Online research in philosophy

Theoretical identity statements of the form "water is H2O‟ are allegedly necessary truths knowable a posteriori, and assert that nothing could be water and not be H2O. The necessary a posteriori nature of these identity claims has been taken by Kripke, Putnam and Donnellan to justify a move from talk of reference (language) to talk of essence (metaphysics), and has motivated much of contemporary essentialism. In this paper I will contest this move from reference to essence, and argue that (i.) the only way to derive essentialism from semantics (specifically direct reference) is to assume it as a premise, (ii.) that contemporary essentialism is a metaphysical assumption not a thesis, and (iii.) – assuming the accuracy of the analogy between proper names and natural kind terms – present an alternative version of natural kinds classification that is interest-relative, dependent on practical application and reflects the contingent state of affairs which is our world.

The “scientific essentialist” doctrine asserts that the following are examples of a posteriori necessary identities: water is H2O; gold is the element with atomic number 79; and heat is the motion of molecules. Evidence in support of this assertion, however, is difficult to find. Both Hilary Putnam and Saul Kripke have argued convincingly for the existence of a posteriori necessities. Furthermore, Kripke has argued for the existence of a posteriori necessary identities in regard to a particular class of statements involving proper names. Neither Kripke nor Putnam, however, has argued convincingly that sentences containing syntactically complex terms or descriptive phrases can express a posteriori necessary identities. I will argue by way of a hypothetical example that ‘water is H2O’ does not express a necessary identity. My argument is unique in that it attacks the relevant sufficiency claim needed to underwrite this putative necessary identity.1 That is, even if we grant that water is necessarily composed of H2O, we should not accept that H2O necessarily forms water.

Scientific Essentialism defends the view that the fundamental laws of nature depend on the essential properties of the things on which they are said to operate, and are therefore not independent of them. These laws are not imposed upon the world by God, the forces of nature, or anything else, but rather are immanent in the world. Ellis argues that ours is a dynamic world consisting of more or less transient objects which are constantly interacting with each other, and whose identities depend on their roles in these processes. Natural objects must behave as they do, because to do otherwise would be contrary to their natures. The laws of nature are, therefore, metaphysically necessary, and consequently, there are necessary connections between events. Brian Ellis calls for the rejection of the theory of Humean Supervenience and an implementation of a new kind of realism in philosophical analysis.

Scientific essentialism is the view that some necessities (e.g., water = H2O) can be known only with the aid of empirical science. The thesis of the paper is that scientific essentialism does not extend to the central questions of philosophy and that these questions can be answered a priori. The argument is that the evidence required for the defense of scientific essentialism (e.g., twin earth intuitions) is reliable only if the intuitions required by philosophy to answer its central questions is also reliable. Included is an outline of a modal reliabilist theory of basic evidence and a concept-possession account of the reliability of a priori intuition.

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 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.

The striking difference between the orthodox nomological necessitation view of laws and the claims made recently by Scientific Essentialism is that on the latter interpretation laws are metaphysically necessary while they are contingent on the basis of the former. This shift is usually perceived as an upgrading: essentialism makes the laws as robust as possible. The aim of my paper—in which I contrast Brian Ellis’s Scientific Essentialism and David Armstrong’s theory of nomological necessity—is threefold. (1) I first underline the familiar fact that metaphysical necessity (of Kripkean “water is necessarily H2O” kind) is not a stronger kind of necessity than nomological necessity but an entirely different kind of thing: nomological, but not metaphysical necessity, is an intra-world necessitation which Armstrong (almost) identifies with causation; metaphysical, but not nomological necessitation, has a canonical link to possible world considerations and counterfactual reasoning. Hence, the change from one necessity to the other is not an upgrading but a substantial shift. (2) I will explain how the essentialists, who promote this shift, are nonetheless able to retain the features of nomological necessity. (3) I also explore, for both the essentialist and the Armstrongian, whether they could extract a modal force from intra-world nomological necessity which it does not have per se. I argue that such a modal force is, indeed, obtainable for them. I will close the paper with some remarks and questions about the relation between Kripkean metaphysical necessity and the modal version of nomological necessity as defined in (3).

Scientific essentialism holds that: (1) each scientific kind is associated with the same set of properties in every possible world; and (2) every individual member of a scientific kind belongs to that kind in every possible world in which it exists. Recently, Ellis (Scientific essentialism, 2001 ; The philosophy of nature 2002 ) has provided the most sustained defense of scientific essentialism, though he does not clearly distinguish these two claims. In this paper, I argue that both claims face a number of formidable difficulties. The necessities of scientific essentialism are not adequately distinguished from semantic necessities, they have not been shown to be necessities in the strictest sense, they must be relativized to context, and they must either be confined to a subset of scientific properties without warrant or their connection to causal powers must be revoked. Moreover, upon closer examination (1) turns out to be a trivial thesis that can be satisfied by non-kinds, and (2) is inapplicable to some of the most fundamental kinds in the basic sciences.

In 'Necessarily, salt dissolves in water' (Analysis 61 (2001)), I argued that because the laws required for the existence of salt entail the laws that ensure dissolving in water, there is no possible world in which salt exists but fails to dissolve in water. In this paper I respond to criticisms from Helen Beebee and Stathis Psillos (Analysis 62 (2002)). I also introduce the 'down-and-up' structure, generalising the case. Whether or not this structure is instantiated is a matter for a posteriori discovery. Hence not only are some laws necessary (but known a posteriori), but furthermore whether a given law is necessary or contingent will also be a matter of a posteriori discovery.

Laws of nature are puzzling because they have a 'modal character'—they seem to be 'necessary-ish'—even though they also seem to be metaphysically contingent. And it is hard to understand how contingent truths could have such a modal character. Scientific essentialism is a doctrine that seems to dissolve this puzzle, by showing that laws of nature are actually metaphysically necessary. I argue that even if the metaphysics of natural kinds and properties offered by scientific essentialism is correct, there are still some metaphysically contingent truths that share the modal character of the laws of nature. I argue that these contingent truths should be considered laws of nature. So even if scientific essentialism is true, at least some laws of nature are metaphysically contingent.

In this paper I aim to show that a certain law of nature, namely that common salt (sodium chloride) dissolves in water, is metaphysically necessary. The importance of this result is that it conflicts with a widely shared intuition that the laws of nature (most if not all) are contingent. There have been debates over whether some laws, such as Newton’s second law, might be definitional of their key terms and hence necessary. But the law that salt dissolves in water is not that kind of law. The law statement ‘salt dissolves in water’ is clearly synthetic. It appears a classic case of a contingent law. We like to believe that there are possible worlds in which the laws of nature are different and in which salt does not dissolve in water.