Modal Scepticism, Unqualified Modality, and Modal Kinds

I formulate and defend two sceptical theses on specific parts of our modal knowledge (unqualified and absolute modalities). My main point is that unqualified modal sentences are defective in that they fail to belong unambiguously to specific modal kinds and thus cannot be evaluated; hence, we must be sceptical of beliefs involving them.     

Modal Mereology and Modal Supervenience

David Lewis insists that restrictivist composition must be motivated by and occur due to some intuitive desiderata for a relation R among parts that compose wholes, and insists that a restrictivist??s relation R must be vague. Peter van Inwagen agrees. In this paper, I argue that restrictivists need not use such examples of relation R as a criterion for composition, and any restrictivist should reject a number of related mereological theses. This paper critiques Lewis and van Inwagen (and others) on their respective mereological metaphysics, and offers a Golden Mean between their two opposite extremes. I argue for a novel account of mereology I call Modal Mereology that is an alternative to Classical Mereology. A modal mereologist can be a universalist about the possible composition of wholes from parts and a restrictivist about the actual composition of wholes from parts. I argue that puzzles facing Modal Mereology (e.g., puzzles concerning Cambridge changes and the Problem of the Many, and how to demarcate the actual from the possible) are also faced in similar forms by classical universalists. On my account, restricted composition is rather motivated by and occurs due to a possible whole??s instantiating an actual type. Universalists commonly believe in such types and defend their existence from objections and puzzles. The Modal Mereological restrictivist can similarly defend the existence of such types (adding that such types are the only wholes) from similar objections and puzzles.     

Modal Persistence and Modal Travel

We argue that there is an interesting modal analogue of temporal persistence, namely modal persistence, and an interesting modal analogue of time travel, namely modal travel. We explicate each of these notions and then argue that there are plausible conditions under which some ordinary objects modally persist. We go on to consider whether it is plausible that any modally persistent objects also modally travel. 1     

Modal Rationalism and Modal Monism

Modal rationalism includes the thesis that ideal primary positive conceivability entails primary possibility. Modal monism is the thesis that the space of logically possible worlds is coextensive with the space of metaphysically possible worlds. In this paper I explore the relation between the two theses. My aim is to show that the former thesis implies the latter thesis, and that problems with the latter make the former implausible as a complete picture of the epistemology of modality. My argument explores the relation between logical modality and metaphysical modality.

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Modal Realism with Modal Tense 1

Modal realists should fashion their theory by postulating and taking seriously the modal equivalent of tense, or modal tense. This will give them a uniform way to respond to five different objections, one each by Skyrms, Quine, and Peacocke, and two by van Inwagen, and suggest a non-Lewisian path to modal realism.     

Conceivability,Imagination and Modal Knowledge*

The notion of conceivability has traditionally been regarded as crucial to an account of modal knowledge. Despite its importance to modal epistemology, there is no received explication of conceivability. One purpose of this paper is to argue that the notion is not fruitfully explicated in terms of the imagination. The most natural way of presenting a notion of conceivability qua imaginability is open to cogent criticism. In order to avoid such criticism, an advocate of the modal insightfulness of the imagination must broaden the idea of what it is to be imaginable. I argue that this required broadening renders the imagination idle (in this context). Consequently, I distinguish two different accounts of the evidential basis of modal knowledge and present a more general argument that concludes that the very notion of conceivability should be eschewed in modal epistemology.     

Modal operators with probabilistic interpretations,I

We present a class of normal modal calculi P_FD, whose syntax is endowed with operators M _r (and their dual ones, L _r), one for each r [0,1]: if a is sentence, M _r is to he read the probability that a is true is strictly greater than r and to he evaluated as true or false in every world of a F-restricted probabilistic kripkean model. Every such a model is a kripkean model, enriched by a family of regular (see below) probability evaluations with range in a fixed finite subset F of [0,1]: there is one such a function for every world w, P _F(w,-), and this allows to evaluate M ^ra as true in the world w iff p _F(w, ) r.For every fixed F as before, suitable axioms and rules are displayed, so that the resulting system P _FD is complete and compact with respect to the class of all the F-restricted probabilistic kripkean models.     

Modal Logic,Truth, and the Master Modality

In the paper (Braüner, 2001) we gave a minimal condition for the existence of a homophonic theory of truth for a modal or tense logic. In the present paper we generalise this result to arbitrary modal logics and we also show that a modal logic permits the existence of a homophonic theory of truth if and only if it permits the definition of a so-called master modality. Moreover, we explore a connection between the master modality and hybrid logic: We show that if attention is restricted to bidirectional frames, then the expressive power of the master modality is exactly what is needed to translate the bounded fragment of first-order logic into hybrid logic in a truth preserving way. We believe that this throws new light on Arthur Prior's fourth grade tense logic.     

Modality,Si! Modal Logic,No!

This article is oriented toward the use of modality in artificial intelligence (AI). An agent must reason about what it or other agents know, believe, want, intend or owe. Referentially opaque modalities are needed and must be formalized correctly. Unfortunately, modal logics seem too limited for many important purposes. This article contains examples of uses of modality for which modal logic seems inadequate.I have no proof that modal logic is inadequate, so I hope modal logicians will take the examples as challenges.Maybe this article will also have philosophical and mathematical logical interest.     

Modal Expansionism

There are various well-known paradoxes of modal recombination. This paper offers a solution to a variety of such paradoxes in the form of a new conception of metaphysical modality. On the proposed conception, metaphysical modality exhibits a type of indefinite extensibility. Indeed, for any objective modality there will always be some further, broader objective modality; in other terms, modal space will always be open to expansion.

     

Modal reasoning, models, and Manktelow and Over.

Manktelow and Over (1991) argue that their studies of Wason's selection task favor explanations of deontic reasoning based on mental models, but that such theories need to incorporate utilities. This theoretical note proposes a simpler explanation of the phenomena: subjects in the selection task consider only those cards that are explicitly represented in their models of the conditional, and so insight into the task depends on constructing fully explicit models. Such models for modal conditionals of the form, If p occurs then q may occur are: [formula: see text] Each line denotes a separate model, and the models represent either what is possible, or, in the deontic interpretation, what is permissible. A deontic rule is accordingly violated by the contingency: [symbol: see text] p and q, for example the rule, "If you spend more than 100 pounds, then you may take a free gift" is violated by taking the free gift (q) but not spending more than 100 pounds ([symbol: see text] p). If the rule is interpreted as a bi-conditional, then the second of the models, p and [symbol: see text] q, is also now a violation, for example spending more than 100 pounds (p) but not getting the free gift ([symbol: see text] q). Manktelow and Over's instructions lead subjects to focus on one or other of the two sorts of violations of the rule. There is accordingly no need to introduce utilities into models in order to explain the phenomena.     

Modal Epistemology

Philosophical Studies -     

Conceivability,Counterfactual Thinking and Philosophical Exceptionality of Modal Knowledge

Topoi - According to Williamson (The philosophy of philosophy, Blackwell, Oxford, 2007), our knowledge of metaphysical necessities and possibilities is just a “special case” of our...