模态与本质

模态(modality)是指可能性、必然性等哲学范畴。根据关涉对象的不同,它可以分为从言模态与从物模态两类:若模态性质指的是命题或语句为真的可能性与必然性,则它是从言模态;若模态性质指的是事物具有某种性质或关系的可能性与必然性,则它是从物模态。     

Abduction and Modality

This paper introduces a modal epistemology that centers on inference to the best explanation (i.e. abduction). In introducing this abduction‐centered modal epistemology, the paper has two main goals. First, it seeks to provide reasons for pursuing an abduction‐centered modal epistemology by showing that this epistemology aids a popular stance on the mind‐body problem and allows an appealing approach to modality. Second, the paper seeks to show that an abduction‐centered modal epistemology can work by showing that abduction can establish claims about necessity/possibility (i.e. modal claims)—where ‘necessity’ and ‘possibility’ denote metaphysical necessity and possibility, ways things may or may not have been given how they actually are.     

Modality and Mellor's McTaggart

This paper explores a modal analogue of Hugh Mellor's version of McTaggart's argument against the reality of tense. I show that if Mellor's argument succeeds in showing that the present moment cannot be any more real than any other moment then it also shows that the actual world cannot be any more real than any other possible world.     

Virtual Modality

Model-theoretic 1-types overa given first-order theory T may be construed as natural metalogical miniatures of G. W. Leibniz' ``complete individual notions', ``substances' or ``substantial forms'. This analogy prompts this essay's modal semantics for an essentiallyundecidable first-order theory T, in which one quantifies over such ``substances' in a boolean universe V(C), where C is the completion of the Lindenbaum-algebra of T.More precisely, one can define recursively a set-theoretic translate of formulae _N of formulae of a normal modal theory T_m based on T, such that the counterpart `<sub>i</sub>' of a the modal variable `x_i' of L(T_m) in this translation-scheme ranges over elements of V(C) that are 1-types of T with value 1 (sometimes called `definite' C-valued 1-types of T).The article's basic completeness-result (2.13) then establishes that varphi; is a theorem of T<sub>m</sub> iff [[ <sub>N</sub> () is aconsequenceof <sub>N</sub> (T<sub>m</sub>) for each extension N of T which is a subtheory of the canonical generic theory (ultrafilter) u]] = 1 – or equivalently, that T<sub>m</sub> is consistent iff[[there is anextension N of T such that N is a subtheory of the canonical generic theory u, and <sub>N</sub>() for all in T<sub>m</sub>]] > 0.The proof of thiscompleteness-result also shows that an N which provides a countermodel for a modally unprovable – or equivalently, a closed set in the Stone space St(T) in the sense of V(C) – is intertranslatable with an `accessibility'-relation of a closely related Kripke-semantics whose `worlds' are generic extensions of an initial universe V via C.This interrelation providesa fairly precise rationale for the semantics' recourse to C-valued structures, and exhibits a sense in which the boolean-valued context is sharp.     

Causal Necessitation and Dispositional Modality

Philosophia - Rani Lill Anjum and Stephen Mumford have recently defended a new kind of modality, which they call ‘dispositional modality’. The key reason to adopt dispositional...     

Vagueness as a Modality

I present a modal conception of vagueness and vague objects, according to which a vague object is a transworld object which coincides with one precise object in one world and with another precise object in another world. Such worlds are called precisifications; they are modal, worldly counterparts of the precisifications postulated in supervaluationism. I criticize Evans' argument against vague objects, admitting the validity of the argument, but rejecting its basic assumption that if there are vague objects, certain identity statements must be indefinite in truth value. I distinguish identity from coincidence, and claim that if there are vague objects, some statements of coincidence will be indefinite in truth-value, not statements of identity. To establish this point, I compare vagueness with temporal modality.     

Modality and variability of synesthetic experience

In synesthesia, stimulation of one sensory or cognitive pathway leads to additional, involuntary experiences in a second sensory or cognitive pathway. We here review previous surveys on this neurologically based phenomenon and report the results of 63 synesthetes who completed our Internet and paper questionnaire on synesthesia. In addition to asking for personal data and information on the participant's synesthesia, the questionnaire focused on the components of the inducer that elicit or modulate synesthesia. Synesthesia was most often developmental (92%) and of the grapheme-color type (86%). Sixty-two percent of the participants perceived time-related words in a spatial configuration. Music-color synesthesia was common (41%), and synesthesia for natural and artificial sounds (33%) was higher than in previous estimates. Eighty-one percent of participants experienced more than one form of synesthesia. Multimodal synesthesia, in which inducer and concurrent belong to 2 different sensory modalities, occurred in 92% of the participants. Overall, auditory stimuli were most often reported as inducers, and visual concurrents were most common. Modulations of the synesthetic experiences such as changes of the concurrent color, expansion within the same or to a different sensory modality, or reduction of the number of inducers over time were reported by 17% of participants. This challenges the presumed consistency of synesthesia and the adequacy of the test-retest consistency score still most commonly used to assess the veracity of reported synesthesia. Implications of the high prevalence of cross-modal synesthesia and the variability of synesthesia are discussed.     

Modality,Quantification, and Many Vlach-Operators

Consider two standard quantified modal languages \(\textbf{\textsf{A}}\) and \(\textbf{\textsf{P}}\) whose vocabularies comprise the identity predicate and the existence predicate, each endowed with a standard S5 Kripke semantics where the models have a distinguished actual world, which differ only in that the quantifiers of \(\textbf{\textsf{A}}\) are actualist while those of \(\textbf{\textsf{P}}\) are possibilist. Is it possible to enrich these languages in the same manner, in a non-trivial way, so that the two resulting languages are equally expressive—i.e., so that for each sentence of one language there is a sentence of the other language such that given any model, the former sentence is true at the actual world of the model iff the latter is? Forbes (1989) shows that this can be done by adding to both languages a pair of sentential operators called Vlach-operators, and imposing a syntactic restriction on their occurrences in formulas. As Forbes himself recognizes, this restriction is somewhat artificial. The first result I establish in this paper is that one gets sameness of expressivity by introducing infinitely many distinct pairs of indexed Vlach-operators. I then study the effect of adding to our enriched modal languages a rigid actuality operator. Finally, I discuss another means of enriching both languages which makes them expressively equivalent, one that exploits devices introduced in Peacocke (1978). Forbes himself mentions that option but does not prove that the resulting languages are equally expressive. I do, and I also compare the Peacockian and the Vlachian methods. In due course, I introduce an alternative notion of expressivity and I compare the Peacockian and the Vlachian languages in terms of that other notion.