Modal dispositionalists hold that dispositions provide the foundation of metaphysical necessity and possibility. According to the kind of modal dispositionalism that can be found in the present literature, a proposition p is possible just in case some things are disposed to be such that p. In the first part of this paper I show that combining this classic form of dispositionalism with the assumptions that the laws of nature are necessary and deterministic and that all dispositions are forward-looking in time (...) leads to the unattractive conclusion that every truth is necessary. I argue that the classic dispositionalist should be troubled by this result and in the second part of the paper I suggest a novel variant of dispositionalism that avoids it. This extended form of dispositionalism allows that some propositions are only indirectly underwritten by dispositions. (shrink)

Technology and responsibility: reflections on the new tasks of ethics.--Jewish and Christian elements in philosophy: their share in the emergence of the modern mind.--Seventeenth century and after: the meaning of the scientific and technological revolution.--Socio-economic knowledge and ignorance of goals.--Philosophical reflections on experimenting with human subjects.--Against the stream: comments on the definition and redefinition of death.--Biological engineering--a preview--Contemporary problems in ethics from a Jewish perspective.--Biological foundations of individuality.--Spinoza and the theory of organism.--Sight and thought: a review of "visual thinking."--Change and (...) permanence: on the possibility of understanding history.--The gnostic syndrome: typology of its thought, imagination, and mood.--The hymn of the pearl: case study of a symbol, and the claims for a Jewish origin of gnosticism.--Myth and mysticism: a study of objectification and interiorization in religious thought.--Origen's metaphysics of free will, fall, and salvation: a "divine comedy" of the universe.--The soul in gnosticism and Plotinus.--The abyss of the will: philosophical meditations on the seventh chapter of Paul's epistle to the Romans. (shrink)

This paper discusses a puzzle raised by Sharon Berry, published in Analysis. The question in the background of this puzzle is how we should deal with seemingly plausible possibility judgements that commit us to counterfactual truths that find no basis in reality. Three answers to this question and their corresponding solutions to the puzzle will be discussed. The last answer provides a way to make sense of the claim that it is in some cases indeterminate whether a proposition is possible (...) and offers an account of indeterminate modal status. (shrink)

The idea of man in José Gaos could be explained taking in account two essential axes that make an inter-relationship between them and define man substantially: 1) antinomy love-hate-emotions and motions-expression and 2) reason-thought-language. The first is “the condition of possibility” of the second, being the element more suitable and radical that allows man to think concepts. The emotions and motions impose conditions over his will and determine the moral being that is. The man is a unity, but at the (...) same time, is an oscillation between opposites that make him take consciousness of his individuality, from the others, his historicity and intersubjectivity. The Gaos proposal is an important contribution to the anthropological reflection of the moment, because of the analysis categories that offers, of undeniable value, to the better understanding of suitable aspects of the being and acting of the Latino American man. (shrink)

Cette recension a déjà paru dans Critique d'art, le 4 novembre 2014. Renate LORENZ, Not Now! Now! Chronopolitics, Art & Research, Berlin, Sternberg Press, 2014, 187 p. Not Now! Now! prolonge les réflexions engagées lors du colloque international éponyme à l'Academy of Fine Arts de Vienne en 2013 qui réunissait théoriciens et artistes autour des chronopolitics. Si la durée, le rythme et l'ordonnancement du temps sont des enjeux majeurs dans la compréhension des évènements - Recensions.

How does history relate to the past? According to leading historical theorists, the relation to the past in history is reducible to evidential, psychological, practical and retrospective concerns. In contrast, this volume claims that historical relations to the past are irreducible products of the logical commitments of history as method. Ahlskog argues that the method of history shapes and enables relations to past in historical research by invoking past perspectives of meaning for rendering reality intelligible. The book provides a much-needed (...) philosophical clarification of key concepts in one of the most fundamental debates within the humanities today. (shrink)

Nonrelativistic quantum mechanics (QM) works perfectly well for all practical purposes. Once one admits, however, that a successful scientific theory is supposed not only to make predictions but also to tell us a story about the world in which we live, a philosophical problem emerges: in the specific case of QM, it is not possible to associate with the theory a unique scientific image of the world; there are several images. The fact that the theory may be compatible with distinct (...) ontologies, and that those ontologies may themselves be associated with a plurality of metaphysical approaches, gives rise to the problem of metaphysical underdetermination. This paper concludes that the available metametaphysical criteria fail to deliver objectivity in theory choice, and it puts forward its own criterion based on a tension between two methods of metaphysical inquiry: one that is closely related to science and another that is not. (shrink)

ABSTRACTTaking its starting point in an ancient understanding of hospitality and guest friendship, the paper offers a philosophical interpretation of the ethical dimension of alliances. Entering in...

Is the procreation asymmetry intuitively supported? According to a recent article in this journal, an experimental study suggests the opposite. Dean Spears (2020) claims that nearly three-quarters of participants report that there is a reason to create a person just because that person’s life would be happy. In reply, I argue that various confounding factors render the study internally invalid. More generally, I show how one might come to adopt the procreation asymmetry for the wrong reasons by misinterpreting one’s intuitions.

Jonas Olson presents a critical survey of moral error theory, the view that there are no moral facts and so all moral claims are false. Part I explores the historical context of the debate; Part II assesses J. L. Mackie's famous arguments; Part III defends error theory against challenges and considers its implications for our moral thinking.

We discuss the idea that superpositions in quantum mechanics may involve contradictions or contradictory properties. A state of superposition such as the one comprised in the famous Schrödinger’s cat, for instance, is sometimes said to attribute contradictory properties to the cat: being dead and alive at the same time. If that were the case, we would be facing a revolution in logic and science, since we would have one of our greatest scientific achievements showing that real contradictions exist.We analyze that (...) claim by employing the traditional square of opposition.We suggest that it is difficult to make sense of the idea of contradiction in the case of quantum superpositions. From a metaphysical point of view the suggestion also faces obstacles, and we present some of them. (shrink)

This paper sets out to undermine the view that a commitment to the early modern conception of the mind as immortalized in Ryle’s metaphor of the (Cartesian) ghost in the machine and in Quine’s metaphor of the (Lockean) myth of the museum is required to articulate a defence of the sui generis character of humanistic explanations. These powerful metaphors have not only contributed to undermining the claim for methodological pluralism by caricaturizing the arguments for disunity in the sciences; they have (...) also, and more worryingly, planted red herrings that have diverted attention away from the genuine issues at stake. This paper is an exercise in removing these false clues to reveal what the claim for the autonomy of humanistic explanations really amounts to. (shrink)

This paper questions the adequacy of the explicit cancellability test for conversational implicature as it is commonly understood. The standard way of understanding this test relies on two assumptions: first, that that one can test whether a certain content is conversationally implicated, by checking whether that content is cancellable, and second, that a cancellation is successful only if it results in a felicitous utterance. While I accept the first of these assumptions, I reject the second one. I argue that a (...) cancellation can succeed even if it results in an infelicitous utterance, and that unless we take this possibility into account we run the risk of misdiagnosing philosophically significant cases. (shrink)

This entry considers the philosophical subject called 'metaphysics'. There have been many conceptions of metaphysics, and metaphysics has faced severe criticism throughout the history of philosophy and continues to do so. Besides discussing some major trends in analytic metaphysics - understood as 'metaphysics done by analytic philosophers' - we consider some of the criticisms and possible responses.

Organizations that develop and deploy artificial intelligence (AI) systems need to manage the associated risks—for economic, legal, and ethical reasons. However, it is not always clear who is responsible for AI risk management. The three lines of defense (3LoD) model, which is considered best practice in many industries, might offer a solution. It is a risk management framework that helps organizations to assign and coordinate risk management roles and responsibilities. In this article, I suggest ways in which AI companies could (...) implement the model. I also discuss how the model could help reduce risks from AI: it could identify and close gaps in risk coverage, increase the effectiveness of risk management practices, and enable the board of directors to oversee management more effectively. The article is intended to inform decision-makers at leading AI companies, regulators, and standard-setting bodies. (shrink)

Following J.-Y.Béziau in his pioneer work on non-standard interpretations of the traditional square of opposition, we have applied the abstract structure of the square to study the relation of opposition between states in superposition in orthodox quantum mechanics in [1]. Our conclusion was that such states are contraries, contradicting previous analyzes that have led to different results, such as those claiming that those states represent contradictory properties. In this chapter we bring the issue once again into the center of the (...) stage, but now discussing the metaphysical presuppositions which underlie each kind of analysis and which lead to each kind of result, discussing in particular the idea that superpositions represent potential contradictions. We shall argue that the analysis according to which states in superposition are contrary rather than contradictory is still more plausible. (shrink)

In this work, we focus on a very specific case study: assuming that quantum theories deal with “particles” of some kind, what kind of entity can such particles be? One possible answer, the one we shall examine here, is that they are not the usual kind of object found in daily life: individuals. Rather, we follow a suggestion by Erwin Schrödinger, according to which quantum mechanics poses a revolutionary kind of entity: non-individuals. While physics, as a scientific field, is not (...) concerned with whether entities posited by a specific physical theory are individuals or not, answering this question is part of the quest for a better understanding of physical reality. Here lies, in large measure, the relevance of ontology. (shrink)

Experiences—visual, emotional, or otherwise—play a role in providing us with justification to believe claims about the world. Some accounts of how experiences provide justification emphasize the role of the experiences’ distinctive phenomenology, i.e. ‘what it is like’ to have the experience. Other accounts emphasize the justificatory role to the experiences’ etiology. A number of authors have used cases of cognitively penetrated visual experience to raise an epistemic challenge for theories of perceptual justification that emphasize the justificatory role of phenomenology rather (...) than etiology. Proponents of the challenge argue that cognitively penetrated visual experiences can fail to provide the usual justification because they have improper etiologies. However, extant arguments for the challenge’s key claims are subject to formidable objections. In this paper, I present the challenge’s key claims, raise objections to previous attempts to establish them, and then offer a novel argument in support of the challenge. My argument relies on an analogy between cognitively penetrated visual and emotional experiences. I argue that some emotional experiences fail to provide the relevant justification because of their improper etiologies and conclude that analogous cognitively penetrated visual experiences fail to provide the relevant justification because of their etiologies, as well. (shrink)

According to the received view, philosophy of action took a justified turn towards causalism because anti-causalists failed the causalist challenge about efficacious reasons. This paper contests that view by examining the ways in which Georg Henrik von Wright responded to causalism in his later philosophy. First, von Wright attacked the subjectivism of causalism by arguing for an objectivist view that construes reasons not as subjective mental states but as external facts of the agent's situation. Second, von Wright fundamentally disagreed with (...) the view of philosophical inquiry that underpinned causalism. For von Wright, the task of philosophy was conceptual: to explicate what one is looking for when one is looking for the real reasons for action. In contrast, for causalists the task was ontological: to determine what kind of item in the world the real reason for action is. Examining von Wright's account contributes to contemporary assessments of the metaphilosophical dimension of the reasons/causes debate. (shrink)

Let intentionalism be the view that what proposition is expressed in context by a sentence containing indexicals depends on the speaker’s intentions. It has recently been argued that intentionalism makes communicative success mysterious and that there are counterexamples to the intentionalist view in the form of cases of mismatch between the intended interpretation and the intuitively correct interpretation. In this paper, I argue that these objections can be met, once we acknowledge that we may distinguish what determines the correct interpretation (...) from the evidence that is available to the audience, as well as from the standards by which we judge whether or not a given interpretation is reasonable. With these distinctions in place, we see that intentionalism does not render communicative success mysterious, and that cases of mismatch between the intended interpretation and the intuitively correct one can easily be accommodated. The distinction is also useful in treating the Humpty Dumpty problem for intentionalism, since it turns out that this can be treated as an extreme special case of mismatch. (shrink)

According to the communication desideratum (CD), a notion of semantic content must be adequately related to communication. In the recent debate on indexical reference, (CD) has been invoked in arguments against the view that intentions determine the semantic content of indexicals and demonstratives (intentionalism). In this paper, I argue that the interpretations of (CD) that these arguments rely on are questionable, and suggest an alternative interpretation, which is compatible with (strong) intentionalism. Moreover, I suggest an approach that combines elements of (...) intentionalism with other subjectivist approaches, and discuss the role of intuitions in developing and evaluating theories of indexical reference. (shrink)

_ Source: _Page Count 23 The essay examines the recent discussion about a “crisis of testimony” in historiography. Central to this discussion is the question of how it is possible for human testimony to convey information about the limit experiences of 20th century history. Given that the credibility of testimony is assessed by appealing to our previous understanding of what is credible, testimony to limit experiences risks being dismissed as unbelievable or implausible. This issue has recently been addressed in the (...) work of Paul Ricoeur, Hayden White and Gert-Jan van der Heiden among others. In the first part of this essay, I show that the current idea of a crisis of testimony is a consequence of focusing too exclusively on the content of extraordinary testimony. I argue that such a focus has affinities with David Hume’s reductionist understanding of testimonial knowledge; even though the authors discussed cannot properly be labelled reductionists themselves. In the second part of the essay, I open up the issue of extraordinary testimony from a perspective that places the relationship between the speaker and the addressee at the heart of testimonial knowledge. My aim is to show that if we attend to the way in which testimonial knowledge involves dependence on the authority of another person, then the current idea of a crisis of testimony will dissolve itself. In conclusion, I argue that there is an important ethical dimension to the question of understanding extraordinary testimony. (shrink)

In this paper we deal with two applications of the square of opposition to controversial issues in the philosophy of quantum mechanics. The first one concerns the kind of opposition represented by states in superposition. A superposition of “spin up” and “spin down” for a given spatial direction, for instance, is sometimes said to originate particular kinds of opposition such as contradictoriness. The second application concerns the problem of identical particles. Identity and indiscernibility are entangled in discussions of this problem (...) in such a way that a proper conceptual treatment of those issues through the square seems profitable. (shrink)

The Weak Principle of the Identity of Indiscernibles (weak PII), states that numerically distinct items must be discernible by a symmetrical and irreflexive relation. Recently, some authors have proposed that weak PII holds in non relativistic quantum mechanics, contradicting a long tradition claiming PII to be simply false in that theory. The question that arises then is: are relations allowed in the scope of PII? In this paper, we propose that quantum mechanics does not help us in deciding matters concerning (...) that problem, since that is a metaphysical problem rather than a quantum mechanical one. We argue further that weak PII is unmotivated on metaphysical grounds. We examine three metaphysical theses (bundle theory, counting, empiricism) that may provide reasons for one to sustain PII, and we conclude that weak PII gets no independent motivation from them. (shrink)

During the last couple of decades, several attempts have been made to come up with a theory that can handle the various semantic, logical and philosophical problems raised by the vagueness of natural languages. One of the most influential ideas that have come into fashion in recent years is the idea that vagueness should be analysed as a form of context sensitivity. Such contextualist theories of vagueness have gained some popularity, but many philosophers have remained sceptical of the prospects of (...) finding a tenable contextualist solution to the problems of vagueness. This paper provides an introduction to the most popular contextualist accounts, and a discussion of some of the most important arguments for and against them. (shrink)

The first decade of event-related potential (ERP) research had established that the most consistent correlates of the onset of visual consciousness are the early visual awareness negativity (VAN), a posterior negative component in the N2 time range, and the late positivity (LP), an anterior positive component in the P3 time range. Two earlier extensive reviews ten years ago had concluded that VAN is the earliest and most reliable correlate of visual phenomenal consciousness, whereas LP probably reflects later processes associated with (...) reflective/access consciousness. This article provides an update to those earlier reviews. ERP and MEG studies that have appeared since 2010 and directly compared ERPs between aware and unaware conditions are reviewed, and important new developments in the field are discussed. The result corroborates VAN as the earliest and most consistent signature of visual phenomenal consciousness, and casts further doubt on LP as an ERP correlate of phenomenal consciousness. (shrink)

The goal of this paper is to present a new reconstruction of Aristotle's assertoric logic as he develops it in Prior Analytics, A1-7. This reconstruction will be much closer to Aristotle's original...

In Book II of the Republic, Socrates briefly depicts a city where each inhabitant contributes to the welfare of all by performing the role for which he or she is naturally suited. Socrates calls this city the `true city ' and the `healthy one'. Nearly all commentators have argued that Socrates' praise of the city cannot be taken at face value, claiming that it does not represent Socrates' preferred community. The point of this paper is to argue otherwise. The claim (...) is that Socrates genuinely believes the city is a healthy and desirable city, and that he believes that the First City is in fact superior to the Kallipolis. (shrink)

I propose a pragmatic approach to the kind of reference-shifting occurring in indexicals as used in e.g. written notes and answering machine messages. I proceed in two steps. First, I prepare the ground by showing that the arguments against such a pragmatic approach raised in the recent literature fail. Second, I take a first few steps towards implementing this approach, by sketching a pragmatic theory of reference-shifting, and showing how it can handle cases of the relevant kind. While the immediate (...) scope of the paper is restricted to indexicals and reference-shifting, and the discussion is confined to a specific range of theories and cases, the approach proposed is compatible with a fairly broad range of more or less semantically conservative theories, and many of the conclusions drawn are significant for the evaluation of pragmatic explanations in philosophy more generally. The overall goal is to offer a new perspective on the issues under discussion, and to prompt philosophers to reconsider some of the established methods by which pragmatic explanations are evaluated. (shrink)

The strategy of developing an ontology or models of disability as a prior step to settling ethical issues regarding disabilities is highly problematic for two reasons. First, key definitional aspects of disability are normative and cannot helpfully be made value-neutral. Second, if we accept that the contested concept of disability is value-laden, it is far from obvious that there are definitive reasons for choosing one interpretation of the concept over another. I conclude that the concept of disability is better left (...) ethically open-ended or broad enough to encompass the examination of various ethical issues. Alternatively, the concept of disability could be altogether abandoned in order to focus on specific issues without being hindered by debates about the nature of disability. Only political costs, rather than conceptual considerations internal to the models, could be weighed against such a conclusion. (shrink)

Cognitive Science, Volume 46, Issue 7, July 2022.

This paper offers a unified explanation for the procreation asymmetry and the non-identity thesis – two of the most intractable puzzles in population ethics. According to the procreation asymmetry, there are moral reasons not to create lives that are not worth living but no moral reasons to create lives that are worth living. I explain the procreation asymmetry by arguing that there are moral reasons to prevent the bad, but no moral reasons to promote the good. Various explanations for the (...) procreation asymmetry have failed to explain the non-identity thesis: if one could create a person with a good life or a different person with a better life, one has a moral reason to create the better life. I argue that reflections on the misfortune of unfulfilled potential allow us to circumvent the non-identity problem. (shrink)

This paper concerns how extant theorists of predictive coding conceptualize and explain possible instances of cognitive penetration. §I offers brief clarification of the predictive coding framework and relevant mechanisms, and a brief characterization of cognitive penetration and some challenges that come with defining it. §II develops more precise ways that the predictive coding framework can explain, and of course thereby allow for, genuine top-down causal effects on perceptual experience, of the kind discussed in the context of cognitive penetration. §III develops (...) these insights further with an eye towards tracking one extant criterion for cognitive penetration, namely, that the relevant cognitive effects on perception must be sufficiently direct. Throughout these discussions, we extend the analyses of the predictive coding models, as we know them. So one open question that surfaces is how much of the extended analyses are genuinely just part of the predictive coding models, or something that must be added to them in order to generate these additional explanatory benefits. In §IV, we analyze and criticize a claim made by some theorists of predictive coding, namely, that (interesting) instances of cognitive penetration tend to occur in perceptual circumstances involving substantial noise or uncertainty. It is here that our analysis is most critical. We argue that, when applied, the claim fails to explain (or perhaps even be consistent with) a large range of important and uncontroversially interesting possible cases of cognitive penetration. We conclude with a general speculation about how the recent work on the predictive mind may influence the current dialectic concerning top-down effects on perception. (shrink)

In the debate over what determines the reference of an indexical expression on a given occasion of use, we can distinguish between two generic positions. According to the first, the reference is determined by internal factors, such as the speaker’s intentions. According to the second, the reference is determined by external factors, like conventions or what a competent and attentive audience would take the reference to be. It has recently been argued that the first position is untenable, since there are (...) cases of mismatch where the intuitively correct reference differs from the one that would be determined by the relevant internal factors. The aim of this paper is to show that, contrary to this line of argument, it is the proponent of the second position that should be worried, since this position yields counterintuitive consequences regarding communicative success in cases of mismatch. (shrink)

Although the production and recognition of social actions have been central concerns for conversation analysis from the outset, it has recently been argued that CA is yet to develop a systematic analysis of ‘action formation’. As a partial remedy to this situation, John Heritage introduces ‘epistemic status’, which he claims is an unavoidable component of the production and recognition of social action. His proposal addresses the question how is social action produced and recognized? by reference to another question how is (...) relative knowledge recognized? Despite the importance placed on the latter question, it is not clear how it is to be answered in particular cases. We argue that the introduction of epistemic status builds on a reformulation of the action formation problem that unnecessarily de-emphasizes the importance of the sequential environment. Our re-analyses of key sequences cast doubts on the empirical grounding of the epistemic program, and question whether the fundamental role of epistemic status has been convincingly demonstrated. (shrink)

Reality is hierarchically structured, or so proponents of the metaphysical posit of grounding argue. The less fundamental facts obtain in virtue of, or are grounded in, the more fundamental facts. But what exactly is it for one fact to be more fundamental than another? The aim of this paper is to provide a measure of relative fundamentality. I develop and defend an account of the metaphysical hierarchy that assigns to each fact a set of ordinals representing the levels on which (...) it occurs. The account allows one to compare any two facts with respect to their fundamentality and it uses immediate grounding as its sole primitive. In the first section, I will set the stage and point to some shortcomings of a rival account proposed by Karen Bennett. The second section will present my own proposal and the third section will discuss how it can be extended to non-foundationalist settings. The fourth section discusses potential objections. (shrink)

Contextualism about vagueness (hereafter ‘Contextualism’) is the view that vagueness consists in a particular species of context-sensitivity and that properly accommodating this fact into our semantic theory will yield a plausible solution to the sorites paradox.[1],[2] But Contextualism, as many commentators have noted, faces the following immediate objection: if we hold the context fixed, vagueness still remains, therefore vagueness is not a species of context-sensitivity. Call this ‘the simple objection’.[3] Absent a convincing reply to the simple objection, Contextualism is in (...) very bad shape. Oddly enough, defenders of Contextualism have said very little in reply. Proponents of the objection have tended to assume that this is because no reply is in the offing—the simple objection is taken to be unassailable. In this short paper, we sketch two replies to the simple objection which result in two very different kinds of Contextualism: Epistemicist Contextualism and Radical Contextualism. With these two theories in hand, the simple objection loses its force. (shrink)

Discussing Plato's views on knowledge, recollection, dialogue, and epiphany, this ambitious volume offers a systematic analysis of the ways that Platonic approaches to education can help students navigate today's increasingly complex moral environment. Though interest in Platonic education may have waned due to a perceived view of Platonic scholarship as wholly impractical, this volume addresses common misunderstandings of Plato's work and highlights the contemporary relevance of Plato's ideas to contemporary moral education. Building on philosophical interpretations, the book argues persuasively that (...) educators might employ Platonic themes and dialogue in the classroom. Split into two parts, the book looks first to contextualise Plato's theory of moral education within political, ethical, and educational frameworks. Equipped with this knowledge, part two then offers contemporary educators the strategies needed for implementing Plato's educational theory within the pluralistic, democratic classroom setting. A Platonic Theory of Moral Education will be of interest to academics, researchers, and post-graduate students in the fields of: ethics; Plato scholarship; moral psychology; educational foundations; and the philosophy of education. This book would also benefit graduate students and scholars in teacher education. Mark E. Jonas is Professor of Education and Professor of Philosophy at Wheaton College, US. Yoshiaki Nakazawa is Assistant Professor of Education at University of Dallas, US. (shrink)

The past decade has seen a renewed interest in moral psychology. A unique feature of the present endeavor is its unprecedented interdisciplinarity. For the first time, cognitive, social, and developmental psychologists, neuroscientists, experimental philosophers, evolutionary biologists, and anthropologists collaborate to study the same or overlapping phenomena. This review focuses on moral judgments and is written from the perspective of cognitive psychologists interested in theories of the cognitive and affective processes underlying judgments in moral domains. The review will first present and (...) discuss a variety of different theoretical and empirical approaches, including both behavioral and neuroscientific studies. We will then show how these theories can be applied to a selected number of specific research topics that have attracted particular interest in recent years, including the distinction between moral and conventional rules, moral dilemmas, the role of intention, and sacred/protected values. One overarching question we will address throughout the chapter is whether moral cognitions are distinct and special, or whether they can be subsumed under more domain-general mechanisms. (shrink)

Trevor Teitel (2017) has recently argued that combining the assumption that modality reduces to essence with the assumption that possibly some objects contingently exist leads to problems if one wishes to uphold that the logic of metaphysical modality is S5. In this paper I will argue that there is a way for the essentialist to evade the problem described by Teitel. The proposed solution crucially involves the assumption that some propositions possibly fail to exist. I will show how this assumption (...) affords a motivated contingentist response to Teitel’s argument. (shrink)

In the paper we investigate the topos of sheaves on a category of ultrafilters. The category is described with the help of the Rudin-Keisler ordering of ultrafilters. It is shown that the topos is Boolean and two-valued and that the axiom of choice does not hold in it. We prove that the internal logic in the topos does not coincide with that in any of the ultrapowers. We also show that internal set theory, an axiomatic nonstandard set theory, can be (...) modeled in the topos. (shrink)