•  64
    The paper studies first order extensions of classical systems of modal logic (see (Chellas, 1980, part III)). We focus on the role of the Barcan formulas. It is shown that these formulas correspond to fundamental properties of neighborhood frames. The results have interesting applications in epistemic logic. In particular we suggest that the proposed models can be used in order to study monadic operators of probability (Kyburg, 1990) and likelihood (Halpern-Rabin, 1987).
  •  16
    This special issue presents a series of articles focusing on recent work in formal epistemology and formal philosophy. The articles in the latter category elaborate on the notion of context and content and their relationships. This work is not unrelated to recent developments in formal epistemology. Logical models of context, when connected with the representation of epistemic context, are clearly relevant for many issues considered by formal epistemologists. For example, the semantic framework …Read more
  • Quantified Modal Logic
    Journal of the Indian Council of Philosophical Research 27 (2). 2010.
    The chapter is divided in two parts. The first part gives an introduction to issues in quantified modal logic . We provide an overview of recent work in QML and we presuppose the use of a relational semantics. We discuss models for constant domains, increasing domains and varying domains and present axiomatizations for the corresponding logics. We also discuss philosophical issues related to the interpretation of the quantifiers, terms and identity and we present a first-order quantified intensi…Read more
  •  25
    Consider a rational agent X at certain point of time t. X's epistemic state can be represented in different ways
  •  18
    Contextual Modals
    with William Taysom
    In a series of recent articles Angelika Kratzer has argued that the standard account of modality along Kripkean lines is inadequate in order to represent context-dependent modals. In particular she argues that the standard account is unable to deliver a non-trivial account of modality capable of overcoming inconsistencies of the underlying conversational background
  •  135
    Daniel Ellsberg presented in Ellsberg (The Quarterly Journal of Economics 75:643–669, 1961) various examples questioning the thesis that decision making under uncertainty can be reduced to decision making under risk. These examples constitute one of the main challenges to the received view on the foundations of decision theory offered by Leonard Savage in Savage (1972). Craig Fox and Amos Tversky have, nevertheless, offered an indirect defense of Savage. They provided in Fox and Tversky (1995) a…Read more
  •  17
    Building on work that we reported at ISIPTA 2005 we revisit claims made by Fox and Tversky concerning their "comparative ignorance" hypothesis for decision making under uncertainty
  •  104
    Iterative probability kinematics
    Journal of Philosophical Logic 30 (5): 479-524. 2001.
    Following the pioneer work of Bruno De Finetti [12], conditional probability spaces (allowing for conditioning with events of measure zero) have been studied since (at least) the 1950's. Perhaps the most salient axiomatizations are Karl Popper's in [31], and Alfred Renyi's in [33]. Nonstandard probability spaces [34] are a well know alternative to this approach. Vann McGee proposed in [30] a result relating both approaches by showing that the standard values of infinitesimal probability function…Read more
  •  45
    Gerd Gigerenzer and Thomas Sturm have recently proposed a modest form of what they describe as a normative, ecological and limited naturalism. The basic move in their argument is to infer that certain heuristics we tend to use should be used in the right ecological setting. To address this argument, we first consider the case of a concrete heuristic called Take the Best (TTB). There are at least two variants of the heuristic which we study by making explicit the choice functions they induce, ext…Read more
  •  23
    It is now well known that, on pain of triviality, the probability of a conditional cannot be identified with the corresponding conditional probability [27]. This surprising impossibility result has a qualitative counterpart. In fact, Peter Gardenfors showed in [13] that believing 'If A then B' cannot be equated with the act of believing B on the supposition that A
  •  156
    This article elaborates on foundational issues in the social sciences and their impact on the contemporary theory of belief revision. Recent work in the foundations of economics has focused on the role external social norms play in choice. Amartya Sen has argued in [Sen93] that the traditional rationalizability approach used in the theory of rational choice has serious problems accommodating the role of social norms. Sen's more recent work [Sen96, Sen97] proposes how one might represent social n…Read more
  •  24
    Let L be a language containing the modal operator B - for full belief. An information model is a set E of stable L-theories. A sentence is valid if it is accepted in all theories of every model
  •  130
      We present a decision-theoretically motivated notion of contraction which, we claim, encodes the principles of minimal change and entrenchment. Contraction is seen as an operation whose goal is to minimize loses of informational value. The operation is also compatible with the principle that in contracting A one should preserve the sentences better entrenched than A (when the belief set contains A). Even when the principle of minimal change and the latter motivation for entrenchment figure pro…Read more
  •  363
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  •  43
  •  32
    In (Hertwig et al. , 2003) Hertwig et al. draw a distinction between decisions from experience and decisions from description. In a decision from experience an agent does not have a summary description of the possible outcomes or their likelihoods. A career choice, deciding whether to back up a computer hard drive, cross a busy street, etc., are typical examples of decisions from experience. In such decisions agents can rely only of their encounters with the corresponding prospects. By contrast,…Read more
  •  19
    Recent work has shown that in spite of these negative results, the question 'how to accept a conditional?' has a clear answer. Even if conditionals are not truth-carriers, they do have precise acceptability conditions. Nevertheless most epistemic models of conditionals do not provide acceptance conditions for iterated conditionals. One of the main goals of this essay is to provide a comprehensive account of the notion of epistemic conditionality covering all forms of iteration.
  •  100
    The logic of conditionals
    Stanford Encyclopedia of Philosophy. 2007.
    entry for the Entry for the Stanford Encyclopedia of Philosophy, 2007.
  • Review (review)
    Theoria 73 (1): 87-93. 2007.
  •  96
    Journal of Philosophical Logic 34, 97-119, 2005.
  •  23
    Review of Vincent F. Hendricks, Mainstream and Formal Epistemology (review)
    Notre Dame Philosophical Reviews 2006 (7). 2006.
  •  69
    The paper provides a framework for representing belief-contravening hypotheses in games of perfect information. The resulting t-extended information structures are used to encode the notion that a player has the disposition to behave rationally at a node. We show that there are models where the condition of all players possessing this disposition at all nodes (under their control) is both a necessary and a sufficient for them to play the backward induction solution in centipede games. To obtain …Read more
  •  126
    First-order classical modal logic
    Studia Logica 84 (2). 2006.
    The paper focuses on extending to the first order case the semantical program for modalities first introduced by Dana Scott and Richard Montague. We focus on the study of neighborhood frames with constant domains and we offer in the first part of the paper a series of new completeness results for salient classical systems of first order modal logic. Among other results we show that it is possible to prove strong completeness results for normal systems without the Barcan Formula (like FOL + K)in …Read more