an investigation of "the logic of yes-no experiments" (or "questions"). Technically, we use the recently-developed setting of Quantum Dynamic Logic (Baltag and Smets 2005, 2008) to make explicit the operational meaning of quantum-mechanical concepts in our formal semantics. Based on our recent results (Baltag and Smets 2005), we show that the correct interpretation of quantum-logical connectives is dynamical, rather than purely propositional. We conclude that there is no contradiction between classical logic and (our dynamic reinterpretation of) quantum logic. Moreover, we argue that the Dynamic-Logical perspective leads to a better and deeper understanding of the "non-classicality" of quantum behavior than any perspective based on static Propositional Logic. (shrink)

Stalnaker, 169–199 2006) introduced a combined epistemic-doxastic logic that can formally express a strong concept of belief, a concept of belief as ‘subjective certainty’. In this paper, we provide a topological semantics for belief, in particular, for Stalnaker’s notion of belief defined as ‘epistemic possibility of knowledge’, in terms of the closure of the interior operator on extremally disconnected spaces. This semantics extends the standard topological interpretation of knowledge with a new topological semantics for belief. We prove that the belief (...) logic KD45 is sound and complete with respect to the class of extremally disconnected spaces and we compare our approach to a different topological setting in which belief is interpreted in terms of the derived set operator. We also study belief revision as well as belief dynamics by providing a topological semantics for conditional belief and belief update modalities, respectively. Our setting based on extremally disconnected spaces, however, encounters problems when extended with dynamic updates. We then propose a solution consisting in interpreting belief in a similar way based on hereditarily extremally disconnected spaces, and axiomatize the belief logic of hereditarily extremally disconnected spaces. Finally, we provide a complete axiomatization of the logic of conditional belief and knowledge, as well as a complete axiomatization of the corresponding dynamic logic. (shrink)

We present a complete, decidable logic for reasoning about a notion of completely trustworthy evidence and its relations to justifiable belief and knowledge, as well as to their explicit justifications. This logic makes use of a number of evidence-related notions such as availability, admissibility, and “goodness” of a piece of evidence, and is based on an innovative modification of the Fitting semantics for Artemovʼs Justification Logic designed to preempt Gettier-type counterexamples. We combine this with ideas from belief revision and awareness (...) logics to provide an account for explicitly justified knowledge based on conclusive evidence that addresses the problem of omniscience. (shrink)

Since Kaplan : 81–98, 1979) first provided a logic for context-sensitive expressions, it has been thought that the only way to construct a logic for indexicals is to restrict it to arguments which take place in a single context— that is, instantaneous arguments, uttered by a single speaker, in a single place, etc. In this paper, I propose a logic which does away with these restrictions, and thus places arguments where they belong, in real world conversations. The central innovation is (...) that validity depends not just on the sentences in the argument, but also on certain abstract relations between contexts. This enrichment of the notion of logical form leads to some seemingly counter-intuitive results: a sequence of sentences may make up a valid argument in one sequence of contexts, and an invalid one in another such sequence. I argue that this is an unavoidable result of context sensitivity in general, and of the nature of indexicals in particular, and that reflection on such examples will lead us to a better understanding of the idea of applying logic to context sensitive expressions, and thus to natural language in general. (shrink)

In this article I aim to provide the first normative discussion of barter voting markets, namely markets which allow the trading of votes on issues/elections for votes on other issues/elections. The article is framed within the wider literature on the legal permissibility of vote buying, with a particular focus on the recent debate between Christopher Freiman and James Stacey Taylor. I argue that while Taylor's objections successfully defeat Freiman's case in favour of standard voting markets, they are unable to also (...) defeat the type of voting markets outlined here. Furthermore, I argue that there are at least two plausible prima facie reasons in favour of barter voting markets, grounded in their capacity to contribute to the alleviation of injustice for systematically disadvantaged socio‐economic groups and to their capacity to reduce one form of bad voting, i.e. voting from ignorance. (shrink)

We construct logical languages which allow one to represent a variety of possible types of changes affecting the information states of agents in a multi-agent setting. We formalize these changes by defining a notion of epistemic program. The languages are two-sorted sets that contain not only sentences but also actions or programs. This is as in dynamic logic, and indeed our languages are not significantly more complicated than dynamic logics. But the semantics is more complicated. In general, the semantics of (...) an epistemic program is what we call aprogram model. This is a Kripke model of ‘actions’,representing the agents' uncertainty about the current action in a similar way that Kripke models of ‘states’ are commonly used in epistemic logic to represent the agents' uncertainty about the current state of the system. Program models induce changes affecting agents' information, which we represent as changes of the state model, called epistemic updates. Formally, an update consists of two operations: the first is called the update map, and it takes every state model to another state model, called the updated model; the second gives, for each input state model, a transition relation between the states of that model and the states of the updated model. Each variety of epistemic actions, such as public announcements or completely private announcements to groups, gives what we call an action signature, and then each family of action signatures gives a logical language. The construction of these languages is the main topic of this paper. We also mention the systems that capture the valid sentences of our logics. But we defer to a separate paper the completeness proof. (shrink)

In this paper I aim to examine some problematic implications of the fact that individuals are prone to making systematic reasoning errors, for resource egalitarianism. I begin by disentangling the concepts of preferences, choices and ambitions, which are sometimes used interchangeably by egalitarians. Subsequently, I claim that the most plausible interpretation of resource egalitarianism takes preferences, not choices, as the site of responsibility. This distinction is salient, since preference-sensitive resource egalitarianism is faced with an important objection when applied to situations (...) in which the empirically reasonable assumption that individuals have different degrees of computational abilities is introduced. I first show that this objection can be raised in cases involving individuals who have incomplete information, but that it ultimately fails for such cases since we can appeal to higher order insurance markets in order to mitigate any initial concerns. I further claim, however, that the objection is much more powerful in cases involving individuals who have different reasoning skills, since the appeal to higher order insurance markets is no longer tenable. Consequently, the ideal principle of justice proposed by Dworkin is met with a new feasibility challenge. Finally, I claim that the problem of reasoning errors and various forms of cognitive biases also affect Dworkin’s non-ideal principle of justice, skewing the outputs of the hypothetical insurance mechanism in an unjustifiable manner. (shrink)

In this paper, I propose a new way to distinguish between indexicals, like “I” and “today”, and demonstratives, like “she” and “this”. The main test case is the second person singular pronoun “you”. The tradition would generally count it as a demonstrative, because the speaker’s intentions play a role in providing it with a semantic value. I present cross-linguistic data and explanations offered of the data in typology and semantics to show that “you” belongs on the indexical side, and argue (...) that they can be generalized to a novel criterion for distinguishing between indexicals and demonstratives. The central theoretical claim is that the semantic values of indexicals are objects which play certain utterance-related roles, which are fixed independently of the words being used in the utterance. For instance, the speaker plays the speaker role whether or not she uses the word “I”, and the addressee plays that role whether or not the speaker uses the word “you”. Demonstratives, on the other hand, pick out objects that play no such role, and are instead helped by the speaker’s word-specific intentions. (shrink)

It is now well-established that physical activity has positive effects on both physical and mental health. However, the influence of organized physical activity on school adaptive behavior of adolescents with disabilities and/or behavioral disorders remains unclear. School behavior adaptation involves the ability to learn, conform to school norms and manage school activities without major behavior conflicts. A cross-sectional study was conducted to test the differences between organized physical activity and non-organized physical activity in an after school program. Eighty Romanian adolescents (...) were recruited and allocated to three groups: with disabilities [Ds; N = 17, Mage = 14.55 years, 12 males and 5 females], with conduct disorders [CDs, N = 21, Mage = 14.52 years 16 males and 5 females], and participants who had not shown signs of conduct disorders or disabilities [as a control group; N = 42, Mage = 14.2 years 20 males and 22 females]. Personality traits, school behavior, and sensorimotor coordination were assessed by using the Eysenck personality questionnaire—junior scale, school in-adaptability questionnaire scale, and Vienna Test System Sport respectively. Multivariate analysis of variance MANOVA and discriminant analysis were used to examine differences between the psychological and sensorimotor coordination outcomes across three groups and three types of physical activity context: organized physical activity, non-organized physical activity, and no physical activity. The findings indicate that not participating in an organized physical activity program results in a reduced level of physical mobility and consequently is associated with maladaptive social and psychological outcomes. Thus, we argued that attending in an organized physical activity program is more beneficial for participants with disabilities and/or behavior disorders, due to an increase in the probability of school integration and development of their motor skills. Clearly more research is needed in order to investigate these effects in neurophysiological levels. (shrink)

Many intergovernmental organizations have recently established offices of internal oversight. Yet scandals have revealed serious flaws in the design of these institutions. This study argues that this is due, in great part, to the initial use of an imperfect domestic model.

In this paper we aim to examine a novel view on distributive justice, i.e. limitarianism, which claims that it is morally impermissible to be rich. Our main goal is to assess the two arguments provided by Ingrid Robeyns in favour of limitarianism, namely the democratic argument and the argument from unmet urgent needs and the two distinct limitarian views which these arguments give rise to. We claim that strong limitarianism, which is supported by the democratic argument, should be rejected as (...) it fails to fully instantiate the value of political equality, while having some other unattractive implications as well. By contrast, we argue that weak limitarianism, which is supported by the argument from unmet urgent needs, should be endorsed, albeit in a qualified version which also takes responsibility constraints into consideration. (shrink)

We investigate the discrete (finite) case of the Popper–Renyi theory of conditional probability, introducing discrete conditional probabilistic models for knowledge and conditional belief, and comparing them with the more standard plausibility models. We also consider a related notion, that of safe belief, which is a weak (non-negatively introspective) type of “knowledge”. We develop a probabilistic version of this concept (“degree of safety”) and we analyze its role in games. We completely axiomatize the logic of conditional belief, knowledge and safe belief (...) over conditional probabilistic models. We develop a theory of probabilistic dynamic belief revision, introducing probabilistic “action models” and proposing a notion of probabilistic update product, that comes together with appropriate reduction laws. (shrink)

The goal of this paper is to present a collection of properties of the set of atoms and the set of finite injective tuples of atoms, as well as of the powersets of atoms in the framework of finitely supported structures. Some properties of atoms are obtained by translating classical Zermelo–Fraenkel results into the new framework, but several important properties are specific to finitely supported structures.

We present a semantic analysis of the Ramsey test, pointing out its deep underlying flaw: the tension between the “static” nature of AGM revision (which was originally tailored for revision of only purely ontic beliefs, and can be applied to higher-order beliefs only if given a “backwards-looking” interpretation) and the fact that, semantically speaking, any Ramsey conditional must be a modal operator (more precisely, a dynamic-epistemic one). Thus, a belief about a Ramsey conditional is in fact a higher-order belief, hence (...) the AGM revision postulates are not applicable to it, except in their “backwards-looking” interpretation. But that interpretation is consistent only with a restricted (weak) version of Ramsey’s test (in-applicable to already revised theories). The solution out of the conundrum is twofold: either accept only the weak Ramsey test; or replace the AGM revision operator ∗ by a truly “dynamic” revision operator ⊗, which will not satisfy the AGM axioms, but will do something better: it will “keep up with reality”, correctly describing revision with higher-order beliefs. (shrink)

The value in Hartmann’s point of view can be watched from the perspective of some heteronymous plans - an ideal one, which would be “the modality of existence”, and a real one, which would be “the modality of knowing” the value. In Hartmann’s expression we deal with “the absolute character” 1 of values and “the apriority of knowing the values”. It’s interfering here the problem of the validity of values. The question is if the existence of values is reduced to (...) their validity, or if they exist without the dependence of the real states of the world. This validity, for Hartmann, is strictly referring to the second plan, the real one, which is dealing with values. The values are valid “for” – we have here the connection with the existing- but they have their own “world” beside this nip with reality that we call unbiased 2 . The validity of value is aprioristic, no matter the appreciation - like one “pure subjective”, arbitrary - the apriority of value is not depending of some constrain and converge at the level of the logical schemes of thinking. In the general conception of Hartmann’s philosophy the problem of value is diminishing in the analysis of the distinction between the theory of knowledge plan, which is aiming at the subject-object domain, and the ontological one, represented by the relation objective - trans-objective. Although the philosophical analysis will be done from the perspective of the theory of knowledge domain of the relation subject-object, the problem that will concern mostly Hartman will be the objective - trans-objective report seen from the angle of one “critic ontology”, trying to solve the problem of the report between general and specific in the way of being of the axiological structure. (shrink)

The present article represents an attempt to argue in the favor of the thesis that, in the First Meditation, in the fragment where the problem of madness is spoken of, Descartes’ view aims to exclude the possibility that the knowing subject, the Cogito, could be insane, and not only to avoid the problem of madness because of various reasons or to replace the madness-example with a dreaming-example. In other words, this research aims to expose and to argue for Michel Foucault’s (...) point of view regarding the Cartesian problem of madness, and also to argue against Jacques Derrida’s view on the same issue. More broadly speaking, beyond the highlight of a possible different approach to Descartes’ text or the analysis of the Derrida-Foucault controversy, the main aim of this article is to emphasize a problem maybe less discussed of the act of knowing: beyond the proper usage of a wrong method, the misusage of a correct method or the poor practice of some spiritual exercises, the errors in the act of knowledge could as well follow from a deficiency in the knowing subject itself. (shrink)

Résumé Des artistes roumains se rassemblent pour collaborer, dans leur pratique indissociablement artistique et politique, mais aussi bien au-delà. À travers leurs forces collectives, ils peuvent mieux résister contre le contrôle des forces de polices qui occupent tout espace d’organisation. Le collectif les aide aussi à voir en quoi l’amitié est aujourd’hui une valeur éminemment politique.

This paper presents a simple decidable logic of functional dependence LFD, based on an extension of classical propositional logic with dependence atoms plus dependence quantifiers treated as modalities, within the setting of generalized assignment semantics for first order logic. The expressive strength, complete proof calculus and meta-properties of LFD are explored. Various language extensions are presented as well, up to undecidable modal-style logics for independence and dynamic logics of changing dependence models. Finally, more concrete settings for dependence are discussed: continuous (...) dependence in topological models, linear dependence in vector spaces, and temporal dependence in dynamical systems and games. (shrink)

This paper aims to show that there is a lot of philosophy in the philosophy of chemistry—not only in the problems and questions specific to chemistry, which this science brings up in philosophical discussions, but also in the topics of wider interest like reductionism and emergence, for which chemistry proves to be an ideal case study. The fact that chemical entities and properties are amenable to a quantitative understanding, to measurement and experiment to a greater extent than those in psychology (...) or biology, makes chemistry an ideal case study for those interested in reductionism and emergence. (shrink)

Standard accounts of democratic disenfranchisement either start from a presumption of universal inclusion and justify electoral exclusions as deviations from the norm, or attempt to draw a demarcation line between justifiable inclusion and exclusion relying on membership in the political community. Even when successfully employed, each strategy only provides a partial view of disenfranchisement, which is usually targeted at just one or two groups of agents. In this article, I develop a generally applicable account of disenfranchisement, grounded in a respect-based (...) understanding of the relational value of democracy. This account simultaneously provides the normative basis for widespread enfranchisement under equal terms and for justified electoral exclusions. (shrink)

In the wake of 9/11 and the assessment of Iraq's WMD, several inquiries placed the blame primarily on the Intelligence Community. Part of the reform that followed was a codification of analytic tradecraft standards into Intelligence Community Directive (ICD) 203 and the appointment of an analytic ombudsman in the newly created Office of the Director of National Intelligence charged with monitoring the quality of analytic products from across the intelligence community. In this paper we identify three assumptions behind ICD203: (1) (...) tradecraft standards can be employed consistently; (2) tradecraft standards sufficiently capture the key elements of good reasoning; (3) good reasoning leads to more accurate judgments. We then report on two controlled experiments that uncover operational constraints in the reliable application of the ICD203 criteria for the assessment of intelligence products. Despite criticisms of the post-9/11 and post-Iraq reform, our results highlight that ICD203, properly applied, holds potential to improve precision and accountability of intelligence processes and products. (shrink)

We formalise a notion of dynamic rationality in terms of a logic of conditional beliefs on (doxastic) plausibility models. Similarly to other epistemic statements (e.g. negations of Moore sentences and of Muddy Children announcements), dynamic rationality changes its meaning after every act of learning, and it may become true after players learn it is false. Applying this to extensive games, we “simulate” the play of a game as a succession of dynamic updates of the original plausibility model: the epistemic situation (...) when a given node is reached can be thought of as the result of a joint act of learning (via public announcements) that the node is reached. We then use the notion of “stable belief”, i.e. belief that is preserved during the play of the game, in order to give an epistemic condition for backward induction: rationality and common knowledge of stable belief in rationality. This condition is weaker than Aumann’s and compatible with the implicit assumptions (the “epistemic openness of the future”) underlying Stalnaker’s criticism of Aumann’s proof. The “dynamic” nature of our concept of rationality explains why our condition avoids the apparent circularity of the “backward induction paradox”: it is consistent to (continue to) believe in a player’s rationality after updating with his irrationality. (shrink)

This book is a puzzle inspired by the fresh, colourful rolling landscapes of Gruyère, where a wise man once asked me, “Does the castle over the mountain exist if nobody sees it?” “Yes,” I answered, “as we have all learned that what we know is not always what reality is.” We agree that theoretical ‘knowledge’ needs practical confirmation within reality. But what if we find reality in its very essence, intelligence or knowledge, as Neoplatonists did? The unknown would become unreal, (...) void. When investigating the existence of a cause of all things—the One origin—Damascius, the last head of Plato’s Academy (which closed in 529), writes about its complete ineffability: its lack of position and absence in relation to reality, whether intelligible or not. This void is further reversed into a theoretical framework that defines causality as a global, systemic condition of the world as a whole.About the author: Alexandru Pelin is a philosopher and cyber security professional. (shrink)

The past decade or so has witnessed an increase in the number of philosophical discussions about emergence and reduction in science. However, many of these discussions (though not all) remain too abstract and theoretical, and are wanting with respect to concrete examples taken from the sciences. This dissertation studies the topics of reduction and emergence in the context of a case study. I focus on the case of chemistry and investigate how emergentism can help us secure the autonomy of this (...) discipline in relation to the underlying microphysics. I develop an account of emergence (called functional emergence) that is, I argue, capable of answering the question of why we have chemistry instead of just applied quantum mechanics. I argue that functionally emergent properties in chemistry -- properties that are defined by their behaviour, not by some shared microphysical constituent -- can help us defend the autonomy of chemistry; they allow for the existence of sui generis chemical regularities, which can be used in sui generis chemical explanations. Functional emergence generates difficulties for some accounts of inter-theoretic reduction, but unlike other theories of emergence it is compatible with weaker forms of reductionism. (shrink)

In this annotated critical edition of Aristotle’s _Metaphysics_ Lambda Stefan Alexandru draws upon many hitherto unexplored sources of the direct and indirect tradition, _inter alia_ upon an independent Greek manuscript he has discovered in the Vatican Library.

We investigate the process of truth-seeking by iterated belief revision with higher-level doxastic information . We elaborate further on the main results in Baltag and Smets (Proceedings of TARK, 2009a , Proceedings of WOLLIC’09 LNAI 5514, 2009b ), applying them to the issue of convergence to truth . We study the conditions under which the belief revision induced by a series of truthful iterated upgrades eventually stabilizes on true beliefs. We give two different conditions ensuring that beliefs converge to “full” (...) (complete) truth , as well as a condition ensuring only that they converge to true (but not necessarily complete) beliefs. (shrink)

In this paper, we investigate the social herding phenomenon known as informational cascades, in which sequential inter-agent communication might lead to epistemic failures at group level, despite availability of information that should be sufficient to track the truth. We model an example of a cascade, and check the correctness of the individual reasoning of each agent involved, using two alternative logical settings: an existing probabilistic dynamic epistemic logic, and our own novel logic for counting evidence. Based on this analysis, we (...) conclude that cascades are not only likely to occur but are sometimes unavoidable by "rational" means: in some situations, the group’s inability to track the truth is the direct consequence of each agent’s rational attempt at individual truth-tracking. Moreover, our analysis shows that this is even so when rationality includes unbounded higher-order reasoning powers, as well as when it includes simpler, non-Bayesian forms of heuristic reasoning. (shrink)

In this paper we show how ideas coming from two areas of research in logic can reinforce each other. The first such line of inquiry concerns the "dynamic turn" in logic and especially the formalisms inspired by Propositional Dynamic Logic (PDL); while the second line concerns research into the logical foundations of Quantum Physics, and in particular the area known as Operational Quantum Logic, as developed by Jauch and Piron (Helve Phys Acta 42: 842-848, 1969), Pirón (Foundations of Quantum Physics, (...) 1976). By bringing these areas together we explain the basic ingredients of Dynamic Quantum Logic, a new direction of research in the logical foundations of physics. (shrink)

This paper raises some concerns about Paul Humphreys’ fusion emergence in general and about his core example of fusion emergence (i.e., covalent bonding) in particular. It argues that the extent to which covalent bonding undermines the idea that our world’s ontology is wholly compositional has been overstated.

In this article I aim to offer a first critical assessment of the most prominent arguments in favour of restricting the voting rights of senior citizens. The first argument discussed, most thoroughly articulated by van Parijs, maintains that intergenerational justice would be improved under schemes which restrict the voting rights of senior citizens, thereby diminishing their overall electoral weight. The second argument, reconstructed from Lau's defence of child enfranchisement, maintains that the cognitive decline associated with the process of aging should (...) lead us to treat children and senior citizens identically in respect to electoral rights; thus, if we agree that children should not have the right to vote, consistency dictates that senior citizens should be disenfranchised as well. I respond to these arguments with several objections, arguing that the former relies on a number of faulty empirical premises and has deeply unattractive implications for enfranchisement once consistently applied, and that the latter fails to make empirically salient distinctions between children and senior citizens when it comes to the political domain. (shrink)