Sets are central to mathematics and its foundations, but what are they? In this book Luca Incurvati provides a detailed examination of all the major conceptions of set and discusses their virtues and shortcomings, as well as introducing the fundamentals of the alternative set theories with which these conceptions are associated. He shows that the conceptual landscape includes not only the naïve and iterative conceptions but also the limitation of size conception, the definite conception, the stratified conception and the graph (...) conception. In addition, he presents a novel, minimalist account of the iterative conception which does not require the existence of a relation of metaphysical dependence between a set and its members. His book will be of interest to researchers and advanced students in logic and the philosophy of mathematics. (shrink)

According to the iterative conception of set, each set is a collection of sets formed prior to it. The notion of priority here plays an essential role in explanations of why contradiction-inducing sets, such as the Russell set, do not exist. Consequently, these explanations are successful only to the extent that a satisfactory priority relation is made out. I argue that attempts to do this have fallen short: understanding priority in a straightforwardly constructivist sense threatens the coherence of the empty (...) set and raises serious epistemological concerns; but the leading realist interpretations---ontological and modal interpretations of priority---are deeply problematic as well. I conclude that the purported explanatory virtues of the iterative conception are, at present, unfounded. (shrink)

The use of tensed language and the metaphor of set ‘formation’ found in informal descriptions of the iterative conception of set are seldom taken at all seriously. Both are eliminated in the nonmodal stage theories that formalise this account. To avoid the paradoxes, such accounts deny the Maximality thesis, the compelling thesis that any sets can form a set. This paper seeks to save the Maximality thesis by taking the tense more seriously than has been customary (although not literally). A (...) modal stage theory, MST, is developed in a bimodal language, governed by a tenselike logic. Such a language permits a very natural axiomatisation of the iterative conception, which upholds the Maximality thesis. It is argued that the modal approach is consonant with mathematical practice and a plausible metaphysics of sets and shown that MST interprets a natural extension of Zermelo set theory less the axiom of Infinity and, when extended with a further axiom concerning the extent of the hierarchy, interprets Zermelo–Fraenkel set theory. (shrink)

Conceptions of Set and the Foundations of Mathematics By IncurvatiLucaCambridge University Press, 2020. xvi + 238 pp.

Hilary Putnam once suggested that “the actual existence of sets as ‘intangible objects’ suffers… from a generalization of a problem first pointed out by Paul Benacerraf… are sets a kind of function or are functions a sort of set?” Sadly, he did not elaborate; my aim, here, is to do so on his behalf. There are well-known methods for treating sets as functions and functions as sets. But these do not raise any obvious philosophical or foundational puzzles. For that, we (...) first need to provide a full-fledged function theory. I supply such a theory: it axiomatizes the iterative notion of function in exactly the same sense that ZF axiomatizes the iterative notion of set. Indeed, this function theory is synonymous with ZF. It might seem that set theory and function theory present us with rival foundations for mathematics, since they postulate different ontologies. But appearances are deceptive. Set theory and function theory provide the very same judicial foundation for mathematics. They do not supply rival metaphysical foundations; indeed, if they supply metaphysical foundations at all, then they supply the very same metaphysical foundations. (shrink)

The iterative conception of set commonly is regarded as supporting the axioms of Zermelo-Fraenkel set theory (ZF). This paper presents a modified version of the iterative conception of set and explores the consequences of that modified version for set theory. The modified conception maintains most of the features of the iterative conception of set, but allows for some non-wellfounded sets. It is suggested that this modified iterative conception of set supports the axioms of Quine's set theory NF.

The non-well-founded set theories described by Aczel (1988) have received attention from category theorists and computer scientists, but have been largely ignored by philosophers. At the root of this neglect might lie the impression that these theories do not embody a conception of set, but are rather of mere technical interest. This paper attempts to dispel this impression. I present a conception of set which may be taken as lying behind a non-well-founded set theory. I argue that the axiom AFA (...) is justified on the conception, which provides, contra Rieger (Mind 109:241–253, 2000), a rationale for restricting attention to the system based on this axiom. By making use of formal and informal considerations, I then make a case that most of the other axioms of this system are also justified on the conception. I conclude by commenting on the significance of the conception for the debate about the justification of the Axiom of Foundation. (shrink)

Multiverse Views in set theory advocate the claim that there are many universes of sets, no-one of which is canonical, and have risen to prominence over the last few years. One motivating factor is that such positions are often argued to account very elegantly for technical practice. While there is much discussion of the technical aspects of these views, in this paper I analyse a radical form of Multiversism on largely philosophical grounds. Of particular importance will be an account of (...) reference on the Multiversist conception, and the relativism that it implies. I argue that analysis of this central issue in the Philosophy of Mathematics indicates that Radical Multiversism must be algebraic, and cannot be viewed as an attempt to provide an account of reference without a softening of the position. (shrink)

The phrase ‘The iterative conception of sets’ conjures up a picture of a particular settheoretic universe – the cumulative hierarchy – and the constant conjunction of phrasewith-picture is so reliable that people tend to think that the cumulative hierarchy is all there is to the iterative conception of sets: if you conceive sets iteratively, then the result is the cumulative hierarchy. In this paper, I shall be arguing that this is a mistake: the iterative conception of set is a good (...) one, for all the usual reasons. However, the cumulative hierarchy is merely one way among many of working out this conception, and arguments in favour of an iterative conception have been mistaken for arguments in favour of this one special instance of it. (This may be the point to get out of the way the observation that although philosophers of mathematics write of the iterative conception of set, what they really mean – in the terminology of modern computer science at least – is the recursive conception of sets. Nevertheless, having got that quibble off my chest, I shall continue to write of the iterative conception like everyone else.). (shrink)

Surveying and criticising attitudes towards the role and strength of the iterative conception of set—widely seen as the justificatory basis of Zermelo-Fraenkel set theory with Choice—this paper highlights a tension in both contemporary and historic accounts of the iterative conception’s justificatory role: on the one hand its advocates wish to claim that it justifies ZFC, but on the other hand they abstain from stating whether the preconditions for such justification exists. Expanding the number of axioms that the conception is standardly (...) charged with failing to justify, in the forms of the Emptyset and Powerset, this paper aims to extend the critique that the iterative conception does not justify ZFC to its subsystems. Exploring the historic and contemporary relationship between the iterative conception and set theory, the paper then attempts to defuse strategies that avoid the problems of intrinsic justification by weakening the iterative conception’s role to the ‘motivational’ or ‘heuristic’ by showing that what the iterative conception has been seen to motivate has changed over time. It is suggested that the conjunction of these arguments seriously weakens the programme of reasoning on an ‘atheoretic’ notion of set. (shrink)

이 글의 주된 목적은 반복적 집합 개념을 검토하여 그 개념이 지니는 내부적인 문제들을 드러내고 그 개념에 대한 구성주의적 비판을 제시하는 것이다. 내부적인 문제는 고전수학자들에게 반복적 집합 개념이 불분명한 데에서 기인한다. 이 점은 불로스의 단계이론을 반복적 집합 개념에 관한 다른 설명과 비교하고 치환공리와 선택공리에 관한 논란을 검토하여 드러낼 것이다. 이보다 훨씬 심각한 문제는 구성주의적 비판이다. 특히, 고전적인 반복적 집합 개념에 내재한 무한에 관한 실재론적 이해에 대한 비판과, 집합론에서 고전논리의 사용에 대한 비판 및 비서술성에 관한 비판이 제기될 것이며, 반복적 집합 개념이 구성적으로 (...) 이해될 때, 어떤 원칙들이 정당화될 수 있는지 검토될 것이다. (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)

In explaining his concept of set Cantor intimates a connection with the metaphysical scheme put forward in Plato’s Philebus to determine the place of pleasure. We argue that these determinations capture key ideas of Cantorian set theory and, moreover, extend to intuitions which continue to play a central role in the modern mathematics of infinity.

Recenze knihy:Luca Incurvati, Conceptions of Set and the Foundations of Mathematics. Cambridge University Press, 2020, 238 s.

Arecent paper by George Boolos suggests that it is philosophically respectable to use monadic second order logic in one’s explication of the iterative concept of set. I shall here give a partial indication of the new range of theories of the iterative hierarchy which are thus madeavailable to philosophers of set theory.

Arecent paper by George Boolos suggests that it is philosophically respectable to use monadic second order logic in one’s explication of the iterative concept of set. I shall here give a partial indication of the new range of theories of the iterative hierarchy which are thus madeavailable to philosophers of set theory.

The aim of this analysis was to examine the concept of time to rejuvenate and extend existing narratives of time within the nursing literature. In particular, we hope to promote a new trajectory in nursing research and practice which focuses on time and person‐centred care, specifically of older people with cognitive impairment hospitalized in the acute care setting. We consider the explanatory power of concepts such as clock time, process time, fast care, slow care and time debt for elucidating (...) the relationship between ‘good care’ and ‘time use’. We conclude by offering two additional concepts of time, plurotemporality and person‐centred time (PCT) which we propose will help advance of nursing knowledge and practice. Nurse clinicians and researchers can use these alternative concepts of time to explore and describe different temporal structures that honour the patient's values and preferences using experiential, observation‐based nursing research approaches. (shrink)

It is shown in this article in how far one has to have a clear picture of Gödel’s philosophy and scientific thinking at hand (and also the philosophical positions of other philosophers in the history of Western Philosophy) in order to interpret one single Philosophical Remark by Gödel. As a single remark by Gödel (very often) mirrors his whole philosophical thinking, Gödel’s Philosophical Remarks can be seen as a philosophical monadology. This is so for two reasons mainly: Firstly, because it (...) pictures a monadology already via its form. And secondly, because Gödel wanted to establish in his Philosophical Remarks a modern monadology in adapting the philosophical principles of Leibniz’s monadology to modern science. This article will only deal with the first aspect that has been mentioned namely that a single remark by Gödel (very often) mirrors his whole philosophy (at the time) for example: set theory, perception and intuition of mathematical objects and axioms, the nature of the human mind, the concept and existence of God, and so on. This renders it extremely difficult to interpret Gödel’s philosophical remarks but interpreting it provides also a deep insight in Gödel’s philosophical thoughts. (shrink)

We describe a first-order theory of generalized sets intended to allow a similar treatment of sets and proper classes. The theory is motivated by the iterative conception of set. It has a ternary membership symbol interpreted as membership relative to a set-building step. Set and proper class are defined notions. We prove that sets and proper classes with a defined membership form an inner model of Bernays-Morse class theory. We extend ordinal and cardinal notions to generalized sets and prove ordinal (...) and cardinal results in the theory. We prove that the theory is consistent relative to ZFC + (∃ x) [ x is a strongly inaccessible cardinal]. (shrink)

Transfinite recursion is an essential component of set theory. In this paper, we seek intrinsically justified reasons for believing in recursion and the notions of higher computation that surround it. In doing this, we consider several kinds of recursion principles and prove results concerning their relation to one another. We then consider philosophical motivations for these formal principles coming from the idea that computational notions lie at the core of our conception of set. This is significant because, while the iterative (...) conception of set has been widely recognized as insufficient to establish replacement and recursion, its supplementation by considerations pertaining to algorithms suggests a new and philosophically well-motivated reason to believe in such principles. (shrink)

Although a large body of literature exists propounding the importance of space in aged care and care of the older person with dementia, there is, however, only limited exploration of the ‘acute care space’ as a particular type of space with archetypal constraints that maybe unfavourable to older people with cognitive impairment and nurses wanting to provide care that is person‐centred. In this article, we explore concepts of space and examine the implications of these for the delivery of care to (...) older people who are cognitively impaired. Our exploration is grounded in theorisations of space offered by key geographers and phenomenologists, but also draws on how space has been constructed within the nursing literature that refers specifically to acute care. We argue that space, once created, can be created and that nursing has a significant role to play in the process of its recreation in the pursuit of care that is person‐centred. We conclude by introducing an alternative logic of space aimed at promoting the creation of more salutogenic spaces that invokes a sense of sanctuary, safeness, and inclusion, all of which are essential if the care provided to the older person with cognitive impairment is apposite to their needs. The concept of ‘person‐centred space’ helps to crystallize the relationship between space and person‐centred care and implies more intentional manipulation of space that is more conducive to caring and healing. Significantly, it marks a return to Nightingale's wisdom, that is, to put the person in the best possible conditions for nature to act upon them. (shrink)

The main concern of this paper is the justification of the axioms of Zermelo-Fraenkel set theory, either as true statements about a concept of set or, alternatively, as true statements about abstract objects . I want to argue here that, in either case, set theory can be seen as a body of knowledge largely built on intuitive foundations . I call this inquiry “phenomenological” for it approaches its subject from the perspective of the intentional acts that originate sets as (...) doubly dependent objects . Such an inquiry, I believe, brings to light the essential characters of sets as objects or, alternatively, the concept of set, which the axioms of the theory express. (shrink)

The main concern of this paper is the justification of the axioms of Zermelo-Fraenkel set theory, either as true statements about a concept of set or, alternatively, as true statements about abstract objects. I want to argue here that, in either case, set theory can be seen as a body of knowledge largely built on intuitive foundations. I call this inquiry “phenomenological” for it approaches its subject from the perspective of the intentional acts that originate sets as doubly dependent (...) objects. Such an inquiry, I believe, brings to light the essential characters of sets as objects or, alternatively, the concept of set, which the axioms of the theory express. (shrink)

In the late 1940s and early 1950s Lorenzen developed his operative logic and mathematics, a form of constructive mathematics. Nowadays this is mostly seen as the precursor to the more well-known dialogical logic and one could assumed that the same philosophical motivations were present in both works. However we want to show that this is not always the case. In particular, we claim, that Lorenzen’s well-known rejection of the actual infinite as stated in Lorenzen (1957) was not a major motivation (...) for operative logic and mathematics. In this article, we claim that this is in fact not the case. Rather, we argue for a shift that happened in Lorenzen’s treatment of the infinite from the early to the late 1950s. His early motivation for the development of operativism is concerned with a critique of the Cantorian notion of set and related questions about the notion of countability and uncountability; only later, his motivation switches to focusing on the concept of infinity and the debate about actual and potential infinity. (shrink)

In the late 1940s and early 1950s, Lorenzen developed his operative logic and mathematics, a form of constructive mathematics. Nowadays this is mostly seen as a precursor of the better-known dialogical logic, and one might assume that the same philosophical motivations were present in both works. However, we want to show that this is not everywhere the case. In particular, we claim that Lorenzen’s well-known rejection of the actual infinite, as stated in Lorenzen, was not a major motivation for operative (...) logic and mathematics. Rather, we argue that a shift happened in Lorenzen’s treatment of the infinite from the early to the late 1950s. His early motivation for the development of operationism is concerned with a critique of the Cantorian notion of set and with related questions about the notions of countability and uncountability; it is only later that his motivation switches to focusing on the concept of infinity and the debate about actual and potential infinity. (shrink)

Individuals with high self-concept will likely have high life satisfaction, they easily get adjusted to life, and they communicate their feeling more appropriately. However, it was not certain whether self-concept would decline or improve as individuals age, or whether self-concept would vary between genders and ethnic groups. To prove, a study was carried out to compare the self-concept of college students in an Asian context. The inquiry utilized the cross-sectional design in finding out significant differences in (...) the self-concept of participants in terms of age, gender, and ethnicity. A 22-item questionnaire was adapted and administered to 222 Bachelor of Public Administration and Bachelor of Science in Business Administration students from the satellite campus of Bukidnon State University in the Philippines. Initially, a sample was randomly drawn from the population. During the actual data collection, the researchers had difficulty getting the responses from the randomly selected individuals due to internet connection and it was done amidst a pandemic. Instead, it took all responses from those who were available, have access to the internet, and could accomplish the google forms. The data were analyzed using Mean, Standard Deviation, T-test for independent sample, ANOVA and Post Hoc test. The results revealed that college students at the locale have a high level of self-concept in self-fulfilment, emotional adjustment, and honesty. Yet, they only had a moderate level of self-concept in autonomy. Further, there were significant differences in college students’ autonomy and honesty in terms of age and gender. Furthermore, there were significant differences in their emotional adjustment and self-fulfilment as to their ethnicity. The results have implications for instruction, administration, guidance services, and future research. (shrink)