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 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)

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)

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)

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)

The classical rule of Repetition says that if you take any sentence as a premise, and repeat it as a conclusion, you have a valid argument. It's a very basic rule of logic, and many other rules depend on the guarantee that repeating a sentence, or really, any expression, guarantees sameness of referent, or semantic value. However, Repetition fails for token-reflexive expressions. In this paper, I offer three ways that one might replace Repetition, and still keep an interesting notion of (...) validity. Each is a fine way to go for certain purposes, but I argue that one in particular is to be preferred by the semanticist who thinks that there are token-reflexive expressions in natural languages. (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)

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)

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)

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)

In the context of the late modernity, Karl Rahner endeavoured to offer a theological solution to the current and complicated issue of the religious pluralism. What are the apriorical anthropological data of religions? Has God revealed Himself in a redeeming way also in the extra-biblical religions? Is it still possible to postulate a universal salvation way and an absolute religious truth? Is it possible to acknowledge other religions as ways of salvation and their prophets redeeming, at the same time calling (...) Christianity the religion of salvation and Jesus Christ absolute Saviour? What justification and what entitlement still has the Christian apostolate if salvation is possible also in the other religions? And what could animate an “anonymous Christian“ to wish to move from the implicit, anonymous belief, of which he is not aware, to the explicit one? In a world of religious diversity and „weak faith”, what strategies of “accommodation” and service should adopt “the little flock” to continue to be the soul of the world? Promoting a Christological-inclusivist perspective – according to which Christ is in the religions of the world and is their fulfillment, and not against or above them – and claiming the mystical apostolate of the good news of the universality of salvation, Rahner offered an answer to all these questions. His answer and the topicality of this answer are the subjects treated in this study. (shrink)

The present paper starts from the postulate that religion in general, and Christianity in particular, has had and continues to have a significant role in political debates and in the structuring of the public arena. Expounding – in the context of “God’s return” into the life of postsecular society – the vision of the famous theologian Joseph Ratzinger on democracy and its opponents, this paper also dwells on the manifestations of irrationality in secular religions. Finding its theoretical grounds in myths (...) and utopias, monism of power gives free rein to irrationality in history and ends up in ideology, totalitarianism and crime. Pluralistic democracy, so challenged by enemies from within as well as without can be defended and reinvigorated – and Europe alongside it –, Ratzinger states, by restoring Christianity and its values to their rightful place within the public sphere, by means of a fruitful collaboration between reason and faith in the cultural and political life, and by grounding the law in stable, universal ethical principles, which ought to take precedence over any other type of consensus, such as the natural moral law or the dictates of conscience. “The central concern of ecclesiastic policy”, according to pope Benedict XVI, is defending and promoting freedom, even to the point of martyrdom, by cultivating the dualism of power. (shrink)

We study the learning power of iterated belief revision methods. Successful learning is understood as convergence to correct, i.e., true, beliefs. We focus on the issue of universality: whether or not a particular belief revision method is able to learn everything that in principle is learnable. We provide a general framework for interpreting belief revision policies as learning methods. We focus on three popular cases: conditioning, lexicographic revision, and minimal revision. Our main result is that conditioning and lexicographic revision can (...) drive a universal learning mechanism, provided that the observations include only and all true data, and provided that a non-standard, i.e., non-well-founded prior plausibility relation is allowed. We show that a standard, i.e., well-founded belief revision setting is in general too narrow to guarantee universality of any learning method based on belief revision. We also show that minimal revision is not universal. Finally, we consider situations in which observational errors may occur. Given a fairness condition, which says that only finitely many errors occur, and that every error is eventually corrected, we show that lexicographic revision is still universal in this setting, while the other two methods are not. (shrink)

In this paper I show that Elga’s argument for a restricted principle of indifference for self-locating belief relies on the kind of mistaken reasoning that recommends the ‘staying’ strategy in the Monty Hall problem.

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)

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 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)

We formalise a notion of dynamic rationality in terms of a logic of conditional beliefs on plausibility models. Similarly to other epistemic statements, 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 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 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 believe in a player's rationality after updating with his irrationality. (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 logical calculus for reasoning about information flow in quantum programs. In particular we introduce a dynamic logic that is capable of dealing with quantum measurements, unitary evolutions and entanglements in compound quantum systems. We give a syntax and a relational semantics in which we abstract away from phases and probabilities. We present a sound proof system for this logic, and we show how to characterize by logical means various forms of entanglement (e.g. the Bell states) and various (...) linear operators. As an example we sketch an analysis of the teleportation protocol. (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)

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 a recent paper, Okasha imports Arrow’s impossibility theorem into the context of theory choice. He shows that there is no function (satisfying certain desirable conditions) from profiles of preference rankings over competing theories, models or hypotheses provided by scientific virtues to a single all-things-considered ranking. This is a prima facie threat to the rationality of theory choice. In this paper we show this threat relies on an all-or-nothing understanding of scientific rationality and articulate instead a notion of rationality by (...) degrees. The move from all-or-nothing rationality to rationality by degrees will allow us to argue that theory choice can be rational enough. (shrink)

This paper discusses the proposal made by Lombardi and Labarca (Found Chem 7:125–148, 2005) that internal realism can secure the ontological autonomy of chemistry. I argue that internal realism is not, by itself, sufficient to accomplish this task. The fact that conceptual schemes may differ with respect to their theoretical virtues, and the possibility that the relations between them may be reductive undermine the premise that each conceptual scheme has an equal right to define its own ontology, which is a (...) key premise in Lombardi and Labarca’s proposal. (shrink)

Public announcement logic is an extension of multiagent epistemic logic with dynamic operators to model the informational consequences of announcements to the entire group of agents. We propose an extension of public announcement logic with a dynamic modal operator that expresses what is true after any announcement: after which , does it hold that Kφ? We give various semantic results and show completeness for a Hilbert-style axiomatization of this logic. There is a natural generalization to a logic for arbitrary events.

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)

Kuhn argued that scientific theory choice is, in some sense, a rational matter, but one that is not fully determined by shared objective scientific virtues like accuracy, simplicity, and scope. Okasha imports Arrow’s impossibility theorem into the context of theory choice to show that rather than not fully determining theory choice, these virtues cannot determine it at all. If Okasha is right, then there is no function from ‘preference’ rankings supplied by scientific virtues over competing theories to a single all-things-considered (...) ranking. This threatens the rationality of science. In this paper we show that if Kuhn’s claims about the role that subjective elements play in theory choice are taken seriously, then the threat dissolves. (shrink)

The prospect of cognitive enhancement well beyond current human capacities raises worries that the fundamental equality in moral status of human beings could be undermined. Cognitive enhancement might create beings with moral status higher than persons. Yet, there is an expressibility problem of spelling out what the higher threshold in cognitive capacity would be like. Nicholas Agar has put forward the bold claim that we can show by means of inductive reasoning that indefinite cognitive enhancement will probably mark a difference (...) in moral status. The hope is that induction can determine the plausibility of post‐personhood existence in the absence of an account of what the higher status would be like. In this article, we argue that Agar's argument fails and, more generally, that inductive reasoning has little bearing on assessing the likelihood of post‐personhood in the absence of an account of higher status. We conclude that induction cannot bypass the expressibility problem about post‐persons. (shrink)

Although there has been steady progress elucidating the influence of emotion on cognition, it remains unclear precisely when and why emotion impairs or facilitates cognition. The present study investigated the mechanisms involved in the influence of emotion on perception and working memory, using modified 0-back and 2-back tasks, respectively. First, results showed that attentional focus modulated the impact of emotion on perception. Specifically, emotion facilitated perceptual task performance when it was relevant to the task, but it impaired performance when it (...) was irrelevant to the task. The differential behavioural effect of emotion on perception as a function of attentional focus diminished under high WM load. Second, attentional focus did not directly modulate the impact of emotion on WM, but rather its influence depended on the dynamic relationship between internal representations. Specifically, WM performance was worse when the material already being held online and the new input were of matching emotions, compared to when they were not. We propose that the competition between “bottom-up” and “top-down” processing for limited cognitive resources explains the nature of the influence of emotion on both perception and WM. (shrink)

The article conveys the portrait of a man for whom understanding was a matter of the highest spiritual intimacy, a man who continuously disregarded his possible engagement in the public life as a philosopher, finally a man whom we find, in the twilight of his life, concerned with the intricate tension between the “muteness” of philosophy (as being able “only” to double life by means of rational discourse) and religion. Alexandru Dragomir’s portrait is portrayed in comparison to another important (...) Romanian philosopher, Constantin Noica. The comparison is not accidental, since they both come to represent two paradigmatic ways of making philosophy: traditional ontology (centered around Descartes – Kant – Hegel) vs. modern phenomenology (centered around Husserl – Heidegger). (shrink)

According to the social contract theory, in order to achieve justice, people grouped themselves in societies. Historically speaking, judges appeared long before the legislator which means that justice was the first element of the social life. Therefore, it expresses the social ethics of a particular time and requires a minimum of credibility. Excessive pragmatism and utilitarianism have kidnapped more and more of what is humane, superior and sacred in the act of justice, and “secularized” it. As Eliade said in The (...) Sacred and the Profane, the sacred is something which is totally different, a space of radical otherness which overshadows the physical territory. This shading manifests itself through limitation, sequencing, reiteration and keeping what is sacred there, even in a courtroom, through ritualization. (shrink)

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)

Synonymy, at its most basic, is sameness of meaning. A token-reflexive expression is an expression whose meaning assigns a referent to its tokens by relating each particular token of that particular expression to its referent. In doing so, the formulation of its meaning mentions the particular expression whose meaning it is. This seems to entail that no two token-reflexive expressions are synonymous, which would constitute a strong objection against token-reflexive semantics. In this paper, I propose and defend a notion of (...) synonymy for token-reflexive expressions that allows such expressions to be synonymous, while being a fairly conservative extension of the customary notion of synonymy. (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.