Natural kind terms have exercised philosophical fancy ever since Kripke, in Naming and Necessity, claimed them to be rigid designators. He there drew attention to the peculiar, name-like behavior of a family of prima facie loosely related general terms of ordinary English: terms such as ‘water’, ‘tiger’, ‘heat’, and ‘red’. Just as for ordinary proper names, Kripke argued that such terms cannot be synonymous with any of the definite descriptions ordinary speakers associate with them. Rather, the name-like behavior of these (...) so-called natural kind terms is to be explained, just as in in the case of proper names, by the doctrine of rigid designation. And as a consequence of thus extending the notion of rigid designation to general terms, he famously endorsed the claim that so-called ‘theoretical identifications’, i.e. statements like (1) Water is H2O, are necessary, if true. (shrink)

It has been argued that a combination of game-theoretic semantics and independence-friendly (IF) languages can provide a novel approach to the conceptual foundations of mathematics and the sciences. I introduce and motivate an IF first-order modal language endowed with a game-theoretic semantics of perfect information. The resulting interpretive independence-friendly logic (IIF) allows to formulate some basic model-theoretic notions that are inexpressible in the ordinary quantified modal logic. Moreover, I argue that some key concepts of Kripke’s new theory of reference are (...) adequately modeled within IIF. Finally, I compare the logic IIF to David Lewis' counterpart theory, drawing some morals concerning the interrelation between metaphysical and semantic issues in possible-world semantics. (shrink)

According to the simple proposal, a predicate is rigid iff it signifies the same property across the different possible worlds. The simple proposal has been claimed to suffer from an over-generalization problem. Assume that one can make sense of predicates signifying properties, and assume that trivialization concerns, to the effect that the notion would cover any predicate whatsoever, can be overcome. Still, the proposal would over-generalize, the worry has it, by covering predicates for artifactual, social, or evaluative properties, such as (...) 'is a knife,' 'is a bachelor,' or 'is funny.' In defense, it is argued that rigidity for predicates as characterized plays the appropriate theoretical role, and that the contention that "unnatural" properties are not to be rigidly signified is ungrounded. (shrink)

En este escrito se argumentará que uno de los problemas centrales de la rigidez en los términos generales para clases naturales es consecuencia de no distinguir entre términos rígidos de jure y términos rígidos de facto en dichos casos. Se sostiene que los enunciados de identidad necesarios defendidos por Kripke en Naming and Necessity consideran la ocurrencia de términos que designan a una misma clase (clases que poseen entre sí la relación transmundana de ser una misma clase) a través de (...) dos términos rígidos, uno de jure y uno de facto. Esto permite explicar los problemas que la noción de rigidez plantea en los casos de los términos generales para clases naturales, pues mantiene los requerimientos de conexión causal y a su vez enuncia el criterio de identidad entre tales clases, a través de la(s) propiedad(es) esencial(es) de dicha clase. (shrink)

The causal theory of reference is often taken to provide a solution to the problems, such as incomparability and referential discontinuity, that the meaning-change thesis raised. I show that Kuhn successfully questioned the causal theory and Putnam's idea that reference is determined via the sameness relation of essences that holds between a sample and other members of a kind in all possible worlds. Putnam's single ‘essential' properties may be necessary but not sufficient to determine membership in a kind category. Kuhn (...) argued that extension is fixed by similarity-dissimilarity relations that are liable to change in taxonomic reorganizations of science. *Received October 2009; revised January 2010. †To contact the author, please write to: Institute of Philosophy, University of Leiden, Martin de Vrieshof 4, 2300 RS Leiden, The Netherlands; e-mail: [email protected]. (shrink)

In this paper, I present, generalize and develop the extensionalist theory of rigidity for general terms in light of criteria commonly applied to theories of general term rigidity. According to the theory, a general term is rigid if its extension is constant across all possible worlds. This position has been widely dismissed because it conflicts with the seemingly straightforward idea that natural kind terms have varying extensions from world to world. This criticism holds only to the extent that natural kind (...) terms are indeed rigid. If it turns out that we need not view them as rigid, then the extensionalist theory fares well when compared with other theoretical requirements. (shrink)

The notion of rigidity looms large in philosophy of language, but is beset by difficulties. This paper proposes a simple theory of rigidity, according to which an expression has a world-relative semantic property rigidly when it has that property at, or with respect to, all worlds. Just as names, and certain descriptions like The square root of 4, rigidly designate their referents, so too are necessary truths rigidly true, and so too does cat rigidly have only animals in its extension. (...) After spelling out the theory, I argue that it enables us to avoid the headaches that attend the misbegotten desire to have a simple rigid/non-rigid distinction that applies to expressions, giving us a simple solution to the problem of generalizing the notion of rigidity beyond singular terms. (shrink)

It is generally assumed that rigidity plays a key role in explaining the necessary a posteriori status of identity statements, both between proper names and between natural kind terms. However, while the notion of rigid designation is well defined for singular terms, there is no generally accepted definition of what it is for a general term to be rigid. In this paper I argue that the most common view, according to which rigid general terms are the ones which designate the (...) same kind in all possible worlds, fails to deliver a posteriori necessities. I also present an alternative view, on which the work of explaining a posteriori necessities is not done by rigidity, but by a related metasemantic notion, which I call actuality - dependence. (shrink)

Humeans and non-Humeans reasonably agree that there may be necessary connections between entities that are identical or merely partly distinct—between, e.g., sets and their individual members, fusions and their individual parts, instances of determinates and determinables, members of certain natural kinds and certain of their intrinsic properties, and (especially among physicalists) certain physical and mental states. Humeans maintain, however, that as per “Hume’s Dictum”, there are no necessary connections between entities that are wholly distinct;1 and in particular, no necessary causal (...) connections between such entities (even when the background conditions requisite for causation are in place). The Humean’s differential treatment appears principled, in reflecting that commonly accepted necessary connections involve constitutional relations, whereas wholly distinct entities (notably, causes and effects) do not constitute each other. I’ll argue, however, that the appearance of principle is not genuine, as per the following conditional: Constitutional→Causal: If one accepts certain constitutional necessities, one should accept certain causal necessities. This result provides needed leverage in assessing the two main frameworks in the metaphysics of science, treating natural kinds, causes, laws of nature, and the like. These frameworks differ primarily on whether Hume’s Dictum is taken as a working constraint on theorizing; and it has proved difficult for either side to criticize the other without presupposing their preferred stance on the dictum, hence talking past one another. The arguments for Constitutional→Causal are based, however, in general and independent considerations about what facts in the world might plausibly warrant our beliefs in certain constitutional necessities involving broadly scientific entities. The Humean can respond to these arguments, which reveal a deep tension in their view, at attendant costs of implausibilty and adhocery. The non-Humean framework doesn’t face any such tension between constitutional and causal necessities, however, and so in this respect comes out ahead. (shrink)

It is commonly assumed that natural kind terms constitute a distinct semantic category. This idea emerged during the 1970's following Kripke's and Putnam's well-known remarks on natural kind terms. The idea has stayed with us, although it is now recognized that the issues are considerably more complex than initially thought. Thus, it has become clear that much of Kripke's and Putnam's discussions were based on rather simplified views of natural kinds. It also turns out that the semantic issues are less (...) straightforward than assumed - in particular, it is far from clear what it might mean to say that a kind term is rigid. Strikingly, however, these worries have not done much to undermine the confident assumption that natural kind terms form a special semantic category. In the paper I try to shake that confidence. I argue that although natural kind terms are no doubt important (for instance, from an explanatory point of view), we are certainly not warranted in concluding that they form a separate, semantic category among the kind terms. (shrink)