Traditional methods of evaluating and solving world problems are insufficient to deal with today's issues, which are complex and interconnected, and therefore cannot be understood, or solved, in isolation. The author's study aimed to better understand behaviors that impact systemic problems in the capacity-building community. The resultant theory of simulating benevolence conceptualizes a collection of behaviors where change agents undertake activities that are not in the best interest of community members. Instead, activities satisfy the need for activity, involvement, and excitement. (...) This theory has real-world implications in the pursuit of systemic social change. In any social context, a change agent cannot merely go through the motions of change, seemingly behaving active and engaged, at the expense of those that he or she claims to help. (shrink)

Background and Objectives: Stress is a ubiquitous aspect of modern life that affects both mental and physical health. Clinical care settings can be particularly stressful for both patients and providers. Kindness and compassion are buffers for the negative effects of stress, likely through strengthening positive interpersonal connection. In previous laboratory-based studies, simply watching kindness media uplifts viewers, increases altruism, and promotes connection to others. The objective of the present study is to examine whether kindness media can affect viewers in a (...) real-world, pediatric healthcare setting.Methods: Parents and staff in a pediatric dental clinic were studied. Study days were randomized for viewers to watch either original kindness media or the standard televised children’s programming that the clinic shows. Participants scored self-rated pre-media emotions in a survey, watched either media type for 8 min, and then completed the survey. All participants were informed that they would receive a gift card for their participation. After completion of the survey, participants were asked if they wanted to keep the card or donate it to a family in need.Results: Fifty participants completed the study; 28 were parents and 22 were staff. In comparison to viewers of children’s programming, participants who watched kindness media had significant increases in feeling happy, calmer, more grateful, and less irritated, with trends observed in feeling more optimistic and less anxious. Kindness media caused marked increases in viewers’ reports of feeling inspired, moved, or touched. No change was observed in self-reported compassion, although baseline levels were self-rated as very high. People who watched kindness media were also more generous, with 85% donating their honoraria compared to 54% of Standard viewers.Conclusions: Kindness media can increase positive emotions and promote generosity in a healthcare setting. (shrink)

This dissertation aims to provide a comprehensive account of set theory with urelements. In Chapter 1, I present mathematical and philosophical motivations for studying urelement set theory and lay out the necessary technical preliminaries. Chapter 2 is devoted to the axiomatization of urelement set theory, where I introduce a hierarchy of axioms and discuss how ZFC with urelements should be axiomatized. The breakdown of this hierarchy of axioms in the absence of the Axiom of Choice is also explored. (...) In Chapter 3, I investigate forcing with urelements and develop a new approach that addresses a drawback of the existing machinery. I demonstrate that forcing can preserve, destroy, and recover the axioms isolated in Chapter 2 and discuss how Boolean ultrapowers can be applied in urelement set theory. Chapter 4 delves into class theory with urelements. I first discuss the issue of axiomatizing urelement class theory and then explore the second-order reflection principle with urelements. In particular, assuming large cardinals, I construct a model of second-order reflection where the principle of limitation of size fails. (shrink)

After reviewing various natural bi-interpretations in urelement set theory, including second-order set theories with urelements, we explore the strength of second-order reflection in these contexts. Ultimately, we prove, second-order reflection with the abundant atom axiom is bi-interpretable and hence also equiconsistent with the existence of a supercompact cardinal. The proof relies on a reflection characterization of supercompactness, namely, a cardinal κ is supercompact if and only if every Π11 sentence true in a structure M (of any size) containing κ (...) in a language of size less than κ is also true in a substructure m≺M of size less than κ with m∩κ∈κ. (shrink)

We study reflection principles in Kelley-Morse set theory with urelements (KMU). We first show that First-Order Reflection Principle is not provable in KMU with Global Choice. We then show that KMU + Limitation of Size + Second-Order Reflection Principle is mutually interpretable with KM + Second-Order Reflection Principle. Furthermore, these two theories are also shown to be bi-interpretable with parameters. Finally, assuming the existence of a κ+-supercompact cardinal κ in KMU, we construct a model of KMU + Second-Order Reflection (...) Principle where Limitation of Size fails. (shrink)

We show that the theories ZF and ZFU are synonymous, answering a question of Visser.

Boolean-valued models generalize classical two-valued models by allowing arbitrary complete Boolean algebras as value ranges. The goal of my dissertation is to study Boolean-valued models and explore their philosophical and mathematical applications.In Chapter 1, I build a robust theory of first-order Boolean-valued models that parallels the existing theory of two-valued models. I develop essential model-theoretic notions like “Boolean-valuation,” “diagram,” and “elementary diagram,” and prove a series of theorems on Boolean-valued models, including the (strengthened) Soundness and Completeness Theorem, the Löwenheim–Skolem Theorems, (...) the Elementary Chain Theorem, and many more.Chapter 2 gives an example of a philosophical application of Boolean-valued models. I apply Boolean-valued models to the language of mereology to model indeterminacy in the parthood relation. I argue that Boolean-valued semantics is the best degree-theoretic semantics for the language of mereology. In particular, it trumps the well-known alternative—fuzzy-valued semantics. I also show that, contrary to what many have argued, indeterminacy in parthood entails neither indeterminacy in existence nor indeterminacy in identity, though being compatible with both.Chapter 3 (joint work with Bokai Yao) gives an example of a mathematical application of Boolean-valued models. Scott and Solovay famously used Boolean-valued models on set theory to obtain relative consistency results. In Chapter 3, I investigate two ways of extending the Scott–Solovay construction to set theory with urelements. I argue that the standard way of extending the construction faces a serious problem, and offer a new way that is free from the problem.Abstract prepared by Xinhe Wu.E-mail: [email protected]. (shrink)

The usual construction of models of NFU (New Foundations with urelements, introduced by Jensen) is due to Maurice Boffa. A Boffa model is obtained from a model of (a fragment of) Zermelo–Fraenkel with Choice (ZFC) with an automorphism which moves a rank: the domain of the Boffa model is a rank that is moved. “Most” elements of the domain of the Boffa model are urelements in terms of the interpreted NFU. The main result of this paper is that (...) the restriction of the membership relation of the original model of set theory with automorphism to the domain of the Boffa model is first-order definable in the language of NFU. In particular, all information about the extensions in the original model of the urelements of the model of NFU is definable in terms of NFU. A corollary (answering a question of Thomas Forster) is that the urelements in a Boffa model are not homogeneous. (shrink)

is the second-order theory of the part-whole relation. It can express such hypotheses about the size of Reality as that there are inaccessibly many atoms. Take a non-empty class to have exactly its non-empty subclasses as parts; hence, its singleton subclasses as atomic parts. Then standard set theory becomes the theory of the member-singleton function—better, the theory of all singleton functions—within the framework of megethology. Given inaccessibly many atoms and a specification of which atoms are urelements, a singleton function (...) exists, unique up to isomorphism. (This article is partly abridged from my Parts of Classes, partly a sequel.). (shrink)

What follows is a contribution to the theory of space and of spatial objects. It takes as its starting point the philosophical subfield of ontology, which can be defined as the science of what is: of the various types and categories of objects and relations in all realms of being. More specifically, it begins with ideas set forth by Aristotle in his Categories and Metaphysics, two works which constitute the first great contributions to ontological science. Because Aristotle’s ontological ideas were (...) developed prior to the scientific discoveries of the modern era, he approached the objects and relations of everyday reality with the same ontological seriousness with which scientists today approach the objects of physics. We shall seek to show that what Aristotle has to say about these commonsensical objects and relations can, when translated into more formal terms, be of use also to contemporary ontologists. More precisely, we shall argue that his ideas can contribute to the development of a rigorous theory of those social and institutional components of everyday reality – the settings of human behavior – which are the subject of this volume. When modern-day philosophers turn their attentions to ontology they begin not with Aristotle but rather, in almost every case, with a set-theoretic ontology of the sort which is employed in standard model-theoretic semantics. Set-theoretic ontology sees the world in atomistic terms: it postulates a lowest level of atoms or urelements, from out of which successively higher levels of set-theoretic objects are then constructed. The approach to ontology to be defended here, in contrast, starts not with atoms but with the mesoscopic objects by which we are surrounded in our normal day-to-day.. (shrink)

The iterative conception of set is typically considered to provide the intuitive underpinnings for ZFCU (ZFC+Urelements). It is an easy theorem of ZFCU that all sets have a definite cardinality. But the iterative conception seems to be entirely consistent with the existence of “wide” sets, sets (of, in particular, urelements) that are larger than any cardinal. This paper diagnoses the source of the apparent disconnect here and proposes modifications of the Replacement and Powerset axioms so as to allow (...) for the existence of wide sets. Drawing upon Cantor’s notion of the absolute infinite, the paper argues that the modifications are warranted and preserve a robust iterative conception of set. The resulting theory is proved consistent relative to ZFC + “there exists an inaccessible cardinal number.”. (shrink)

We present a formal first-order theory of artificial objects, i.e., objects made out of a finite number of parts and subject to assembling and dismantling processes. These processes are absolutely reversible. The theory is an extension of the theory of finite sets with urelements. The notions of transformation and identity are defined and studied on the assumption that the objects are homogeneous, that is to say, all their atomic parts are of equal ontological importance. Particular emphasis is given to (...) the behavior of classes of artifacts in time. We call such classes satisfying certain preservation conditions worlds. Various results concerning the existence, extension, and completeness of worlds are proved. (shrink)

Frege hat über Jahrzehnte hinweg an einem Buch über die Grundlagen der Logik gearbeitet, dessen erster Teil folgenden Fragen gewidmet sein sollte: Ist Wahrheit definierbar oder ein „logisches Urelement“? Ist Wahrheit die Übereinstimmung eines inneren Bildes mit der Realität, oder ein Spezialfall der Beziehung zwischen dem Sinn eines Zeichens und seinem Bezug? Welchen Beitrag leistet der Sinn des Wortes ,wahr’ zu dem Sinn der Sätze, in denen es vorkommt? Sind die Wahrheitswerte – „das Wahre“ und „das Falsche“ – als Eigenschaften (...) oder als Gegenstände aufzufassen? Gehört das, was wahr oder falsch ist, der Innenwelt an? Was ist eine Tatsache? Frege war jedoch weit davon entfernt, seine Konzeption der Wahrheit in die Form einer systematischen Theorie zu bringen. Sie besteht vielmehr aus einem losen und überaus komplexen Konglomerat wahrheitstheoretischer Doktrinen, die – für sich genommen – sehr unterschiedlichen und teilweise auch gegensätzlichen Richtungen der Wahrheitstheorie zuzuordnen sind. Aus diesen Gründen hat die Konzeption bisher wenig Beachtung gefunden; sie gilt als weitgehend konfus und inkohärent. Die vorliegende Studie versucht dagegen zu zeigen, daß sich die Konzeption bei genauerer Betrachtung als ein Ansatz von hoher Überzeugungskraft und systematischer Geschlossenheit entpuppt. Die exegetische Hauptthese ist, daß die Konzeption auf einem originellen Grundverständnis von Wahrheit basiert, das sich durch die Orientierung an der „behauptenden Kraft“ auszeichnet: Unter „Wahrheit“ versteht Frege das, was in der natürlichen Sprache durch die „Form des Behauptungssatzes“ ausgedrückt wird. (shrink)

Every domain-specific ontology must use as a framework some upper-level ontology which describes the most general, domain-independent categories of reality. In the present paper we sketch a new type of upper-level ontology, which is intended to be the basis of a knowledge modelling language GOL (for: 'General Ontological Language'). It turns out that the upper- level ontology underlying standard modelling languages such as KIF, F-Logic and CycL is restricted to the ontology of sets. Set theory has considerable mathematical power and (...) great flexibility as a framework for modelling different sorts of structures. At the same time it has the disadvantage that sets are abstract entities (entities existing outside the realm of time, space and causality), and thus a set-theoretical framework should be supplemented by some other machinery if it is to support applications in the ripe, messy world of concrete objects. In the present paper we partition the entities of the real world into sets and urelements, and then we introduce several new ontological relations between these urelements. In contrast to standard modelling and representation formalisms, the concepts of GOL provide a machinery for representing and analysing such ontologically basic relations. (shrink)

In many ontological debates there is a familiar challenge. Consider a debate over X s. The “small” or anti-X side tries to show that they can paraphrase the pro-X or “big” side’s claims without any loss of expressive power. Typically though, when the big side adds whatever resources the small side used in their paraphrase, the symmetry breaks down. The big side plus small’s resources is a more expressively powerful and thus more theoretically fruitful theory. In this paper, I show (...) that there is a very general solution to this problem, for the small side. Assuming the resources of set theory, small can successfully paraphrase big. This result depends on a theorem about models of set theory with urelements. After proving this theorem, I discuss some of its philosophical ramifications. (shrink)

Argument-places play an important role in our dealing with relations. However, that does not mean that argument-places should be taken as primitive entities. It is possible to give an account of ‘real’ relations in which argument-places play no role. But if argument-places are not basic, then what can we say about their identity? Can they, for example, be reconstructed in set theory with appropriate urelements? In this article, we show that for some relations, argument-places cannot be modeled in aneutralway (...) in V[A], the cumulative hierarchy with basic ingredients of the relation as urelements. We argue that a natural way to conceive of argument-places is to identify them with abstract, structureless points of a derivative structure exemplified by positional frames. In case the relation has symmetry, these points may be indiscernible. (shrink)

In selected texts by Diderot, including the Encyclopédie article “Cabinet d’histoire naturelle” (along with his comments in the article “Histoire nat-urelle”), the Pensées sur l’interprétation de la nature and the Salon de 1767, I examine the interplay between philosophical naturalism and the recognition of the irreducible nature of artifice, in order to arrive at a provisional definition of Diderot’s vision of Nature as “une femme qui aime à se travestir.” How can a metaphysics in which the concept of Nature has (...) a normative status, also ultimately consider it to be something necessarily artificial? Historically, the answer to this question involves the project of natural history. A present-day reconstruction would have to make sense of this project and relate it to the vision of Nature expressed in Diderot’s phrase. In addition, it would hopefully pinpoint the difference between this brand of Enlightenment naturalism and contemporary naturalism, and by extension, allow us to understand a bit more about what naturalism is in general. (shrink)

The notion of a "class as many" was central to Bertrand Russell''s early form of logicism in his 1903 Principles of Mathematics. There is no empty class in this sense, and the singleton of an urelement (or atom in our reconstruction) is identical with that urelement. Also, classes with more than one member are merely pluralities — or what are sometimes called "plural objects" — and cannot as such be themselves members of classes. Russell did not formally develop this notion (...) of a class but used it only informally. In what follows, we give a formal, logical reconstruction of the logic of classes as many as pluralities (or plural objects) within a fragment of the framework of conceptual realism. We also take groups to be classes as many with two or more members and show how groups provide a semantics for plural quantifier phrases. (shrink)

Argument-places play an important role in our dealing with relations. However, that does not mean that argument-places should be taken as primitive entities. It is possible to give an account of relations in which argument-places play no role. But if argument-places are not basic, then what can we say about their identity? Can they, for example, be reconstructed in set theory with appropriate urelements? In this article, we show that for some relations, argument-places cannot be modeled in a neutral (...) way in V[A], the cumulative hierarchy with basic ingredients of the relation as urelements. We argue that a natural way to conceive of argument-places is to identify them with abstract, structureless points of a derivative structure exemplified by positional frames. In case the relation has symmetry, these points may be indiscernible. (shrink)

The still unsettled decision problem for the restricted purely universal formulae 0-formulae) of the first order set-theoretic language based over =, ∈ is discussed in relation with the adoption or rejection of the axiom of foundation. Assuming the axiom of foundation, the related finite set-satisfiability problem for the very significant subclass of the 0-formulae consisting of the formulae involving only nested variables of level 1 is proved to be semidecidable on the ground of a reflection property over the hereditarily finite (...) sets, and various extensions of this result are obtained. When variables are restricted to range only over sets, in universes with infinitely many urelements the set-satisfiability problem is shown to be solvable provided the axiom of foundation is assumed; if it is not, then the decidability of a related derivability problem still holds. That, in turn, suggests the alternative adoption of an antifoundation axiom under which the set-satisfiability problem is also solvable . Turning to set theory without urelements, assuming a form of Boffa's antifoundation axiom, the complement of the set-satisfiability problem for the full class of Δ0-formulae is shown to be semidecidable; a result that is known not to hold, for the set-satisfiability problem itself, even for a very restricted subclass of the Δ0-formulae. (shrink)

An ω-model (a model in which all natural numbers are standard) of the predicative fragment of Quine's set theory "New Foundations" (NF) is constructed. Marcel Crabbe has shown that a theory NFI extending predicative NF is consistent, and the model constructed is actually a model of NFI as well. The construction follows the construction of ω-models of NFU (NF with urelements) by R. B. Jensen, and, like the construction of Jensen for NFU, it can be used to construct α-models (...) for any ordinal α. The construction proceeds via a model of a type theory of a peculiar kind; we first discuss such "tangled type theories" in general, exhibiting a "tangled type theory" (and also an extension of Zermelo set theory with Δ 0 comprehension) which is equiconsistent with NF (for which the consistency problem seems no easier than the corresponding problem for NF (still open)), and pointing out that "tangled type theory with urelements" has a quite natural interpretation, which seems to provide an explanation for the more natural behaviour of NFU relative to the other set theories of this kind, and can be seen anachronistically as underlying Jensen's consistency proof for NFU. (shrink)

It is shown that the 3-stratifiable sentences are equivalent in to truth-functional combinations of sentences about objects, sets of objects, sets of sets of objects, and sentences stating that there are at least urelements. This is then used to characterize the closed 3-stratifiable theorems of with an externally infinite number of urelements, as those that can be nearly proved in with an externally infinite number of urelements. As a byproduct we obtain a rather simple demonstration of the (...) consistency of 3-stratifiable extensions of. (shrink)

i. Proofless text is based on a variant of ZFC with free logic. Here variables always denote, but not all terms denote. If a term denotes, then all subterms must denote. The sets are all in the usual extensional cumulative hierarchy of sets. There are no urelements.

It is shown that the 3-stratifiable sentences are equivalent in $\mathit{NFU}$ to truth-functional combinations of sentences about objects, sets of objects, sets of sets of objects, and sentences stating that there are at least $n$ urelements. This is then used to characterize the closed 3-stratifiable theorems of $\mathit{NFU}$ with an externally infinite number of urelements, as those that can be nearly proved in $\mathit{TTU}$ with an externally infinite number of urelements. As a byproduct we obtain a rather (...) simple demonstration of the consistency of 3-stratifiable extensions of $\mathit{NFU}$. (shrink)

Let $\mathscr{M}$ be a structure for a language $\mathscr{L}$ on a set $M$ of urelements. $\mathrm{HYP}(\mathscr{M})$ is the least admissible set above $\mathscr{M}$. In $\S 1$ we show that $pp(\mathrm{HYP}(\mathscr{M})) \lbrack = \text{the collection of pure sets in} \mathrm{HYP}(\mathscr{M}\rbrack$ is determined in a simple way by the ordinal $\alpha = \circ(\mathrm{HYP}(\mathscr{M}))$ and the $\mathscr{L}_{\propto\omega}$ theory of $\mathscr{M}$ up to quantifier rank $\alpha$. In $\S 2$ we consider the question of which pure countable admissible sets are of the form $pp(\mathrm{HYP}(\mathscr{M}))$ (...) for some $\mathscr{M}$ and show that all sets $L_\alpha (\alpha$ admissible) are of this form. Other positive and negative results on this question are obtained. (shrink)

This paper discusses a sequence of extensions ofNFU, Jensen's improvement of Quine's set theory “New Foundations” (NF) of [16].The original theoryNFof Quine continues to present difficulties. After 60 years of intermittent investigation, it is still not known to be consistent relative to any set theory in which we have confidence. Specker showed in [20] thatNFdisproves Choice (and so proves Infinity). Even if one assumes the consistency ofNF, one is hampered by the lack of powerful methods for proofs of consistency and (...) independence such as are available for use withZFC; very clever work has been done with permutation methods, starting with [18] and [5], and exemplified more recently by [14], but permutation methods can only be applied to show the consistency or independence of unstratified sentences (see the definition ofNFUbelow for a definition of stratification). For example, there is no method available to determine whether the assertion “the continuum can be well-ordered” is consistent with or independent ofNF. There is one substantial independence result for an assertion with nontrivial stratified consequences, using metamathematical methods: this is Orey's proof of the independence of the Axiom of Counting fromNF(see below for a statement of this axiom).We mention these difficulties only to reassure the reader of their irrelevance to the present work. Jensen's modification of “New Foundations” (in [13]), which was to restrict extensionality to sets, allowing many non-sets (urelements) with no elements, has almost magical effects. (shrink)

Let M be a structure for a language L on a set M of urelements. HYP(M) is the least admissible set above M. In § 1 we show that pp(HYP(M)) [ = the collection of pure sets in HYP(M] is determined in a simple way by the ordinal α = ⚬(HYP(M)) and the $\mathscr{L}_{\propto\omega}$ theory of M up to quantifier rank α. In § 2 we consider the question of which pure countable admissible sets are of the form pp(HYP(M)) (...) for some M and show that all sets L α (α admissible) are of this form. Other positive and negative results on this question are obtained. (shrink)

Every domain-specific ontology must use as a framework some upper-level ontology which describes the most general domain-independent categories of reality. In the present paper we sketch a new type of upper-level ontology, and we outline an associated knowledge modelling language called GOL – for: General Ontological Language. It turns out that the upper-level ontology underlying well-known standard modelling languages such as KIF, F-Logic and CycL is restricted to the ontology of sets. In a set theory which allows Urelements, however, (...) there will be ontological relations between these Urelements which the set-theoretic machinery cannot capture. In contrast to standard modelling and representation formalisms, GOL provides a machinery for representing and analysing such ontologically basic relations. GOL is thus a genuine extension of KIF and of similar languages. In GOL entities are divided into sets and Urelements, the latter being divided in their turn into individuals and universals. Foremost among the individuals are things or substances, tropes or moments, and situoids: entities containing facts as components. (shrink)

An idea attributable to Russell serves to extend Zermelo’s theory of systems of infinitely long propositions to infinitary relations. Specifically, relations over a given domain \ of individuals will now be identified with propositions over an auxiliary domain \ subsuming \. Three applications of the resulting theory of infinitary relations are presented. First, it is used to reconstruct Zermelo’s original theory of urelements and sets in a manner that achieves most, if not all, of his early aims. Second, the (...) new account of infinitary relations makes possible a concise characterization of parametric definability with respect to a purely relational structure. Finally, based on his foundational philosophy of the primacy of the infinite, Zermelo rejected Gödel’s First Incompleteness Theorem; it is shown that the new theory of infinitary relations can be brought to bear, positively, in that connection as well. (shrink)

Let U be an admissible structure. A cPCd(U) class is the class of all models of a sentence of the form $\neg\exists\bar{K} \bigwedge \Phi$ , where K̄ is an U-r.e. set of relation symbols and φ is an U-r.e. set of formulas of L∞ω that are in U. The main theorem is a generalization of the following: Let U be a pure countable resolvable admissible structure such that U is not Σ-elementarily embedded in HYP(U). Then a class K of countable (...) structures whose universes are sets of urelements is a cPCd(U) class if and only if for some Σ formula σ (with parameters from U), M is in K if and only if M is a countable structure with universe a set of urelements and $(\mathrm{HYP}_\mathfrak{U}(\mathfrak{M}), \mathfrak{U}, \mathfrak{M}) \models \sigma$ , where HYPU(M), the smallest admissible set above M relative to U, is a generalization of HYP to structures with similarity type Σ over U that is defined in this article. Here we just note that when Lα is admissible, HYPLα(M) is Lβ(M) for the least β ≥ α such that Lβ(M) is admissible, and so, in particular, that HYPHF(M) is just HYP(M) in the usual sense when M has a finite similarity type. The definition of HYPU(M) is most naturally formulated using Adamson's notion of a +-admissible structure (1978). We prove a generalization from admissible to +-admissible structures of the well-known truncation lemma. That generalization is a key theorem applied in the proof of the generalized Spector-Gandy theorem. (shrink)

This paper discusses a sequence of extensions ofNFU, Jensen's improvement of Quine's set theory “New Foundations” (NF) of [16].The original theoryNFof Quine continues to present difficulties. After 60 years of intermittent investigation, it is still not known to be consistent relative to any set theory in which we have confidence. Specker showed in [20] thatNFdisproves Choice (and so proves Infinity). Even if one assumes the consistency ofNF, one is hampered by the lack of powerful methods for proofs of consistency and (...) independence such as are available for use withZFC; very clever work has been done with permutation methods, starting with [18] and [5], and exemplified more recently by [14], but permutation methods can only be applied to show the consistency or independence of unstratified sentences (see the definition ofNFUbelow for a definition of stratification). For example, there is no method available to determine whether the assertion “the continuum can be well-ordered” is consistent with or independent ofNF. There is one substantial independence result for an assertion with nontrivial stratified consequences, using metamathematical methods: this is Orey's proof of the independence of the Axiom of Counting fromNF(see below for a statement of this axiom).We mention these difficulties only to reassure the reader of their irrelevance to the present work. Jensen's modification of “New Foundations” (in [13]), which was to restrict extensionality to sets, allowing many non-sets (urelements) with no elements, has almost magical effects. (shrink)

Two models of second-order ZFC need not be isomorphic to each other, but at least one is isomorphic to an initial segment of the other. The situation is subtler for impure set theory, but Vann McGee has recently proved a categoricity result for second-order ZFCU plus the axiom that the urelements form a set. Two models of this theory with the same universe of discourse need not be isomorphic to each other, but the pure sets of one are isomorphic (...) to the pure sets of the other. This paper argues that similar results obtain for considerably weaker second-order axiomatizations of impure set theory that are in line with two different conceptions of set, the iterative conception and the limitation of size doctrine. (shrink)

We prove two of the inequalities needed to obtain the following result on the ordinal values of ptykes of type 2, which are definable in Gödel'sT. LetG be a dilator satisfyingG(0)=ω, ∀x:G(x)≧x, and ∀η<Ω:G(η)<Ω, and letg be the ordinal function induced byG. Then sup{A(G)∣A ptyx of type 2 definable in Gödel'sT} = sup{x∣x is∑ 1 g -definable without parameters provably in KP(G)} =J (2 +Id) g (ω) (0) = the “Bachmann-Howard ordinal relative tog”. KP(G) is obtained from Kripke-Platek set theory (...) without urelements KP by adjoining a two-place relation symbolG and axioms expressing thatG is the graph of a total function from ordinals to ordinals.J D g is an iteration hierarchy defined relative tog by primitive recursion on dilators. (2 +Id)(ω) is the dilator $$\mathop {\sup }\limits_{n< \omega } (\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} + Id)_{(n)} $$ with (2 +Id)(0)≔1 and $$(\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} + Id)_{(n + 1)} : = (\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} + Id)^{(2 + Id)_{(n)} } $$ . The “Bachmann-Howard ordinal relative tog” is the closure ordinal of a Bachmann hierarchy of lengthε Ω + 1, which is built on an iteration ofg as initial function.For the caseG=(1+Id)·ω, KP(G) is equivalent to Jäger's theory KPu, and the “Bachmann-Howard ordinal relative tog” is the usual “Bachmann-Howard ordinal”. For the caseG=Ξ1 KP(G) can be replaced by Jäger's theory KPi, andg can be replaced by the functionλx. x +.x + is the successor admissible ofx, andΞ 1 is the sum of all recursive dilators in an arbitrary enumeration. (shrink)

We show that, if non-uniform impredicative stratified comprehension is assumed, Feferman's theories of explicit mathematics are consistent with a strong power type axiom. This result answers a problem, raised by Jäger. The proof relies upon an interpretation into Quine's set theory NF with urelements.

I propose a new theory of mereology based on a mereological reflection principle. Reflective mereology has natural fusion principles but also refutes certain principles of classical mereology such as Universal Fusion and Fusion Uniqueness. Moreover, reflective mereology avoids Uzquiano’s cardinality problem–the problem that classical mereology tends to clash with set theory when they both quantify over everything. In particular, assuming large cardinals, I construct a model of reflective mereology and second-order ZFCU with Limitation of Size. In the model, classical mereology (...) holds when the quantifiers are restricted to the urelements. (shrink)

Let $\mathfrak{U}$ be an admissible structure. A $\mathrm{cPC}_d(\mathfrak{U})$ class is the class of all models of a sentence of the form $\neg\exists\bar{K} \bigwedge \Phi$, where $\bar{K}$ is an $\mathfrak{U}$-r.e. set of relation symbols and $\phi$ is an $\mathfrak{U}$-r.e. set of formulas of $\mathscr{L}_{\infty\omega}$ that are in $\mathfrak{U}$. The main theorem is a generalization of the following: Let $\mathfrak{U}$ be a pure countable resolvable admissible structure such that $\mathfrak{U}$ is not $\Sigma$-elementarily embedded in $\mathrm{HYP}(\mathfrak{U})$. Then a class $\mathbf{K}$ of countable structures (...) whose universes are sets of urelements is a $\mathrm{cPC}_d(\mathfrak{U})$ class if and only if for some $\Sigma$ formula $\sigma$ (with parameters from $\mathfrak{U}$), $\mathfrak{M}$ is in $\mathbf{K}$ if and only if $\mathfrak{M}$ is a countable structure with universe a set of urelements and $(\mathrm{HYP}_\mathfrak{U}(\mathfrak{M}), \mathfrak{U}, \mathfrak{M}) \models \sigma$, where $\mathrm{HYP}_\mathfrak{U}(\mathfrak{M})$, the smallest admissible set above $\mathfrak{M}$ relative to $\mathfrak{U}$, is a generalization of $\mathrm{HYP}$ to structures with similarity type $\Sigma$ over $\mathfrak{U}$ that is defined in this article. Here we just note that when $\mathrm{L}_\alpha$ is admissible, $\mathrm{HYP}_{\mathrm{L}\alpha}(\mathfrak{M})$ is $\mathrm{L}_\beta(\mathfrak{M})$ for the least $\beta \geq \alpha$ such that $\mathrm{L}_\beta(\mathfrak{M})$ is admissible, and so, in particular, that $\mathrm{HYP}_{\mathbb{HF}}(\mathfrak{M})$ is just $\mathrm{HYP}(\mathfrak{M})$ in the usual sense when $\mathfrak{M}$ has a finite similarity type. The definition of $\mathrm{HYP}_\mathfrak{U}(\mathfrak{M})$ is most naturally formulated using Adamson's notion of a +-admissible structure (1978). We prove a generalization from admissible to +-admissible structures of the well-known truncation lemma. That generalization is a key theorem applied in the proof of the generalized Spector-Gandy theorem. (shrink)

Carlo Ginzburg is best known as the author of a popular and widely commented work of microstoria Il formaggio e i vermi, published in 1976. Rather than focusing on Ginzburg's contributions to the genre of microstoria, or on the development of his long and very productive scholarly career, my aim in this article is to reflect on a set of themes that recur, with impressive persistence, in his work, from his earliest publications in the mid-1960s, to his most recent works. (...) Above all, I suggest that two elements recur in his work, and that these, jointly, impart upon it its defining character. They are the concern with epistemological issues of knowing, and the ethical conception of the historian's work, which Ginzburg expressess and defends with urelenting rigour. (shrink)

This paper builds on the system of David Lewis’s “Parts of Classes” to provide a foundation for mathematics that arguably requires not only no distinctively mathematical ideological commitments (in the sense of Quine), but also no distinctively mathematical ontological commitments. Provided only that there are enough individual atoms, the devices of plural quantification and mereology can be employed to simulate quantification over classes, while at the same time allowing all of the atoms (and most of their fusions with which we (...) are concerned) to be individuals (that is, urelements of classes). The final section of the paper canvasses some reasons to be committed to the required ontology for other than mathematical reasons. (shrink)

The essay introduces a non-Diodorean, non-Kantian temporal modal semantics based on part-whole, rather than class, theory. Formalizing Edmund Husserl’s theory of inner time consciousness, §3 uses his protention and retention concepts to define a relation of self-awareness on intentional events. §4 introduces a syntax and two-valued semantics for modal first-order predicate object-languages, defines semantic assignments for variables and predicates, and truth for formulae in terms of the axiomatic version of Edmund Husserl’s dependence ontology (viz. the Calculus [CU] of Urelements) (...) introduced by The Ontology of Intentionality I & II. It then uses the §3 results to define the modalities of truth, and §5 extends the semantics to identity claims. §6 defines and contrasts synthetic a priori truths to analytic a priori truths, and §7 compares Brentano School noetic semantic and Leibnizian possible-world semantic perspectives on modality. The essay argues that the modal logics it defines semantically are two-valued, first-order versions of the type of language which Husserl viewed as the language of any ontology of experience (i.e. of any science), and conceived as the logic of intentionality. (shrink)

Partial models of the theory New Foundations (NF) introduced by Quine have already appeared in the literature, but in every model the membership set of NF is missing. On the other hand, Jensen showed that "NF + Urelements" is consistent with respect to ZF and, in the model built there, the membership set of the theory exists. Here we build a partial model of NF from the one of Jensen in which the membership set exists.

We present a formalization of collections that Cornelius Castoriadis calls “magmas”, especially the property which mainly characterizes them and distinguishes them from the usual cantorian sets. It is the property of their elements to depend on other elements, either in a one-way or a two-way manner, so that one cannot occur in a collection without the occurrence of those dependent on it. Such a dependence relation on a set A of atoms (or urelements) can be naturally represented by a (...) pre-order relation $$\preccurlyeq $$ of A with the extra condition that it contains no minimal elements. Then, working in a mild strengthening of the theory $$\textrm{ZFA}$$, where A is an infinite set of atoms equipped with a primitive pre-ordering $$\preccurlyeq $$, the class of magmas over A is represented by the class $$LO(A,\preccurlyeq )$$ of nonempty open subsets of A with respect to the lower topology of $$\langle A,\preccurlyeq \rangle $$. The non-minimality condition for $$\preccurlyeq $$ implies that all sets of $$LO(A,\preccurlyeq )$$ are infinite and none of them is $$\subseteq $$ -minimal. Next the pre-ordering $$\preccurlyeq $$ is shifted (by a kind of simulation) to a pre-ordering $$\preccurlyeq ^+$$ on $${{\mathcal {P}}}(A)$$, which turns out to satisfy the same non-minimality condition as well, and which, happily, when restricted to $$LO(A,\preccurlyeq )$$ coincides with $$\subseteq $$. This allows us to define a hierarchy $$M_\alpha (A)$$, along all ordinals $$\alpha \ge 1$$, the“magmatic hierarchy”, such that $$M_1(A)=LO(A,\preccurlyeq )$$, $$M_{\alpha +1}(A)=LO(M_\alpha (A),\subseteq )$$, and $$M_\alpha (A)=\bigcup _{\beta <\alpha }M_\beta (A)$$, for a limit ordinal $$\alpha $$. For every $$\alpha \ge 1$$, $$M_\alpha (A)\subseteq V_\alpha (A)$$, where $$V_\alpha (A)$$ are the levels of the universe V(A) of $$\textrm{ZFA}$$. The class $$M(A)=\bigcup _{\alpha \ge 1}M_\alpha (A)$$ is the “magmatic universe above A.” The axioms of Powerset and Union (the latter in a restricted version) turn out to be true in $$\langle M(A),\in \rangle $$. Besides it is shown that three of the five principles about magmas that Castoriadis proposed in his writings (mildly modified and adapted to the needs of formalization), $$M2^*$$, $$M3^*$$ and $$M5^*$$, are true of M(A). A selection of excerpts from these writings, in which the concept of magma was first introduced and elaborated, is presented in the Introduction. (shrink)

A structural (as opposed to Zadeh's quantitative) approach to fuzziness is given, based on the operator "very", which is added to the language of set theory together with some elementary axioms about it. Due to the axiom of foundation and to a lifting axiom, the operator is proved trivial on the cumulative hierarchy of ZF. So we have to drop either foundation or lifting. Since fuzziness concerns complemented predicates rather than sets, a class theory is needed for the very operator. (...) And of them the Kelley-Morse (KM) theory is more appropriate for reasons of class existence. Several definable realizations of the very-operator are presented in KM⁻. In the last section we consider the operator "very" without the lifting axiom on classes of urelements. To each structurally fuzzy set X a traditional quantitative fuzzy set X̄ is assigned -- its quantitative representation. This way we are able partly to recover ordinary fuzzy sets from the structurally fuzzy ones. (shrink)

A structural approach to fuzziness is given, based on the operator "very", which is added to the language of set theory together with some elementary axioms about it. Due to the axiom of foundation and to a lifting axiom, the operator is proved trivial on the cumulative hierarchy of ZF. So we have to drop either foundation or lifting. Since fuzziness concerns complemented predicates rather than sets, a class theory is needed for the very operator. And of them the Kelley-Morse (...) theory is more appropriate for reasons of class existence. Several definable realizations of the very-operator are presented in KM⁻. In the last section we consider the operator "very" without the lifting axiom on classes of urelements. To each structurally fuzzy set X a traditional quantitative fuzzy set X̄ is assigned -- its quantitative representation. This way we are able partly to recover ordinary fuzzy sets from the structurally fuzzy ones. (shrink)