This paper deals with structures ${\langle{\bf T}, I\rangle}$ in which T is a tree and I is a function assigning each moment a partition of the set of histories passing through it. The function I is called indistinguishability and generalizes the notion of undividedness. Belnap’s choices are particular indistinguishability functions. Structures ${\langle{\bf T}, I\rangle}$ provide a semantics for a language ${\mathcal{L}}$ with tense and modal operators. The first part of the paper investigates the set-theoretical properties of the set of indistinguishability (...) classes, which has a tree structure. The significant relations between this tree and T are established within a general theory of trees. The aim of second part is testing the expressive power of the language ${\mathcal{L}}$ . The natural environment for this kind of investigations is Belnap’s seeing to it that (stit). It will be proved that the hybrid extension of ${\mathcal{L}}$ (with a simultaneity operator) is suitable for expressing stit concepts in a purely temporal language. (shrink)

Presentism is the view that only present entities exist. Recently, several authors have asked the question whether presentism is able to account for cross-time relations, i.e., roughly, relations between entities existing at different times. In this paper I claim that this question is to be answered in the affirmative. To make this claim plausible, I consider four types of cross-time relation and show how each can be accommodated without difficulty within the metaphysical framework of presentism.

We show that basic hybridization (adding nominals and @ operators) makes it possible to give straightforward Henkin-style completeness proofs even when the modal logic being hybridized is higher-order. The key ideas are to add nominals as expressions of type t, and to extend to arbitrary types the way we interpret $@_i$ in propositional and first-order hybrid logic. This means: interpret $@_i\alpha _a$ , where $\alpha _a$ is an expression of any type $a$ , as an expression of type $a$ that (...) rigidly returns the value that $\alpha_a$ receives at the i-world. The axiomatization and completeness proofs are generalizations of those found in propositional and first-order hybrid logic, and (as is usual inhybrid logic) we automatically obtain a wide range of completeness results for stronger logics and languages. Our approach is deliberately low-tech. We don’t, for example, make use of Montague’s intensional type s, or Fitting-style intensional models; we build, as simply as we can, hybrid logicover Henkin’s logic. (shrink)

Ockhamism implies that future contingents may be true, their historical contingency notwithstanding. It is thus opposed to both the Peircean view according to which all future contingents are false, and Supervaluationist Indeterminism according to which all future contingents are neither true nor false. The paper seeks to defend Ockhamism against two charges: the charge that it cannot meet the requirement that truths be grounded in reality, and the charge that it proves incompatible with objective indeterminism about the future. In each (...) case, the defence draws on the idea that certain truths are truths only courtesy of others and of what makes the latter true. After introduction of the Ockhamist view, its competitors and implications, a suitable definition of grounded truth is being devised that both is faithful to the spirit of the grounding-requirement and allows the Ockhamist to heed that requirement quite comfortably. Then two senses in which the future might be open are being introduced, indeterminacy as failure of predetermination by past and present facts, and indeterminacy as failure of entailment by past and present truths. It is argued that while openness in the former sense, but not in the latter sense, coheres with the Ockhamist view, it is only openness in the former sense that matters for objective indeterminism. (shrink)

The man who is isolated over against God is as such rejected by God. But to be this man can only be the choice of the Godless man himself. The witness of the Community of God to every individual man points in this direction: that this choice of the Godless is null and void, that he belongs to Jesus Christ from eternity and thus is not rejected, but rather chosen by God in Jesus Christ, that the reprobation which he deserves (...) on the basis of his wrong choice is borne and removed by Jesus Christ; that on the basis of the true, the Divine choice he is chosen for eternal life with God. The promise of his election will determine him as a member of the Church to become himself a carrier of its witness to the whole world. And the revelation of his rejection can determine him only to believe in Jesus Christ as Him by whom it is borne and removed. (Fourth of Karl Barth's "main theses" on God's Election of Grace in his Dogmatic II/2). (shrink)

In recent publications, Kit Fine devises a classification of A-theories of time and defends a non-standard A-theory he calls fragmentalism, according to which reality as a whole is incoherent but fragments into classes of mutually coherent tensed facts. We argue that Fine's classification in not exhaustive, as it ignores another non-standard A-theory we dub dynamic absolutism, according to which there are tensed facts that stay numerically the same and yet undergo qualitative changes as time goes by. We expound this theory (...) in some detail and argue that it is a serious alternative to the positions identified by Fine. (shrink)

Abstract Theories in physics require reference to manifolds of locations and events. Abstract versions of these manifolds, ?space?, ?time? and ?space?time? are frequently used as reference systems. Should they be included in the ontology of physics as well as the material manifolds from which they are abstracted? This problem can be approached through a study of the identity conditions of events. The argument is offered that neither an abstract ?time? of moments is viable, nor is the assumption that events are (...) individuated by their locations necessary. Taken together these conclusions would require reinterpretation of relativity as a grammar of histories and of the Einstein?Podolski?Rosen experiment as displaying the possibility of spatially distributed events. (shrink)

This paper suggests an epistemic interpretation of Belnap’s branching space-times theory based on Everett’s relative state formulation of the measurement operation in quantum mechanics. The informational branching models of the universe are evolving structures defined from a partial ordering relation on the set of memory states of the impersonal observer. The totally ordered set of their information contents defines a linear “time” scale to which the decoherent alternative histories of the informational universe can be referred—which is quite necessary for assigning (...) them a probability distribution. The “historical” state of a physical system is represented in an appropriate extended Hilbert space and an algebra of multi-branch operators is developed. An age operator computes the informational depth of historical states and its standard deviation can be used to provide a universal information/energy uncertainty relation. An information operator computes the encoding complexity of historical states, the rate of change of its average value accounting for the process of correlation destruction inherent to the branching dynamics. In the informational branching models of the universe, the asymmetry of phenomena in nature appears as a mere consequence of the subject’s activity of measuring, which defines the flow of time-information. (shrink)

The apparent 'flow' of time is one of its most mysterious features, and one which discomforts both scientists and philosophers. One of the most striking assaults upon it is McTaggart's argument that the idea of temporal flow is demonstratively incoherent. In this paper I first urge that the idea of temporal flow is an important part of our intuitive understanding of time, underpinning several of our notions about rationality and time. Second, I try to undercut McTaggart's argument by showing that (...) it is not temporal flow which is illusory but rather the vicious regress McTaggart saw in that idea. A steadfast clinging to the notion of now, along with an analysis of McTaggart's argument reveals that the regress halts after but two steps. (shrink)

In this paper I argue that the self-referential component which Searle rightly detects in the truth-conditions of perceptual judgments comes from the perceptual ‘mode' and is not an aspect of the ‘content' of the judgment, contrary to Searle's claim.

A structure is described that can serve as a foundation for a semantics for a modal agentive construction such as sees to it that Q ([ stit: Q]). The primitives are Tree,,Instant, Agent, choice. Eleven simple postulates governing this structure are set forth and motivated. Tree and encode a picture of branching time consisting of moments gathered into maximal chains called histories. Instant imposes a time-like ordering. Agent consists of agents, and choice assigns to each agent and each moment in (...) Tree a set of possible choices, where each possible choice is a set of histories. All of these ingredients are referred to in the semantics suggested for [ stit: Q]. The most complex part of the discussion is the motivation for the definition of what it means for a typically non-terminating chain of moments jointly to witness the truth of [ stit: Q] at a moment.The paper begins with an informal account of the Refref conjecture, which says that the only way to refrain from refraining from seeing to something is to see to it. The paper ends with a consideration of an argument of Prior's that in a certain sense contemplation and action are inconsistent. (shrink)

Hamblin's Action-State Semantics provides a sound philosophical foundation for understanding the character of the imperative. Taking this as our inspiration, in this paper we present a logic of action, which we call ST, that captures the clear ontological distinction between being responsible for the achievement of a state of affairs and being responsible for the performance of an action. We argue that a relativised modal logic of type RT founded upon a ternary relation over possible worlds integrated with a basic (...) tense logic captures intuitions of the Hamblinian model of imperatives. The logic implements a direct mapping of each of Hamblin's key concepts: strategies, partial strategies and wholehearted satisfaction. (shrink)

The paper deals with the problem of axiomatizing a system T1 of discrete tense logic, where one thinks of time as the set Z of all the integers together with the operations +1 ("immediate successor") and-1 ("immediate predecessor"). T1 is like the Segerberg-Sundholm system WI in working with so-called infinitary inference ruldes; on the other hand, it differs from W I with respect to (i) proof-theoretical setting, (ii) presence of past tense operators and a "now" operator, and, most importantly, with (...) respect to (iii) the presence in T1 of so-called systematic frame constants, which are meant to hold at exactly one point in a temporal structure and to enable us to express the irreflexivity of such structures. Those frame constants will be seen to play a paramount role in our axiomatization of T1. (shrink)

The aim of this paper is to consider some logical aspects of the debate between the view that the present is the only 'real' time, and the view that the present is not in any way metaphysically privileged. In particular I shall set out a language of first-order predicate tense logic with a now predicate, and a first order (extensional) language with an abstraction operator, in such a way that each language can be shewn to be exactly translatable into the (...) other. I shew that this translation is preserved at the metalinguistic level, so that equivalent truth conditions can be defined in a tensed metalanguage or an indexical metalanguage. I then make some remarks about the connection between proofs of relative consistency and metaphysical truth; and some historical remarks about Arthur Prior's use of formal logic in expressing his presentist views. (shrink)

Many of the formalisms used in Attribute Value grammar are notational variants of languages of propositional modal logic, and testing whether two Attribute Value Structures unify amounts to testing for modal satisfiability. In this paper we put this observation to work. We study the complexity of the satisfiability problem for nine modal languages which mirror different aspects of AVS description formalisms, including the ability to express re-entrancy, the ability to express generalisations, and the ability to express recursive constraints. Two main (...) techniques are used: either Kripke models with desirable properties are constructed, or modalities are used to simulate fragments of Propositional Dynamic Logic. Further possibilities for the application of modal logic in computational linguistics are noted. (shrink)

Besides their ordinary cardinal and proportional meanings, many and few have been argued to allow for a ‘reverse proportional’ reading. This reading has later been characterised in two opposite directions: Cohen’s reading where the proportion \ matters and Herburger’s where it does not. We develop a compositional analysis that derives the correct truth conditions for both characterisations of Westerståhl-style sentences while maintaining conservativity, assuming a standard syntax/semantics mapping and reducing their context-dependence to mechanisms independently needed for degree constructions in general. (...) In a nutshell, mirroring the decomposition of other degree expressions like tall, many is decomposed into the parametrized determiner many and the operator POS, where POS combines with a contextually salient comparison class C matching the alternatives triggered by some element X\ in the sentence. Non-reverse readings obtain when X\ is external to the original host NP and reverse readings when X\ is internal to the host NP. Cohen’s truth conditions for Westerståhl-style sentences are derived as a reverse proportional reading and Herburger’s interpretation as a sub-case of the non-reverse cardinal reading. (shrink)

I illustrate with three classical examples the mistakes arising from using a modal operator admitting multiple interpretations in the same argument; the flaws arise especially easily if no attention is paid to the range of propositional variables. Premisses taken separately might seem convincing and a substitution for a propositional variable in a modal context might seem legitimate. But there is no single interpretation of the modal operators involved under which all the premisses are plausible and the substitution successful.

In several recent papers, Daniel Deasy has argued that the presentism–eternalism debate is unclear and should be abandoned. According to Deasy, there is no way of spelling out the predicate ‘is present’ that leads to a satisfactory definition of presentism: on some interpretations, presentism turns out to be compatible with eternalism, on others, it is clearly false or unacceptable for other reasons. The aim of this paper is to show that this line of argument should be resisted: if the predicate (...) ‘is present’ is spelled out in terms of where things are located, the result is a definition of presentism that is neither compatible with eternalism nor clearly false. There is thus no need to abandon the debate between presentists and eternalists. (shrink)

I examine Quine’s and Davidson’s arguments to the effect that classical logic is the one and only correct logic. This conclusion is drawn from their views on radical translation and interpretation, respectively. I focus on the latter, but I first address, independently, Quine’s argument to the effect that the ‘deviant’ logician, who departs from classical logic, is merely changing the subject. Regarding logical pluralism, the question is whether there is more than one correct logic. I argue that bivalence may be (...) subject matter dependent, but that distribution and the law of excluded middle can probably not be dropped whilst maintaining the standard meanings of the connectives. In discussing the ramifications of the indeterminacy of interpretation, I ask whether it forces Davidsonian interpreters to adopt Dummett’s epistemic conception of truth vis-à-vis their interpretations. And, if so, does this cohere with their attributing a nonepistemic notion of truth to their interpretees? This would be a form of logical pluralism. In addition, I discuss Davidson’s arguments against conceptual schemes. Schemes incommensurable with our own could be construed as wholesale deviant logics, or so I argue. And, if so, their possibility would yield, in turn, the possibility of a radical logical pluralism. I also address Davidson’s application of Tarski’s definition of truth. (shrink)

A-theorists think there is a fundamental difference between the present and other times. This concern shows up in what kinds of properties they take to be instantiated, what objects they think exist and how they formalize their views. Nearly every contemporary A-theorist assumes that her metaphysics requires a tense logic – a logic with operators like and. In this paper, I show that there is at least one viable A-theory that does not require a logic with tense operators. And I (...) will argue that three common indispensability arguments for tense operators are unsound. (shrink)

Temporal logic is one of the many areas in which a possible world semantics is adopted. Prior's Ockhamist and Peircean semantics for branching-time, though, depart from the genuine Kripke semantics in that they involve a quantification over histories, which is a second-order quantification over sets of possible worlds. In the paper, variants of the original Prior's semantics will be considered and it will be shown that all of them can be viewed as first-order counterparts of the original semantics.

Presentism states that everything is present. Crucial to our understanding of this thesis is how we interpret the ‘is’. Recently, several philosophers have claimed that on any interpretation presentism comes out as either trivially true or manifestly false. Yet, presentism is meant to be a substantive and interesting thesis. I outline in detail the nature of the problem and the standard interpretative options. After unfavourably assessing several popular responses in the literature, I offer an alternative interpretation that provides the desired (...) result. This interpretation is then used to clarify the distinction between ‘real change’ from mere variation and temporal relativisation. Reflecting on my solution, I try to diagnose the source of confusion over these issues. Then, building upon Fine’s distinction between ontic and factive presentism, I elucidate what the presentist thesis specifically concerns and how best to formalise it. In the process I distinguish a weak and strong version of the presentist thesis. Finally, I end by drawing out some limitations of the paper. (shrink)

This paper aims to clarify the connection between the logic of temporal distinctions and the temporal features of propositions. Contra Prior, it argues that the adoption of tense operators does not commit one to the view that propositions can change their truth value over time.

This paper follows Part I of our essay on case-intensional first-order logic ). We introduce a framework of branching histories to take account of indeterminism. Our system BH-CIFOL adds structure to the cases, which in Part I formed just a set: a case in BH-CIFOL is a moment/history pair, specifying both an element of a partial ordering of moments and one of the total courses of events that that moment is part of. This framework allows us to define the familiar (...) Ockhamist temporal/modal connectives, most notably for past, future, and settledness. The novelty of our framework becomes visible in our discussion of substances in branching histories, i.e., in its first-order part. That discussion shows how the basic idea of tracing an individual thing from case to case via an absolute property is applicable in a branching histories framework. We stress the importance of keeping apart extensionality and moment-definiteness, and give a formal account of how the specification of natural sortals and natural qualities turns out to be a coordination task in BH-CIFOL. We also provide a detailed answer to Lewis’s well-known argument against branching histories, exposing the fallacy in that argument. (shrink)

Presentism is held by most to be the intuitive theory of time, due in large part to the view's supposed preservation of time's passage. In this paper, I strike a blow against presentism's intuitive pull by showing how the presentist, contrary to overwhelming popular belief, is unable to establish temporal change upon which the passage of time is based. I begin by arguing that the presentist's two central ontological commitments, the Present Thesis and the Change Thesis, are incompatible. The main (...) problem is that satisfying the Change Thesis to establish passage requires the existence of more than one moment. This conflicts with the Present Thesis that only the present moment exists. The presentist's response is to appeal to surrogates to stand proxy for the past, so as to account for the difference between what does exist and what did exist. I argue that, for this surrogate strategy to be successful, the proposed surrogates must track what actually happened. I demonstrate that there is no guarantee that t.. (shrink)

Fictional truth, or truth in fiction/pretense, has been the object of extended scrutiny among philosophers and logicians in recent decades. Comparatively little attention, however, has been paid to its inferential relationships with time and with certain deliberate and contingent human activities, namely, the creation of fictional works. The aim of the paper is to contribute to filling the gap. Toward this goal, a formal framework is outlined that is consistent with a variety of conceptions of fictional truth and based upon (...) a specific formal treatment of time and agency, that of so-called stit logics. Moreover, a complete axiomatic theory of fiction-making TFM is defined, where fiction-making is understood as the exercise of agency and choice in time over what is fictionally true. The language \ of TFM is an extension of the language of propositional logic, with the addition of temporal and modal operators. A distinctive feature of \ with respect to other modal languages is a variety of operators having to do with fictional truth, including a ‘fictionality’ operator \ . Some applications of TFM are outlined, and some interesting linguistic and inferential phenomena, which are not so easily dealt with in other frameworks, are accounted for. (shrink)

Conceptual metaphors facilitate both productive and pernicious analogical reasoning. This article addresses the question: When and why does the frequently helpful use of metaphor become pernicious? By applying the most influential theoretical framework from cognitive psychology in analysing the philosophically most prominent example of pernicious metaphorical reasoning, we identify a philosophically relevant but previously undescribed fallacy in analogical reasoning with metaphors. We then outline an explanation of why even competent thinkers commit this fallacy and obtain a psychologically informed ‘debunking’ explanation (...) of the kind experimental philosophy’s ‘sources project’ seeks. (shrink)

We investigate the concepts of past, present, and future that build upon a modal distinction between the settled past and the open future. The concepts are defined in terms of a pre-causal ordering and of qualitative differences between alternative histories. Finally, we look what an event's past, present, and future look like in the so-called Minkowskian Branching Structures, in which histories are isomorphic to Minkowski spacetime.

In this paper we argue that hybrid logic is the deductive setting most natural for Kripke semantics. We do so by investigating hybrid axiomatics for a variety of systems, ranging from the basic hybrid language (a decidable system with the same complexity as orthodox propositional modal logic) to the strong Priorean language (which offers full first-order expressivity).We show that hybrid logic offers a genuinely first-order perspective on Kripke semantics: it is possible to define base logics which extend automatically to a (...) wide variety of frame classes and to prove completeness using the Henkin method. In the weaker languages, this requires the use of non-orthodox rules. We discuss these rules in detail and prove non-eliminability and eliminability results. We also show how another type of rule, which reflects the structure of the strong Priorean language, can be employed to give an even wider coverage of frame classes. We show that this deductive apparatus gets progressively simpler as we work our way up the expressivity hierarchy, and conclude the paper by showing that the approach transfers to first-order hybrid logic. (shrink)

Indeterminism, understood as a notion that an event may be continued in a few alternative ways, invokes the question what a region of chanciness looks like. We concern ourselves with its topological and spatiotemporal aspects, abstracting from the nature or mechanism of chancy processes. We first argue that the question arises in Montague-Lewis-Earman conceptualization of indeterminism as well as in the branching tradition of Prior, Thomason and Belnap. As the resources of the former school are not rich enough to study (...) topological issues, we investigate the question in the framework of branching space-times of Belnap (Synthese 92:385–434, 1992). We introduce a topology on a branching model as well as a topology on a history in a branching model. We define light-cones and assume four conditions that guarantee the light-cones so defined behave like light-cones of physical space-times. From among various topological separation properties that are relevant to our question, we investigate the Hausdorff property. We prove that each history in a branching model satisfies the Hausdorff property. As for the satisfaction of the Hausdorff property in the entire branching model, we prove that it is related to the phenomenon of passive indeterminism, which we describe in detail. (shrink)

In diesem Aufsatz wird im Rahmen des Projekts einer Logik des Lebens die Ebene der Zellen und die Beziehung zwischen Lebewesen und Zellen behandelt. Es werden die Beziehungen "ist Zell-Vorfahre von", "ist Zelle von" und "ist Zelle desselben Lebewesens wie" untersucht. Postulate für Lebewesen werden umgedeutet und auf die Zellebene übertragen. Es werden Möglichkeiten diskutiert, die Vorfahren-Relation für Lebewesen auf der Grundlage der Vorfahren-Relation für Zellen zu definieren. Eine besondere Rolle spielen dabei Einzellflaschenhälse ("one-cell bottlenecks" / "single-cell bottlenecks").

“Branching space-times” (BST) is intended as a representation of objective, event-based indeterminism. As such, BST exhibits both a spatio-temporal aspect and an indeterministic “modal” aspect of alternative possible historical courses of events. An essential feature of BST is that it can also represent spatial or space-like relationships as part of its (more or less) relativistic theory of spatio-temporal relations; this ability is essential for the representation of local (in contrast with “global”) indeterminism. This essay indicates how BST might be seen (...) to grow out of Newton’s deterministic and non-relativistic theory by two independent moves: (1) Taking account of indeterminism, and (2) attending to spatio-temporal relationships in a spirit derived from Einstein’s theory of special relativity. Since (1) and (2) are independent, one can see that there is room for four theories: Newtonian determinism, branching time indeterminism, relativistic determinism, and (finally) branching space-times indeterminism. (shrink)

“Branching space-times” is intended as a representation of objective, event-based indeterminism. As such, BST exhibits both a spatio-temporal aspect and an indeterministic “modal” aspect of alternative possible historical courses of events. An essential feature of BST is that it can also represent spatial or space-like relationships as part of its relativistic theory of spatio-temporal relations; this ability is essential for the representation of local indeterminism. This essay indicates how BST might be seen to grow out of Newton ’s deterministic and (...) non-relativistic theory by two independent moves: Taking account of indeterminism, and attending to spatio-temporal relationships in a spirit derived from Einstein’s theory of special relativity. Since and are independent, one can see that there is room for four theories: Newtonian determinism, branching time indeterminism, relativistic determinism, and branching space-times indeterminism. (shrink)

The paper puts forward a theory of historical modalities that is framed in terms of possible continuations rather than possible worlds or histories. The proposal is tested as a semantic theory for a language with historical modalities, tenses, and indexicals.

Chrysippus claims that some propositions perish. including some true conditionals whose consequent is impossible and antecedent is possible, to which he appeals against Diodorus?s Master Argument. On the standard interpretation. perished propositions lack truth values. and these conditionals are true at the same time as their antecedents arc possible and consequents impossible. But perished propositions are false, and Chrysippus?s conditionals are true when their antecedent and consequent arc possible, and false when their antecedent is possible and consequent impossible. The claim (...) of the Master Argument that Chrysippus rejects, then, is stronger ihan usually supposed. (shrink)

Medieval analyses of molecular propositions include many non-truthfunctional connectives in addition to the standard modern binary connectives (conjunction, disjunction, and conditional). Two types of non-truthfunctional molecular propositions considered by a number of 13th- and 14th-century authors are temporal and local propositions, which combine atomic propositions with `while' and `where'. Despite modern interest in the historical roots of temporal and tense logic, medieval analyses of `while' propositions are rarely discussed in modern literature, and analyses of `where' propositions are almost completely overlooked. (...) In this paper we introduce 13th- and 14th-century views on temporal and local propositions, and connect the medieval theories with modern temporal and spatial counterparts. (shrink)

The paper attempts to give a solution to the Fitch's paradox though the strategy of the reformulation of the paradox in temporal logic, and a notion of knowledge which is a kind of ceteris paribus modality. An analogous solution has been offered in a different context to solve the problem of metaphysical determinism.

The logical theory of branching space-times, which provides a relativistic framework for studying objective indeterminism, remains mostly disconnected from discussions of space-time theories in philosophy of physics. Earman has criticized the branching approach and suggested “pruning some branches from branching space-time.” This article identifies the different—order-theoretic versus topological—perspective of both discussions as a reason for certain misunderstandings and tries to remove them. Most important, we give a novel, topological criterion of modal consistency that usefully generalizes an earlier criterion, and we (...) introduce a differential-geometrical version of branching space-times as a non-Hausdorff (generalized) manifold. (shrink)

We discuss some aspects of the concept of “object” and “objectuation” as suggested by the articulation of modern physics. In particular we analyze the new ontological thickness of the notion ofobject in quantum mechanics and in relativistic quantum mechanics.At the end we try to formulate some modifications of the logical approach to quantum theory in order to grasp the new situation connected with relativistic quantum theory.

At the centre of Arthur Prior’s ‘Thank goodness’ argument for the A-theory of time is a particular form of relief. Time must objectively pass, Prior argues, or else the relief felt when a painful experience has ended is not intelligible. In this paper, I offer a detailed analysis of the type of relief at issue in this argument, which I call temporal relief, and distinguish it from another form of relief, which I refer to as counterfactual relief. I also argue (...) that existing discussions of the ‘Thank goodness’ argument—including Prior’s own—fail to give a satisfactory account of temporal relief, and that it needs to be seen as an emotion linked to the ability to engage in fairly sophisticated forms of planning. I also suggest that this has an impact on Prior’s claim that the idea of points in time plays no fundamental role in the semantic analysis of tenses. (shrink)

For branching-time temporal logic based on an Ockhamist semantics, we explore a temporal language extended with two additional syntactic tools. For reference to the set of all possible futures at a moment of time we use syntactically designated restricted variables called fan-names. For reference to all possible futures alternative to the actual one we use a modification of a difference modality, localized to the set of all possible futures at the actual moment of time.We construct an axiomatic system for this (...) extended branching-time logic and prove its soundness and completeness with respect to bundle tree semantics. Finally, we show how our axiomatic system can be extended with a variety of important additional operators, such as Since and Until, a global difference operator, operators for undivided and divided histories, reference pointers, etc. (shrink)

In 1954, A. N. Prior discovered a way to formalize tense-logic—as such, there is no doubt that he is the father of modern tense-logic. Despite this, he considered his early teacher in p...

According to L.E.J. Brouwer, there is room for non-definable real numbers within the intuitionistic ontology of mental constructions. That room is allegedly provided by freely proceeding choice sequences, i.e., sequences created by repeated free choices of elements by a creating subject in a potentially infinite process. Through an analysis of the constitution of choice sequences, this paper argues against Brouwer’s claim.

Logical realism, by Arthur Norman Prior understood as the view that logic is not about language but about reality, is a consistent and strong tenet in all of Prior's philosophical work. Recent disc...

The semantical structures called T×W frames were introduced in (Thomason, 1984) for the Ockhamist temporal-modal language, ℒO, which consists of the usual propositional language augmented with the Priorean operators P and F and with a possibility operator ⋄. However, these structures are also suitable for interpreting an extended language, ℒSO, containing a further possibility operator ⋄s which expresses synchronism among possibly incompatible histories and which can thus be thought of as a cross-history ‘simultaneity’ operator. In the present paper we provide (...) an infinite set of axioms in ℒSO, which is shown to be strongly complete forT ×W-validity. Von Kutschera (1997) contains a finite axiomatization of T×W-validity which however makes use of the Gabbay Irreflexivity Rule (Gabbay, 1981). In order to avoid using this rule, the proof presented here develops a new technique to deal with reflexive maximal consistent sets in Henkin-style constructions. (shrink)