The aim of this chapter is to explore to some extent the relationship between identity and necessity in logic and metaphysics. First, I provide a historically-based summary of proofs of the necessity of identity, highlighting the importance of the role that self-identity plays. Second, I introduce two examples of metaphysical topics where the necessity of identity has played a pivotal role: the necessary a posteriori, and the coincidence of material objects. I argue that (...) important aspects of these debates rest on how we represent identity. Third, I consider some recent work on generalized identity. This opens up new prospects for explaining why identity is necessary. (shrink)

It is tempting to think that in the case of complete spatio-temporal coincidence, the statue is identical with the constituent lump of clay. However, some philosophers have thought that accepting constitution as identity in this type of case forces one to reject the necessity of identity. I show that there is no conflict here. By distinguishing between an object's being necessarily an F and an object's being necessity identical with an F, we can see that accepting (...) the necessity of identity does not, and should not, compel one to reject constitution as identity. (shrink)

Philosophical Investigations, EarlyView.

The source, status, and significance of the derivation of the necessity of identity at the beginning of Kripke’s lecture “Identity and Necessity” is discussed from a logical, philosophical, and historical point of view.

This paper draws attention to a proof of the necessity of identity given by Arthur Prior. In its simplicity, it is comparable to a proof of Quine's, popularised by Kripke, but it is slightly different. Prior's Polish notation is transcribed into a more familiar idiom. Prior's proof is followed by a proof of the necessity of difference, possibly the first such proof in the literature, which is also repeated here and transcribed. The paper concludes with a brief (...) discussion of Prior's views on identity and difference over time. (shrink)

It was an empirical discovery that Phosphorus is Hesperus. According to Kripke, this was also the discovery of a necessary fact. Now, given Kripke’s theory of direct reference one could wonder what kind of discovery this is. For we already knew Phosphorus/Hesperus, and we also knew that any entity is, necessarily, identical to itself. So what is it that was discovered? I want to show that there is more to this widely known case than what usual readings, and critics, reveal; (...) and I want to show this under the Kripkean pattern that what was discovered is the plain fact of identity that Phosphorus is, and necessarily is, Hesperus. Moreover, I will show how both Kripkean theses, the necessity of identity and the direct theory of reference, should not be kept apart to understand the kind of discovery this is. In particular, understanding the kind of discovery we made will help us see how intuition is displayed in metaphysics, and how metaphysical impossibilities, and metaphysical modality in general, can be discerned by reason and separated from other modalities. The study of this discovery will help us see, in a line, how identity belongs to the inner and most profound structure of reality and to the most profound structure of cognition and language. (shrink)

There is a certain popular argument, deriving from Ruth Barcan and Saul Kripke, from the conjunction of the Principle of the Indiscernibility of Identicals (PInI, for short) and the Principle of the Necessity of Self-Identity to the Thesis of the Necessity of Identity. My purpose is to show that this argument does not work, not at least in the form it is often presented. I also give a correct formulation of the argument and point out that (...) PInI is not even needed in the argument for the necessity of identity. (shrink)

An identity statement flanked on both sides with proper names is necessarily true, Saul Kripke thinks, if it's true at all. Thus, contrary to the received view – or at least what was, prior to Kripke, the received view – a statement like(A) Hesperus is Phosphorus.

In ‘Two Spheres, Twenty Spheres, and the Identity of Indiscernibles,’ Della Rocca argues that any counterexample to the PII would involve ‘a brute fact of non-identity [. . .] not grounded in any qualitative difference.’ I respond that Adams's so-called Continuity Argument against the PII does not postulate qualitatively inexplicable brute facts of identity or non-identity if understood in the context of Kripkean modality. One upshot is that if the PII is understood to quantify over modal (...) as well as non-modal properties, the qualitative explicability of numerical distinctness requires not the PII but a principle of the identity of necessary indiscernibles. (shrink)

Blum (Philosophical Investigations 46, 2023, 264) argues that Tarski's T‐schema and the thesis of the necessity of identity are mutually inconsistent. It is argued that his argument fails.

Philosophical Investigations, EarlyView.

John Locke is often understood as the inaugurator of the modern discussion of personal human identity—a discussion that inevitably falls back on his own theory with its critical reliance on memory. David Hume and Sigmund Freud would later make arguments for what constituted personal identity, both relying, like Locke, on memory, but parting from Locke's company in respect the role that memory played. The purpose of this paper will be to sketch the groundwork for Locke's own theory of (...) personal identity and consider some common objections tied to his special reliance on memory. Then, we will investigate the extent to which Hume and Freud refined their respective concepts of self-identity in ways that escape some of the most intractable objections to Locke's theory in its dependence on memory. Finally, we will consider which theorist's conception of self-identity best accords with our notion of the cyber-self, or psychological subjectivity in the context of cyberspace. For Locke, the nature of self-identity is that it is continuous across time, and to remain uninterrupted it must be beholden to a psychological process, rather than a material or immaterial substance. (shrink)

Identity: The Necessity of a Modern Idea is the first comprehensive history of the concept that answers the question, "who, or what, am I?" Gerald Izenberg contends that our most important identities, while historically conditioned, are rooted in permanent categories of human existence, such as sexuality, sociality, and labor.

We show that the thesis that identity is necessary is equivalent to the thesis that everything is necessarily what it is. Hence the challenges facing either, faces them both.

Occasions of Identity is an exploration of timeless philosophical issues about persistence, change, time, and sameness. Andre Gallois offers a critical survey of various rival views about the nature of identity and change, and puts forward his own original theory. He supports the idea of occasional identities, arguing that it is coherent and helpful to suppose that things can be identical at one time but distinct at another. Gallois defends this view, demonstrating how it can solve puzzles about (...) persistence dating back to the Ancient Greeks, and investigates the metaphysical consequences of rejecting the necessity and eternity of identities. (shrink)

An essentialist theory of modality claims that the source of possibility and necessity lies in essence, where essence is then not to be defined in terms of necessity. Hence such theories owe us an account of why it is that the essences of things give rise to necessities in the way required. A new approach to understanding essence in terms of the notion of generalized identity promises to answer this challenge by appeal to the necessity of (...) identity. I explore the prospects for this approach, and argue that it fails. If one favours an account of essence in terms of generalized identity, then one will not, I argue, be able to satisfactorily defend an essentialist theory of modality against the challenge; if one wishes to defend an essentialist theory of modality, and thereby to give an explanation of how necessity arises from essence, one should not understand essence in terms of generalized identity. (shrink)

We construct a Hilbert style system RPL for the notion of plausibility measure introduced by Halpern J, and we prove the soundness and completeness with respect to a neighborhood style semantics. Using the language of RPL, we demonstrate that it can define well-studied notions of necessity, conditionals and propositional identity.

Saul Kripke, in a series of classic writings of the 1960s and 1970s, changed the face of metaphysics and philosophy of language. Christopher Hughes offers a careful exposition and critical analysis of Kripke's central ideas about names, necessity, and identity. He clears up some common misunderstandings of Kripke's views on rigid designation, causality and reference, and the necessary a posteriori and contingent a priori. Through his engagement with Kripke's ideas Hughes makes a significant contribution to ongoing debates on, (...) inter alia, the semantics of natural kind terms, the nature of natural kinds, the essentiality of origin and constitution, the relative merits of 'identitarian' and counterpart-theoretic accounts of modality, and the identity or otherwise of mental types and tokens with physical types and tokens. No specialist knowledge in either the philosophy of language or metaphysics is presupposed; Hughes's book will be valuable for anyone working on the ideas which Kripke made famous in the philosophy world. (shrink)

The necessity of origin suggests that a person’s identity is determined by the particular pair of gametes from which the person originated. An implication is that speculative scenarios concerning how we might otherwise have been had our gametic origins been different are dismissed as being metaphysically impossible. Given, however, that many of these speculations are intelligible and commonplace in the discourses of competent speakers, it is overhasty to dismiss them as mistakes. This paper offers a way of understanding (...) these speculations that does not commit them to incoherence but aims to make the best sense of what they are expressing. Using the philosophical framework of two‐dimensional semantics, it proposes that the speculative scenarios are best analysed as epistemic possibilities, rather than as metaphysical possibilities. It then explores some implications of this analysis for the ethical challenges associated with the non‐identity problem. (shrink)

A highly contentious issue in recent philosophy of logic has been the question of whether there can be contingently true identity statements. In this paper I want to investigate a possible loop-hole in the standard argument of the necessitarians (i.e., those who maintain that any true identity statement is necessarily true).

In the addenda to his Naming and Necessity, Kripke provides an account of how necessary aposteriori statements are possible. In such a case, there is an apriori general principle telling us that it is necessary if true at all. Though straightforward in its broad compass, this account faces two obvious questions in its application: in each case of necessary aposteriori statements, what is the underlying principle and how is it established apriori? I treat these questions with respect to theoretical (...) identity statements concerning chemical substances, such as ‘water is H2OH2O’. I argue that the general principle underlying the necessity of the statements is that if a chemical substance has a certain chemical composition, then it could not have had any other chemical composition. Then I defend the view that the principle is a conceptual truth by providing a novel derivation of it from the theoretical concept of chemical substance with a sufficient level of formal rigor. The logical principles required for the derivation will also be stated and defended. (shrink)

are synthetic a priori judgements possible?" In both cases, i~thas usually been t'aken for granted in fife one case by Kant that synthetic a priori judgements were possible, and in the other case in contemporary,'d-". philosophical literature that contingent statements of identity are ppss. ible. I do not intend to deal with the Kantian question except to mention:ssj~".

We construct a Hilbert style system RPL for the notion of plausibility measure introduced by Halpern J, and we prove the soundness and completeness with respect to a neighborhood style semantics. Using the language of RPL, we demonstrate that it can define well-studied notions of necessity, conditionals and propositional identity.

The subject of this paper is the epistemology of identity: a general theory of knowledge, evidence and justification for the claim that one thing is identical to another. Although identity figures significantly in our epistemic lives, this is a topic that, to the best of my knowledge, has gone entirely unexplored. Initial attempts to integrate such an epistemology into existing theories of evidence---many of which are tailor-made for contingent propositions---are confounded by the necessity of identity. I (...) defend a restricted form of skepticism according to which the only knowable identity claims are trivial. (shrink)

The philosophy problem of identity and the related problem of change go back to the ancient Greek philosophers and fascinated later figures including Leibniz, Locke and Hume. Heraclitus argued that one could not swim in the same river twice because new waters were ever flowing in. When is a river not the same river? If one removes one plank at a time when is a ship no longer a ship? What is the basic nature of identity and persistence? (...) This book introduces and asseses the philosophical puzzles posed by things persisting through time. Beginning with essential historical background to the problem it explores the following key topics and debates: mereology and identity, including 'Leibniz's Law' the constitution view of identity the 'relative identity' argument concerning identity temporary identity four-dimensionalism, counterpart and mulitiple counterpart theory supervenience the problem of temporary intrinsics the necessity of identity presentism ontological and epistemological criteria for persistence and the difference between them. Including chapter summaries, annotated further reading and a glossary this book is essential reading for anyone seeking a clear and informative introduction to and assessement of the metaphysics of identity. (shrink)

In this paper I discuss and evaluate different arguments for the view that the laws of nature are metaphysically necessary. I conclude that essentialist arguments from the nature of natural kinds fail to establish that essences are ontologically more basic than laws, and fail to offer an a priori argument for the necessity of all causal laws. Similar considerations carry across to the argument from the dispositionalist view of properties, which may end up placing unreasonable constraints on property (...) class='Hi'>identity across possible worlds. None of my arguments preclude the possibility that the laws may turn out to be metaphysically necessary after all, but I argue that this can only be established by a posteriori scientific investigation. I therefore argue for what may seem to be a surprising conclusion: that a fundamental metaphysical question – the modal status of laws of nature – depends on empirical facts rather than purely on a priori reasoning. (shrink)

Quine and others have put many problems to quantified modal logic. Their purpose is to show the logic to be paradoxical or at least very peculiar. Many of these problems center around the interplay between modality, quantification and identity.

We argue that the inference from dispositional essentialism about a property (in the broadest sense) to the metaphysical necessity of laws involving it is invalid. Let strict dispositional essentialism be any view according to which any given property’s dispositional character is precisely the same across all possible worlds. Clearly, any version of strict dispositional essentialism rules out worlds with different laws involving that property. Permissive dispositional essentialism is committed to a property’s identity being tied to its dispositional profile (...) or causal role, yet is compatible with moderate interworld variation in a property’s dispositional profile. We provide such a model of dispositional essentialism about a property and metaphysical contingency of the laws involving it. (shrink)

It may be that all that matters for the modalities, possibility and necessity, is the object named by the proper name, not which proper name names it. An influential defender of this view is Saul Kripke. Kripke’s defense is criticized in the paper.

The discourse of identity in the Arab context in general and in the Maghrebi context in particular is a modern phenomenon and is of central importance. In the Maghreb this discourse is related to modernization efforts, with the de-colonization struggle and its ideology, and with the nation-state-building genesis, process, and legitimisation after independence. A fundamental part in the developmental process of this discourse, there-fore, is the difference from, as well as the non-negotiable and hegemonic presence of, the "Other". The (...) evolution of a Maghrebi discourse of identity in this instance is a peculiar formation of consciousness or awareness with regard to a self-evident constancy, namely, the own identity, which had not been in doubt up to that point. From the challenging encounter with the western European hegemonic "Other" comes the necessity to bring forth such a discourse. The Difference is thus a fundamental aspect in the beginnings of the Maghrebi discourse of identity. (shrink)

There is a certain argument against the principle of the indiscernibility of identicals, or the thesis that whatever is true of a thing is true of anything identical with that thing. In this argument, PInI is used together with the self-evident principle of the necessity of self-identity to reach the conclusion, which is held to be paradoxical and, thus, fatal to PInI. My purpose is to show that the argument in question does not have this consequence. Further, I (...) argue that PInI is a universally valid principle which can be used to prove the necessity of identity. (shrink)

This volume is an act of talking back, of talking heresy. To reclaim the term “realism,” to maintain the epistemic significance of identity, to defend any version of identity politics today is to swim upstream of strong academic currents in feminist theory, literary theory, and cultural studies. It is to risk, even to invite, a dismissal as naive, uninformed, theoretically unsophisticated. And it is a risk taken here by people already at risk in the academy, already assumed more (...) often than not to be uninformed and undereducated precisely because of their real identities. Of course, identity is today a growth industry in the academy, across the humanities and social sciences, influencing even law and communication studies. The constitutive power of gender, race, ethnicity, sexuality and other forms of identity has, finally, suddenly, been recognized as a relevant aspect of almost all projects of inquiry. However, as I shall discuss in this essay, simultaneous to this academic commodification of identity is an increasing tendency to view identity as politically and metaphysically problematic, some have even said pathological. So on the one hand the theoretical relevance of identities has become visible, while on the other hand many theorists are troubled by the implications of the claim that identity makes a difference. Increasingly, then, the attachment to identity has become suspect. If identity has become suspect, identity politics has been prosecuted, tried, and sentenced to death. To espouse identity politics in the academy today risks being viewed as a member of the Flat-Earth Society. Like “essentialism,” identity politics has become the shibboleth of cultural studies and social theory, and denouncing it has become the litmus test of academic respectability, political acceptability, and even a necessity for the very right to be heard. In contrast, there has been a noticeable thaw regarding the term essentialism. What was once perfunctorily denounced at the start of every paper in feminist theory has recently been tentatively examined by a few theorists for possible signs of validity.. (shrink)

The once deeply held conviction that all necessary truths are known a priori is now widely, although by no means universally agreed to have been subjected to penetrating, if not devastating criticism. Scott Soames, for example, on behalf of Saul Kripke, and indirectly of Hilary Putnam, argues that in respect of natural kinds, the introduction of basic essentialist assumptions grounded in our pre-theoretical habits of thinking and speaking – for example, that atomic or molecular structure provides the underlying essence of (...) a substance – allows a sentence like "water = H 2 0," in which the identity sign is flanked by rigid designators to express a metaphysically necessary truth. Yet doubts and puzzlement remain over the status of a posteriori necessities, including those relating to an individual's origin. This paper considers some prominent criticisms that have been made of the Kripke–Putnam approach by A. J. Ayer and Frank Ebersole among others and reveals in what respects they are valid, where they are misplaced, and, perhaps more importantly, why the most valuable aspect of this approach can be seen to reflect aspects of our scientific procedures that do indeed point towards an application for a distinction that roughly mirrors that between epistemic and metaphysical possibility, yet one that is grounded instead in the nature of our actual practices. (shrink)

I show that intuitive and logical considerations do not justify introducing Leibniz’s Law of the Indiscernibility of Identicals in more than a limited form, as applying to atomic formulas. Once this is accepted, it follows that Leibniz’s Law generalises to all formulas of the first-order Predicate Calculus but not to modal formulas. Among other things, identity turns out to be logically contingent.

This article examines the existing and emerging morphology of caste-based discrimination in urban and academic spaces in India. Practices of caste-based profiling are similar to racial profiling or policing but are not acknowledged as caste-based discrimination by the public and the law, since they do not match constitutionally recognized practices of discrimination like untouchability. Caste-based profiling is deeply ingrained in how upper-caste people in urban and academic spaces speak, read, and think. Profiling performs the same function as untouchability, since it (...) weeds out the Dalit from public spaces that pretend to be liberal and secular. Profiling is part of a larger process of “casteization,” which ensures the continuation of caste-based discrimination in newer forms to maintain caste hierarchy and upper-caste hegemony. Profiling traps the urban Dalit in a conundrum with respect to self-representation—should they reveal their Dalit identity to build solidarity with the Dalit, Bahujan, and Adivasi community but risk social ostracization and stigmatization, or should they hide their Dalit identity and try to evade caste-based discrimination? This article defines the emphasis of a new political movement inaugurated by Dalit writers called “Dalitude,” which attempts to break out of this conundrum, challenges casteization, and aims to empower a lower-caste majority. (shrink)

A thought that we all entertain at some time or other is that the course of our lives might have been very different from the way they in fact have been, with the consequence that we might have been rather different sorts of persons than we actually are. A less common, but prima facie intelligible thought is that we might never have existed at all, though someone rather like us did. Arguably, any plausible theory of personal identity should be (...) able to accommodate both possibilities. Certain currently popular Reductionist theories of personal identity, however, seem to be deficient in precisely this respect. This paper explores some Reductionist responses to that challenge. (shrink)

There is a tension between the “growing block” account of time (closed past, open future) and the possibility of backwards time travel. If Tim the time traveler can someday travel backwards through time, then he has (in a certain sense) already been. He might discover this fact before (in another sense) he goes. Hence a dilemma: it seems that either Tim’s future is determined in an odd way or cases of (temporary) ontic indeterminate identity are possible. Either Tim cannot (...) avoid heading for the past or he is only indeterminately that guy who appeared in the past with many of Tim’s memories. Determinacy in the past implies a degree of determinism in the future; indeterminism about the future seeps back to the past. (shrink)

There are well-known quasi-formal arguments that identity is a "strict" relation in at least the following three senses: (1) There is a single identity relation and a single distinctness relation; (2) There are no contingent cases of identity or distinctness; and (3) There are no vague or indeterminate cases of identity or distinctness. However, the situation is less clear cut than it at first may appear. There is a natural formal theory of identity that is (...) very close to the standard classical theory but which does not validate the formal analogues of (1)-(3). The core idea is simple: We weaken the Principle of the Indiscernibility of Identicals from a conditional to an entailment and we adopt a weakly classical logic. This paper investigates this weakly classical theory of identity (and related theories) and discusses its philosophical ramifications. It argues that we can accept a reasonable theory of identity without committing ourselves to the uniqueness, necessity, or determinacy of identity. (shrink)

Attacks on ?closest continuer? and ?best candidate? theories of identity have something correct in them while still failing to discredit the theories they oppose. What follows from Noonan's and Wiggins's objections to such theories is that they need to be so formulated as not to deny the necessity of identity. The best metaphysics for best?candidate theories to adopt is one in which everyday objects are taken to transcend, in a certain sense, their life histories in given worlds. (...) This metaphysics also has the potential for solving problems about contingent identity, transworld identity, and the issue of haecceitism or individual essence. To develop the metaphysics, it is only necessary to follow through the analogy between worlds and times suggested by writers like Plantinga and Schlesinger. (shrink)