To define new property terms, we combine already familiar ones by means of certain logical operations. Given suitable constraints, these operations may presumably include the resources of first-order logic: truth-functional sentence connectives and quantification over objects. What is far less clear is whether we can also use modal operators for this purpose. This paper clarifies what is involved in this question, and argues in favor of modal property definitions.

Many theories assimilate the idioms of modality to those of quantification; they hold that so-and-so is possible iff there is a "world" at which it is true that so-and-so. "Modal realism" identifies worlds with certain concrete particulars, and truth at a world with what is true of it. Rival "ersatz" theories identify worlds with certain abstract entities and identify what is true at them with what they represent. ;David Lewis argues that pre-theoretic modal intuitions are best explained by (...) modal realism. I try to make a case for ersatzism. ;First, I argue that modal realism is flawed on the grounds that it entails the impossibility of certain intuitively possible spatiotemporal structures; it fails to explain fully even those intuitions with which it is compatible; and it renders the origin of modal knowledge mysterious. ;Next, I argue that objections to ersatzism are not conclusive. ;Lewis objects that even a generic version of ersatzism requires an unnameable and maybe unintelligible primitive relation. I suggest that the problems with naming are perfectly general; they have nothing to do with metaphysical theories of modality in particular. And I suggest a solution taken from Lewis himself. I also argue that any purported unintelligibility is due to illegitimately assimilating the relation to spatiotemporal relations. ;Finally, I consider some difficulties with a version of ersatzism that aims to reduce modality to impure set-theory. One concerns the accommodation of intuitions about properties that are not, but might have been, instantiated. Another concerns accommodation of intuitions about relations of exclusion and entailment among properties. I suggest that these difficulties are due to faulty assumptions about the nature of properties rather than any fundamental flaws in this ersatz approach. So I propose an account of properties that when incorporated into ersatzism circumvents these difficulties and allows it to claim the advantages of modal realism without its drawbacks. Unlike traditional accounts, this takes the essence of a property to consist in its role in imposing a certain classificational structure on the particulars that instantiate it, rather than in any unique and irreducible "quiddity". (shrink)

Our purpose in this paper is to delineate an ontology for quantum mechanics that results adequate to the formalism of the theory. We will restrict our aim to the search of an ontology that expresses the conceptual content of the recently proposed modal-Hamiltonian interpretation, according to which the domain referred to by non-relativistic quantum mechanics is an ontology of properties. The usual strategy in the literature has been to focus on only one of the interpretive problems of the (...) theory and to design an interpretation to solve it, leaving aside the remaining difficulties. On the contrary, our aim in the present work is to formulate a “global” solution, according to which different problems can be adequately tackled in terms of a single ontology populated of properties, in which systems are bundles of properties. In particular, we will conceive indistinguishability between bundles as a relation derived from indistinguishability between properties, and we will show that states, when operating on combinations of indistinguishable bundles, act as if they were symmetric with no need of a symmetrization postulate. (shrink)

I investigate the character of the definite properties defined by the Basic Rule in the Vermaas and Dieks' (1995) version of the modal interpretation of quantum mechanics, specifically for the case of the continuous model of decoherence by Joos and Zeh (1985). While this model suggests that the characteristic length that might be associated with the localisation of an individual system is the coherence length of the state (which converges rapidly to the thermal de Broglie wavelength), I show (...) in an exactly soluble case that the definite properties that are possessed with overwhelming probability in this modal interpretation are delocalized over the entire spread of the state. (shrink)

The paper pinpoints certain unrecognized difficulties that surface for recombination and duplication in modal realism when we ask whether the following inter-world fixity claims hold true: 1) A property is perfectly natural in a world iff it is perfectly natural in every world where it is instantiated; 2) Something is mereologically atomic in a world iff all of its duplicates in every world are atomic. In connection to 1), the hypothesis of idlers prompts four variants of Lewis’s doctrine of (...) perfectly natural properties, all deemed unsatisfactory for the purposes of duplication and recombination. By means of 2), instead, we show that the principle of recombination does not countenance the atomicity or non-atomicity of duplicates; but it should, because it is genuinely possible that: a) something, which is atomic, is non-atomic; and b) something, which is non-atomic, is atomic. In discussing 1) and 2), the paper substantiates a tension in Lewis’s metaphysics between modal intuitions and the reliance on the natural sciences. (shrink)

We are concerned with modal logics in the class EM0 of extensions of M0 . G denotes re exive frames. MG the modal logic on G in the sense of Kripke. M is nite if M = MG for some nite G. Finite G's will be drawn as framed diagrams, e.g. G = ! ; G = ! ; the latter shorter denoted by . EM0 is a complete lattice with zero M0 and one M . If M (...) M0 M0 is a succ of M. An ip of M is an immediate predecessor of M. E.g. M ! and M are the only ip's of M in ES4. M[P] denotes the extension of M adding P as a \new axiom", e.g. S4 = M0 [p ! p]. M is nitely axiomatizable if M = M0 [P] for some formula P. One easily shows if M is f.a. then each predecessor is separated from M by an ip of M. It is known that each nite M is f.a. and has only nitely many succ's all of which are nite. (shrink)

This paper aims to build a bridge between two areas of philosophical research, the structure of kinds and metaphysical modality. Our central thesis is that kinds typically involve super-explanatory properties, and that these properties are therefore metaphysically essential to natural kinds. Philosophers of science who work on kinds tend to emphasize their complexity, and are generally resistant to any suggestion that they have “essences”. The complexities are real enough, but they should not be allowed to obscure the way (...) that kinds are typically unified by certain core properties. We shall show how this unifying role offers a natural account of why certain properties are metaphysically essential to kinds. (shrink)

In the framework of the topos approach to quantum mechanics we give a representation of physical properties in terms of modal operators on Heyting algebras. It allows us to introduce a classical type study of the mentioned properties.

The modal logic S4.2 is S4 with the additional axiom ◊□A ⊃ □◊A. In this article, the sequent calculus GS4.2 for this logic is presented, and by imposing an appropriate restriction on the application of the cut-rule, it is shown that, every GS4.2-provable sequent S has a GS4.2-proof such that every formula occurring in it is either a subformula of some formula in S, or the formula □¬□B or ¬□B, where □B occurs in the scope of some occurrence of (...) □ in some formula of S. These are just the K5-subformulas of some formula in S which were introduced by us to show the modied subformula property for the modal logics K5 and K5D : 115–122, 2001). Some corollaries including the interpolation property for S4.2 follow from this. By slightly modifying the proof, the finite model property also follows. (shrink)

Our purpose in this paper is to delineate an ontology for quantum mechanics that results adequate to the formalism of the theory. We will restrict our aim to the search of an ontology that expresses the conceptual content of the recently proposed modal-Hamiltonian interpretation, according to which the domain referred to by non-relativistic quantum mechanics is an ontology of properties. The usual strategy in the literature has been to focus on only one of the interpretive problems of the (...) theory and to design an interpretation to solve it, leaving aside the remaining difficulties. On the contrary, our aim in the present work is to formulate a “global” solution, according to which different problems can be adequately tackled in terms of a single ontology populated of properties, in which systems are bundles of properties. In particular, we will conceive indistinguishability between bundles as a relation derived from indistinguishability between properties, and we will show that states, when operating on combinations of indistinguishable bundles, act as if they were symmetric with no need of a symmetrization postulate. (shrink)

The tangle modality is a propositional connective that extends basic modal logic to a language that is expressively equivalent over certain classes of finite frames to the bisimulation-invariant fragments of both first-order and monadic second-order logic. This paper axiomatises several logics with tangle, including some that have the universal modality, and shows that they have the finite model property for Kripke frame semantics. The logics are specified by a variety of conditions on their validating frames, including local and global (...) connectedness properties. Some of the results have been used to obtain completeness theorems for interpretations of tangled modal logics in topological spaces. (shrink)

This paper proposes a semantic description of the linear step-like temporal multi-agent logic with the universal modality \(\mathcal{LTK}.sl_U\) based on the idea of non-reflexive non-transitive nature of time. We proved a finite model property and projective unification for this logic.

This paper deals with the modal logics associated with (possibly nonstandard) provability predicates of Peano Arithmetic. One of our goals is to present some modal systems having the fixed point property and not extending the Gödel-Löb system GL. We prove that, for every has the explicit fixed point property. Our main result states that every complete modal logic L having the Craig's interpolation property and such that , where and are suitable modal formulas, has the explicit (...) fixed point property. (shrink)

Why is it that whenever a structural property is instantiated, its constituent properties are instantiated as well, by proper parts of the original object? By developing a suggestion from Lewis :25–46, 1986), Hawley :117–133, 2010) rises to this explanatory challenge by taking structural properties to be mereologically composed by their constituents, and by taking composition to be analogous to identity. However, setting up a plausible framework for composition and CAI claims about properties, I will argue that structural (...) properties are not identical to their constituents, at least not in any sense robust enough to warrant an Hawley-style argument—and perhaps not identical to them in any sense whatsoever. More generally, core principles of extensional mereology are in danger when applied to structural properties, which may force an extensionalist to either reconsider the application altogether, or reconsider mereological monism, thus granting the mereology of structural properties a peculiarly non-extensional status. Finally, although this debate has been traditionally framed as a debate about universals, an appeal to structural tropes can reconcile, at least to some extent, the mereology of structural properties with Lewisian extensional mereology— CAI included. (shrink)

Hans van Ditmarsch, Wiebe van der Hoek and Barteld Kooi (2011). Reasoning about local properties in modal logic. In K. Tumer and P. Yolum and L. Sonenberg and P. Stone (editors). Proceedings of the 10th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2011), pp. 711-718.

The first example of an intuitively meaningful propositional logic without the finite model property, and still the simplest one in the literature. The question of its decidability appears still to be open.

The main purpose of this paper is to give alternative proofs of syntactical and semantical properties, i.e. the subformula property and the nite model property, of the sequent calculi for the modal logics K4.3, KD4.3, and S4.3. The application of the inference rules is said to be acceptable, if all the formulas in the upper sequents are subformula of the formulas in lower sequent. For some modal logics, Takano analyzed the relationships between the acceptable inference rules and (...) semantical properties by constructing models. By using these relationships, he showed Kripke completeness and subformula property. However, his method is difficult to apply to inference rules for the sequent calculi for K4.3, KD4.3, and S4.3. Lookinglosely at Takano's proof, we nd that his method can be modied to construct nite models based on the sequent calculus for K4.3, if the calculus has and all the applications of the inference rules are acceptable. Similarly, we can apply our results to the calculi for KD4.3 and S4.3. This leads not only to Kripke completeness and subformula property, but also to finite model property of these logics simultaneously. (shrink)

We introduce and investigate the notion of uniform Lyndon interpolation property which is a strengthening of both uniform interpolation property and Lyndon interpolation property. We prove several propositional modal logics including \, \, \ and \ enjoy ULIP. Our proofs are modifications of Visser’s proofs of uniform interpolation property using layered bisimulations Gödel’96, logical foundations of mathematics, computer science and physics—Kurt Gödel’s legacy, Springer, Berlin, 1996). Also we give a new upper bound on the complexity of uniform interpolants for (...) \ and \. (shrink)

We systematically study several versions of the disjunction and the existence properties in modal arithmetic. First, we newly introduce three classes $\mathrm {B}$, $\Delta (\mathrm {B})$, and $\Sigma (\mathrm {B})$ of formulas of modal arithmetic and study basic properties of them. Then, we prove several implications between the properties. In particular, among other things, we prove that for any consistent recursively enumerable extension T of $\mathbf {PA}(\mathbf {K})$ with $T \nvdash \Box \bot $, the $\Sigma (...) (\mathrm {B})$ -disjunction property, the $\Sigma (\mathrm {B})$ -existence property, and the $\mathrm {B}$ -existence property are pairwise equivalent. Moreover, we introduce the notion of the $\Sigma (\mathrm {B})$ -soundness of theories and prove that for any consistent recursively enumerable extension of $\mathbf {PA}(\mathbf {K4})$, the modal disjunction property is equivalent to the $\Sigma (\mathrm {B})$ -soundness. (shrink)

LetL be one of the intuitionistic modal logics considered in [7] (or one of its extensions) and letM L be the “algebraic semantics” ofL. In this paper we will extend toL the equivalence, proved in the classical case (see [6]), among he weak Craig interpolation theorem, the Robinson theorem and the amalgamation property of varietyM L. We will also prove the equivalence between the Craig interpolation theorem and the super-amalgamation property of varietyM L. Then we obtain the Craig interpolation (...) theorem and Robinson theorem for two intuitionistic modal logics, one ofS 4-type and the other one ofS 5-type, showing the super-amalgamation property of the corresponding algebraic semantics. (shrink)

This paper deals with the system of modal logicGL, in particular with a formulation of it in terms of sequents. We prove some proof theoretical properties ofGL that allow to get the cut-elimination theorem according to Gentzen's procedure, that is, by double induction on grade and rank.

A restriction of R-Mingle with the variable-sharing property and the Ackermann properties is defined. From an intuitive semantical point of view, this restriction is an alternative to Anderson and Belnap’s logic of entailment E.

Let L be one of the intuitionistic modal logics considered in [4]. As in the classical modal case (see [7]), we define two different forms of the Beth property for L, which are denoted by B 1 and B 2 ; in this paper we study the relation among B 1 ,B 2 and the interpolation properties C 1 and C 2 , introduced in [4]. It turns out that C 1 implies B 1 , but contrary (...) to the boolean case, is not equivalent to B 1 . It is shown that B 2 and C 2 are independent, and moreover it comes out that, in contrast to classical case, there exists an extension of the intuitionistic modal logic of S 4 -type, that has not the property B 2 . Finally we give two algebraic properties, that characterize respectively B 1 and B 2. (shrink)

Physicalists about the mind are committed to claims about property identities. Following Kripke's well-known discussion, modal arguments have emerged as major threats to such claims. This paper argues that modal arguments can be resisted by adopting a counterpart theoretic account of modal claims, and in particular modal claims involving properties. Thus physicalists have a powerful motive to adopt non-Kripkean accounts of the metaphysics of modality and the semantics of modal expressions.

Orthodox quantum mechanics includes the principle that an observable of a system possesses a well-defined value if and only if the presence of that value in the system is certain to be confirmed on measurement. Modal interpretations reject the controversial ‘only if’ half of this principle to secure definite outcomes for quantum measurements that leave the apparatus entangled with the object it has measured. However, using a result that turns on the construction of a Kochen–Specker contradiction, I argue that (...) modal interpretations cannot deliver a metaphysically tenable conception of properties in quantum mechanics unless they also abandon the less controversial ‘if’ half of the orthodox principle. (shrink)

Graphs are among the most frequently used structures in Computer Science. Some of the properties that must be checked in many applications are connectivity, acyclicity and the Eulerian and Hamiltonian properties. In this work, we analyze how we can express these four properties with modal logics. This involves two issues: whether each of the modal languages under consideration has enough expressive power to describe these properties and how complex it is to use these logics (...) to actually test whether a given graph has some desired property. First, we show that these properties are not definable in a basic modal logic or in any bisimulation-invariant extension of it, like the modal μ-calculus. We then show that it is possible to express some of the above properties in a basic hybrid logic. Unfortunately, the Hamiltonian and Eulerian properties still cannot be efficiently checked. In a second attempt, we propose an extension of CTL* with nominals and show that the Hamiltonian property can be more efficiently checked in this logic than in the previous one. In a third attempt, we extend the basic hybrid logic with the ↓ operator and show that we can check the Hamiltonian property with optimal complexity in this logic. Finally, we tackle the Eulerian property in two different ways. First, we develop a generic method to express edge-related properties in hybrid logics and use it to express the Eulerian property. Second, we express a necessary and sufficient condition for the Eulerian property to hold using a graded modal logic. (shrink)

We show that modal logics characterized by a class of frames satisfying the insertion property are suitable for Reiter's default logic. We refine the canonical fix point construction defined by Marek, Schwarz and Truszczyński for Reiter's default logic and thus we addrress a new paradigm for nonmonotonic logic. In fact, differently from the construction defined by these authors. we show that suitable modal logics for such a construction must indeed contain K D4. When reflexivity is added to the (...) modal logic used for the fix point construction then we come to the Marek Schwarz and Truszczyński framework for Reiter's default logic. Our framework, in fact, is appropriate also to the family of modal logics in between S4 and S4f. If, instead, reflexivity is dropped, then we show that a new family of modal logics is gained, namely the modal logics in between KD4 and KD4Z. The upper bound can be extended to the modal logic KD4LZ whenever the propositional language taken into account is finite. (shrink)

Eliminativist metaphysicians have recently explored various arguments, including those about over-determination, colocation, the problem of the Many and ontological parsimony, for dispensing with kinds and their token continuants. Further, David Lewis’s missing “real temporary intrinsics” has paved the way to treating the sortal and the modal properties yielding the persistence conditions of continuants as unreal because they are extrinsic. In this paper I show, first, that none of the arguments mentioned above are decisive against the disputed entities. Second, (...) I argue that the sortal/modal properties, while extrinsic, are also real, because they are constitutive of kinds. The general point is that modal conceptualism should not be conflated with a cheap version of semanticism. The position advocated here is based on closing the gap between the metaphysical and the epistemic perspectives.Eliminativistički metafizičari u novije su doba istražili razne argumente, uključujući argumente pretjerane determininacije, kolokacije, problem mnoštva i ontološke štedljivosti, kako bi se riješili vrsta i njihovih primjeraka kontinuanata. Nadalje, Lewisova nedostajuća “stvarna privremena intrinzična svojstva” utrla su put shvaćanju sortalnih i modalnih svojstava koja pružaju uvjete ustrajavanja kontinuanata kao nestvarnih, budući da su ekstrinzična. U ovome članku pokazujem, prvo, da nijedan od spomenutih argumenata ne daje odlučne razloge protiv prijepornih entiteta. Drugo, tvrdim da su sortalna/modalna svojstva, iako su ekstrinzična, također stvarna, budući da su konstitutivna za vrste. Općenito, modalni konceptualizam ne treba brkati s jeftinom verzijom semanticizma. Stajalište koje se ovdje zagovara zasniva se na zatvaranju jaza između metafizičke i epistemičke perspektive. (shrink)

Technical results about the time dependence of eigenvectors of reduced density operators are considered, and the relevance of these results is discussed for modal interpretations of quantum mechanics which take the corresponding eigenprojections to represent definite properties. Continuous eigenvectors can be found if degeneracies are avoided. We show that, in finite dimensions, the space of degenerate operators has co-dimension 3 in the space of all reduced operators, suggesting that continuous eigenvectors almost surely exist. In any dimension, even when (...) degeneracies are hit, we find conditions under which a theorem due to Rellich can provide continuous eigenvectors. We use this result to formulate an extended version of the modal interpretation. We also discuss eigenvector instability which we argue poses a serious problem for the modal interpretation, even in our extended version. Many examples are given to illustrate the mathematics. (shrink)

This chapter contains section titled: Preliminaries The Work‐Relativity of Modality A Strategy for Accommodating the Work‐Relativity of Modality Appendix: A Defense of the “Modality Principle”.

MIPC is a well-known intuitionistic modal logic of Prior and Bull . It is shown that every normal intuitionistic modal logic L over MIPC has the finite model property whenever L is Kripke-complete and universal.

In this note we introduce the variety $${{\mathcal C}{\mathcal D}{\mathcal M}_\square}$$ of classical modal De Morgan algebras as a generalization of the variety $${{{\mathcal T}{\mathcal M}{\mathcal A}}}$$ of Tetravalent Modal algebras studied in [ 11 ]. We show that the variety $${{\mathcal V}_0}$$ defined by H. P. Sankappanavar in [ 13 ], and the variety S of Involutive Stone algebras introduced by R. Cignoli and M. S de Gallego in [ 5 ], are examples of classical modal (...) De Morgan algebras. We give a representation theory, and we study the regular filters, i.e., lattice filters closed under an implication operation. Finally we prove that the variety $${{{\mathcal T}{\mathcal M}{\mathcal A}}}$$ has the Amalgamation Property and the Superamalgamation Property. (shrink)

Barsalou has recently argued against the strategy of identifying amodal neural representations by using their cross-modal responses (i.e., their responses to stimuli from different modalities). I agree that there are indeed modal structures that satisfy this “cross-modal response” criterion (CM), such as distributed and conjunctive modal representations. However, I argue that we can distinguish between modal and amodal structures by looking into differences in their cross-modal responses. A component of a distributed cell assembly can (...) be considered unimodal because its responses to stimuli from a given modality are stable, whereas its responses to stimuli from any other modality are not (i.e., these are lost within a short time, plausibly as a result of cell assembly dynamics). In turn, conjunctive modal representations, such as superior colliculus cells in charge of sensory integration, are multimodal because they have a stable response to stimuli from different modalities. Finally, some prefrontal cells constitute amodal representations because they exhibit what has been called ‘adaptive coding’. This implies that their responses to stimuli from any given modality can be lost when the context and task conditions are modified. We cannot assign them a modality because they have no stable relation with any input type. (shrink)