Temporal Logic: From Ancient Ideas to Artificial Intelligence deals with the history of temporal logic as well as the crucial systematic questions within the field. The book studies the rich contributions from ancient and medieval philosophy up to the downfall of temporal logic in the Renaissance. The modern rediscovery of the subject, which is especially due to the work of A. N. Prior, is described, leading into a thorough discussion of the use of temporal logic in computer science and the (...) understanding of natural language. Temporal Logic: From Ancient Ideas to Artificial Intelligence thus interweaves linguistic, philosophical and computational aspects into an informative and inspiring whole. (shrink)

This paper is a critical discussion of A.N. Prior’s contribution to the modern understanding of indeterminism and human freedom of choice. Prior suggested that these ideas should be conceived in terms of his tense logic. It can be demonstrated that his approach provides an attractive formalization that makes it possible to discuss indeterminism and human freedom of choice in a very precise manner and in a broader metaphysical context. It is also argued that Prior’s development of this approach was closely (...) linked to his very personal struggles with fundamental religious and metaphysical questions. In his opinion, holding the doctrine of divine foreknowledge together with the doctrine of human freewill gives rise to difficult logical and philosophical problems. It appears that Prior, rather early on, decided to support what was later known as the Peircean solution, although he also analysed what he considered to be the most important alternative solution—the Ockhamist solution. This paper offers a discussion of some of Prior’s published books and papers as well as some of the papers in his Nachlass. (shrink)

In his paper, The logic of obligation and the obligations of the logician, A.N. Prior considers Hintikka's theorem, according to which a statement cannot be both impossible and permissible. This theorem has been seen as problematic for the very idea of a logic of obligation. However, Prior rejects the view that the logic of obligation cannot be formalised. He sees this resistance against such a view as an important part of what could be called the obligation of the logician. Prior (...) argues that Hintikka's theorem should not be seen as something paradoxical. On the contrary, it should be seen as a fully acceptable consequence of a basic and reasonable assumption in deontic logic, namely Hintikka's rule. (shrink)

This review article offers a discussion of some aspects of the historical and conceptual context when the term “ontology” (Lat. ontologia) was first introduced in the scholarly circles of the early 17th century. In particular, Barry Smith's (2022) analysis of the birth of ontology provides a springboard for some further remarks on the author of the work with the first known occurrence of the word “ontologia”, Jacob Lorhard, including an analysis of his relationship with earlier philosophers Petrus Ramus and Clemens (...) Timpler. (shrink)

In his famous letter to A. N. Prior dated 3 September 1958, Saul Kripke suggested the use of branching time in temporal logic. In this paper, however, it is argued that Prior worked with an idea close to the notion of branching time (‘the big Y’) already the year before he received Kripke’s letter. It is likely that Prior’s findings based on this early study can explain why Prior so quickly accepted the idea of branching time when he received Kripke’s (...) letter. (shrink)

The paper defends the thesis of conventionality in distant simultaneity within the special theory of relativity. The thesis can be expressed in the following way: There is no method independent of standard synchronization by which the one-way velocity of light can be measured if all empirical consequences of the special theory of relativity are to be accepted. Three methods which have recently been suggested are investigated. It is shown that they all depend on the method of standard synchronization. It is (...) finally claimed that nobody has suggested a method which cannot be shown to depend on the method of standard synchronization. (shrink)

This paper deals with certain ethical problems inherent in psychological research based on internet communication as stored information. Section 1 contains an analysis of research on Internet debates. In particular, it takes into account a famous example of deception for psychology research purposes. In section 2, the focus is on research on personal data in texts published on the Internet. Section 3 includes an attempt to formulate some ethical principles and guidelines, which should be regarded as fundamental in research on (...) stored information. (shrink)

In diesem Artikel wird der wissenschaftstheoretische Stand der Geochronologie mit Hintergrund in den Arbeiten von Kuhn und besonders Popper diskutiert. Die Geochronologie wird untersucht mit Hinblick auf generelle methodologische Voraussetzungen, Terminologie, normal-wissenschaftliche Aktivitätsform und "theoretische Dogmatik". Als Konklusion ergibt sich, daß die fundamentalen Theoriekonstruktionen der Geochronologie nicht testbar sind, sondern als ein metaphysisches Forschungsprogramm im Sinne Poppers charakterisiert werden müssen.

Some very good arguments can be given in favor of the Augustinean wisdom, according to which it is impossible to provide a satisfactory definition of the concept of time. However, even in the absence of a proper definition, it is possible to deal with conceptual problems regarding time. It can be done in terms of analogies and metaphors. In particular, it is attractive to make use of Peirce's diagrams by means of which various kinds of conceptual experimentation can be carried (...) out. This paper investigates how Peircean diagrams can be used within the study of time. In particular, we discuss 1) the topological properties of time, 2) the implicative structure in tense logic, 3) the notions of open future and branching time models, and finally 4) tenselogical alternatives to branching time models. (shrink)

A. N. Prior very much admired the logic and philosophy of C.S. Peirce. In the spring of 1962 Prior went to Chicago to study Peirce's ideas. One of the topics that caught his attention was Peirce's existential graphs. This interest continued when he returned to England. In this paper Prior's grappling with the existential graphs will be discussed.

The impact of induced mild positive feelings on working memory and complex decision making among older adults (aged 63–85) was examined. Participants completed a computer administered card task in which participants could win money if they chose from “gain” decks and lose money if they chose from “loss” decks. Individuals in the positive-feeling condition chose better than neutral-feeling participants and earned more money overall. Participants in the positive-feeling condition also demonstrated improved working-memory capacity. These effects of positive-feeling induction have implications (...) for affect theory, as well as, potentially, practical implications for people of all ages dealing with complex decisions. (shrink)

Purpose – The purpose of this paper is to explore artificial moral agency by reflecting upon the possibility of a Moral Turing Test and whether its lack of focus on interiority, i.e. its behaviouristic foundation, counts as an obstacle to establishing such a test to judge the performance of an Artificial Moral Agent. Subsequently, to investigate whether an MTT could serve as a useful framework for the understanding, designing and engineering of AMAs, we set out to address fundamental challenges within (...) the field of robot ethics regarding the formal representation of moral theories and standards. Here, typically three design approaches to AMAs are available: top-down theory-driven models and bottom-up approaches which set out to model moral behaviour by means of models for adaptive learning, such as neural networks, and finally, hybrid models, which involve components from both top-down and bottom-up approaches to the modelling of moral agency. With inspiration from Allen and Wallace as well as Prior, we elaborate on theoretically driven approaches to machine ethics by introducing deontic tense logic. Finally, within this framework, we explore the character of human interaction with a robot which has successfully passed an MTT. Design/methodology/approach – The ideas in this paper reflect preliminary theoretical considerations regarding the possibility of establishing a MTT based on the evaluation of moral behaviour, which focusses on moral reasoning regarding possible actions. The thoughts reflected fall within the field of normative ethics and apply deontic tense logic to discuss the possibilities and limitations of artificial moral agency. Findings – The authors stipulate a formalisation of logic of obligation, time and modality, which may serve as a candidate for implementing a system corresponding to an MTT in a restricted sense. Hence, the authors argue that to establish a present moral obligation, we need to be able to make a description of the actual situation and the relevant general moral rules. Such a description can never be complete, as the combination of exhaustive knowledge about both situations and rules would involve a God eye’s view, enabling one to know all there is to know and take everything relevant into consideration before making a perfect moral decision to act upon. Consequently, due to this frame problem, from an engineering point of view, we can only strive for designing a robot supposed to operate within a restricted domain and within a limited space-time region. Given such a setup, the robot has to be able to perform moral reasoning based on a formal description of the situation and any possible future developments. Although a system of this kind may be useful, it is clearly also limited to a particular context. It seems that it will always be possible to find special cases in which a given system does not pass the MTT. This calls for a new design of moral systems with trust-related components which will make it possible for the system to learn from experience. Originality/value – It is without doubt that in the near future we are going to be faced with advanced social robots with increasing autonomy, and our growing engagement with these robots calls for the exploration of ethical issues and stresses the importance of informing the process of engineering ethical robots. Our contribution can be seen as an early step in this direction. (shrink)

This paper deals with the historical and philosophical background of the introduction of the notion of branching time in philosophical logic as it is revealed in the hitherto unpublished mail-correspondence between Saul Kripke and A.N. Prior in the late 1950s. The paper reveals that the idea was first suggested by Saul Kripke in a letter to A.N. Prior, dated September 3, 1958, and it is shown how the elaboration of the idea in the course of the correspondence was intimately intervowen (...) with considerations of how to represent indeterminism and of the adequacy of tensed logic in light of special relativity. The correspondence underpins the point that Prior's later development of branching time may be understood as a crucial part of his attempt at the formulating a conceptual framework integrating basic human notions of time and free choice. (shrink)

Arthur Norman Prior (1914 – 1969) and Georg Henrik von Wright (1916 – 2003) both attended a conference in England sometime in the spring of 1956, after which they corresponded on Anselm’s ontological argument. Prior had at the conference presented a formal treatment of the ontological argument. Based upon notes from the Prior archive at the Bodleian Library, and correspondence with von Wright, we here presents Prior’s and von Wrights’ discussion of Anselm’s argument in light of Prior’s published, as well (...) as unpublished writings on the ontological argument. Three versions of the ontological argument from Prior’s unpublished as well as published papers is presented: a non-modal, an argument from possible existence and finally a modal version. While Prior dismissed the first on the basis of a meta-theorem for proof in argumentation, the second on the basis of a fallacious commutation of operators, he argued that a valid version of the ontological argument can be proven from the distinctive S5 thesis of Lewis modal logic. While Prior gave reasons for a rejection of those distinct S5 thesis, in favour of Lewis S4 system, he also provided a novel argument in favour of accepting the S5 thesis for necessity and possibility. Finally we relate Prior’s work to Plantinga (1974) and consider objections raised by Oppy (2012) and Gale (2007) toward the modal versions of the ontological argument. (shrink)

Which systems/organisms are conscious? New tests for consciousness (‘C-tests’) are urgently needed. There is persisting uncertainty about when consciousness arises in human development, when it is lost due to neurological disorders and brain injury, and how it is distributed in nonhuman species. This need is amplified by recent and rapid developments in artificial intelligence (AI), neural organoids, and xenobot technology. Although a number of C-tests have been proposed in recent years, most are of limited use, and currently we have no (...) C-tests for many of the populations for which they are most critical. Here, we identify challenges facing any attempt to develop C-tests, propose a multidimensional classification of such tests, and identify strategies that might be used to validate them. (shrink)

Much has been written through the years of the clash between Darwinism and natural theology, and the basic tenants of this debate are well understood (Gillispie 1959; Bowler 1977; Ruse 2003; McGrath 2011). However, the literature is still growing, and one may wonder if anything new may yet be added. Of these new literary sources, one of the richest is the online Darwin Correspondence Project, which makes it possible to search and read the full texts of all correspondence either sent (...) or received by Darwin, up to the year 1868. (This project is ongoing and letters are still being recovered and added.) The purpose of this article is to outline the role of the intelligent design argument, as espoused by its principal .. (shrink)

Logic has sometimes been seen as an alternative to metaphysics and to speculation. In this paper it is argued that a different story should be told when it comes to temporal logic and tense-logic in particular. A. N. Prior’s first formulation of tense logic was mainly established in order to qualify the discussion of certain metaphysical and conceptual problems. Although temporal logic has now been developed in various abstract and rather technical ways, it may still serve as a great help (...) for anyone who wants to clarify the discussion of important existential questions like the nature of time, determinism, future contingency or freedom of choice. (shrink)

Logic has sometimes been seen as an alternative to metaphysics and to speculation. In this paper it is argued that a different story should be told when it comes to temporal logic and tense-logic in particular. A.N. Prior’s first formulation of tense logic was mainly established in order to qualify the discussion of certain metaphysical and conceptual problems. Although temporal logic has now been developed in various abstract and rather technical ways, it may still serve as a great help for (...) anyone who wants to clarify the discussion of important existential questions like the nature of time, determinism, future contingency or freedom of choice. (shrink)

A. N. Prior’s writings should obviously be studied already for historical reasons. His inventions of modern temporal logic and hybrid logic are clearly important events in the history of logic. But the enduring importance of studying his works also rests on his methodological approach, which remains highly relevant also for systematical reasons. In this paper we argue that Prior’s formulation in the 1950s of a tense-logical paradigm for the study of time should be understood in the light of at least (...) three other principles or perspectives which were manifest already in his studies during the 1940s and further developed in the 1950s: his emphasis on the value of interdisciplinary studies, his reflections on formalisation and his view of the role of symbolic logic in conceptual studies and in the philosophy of science. Our investigation into Prior’s basic tenets and principles makes extensive use of Prior’s Nachlass. It is thereby also exemplified how his correspondence and unpublished papers contain important information for a deeper understanding of Prior’s paradigm for the study of time. (shrink)