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 naive 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.

Our minds have physical effects. This happens, for instance, when we move our bodies when we act. How is this possible? Thomas Kroedel defends an account of mental causation in terms of difference-making: if our minds had been different, the physical world would have been different; therefore, the mind causes events in the physical world. His account not only explains how the mind has physical effects at all, but solves the exclusion problem - the problem of how those effects can have both mental and physical causes. It is also unprecedented in scope, because it is available to dualists about the mind as well as physicalists, drawing on traditional views of causation as well as on the latest developments in the field of causal modelling. It will be of interest to a range of readers in philosophy of mind and philosophy of science. This book is also available as Open Access.

I have been thinking about the philosophical issue of truth for more than two decades. It is one of several fascinating philosophical issues that motivated me to change my primary re ective interest to philosophy after receiving BS in mathem- ics in 1982. Some serious academic work in this connection started around the late eighties when I translated into Chinese a dozen of Donald Davidson's representative essays on truth and meaning and when I assumed translator for Adam Morton who gave a series of lectures on the issue in Beijing (1988), which was co-sponsored by my then institution (Institute of Philosophy, Chinese Academy of Social Science). I have loved the issue both for its own sake (as one speci c major issue in the phil- ophy of language and metaphysics) and for the sake of its signi cant involvement in many philosophical issues in different subjects of philosophy. Having been attracted to the analytic approach, I was then interested in looking at the issue both from the points of view of classical Chinese philosophy and Marxist philosophy, two major styles or frameworks of doing philosophy during that time in China, and from the point of view of contemporary analytic philosophy, which was then less recognized in the Chinese philosophical circle.

While logical principles seem timeless, placeless, and eternal, their discovery is a story of personal accidents, political tragedies, and broad social change. If A, Then B begins with logic's emergence twenty-three centuries ago and tracks its expansion as a discipline ever since. It explores where our sense of logic comes from and what it really is a sense of. It also explains what drove human beings to start studying logic in the first place. Logic is more than the work of logicians alone. Its discoveries have survived only because logicians have also been able to find a willing audience, and audiences are a consequence of social forces affecting large numbers of people, quite apart from individual will. This study therefore treats politics, economics, technology, and geography as fundamental factors in generating an audience for logic-grounding the discipline's abstract principles in a compelling material narrative. The authors explain the turbulent times of the enigmatic Aristotle, the ancient Stoic Chrysippus, the medieval theologian Peter Abelard, and the modern thinkers Rene Descartes, David Hume, Jeremy Bentham, George Boole, Augustus De Morgan, John Stuart Mill, Gottlob Frege, Bertrand Russell, and Alan Turing. Examining a variety of mysteries, such as why so many branches of logic (syllogistic, Stoic, inductive, and symbolic) have arisen only in particular places and periods, If A, Then B is the first book to situate the history of logic within the movements of a larger social world. If A, Then B is the 2013 Gold Medal winner of Foreword Reviews' IndieFab Book of the Year Award for Philosophy.

The purpose of this book is to present unpublished papers at the cutting edge of research on dialetheism and to reflect recent work on the applications of the theory. It includes contributions from some of the most respected scholars in the field, as well as from young, up-and-coming philosophers working on dialetheism. Moving from the fringes of philosophy to become a main player in debates concerning truth and the logical paradoxes, dialetheism has thrived since the publication of Graham Priest's In Contradiction, and several of the papers find their roots in a conference on dialetheism held in Glasgow to mark the 25th anniversary of Priest's book. The content presented here demonstrates the considerable body of work produced in this field in recent years. With a broad focus, this book also addresses the applications of dialetheism outside the more familiar area of the logical paradoxes, and includes pieces discussing the application of dialetheism in metaphysics, philosophy of language, and philosophy of mind.

This book is a consideration of Hegel's view on logic and basic logical concepts such as truth, form, validity, and contradiction, and aims to assess this view's relevance for contemporary philosophical logic. The literature on Hegel's logic is fairly rich. The attention to contemporary philosophical logic places the present research closer to those works interested in the link between Hegel's thought and analytical philosophy (Stekeler-Weithofer 1992 and 2019, Berto 2005, Rockmore 2005, Redding 2007, Nuzzo 2010 (ed.), Koch 2014, Brandom 2014, 1-15, Pippin 2016, Moyar 2017, Quante & Mooren 2018 among others). In this context, one particularity of this book consists in focusing on something that has been generally underrated in the literature: the idea that, for Hegel as well as for Aristotle and many other authors (including Frege), logic is the study of the forms of truth, i.e. the forms that our thought can (or ought to) assume in searching for truth. In this light, Hegel's thinking about logic is a fundamental reference point for anyone interested in a philosophical foundation of logic.

The conditional, if...then, is probably the most important term in natural language and forms the core of systems of logic and mental representation. It occurs in all human languages and allows people to express their knowledge of the causal or law-like structure of the world and of others' behaviour, e.g., if you turn the key the car starts, if John walks the dog he stops for a pint of beer; to make promises, e.g., if you cook tonight, I'll wash up all week; to regulate behaviour, e.g., if you are drinking beer, you must be over 18 years of age; to suggest what would have happened had things been different, e.g., if the match had been dry it would have lit, among many other possible uses. The way in which the conditional is modelled also determines the core of most logical systems. Unsurprisingly, it is also the most researched expression in the psychology of human reasoning.
Cognition and Conditionals is the first volume for over 20 years (On Conditionals, 1986, CUP) that brings together recent developments in the cognitive science and psychology of conditional reasoning. Over the last 10 to 15 years, research on conditionals has come to dominate the psychology of reasoning providing a rich seam of results that have created new theoretical possibilities. This book shows how these developments have led researchers to view people's conditional reasoning behaviour more as succesful probabilistic reasoning rather than as errorful logical reasoning. It shows how the multifarious, and apparently competing, theoretical positions developed over the last 50 years in this area - mental logics, mental models, heuristic approaches, dual process theory, and probabilistic approaches-have responded to these insights. Its organisation reflects the view that an integrative approach is emerging that may need to exploit aspects of all these theoretical positions to explain the rich and complex phenomenon of reasoning with conditionals. It includes an introductory chapter relating the development of the psychology of reasoning to developments in the logic and semantics of the conditional. It also includes chapters by many of the leading figures in this field.
Cognition and Conditionals will be a valuable resource for cognitive scientists, psychologists and philosophers interested how people actually reason with conditionals.

A long tradition, going back to Aristotle, conceives of logic in terms of necessity and possibility: a deductive argument is correct if it is not possible for the conclusion to be false when the premises are true. A relatively unknown feature of the analytic tradition in philosophy is that, at its very inception, this venerable conception of the relation between logic and necessity and possibility - the concepts of modality - was put into question. The founders of analytic philosophy, Gottlob Frege and Bertrand Russell, held that these concepts are empty: there are no genuine distinctions among the necessary, the possible, and the actual. In this book, the first of two volumes, Sanford Shieh investigates the grounds of this position and its consequences for Frege's and Russell's conceptions of logic. The grounds lie in doctrines on truth, thought, and knowledge, as well as on the relation between mind and reality, that are central to the philosophies of Frege and Russell, and are of enduring philosophical interest. The upshot of this opposition to modality is that logic is fundamental, and, to be coherent, modal concepts would have to be reconstructed in logical terms. This rejection of modality in early analytic philosophy remains of contemporary significance, though the coherence of modal concepts is rarely questioned nowadays because it is generally assumed that suspicion of modality derives from logical positivism, which has not survived philosophical scrutiny. The anti-modal arguments of Frege and Russell, however, have nothing to do with positivism and remain a challenge to the contemporary acceptance of modal notions.

First published in 1986. Routledge is an imprint of Taylor & Francis, an informa company.

An agent often does not have precise probabilities or utilities to guide resolution of a decision problem. I advance a principle of rationality for making decisions in such cases. To begin, I represent the doxastic and conative state of an agent with a set of pairs of a probability assignment and a utility assignment. Then I support a decision principle that allows any act that maximizes expected utility according to some pair of assignments in the set. Assuming that computation of an option's expected utility uses comprehensive possible outcomes that include the option's risk, no consideration supports a stricter requirement.

Are there objects that are "thin" in the sense that not very much is required for their existence? Frege famously thought so. He claimed that the equinumerosity of the knives and the forks suffices for there to be objects such as the number of knives and the number of forks, and for these objects to be identical. The idea of thin objects holds great philosophical promise but has proved hard to explicate. Oystein Linnebo aims to do so by drawing on some Fregean ideas. First, to be an object is to be a possible referent of a singular term. Second, singular reference can be achieved by providing a criterion of identity for the would-be referent. The second idea enables a form of easy reference and thus, via the first idea, also a form of easy being. Paradox is avoided by imposing a predicativity restriction on the criteria of identity. But the abstraction based on a criterion of identity may result in an expanded domain. By iterating such expansions, a powerful account of dynamic abstraction is developed. The result is a distinctive approach to ontology. Abstract objects such as numbers and sets are demystified and allowed to exist alongside more familiar physical objects. And Linnebo also offers a novel approach to set theory which takes seriously the idea that sets are "formed" successively.

This study of Plato's Phaedo promotes better understanding of its arguments for the soul's immortality by showing how Plato intended them, not as proofs, but as properly dialectical arguments functioning in accordance with the method of hypothesis. Unlike the argument for the soul's immortality in the Phaedrus, which does seem intended as a proof, the Phaedo arguments are proceeding toward the first principles that could serve as the basis for a proof - the most important being an account of the soul's own essential nature. This study attends to the substantial progress the Phaedo makes toward such an account. It also considers Socrates' epistemic situation in the dialogue and the problem of whether his confidence in the face of death is misplaced if his arguments have not been proofs before considering how the concluding myth draws together several of the dialogue's main themes.

Quine's set theory, New Foundations, has often been treated as an anomaly in the history and philosophy of set theory. In this book, Sean Morris shows that it is in fact well-motivated, emerging in a natural way from the early development of set theory. Morris introduces and explores the notion of set theory as explication: the view that there is no single correct axiomatization of set theory, but rather that the various axiomatizations all serve to explicate the notion of set and are judged largely according to pragmatic criteria. Morris also brings out the important interplay between New Foundations, Quine's philosophy of set theory, and his philosophy more generally. We see that his early technical work in logic foreshadows his later famed naturalism, with his philosophy of set theory playing a crucial role in his primary philosophical project of clarifying our conceptual scheme and specifically its logical and mathematical components.

This book articulates and defends Fregean realism, a theory of properties based on Frege's insight that properties are not objects, but rather the satisfaction conditions of predicates. Robert Trueman argues that this approach is the key not only to dissolving a host of longstanding metaphysical puzzles, such as Bradley's Regress and the Problem of Universals, but also to understanding the relationship between states of affairs, propositions, and the truth conditions of sentences. Fregean realism, Trueman suggests, ultimately leads to a version of the identity theory of truth, the theory that true propositions are identical to obtaining states of affairs. In other words, the identity theory collapses the gap between mind and world. This book will be of interest to anyone working in logic, metaphysics, the philosophy of language or the philosophy of mind.

Vagueness is the study of concepts that admit borderline cases: the property of being bald is vague because there are people who are neither definitely bald, nor definitely not bald. The epistemology of vagueness concerns the sorts of attitudes we ought to have towards propositions we know to be borderline. Is it possible to discover whether a borderline bald man is bald? Could two people with access to the same facts reasonably disagree about whether he is bald? Does it matter, when making practical decisions, whether he is bald? By drawing on such considerations, Andrew Bacon develops a novel theory of vagueness in which vagueness is fundamentally a property of propositions, and is explicated in terms of its role in thought. On this theory, language plays little role in explaining the central puzzles of vagueness. Part I of the book outlines some of the central questions regarding the logic and epistemology of vagueness, and criticizes some extant approaches to them. Part II concerns issues in the epistemology of vagueness, touching on the ramifications of vague thoughts on the study of evidence, ignorance, desire, probability theory, and decision theory. By examining the effects of vague information on one's beliefs about the precise, a positive theory of vagueness is proposed. Part III concerns the logic of vagueness, including the interaction between vagueness and modality, vague identity, and the paradoxes of higher-order vagueness. Bacon suggests that some familiar philosophical notions - including the concept of a fundamental proposition, a possible world and a precisification - need to be revised.

This comprehensive account of the concept and practices of deduction is the first to bring together perspectives from philosophy, history, psychology and cognitive science, and mathematical practice. Catarina Dutilh Novaes draws on all of these perspectives to argue for an overarching conceptualization of deduction as a dialogical practice: deduction has dialogical roots, and these dialogical roots are still largely present both in theories and in practices of deduction. Dutilh Novaes' account also highlights the deeply human and in fact social nature of deduction, as embedded in actual human practices; as such, it presents a highly innovative account of deduction. The book will be of interest to a wide range of readers, from advanced students to senior scholars, and from philosophers to mathematicians and cognitive scientists.

Is mathematics 'entangled' with its various formalisations? Or are the central concepts of mathematics largely insensitive to formalisation, or 'formalism free'? What is the semantic point of view and how is it implemented in foundational practice? Does a given semantic framework always have an implicit syntax? Inspired by what she calls the 'natural language moves' of Goedel and Tarski, Juliette Kennedy considers what roles the concepts of 'entanglement' and 'formalism freeness' play in a range of logical settings, from computability and set theory to model theory and second order logic, to logicality, developing an entirely original philosophy of mathematics along the way. The treatment is historically, logically and set-theoretically rich, and topics such as naturalism and foundations receive their due, but now with a new twist.

Fred Stoutland was a major figure in the philosophy of action and philosophy of language. This collection brings together essays on truth, language, action and mind and thus provides an important summary of many key themes in Stoutland's own work, as well as offering valuable perspectives on key issues in contemporary philosophy.

The perception of what he calls 'aspects' preoccupied Wittgenstein and gave him considerable trouble in his final years. The Wittgensteinian aspect defies any number of traditional philosophical dichotomies: the aspect is neither subjective (inner, metaphysically private) nor objective; it presents perceivable unity and sense that are (arguably) not (yet) conceptual; it is 'subject to the will', but at the same time is normally taken to be genuinely revelatory of the object perceived under it. This Element begins with a grammatical and phenomenological characterization of Wittgensteinian 'aspects'. It then challenges two widespread ideas: that aspects are to be identified with concepts; and that aspect perception has a continuous version that is characteristic of (normal) human perception. It concludes by proposing that aspect perception brings to light the distinction between the world as perceived and the world as objectively construed, and the role we play in the constitution of the former.

In this book we deal with combinations of concepts defining individuals in the Talmud. Consider for example Yom Kippur and Shabbat. Each concept has its own body of laws. Reality forces us to combine them when they occur on the same day. This is a case of "Identity Merging." As the combined body of laws may be inconsistent, we need a belief revision mechanism to reconcile the conflicting norms. The Talmud offers three options: 1 Take the union of the sets of the rules side by side 2. Resolve the conflicts using further meta-level Talmudic principles (which are new and of value to present day Artificial Intelligence) 3. Regard the new combined concept as a new entity with its own Halachic norms and create new norms for it out of the existing ones. This book offers a clear and precise logical model showing how the Talmud deals with these options.

W. V. Quine was one of the most influential figures of twentieth-century American analytic philosophy. Although he wrote predominantly in English, in Brazil in 1942 he gave a series of lectures on logic and its philosophy in Portuguese, subsequently published as the book O Sentido da Nova Logica. The book has never before been fully translated into English, and this volume is the first to make its content accessible to Anglophone philosophers. Quine would go on to develop revolutionary ideas about semantic holism and ontology, and this book provides a snapshot of his views on logic and language at a pivotal stage of his intellectual development. The volume also includes an essay on logic which Quine also published in Portuguese, together with an extensive historical-philosophical essay by Frederique Janssen-Lauret. The valuable and previously neglected works first translated in this volume will be essential for scholars of twentieth-century philosophy.

Numbers and other mathematical objects are exceptional in having no locations in space or time and no causes or effects in the physical world. This makes it difficult to account for the possibility of mathematical knowledge, leading many philosophers to embrace nominalism, the doctrine that there are no abstract entitles, and to embark on ambitious projects for interpreting mathematics so as to preserve the subject while eliminating its objects. A Subject With No Object cuts through a host of technicalities that have obscured previous discussions of these projects, and presents clear, concise accounts, with minimal prerequisites, of a dozen strategies for nominalistic interpretation of mathematics, thus equipping the reader to evaluate each and to compare different ones. The authors also offer critical discussion, rare in the literature, of the aims and claims of nominalistic interpretation, suggesting that it is significant in a very different way from that usually assumed.

A relative change occurs when some item changes a relation. This Element examines how Plato, Aristotle, Stoics and Sextus Empiricus approached relative change. Relative change is puzzling because the following three propositions each seem true but cannot be true together: (1) No relative changes are intrinsic changes; (2) Only intrinsic changes are proper changes; (3) Some relative changes are proper changes. Plato's Theaetetus and Phaedo property relative change. I argue that these dialogues assume relative changes to be intrinsic changes, so denying (1). Aristotle responds differently, by denying (3) that relative change is proper change. The Stoics claimed that some non-intrinsic changes are changes (denying (2)). Finally, I discuss Sextus' argument that relative change shows that there are no relatives at all.

Ideas about relativity underlie much ancient Greek philosophy, from Protagorean relativism, to Plato's theory of Forms, Aristotle's category scheme, and relational logic. In Ancient Relativity Matthew Duncombe explores how ancient philosophers, particularly Plato, Aristotle, the Stoics, and Sextus Empiricus, understood the phenomenon and how their theories of relativity affected, and were affected by, their broader philosophical outlooks. He argues that ancient philosophers shared a close-knit family of views referred to as 'constitutive relativity', whereby a relative is not simply linked by a relation but is constituted by it. Plato exploits this view in some key arguments concerning the Forms and the partition of the soul. Aristotle adopts the constitutive view in his discussions of relativity in Categories 7 and the Topics and retains it in Metaphysics Delta 15. Duncombe goes on to examine the role relativity plays in Stoic philosophy, especially Stoic physics and metaphysics, and the way Sextus Empiricus thinks about relativity, which does not appeal to the nature of relatives but rather to how we conceive of things as correlative.