First-Order Modal Logic with an 'Actually' Operator

Stephanou, Yannis

doi:10.1305/ndjfl/1134397658

Cited by 8 publications

(6 citation statements)

References 6 publications

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“…Hodes 1984H. Hodes , 1984Stephanou 2005). On this account, then, actualism is the thesis that everything is actually identical to something, i.e.,…”

Section: The Modern P-a Distinctionmentioning

confidence: 99%

“…An objection to these modifications of POSS and ACT might be heard from so-called serious actualists, who hold that property exemplification entails existence (Prior 1957 (p. 31), Plantinga 1983, Hudson 1997, Caplan 2007, Stephanou 2007. For, on the account of essential properties that the actualist is conceding to Williamson here, contingent beings have their essential properties necessarily.…”

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confidence: 99%

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In defense of the possibilism–actualism distinction

Menzel

2019

Philos Stud

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In his important 2013 book Modal Logic as Metaphysics, Timothy Williamson claims that "there is a widespread feeling of dissatisfaction with the possibilism-actualism [P-A] distinction" and, indeed, that usage of the terms 'possibilism' and 'actualism' "has become badly confused". The claim is surprising, as the P-A distinction is widely discussed in the philosophical literature and, while there is substantial metaphysical disagreement to be found, there is in fact very little evidence of any deep confusions over exactly what the disagreement concerns. The reason for that, I will argue, is that the distinction is entirely coherent and that Williamson's charges are mostly unwarranted. Specifically, in §1 of this paper I discuss some of the historical antecedents of what I call the modern subsistence conception of the P-A distinction, which I refine in §2. I then turn to Williamson's attack on the P-A distinction in §3 and examine in particular two arguments that he sketches that purport to show that problems will arise for any proposed definition of the distinction; I find both arguments wanting. In §4 I discuss Williamson's preferred distinction between necessitism and contingentism and argue that, broadened so as to enable necessitists to fend My thanks to

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“…Hodes 1984H. Hodes , 1984Stephanou 2005). On this account, then, actualism is the thesis that everything is actually identical to something, i.e.,…”

Section: The Modern P-a Distinctionmentioning

confidence: 99%

mentioning

confidence: 99%

In defense of the possibilism–actualism distinction

Menzel

2019

Philos Stud

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“…13 Some austere systems of first-order modal logic do capture the actual truth of the theorems of classical first-order logic. Examples are Menzel's (1991) system A and the systems described in Stephanou (2005). We are sympathetic to the way individual constants are treated in these logics, as they only take as values (in a model) entities in the domain of the actual world.…”

Section: (Bf M )mentioning

confidence: 99%

“…The reader will be directed to aspects of that proof at several stages. 69 A different completeness proof, for a different axiomatisation of a system similar to SR SL {'2','@'} , can be found in (Stephanou, 2005).…”

Section: The Strength Of Strongly Millian Logics Williamson Offers Nmentioning

confidence: 99%

Strongly Millian Second-Order Modal Logics

Jacinto

2017

The Review of Symbolic Logic

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The most common first- and second-order modal logics either have as theorems every instance of the Barcan and Converse Barcan formulae and of their second-order analogues, or else fail to capture the actual truth of every theorem of classical first- and second-order logic. In this paper we characterise and motivate sound and complete first- and second-order modal logics that successfully capture the actual truth of every theorem of classical first- and second-order logic and yet do not possess controversial instances of the Barcan and Converse Barcan formulae as theorems, nor of their second-order analogues. What makes possible these results is an understanding of the individual constants and predicates of the target languages as strongly Millian expressions, where a strongly Millian expression is one that has an actually existing entity as its semantic value. For this reason these logics are called ‘strongly Millian’. It is shown that the strength of the strongly Millian second-order modal logics here characterised afford the means to resist an argument by Timothy Williamson for the truth of the claim that necessarily, every property necessarily exists.

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“…Stephanou's (2005) paper provides a recent example.4 For example,Lewis (1986).5 We use this notation, though differing from Gregory's original, to coincide with our own. 6 It is worth noting that our treatment can be extended, in the manner ofForbes (1989), to include indexed modal and actuality operators.…”

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confidence: 99%

Completeness Results for Some Two-Dimensional Logics of Actuality

Gilbert

Mares

2012

The Review of Symbolic Logic

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We provide a Hilbert-style axiomatization of the logic of 'actually', as well as a twodimensional semantics with respect to which our logics are sound and complete. Our completeness results are quite general, pertaining to all such actuality logics that extend a normal and canonical modal basis. We also show that our logics have the strong finite model property and permit straightforward first-order extensions.

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First-Order Modal Logic with an 'Actually' Operator

Cited by 8 publications

References 6 publications

In defense of the possibilism–actualism distinction

In defense of the possibilism–actualism distinction

Strongly Millian Second-Order Modal Logics

Completeness Results for Some Two-Dimensional Logics of Actuality

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