Paul Needham

A view of individuals as constituted of quantities of matter, both understood as continuants enduring over time, is elaborated in some detail. Constitution is a three-place relation which can't be collapsed to identity because of the place-holder for a time and because individuals and quantities of matter have such a radically different character. Individuals are transient entities with limited lifetimes, whereas quantities are permanent existents undergoing change in physical and chemical properties from time to time. Coincidence, considered as a matter of occupying the same place, is developed, alongside sameness of constitutive matter, as a criterion of identity for individuals. Quantities satisfy the mereological criterion of identity, applicable to entities subject to mereological relations and operations such as regions of space and intervals of time. A time-dependent analogue of mereological parthood is defined for individuals, in terms of which analogues of the other mereological relations can be defined. But it is argued that there is no analogue of the mereological operation of summation for individuals

Chemistry is the study of the structure and transformation of matter. When Aristotle founded the field in the 4th century BCE, his conceptual grasp of the nature of matter was tailored to accommodate a relatively simple range of observable phenomena. In the 21st century, chemistry has become the largest scientific discipline, producing over half a million publications a year ranging from direct empirical investigations to substantial theoretical work. However, the specialized interest in the conceptual issues arising in chemistry, hereafter Philosophy of Chemistry, is a relatively recent addition to philosophy of science. Philosophy of chemistry has two major parts. In the first, conceptual issues arising within chemistry are carefully articulated and analyzed. Such questions which are internal to chemistry include the nature of substance, atomism, the chemical bond, and synthesis. In the second, traditional topics in philosophy of science such as realism, reduction, explanation, confirmation, and modeling are taken up within the context of chemistry.

During the 19th century atomism was a controversial issue in chemistry. It is an oversimplification to dismiss the critics' arguments as all falling under the general positivist view that what can't be seen can't be. The more interesting lines of argument either questioned whether any coherent notion of an atom had ever been formulated or questioned whether atoms were ever really given any explanatory role. At what point, and for what reasons, did atomistic hypotheses begin to explain anything in chemistry? It is argued that 19th-century atomic accounts of constant proportions and isomerism had little to offer, whereas a non-atomic explanation of chemical combination was developed. Not until the turn of the century did atomism begin to do serious explanatory work in chemistry.

In response to difficulties in understanding the notion of chemical substance at issue in Gibbs’ phase rule, there is a long tradition of reformulating the simple statement of the rule. The leading idea is to rewrite the rule with a term for the number of substances actually present and to introduce additional terms making explicit the various kinds of restrictions which in the original formulation are taken to be incorporated into Gibbs’ notion of the number of independent substances. Although the number of independent substances cannot in general be interpreted as the number of substances actually present, it is not an entirely derivative concept as the authors of the reformulations sometimes seem to presuppose. In particular, it is doubtful whether the number of substances actually present is a clearly delimited concept which can be determined prior to the application of the phase rule. In that case, the phase rule provides a useful source of information for the determination of the number and nature of the substances actually present in a mixture which should be properly reflected in an adequate interpretation of Gibbs’ notion of independent substances. For this purpose, I propose a mereological interpretation of the way independent substances are related to the substances actually present which makes sense of the fact that the former are not uniquely fixed but can be chosen from the latter in several ways.

In a recent critique of the doctrine of emergentism championed by its classic advocates up to C. D. Broad, Jaegwon Kim (Philosophical Studies 63:31–47, 1999) challenges their view about its applicability to the sciences and proposes a new account of how the opposing notion of reduction should be understood. Kim is critical of the classic conception advanced by Nagel and uses his new account in his criticism of emergentism. I question his claims about the successful reduction achieved in the sciences and argue that his new account has not improved on Nagel’s and that the critique of emergentism he bases on it is question-begging in important respects.

The creators of equilibrium and irreversible thermodynamics developed a conception of processes which bears on metaphysical discussions of change, occurrents, and continuants and merits the attention of contemporary analytic metaphysicians. It concerns the macroscopic domain, from which metaphysicians normally take their examples, and is unjustly ignored on the grounds that it is not ‘fundamental science’. Why this often-voiced view should disqualify just thermodynamics, and not the broad range of considerations normally raised, is a moot point. But even if there were an adequate reductive argument, that wouldn’t eliminate the ontological claims. It is argued that processes cannot be defined as changes in the state of enduring objects, but should be considered autonomous entities. The relational character of processes involving several continuants is developed, alongside their mereological features and their relation to space and time. Some aspects of the historical development of the notions of reversible and irreversible processes in thermodynamics are taken up in the course of the discussion, but the paper is not concerned with the mathematical foundations of equilibrium and irreversible thermodynamics. 1 Introduction2 Change3 Distinguishing Processes from States4 Causings5 The Relational Character and Mereological Structure of Processes6 Concluding Comments

Late nineteenth‐century opponents of atomism questioned whether the evidence required any notion of an atom. In this spirit, Duhem developed an account of the import of chemical formulas that is clearly neutral on the atomic question rather than antiatomistic. The argument is supplemented with specific inadequacies of atomic theories of chemical combination and considerably strengthened by the theory of chemical combination provided by thermodynamics. Despite possible counterevidence available at the time, which should have tempered some of Duhem's concluding remarks, there was no atomic theory of chemical combination, which is wholly a product of the twentieth century. †To contact the author, please write to: Department of Philosophy, University of Stockholm, SE‐106 91 Stockholm, Sweden; e‐mail: [email protected].

‘Water is H 2 O’ is naturally construed as an equivalence. What are the things to which the two predicates ‘is water’ and ‘is H 2 O’ apply? The equivalence presupposes that substance properties are distinguished from phase properties. A substance like water (H 2 O) exhibits various phases (solid, liquid, gas) under appropriate conditions, and a given (say liquid) phase may comprise several substances. What general features distinguish substance from phase properties? I tackle these questions on the basis of an interpretation of a theorem of thermodynamics known as Gibbs' phase rule which systematically relates these two kinds of feature of matter. The interpretation develops the idea that the things substance and phase predicates apply to are quantities of matter which sustain mereological relations and operations and exploits these mereological features in distinguishing the two kinds of property. Gibbs' phase rule is a macroscopic principle applicable for macroscopic intervals of time. Bringing intervals of time into the picture calls for a more detailed consideration of the relation between macroscopic equilibria and the corresponding dynamic equilibria at the microlevel and throws into question the simple idea that quantities can always be regarded as collections of molecules. The account provides some insight into how the continuous, macroscopic conception of matter (‘gunk’) is reconciled with the discrete microscopic conception and illuminates the interpretation of substances present in mixtures

Eric Scerri has proposed an account of how reduction might be understood in chemistry. He claims to build on a general aspect of Popper's views which survives his otherwise heavy criticism, namely adherence to actual scientific practice. This is contrasted with Nagel's conception, which Scerri takes to be the philosopher's standard notion. I argue that his proposal, interesting though it is, is not so foreign to ideas in the tradition within which Nagel wrote as Scerri would have us believe. Moreover, actual scientific practice can be commandeered in support of a holistic conception which Popper contrasted with what he saw as the admirable strivings towards reduction in science.

Prima facie, there are two kinds of expression used in English to make reference to time: those involving explicit mention of time and temporal ordering relations, and tenses involving no such explicit reference. Taking as a criterion of adequacy the unification of both these aspects, a systematization is proposed (owing much to Reichenbach) which provides a characterization of tenses. The theory is not based on the notion of a proposition with variable truth value which formed the cornerstone of Arthur Prior’s work. His conception receives a good deal of criticism, ultimately on the ground that relativising to exactly one time is inadequate. We don’t know in advance whether or not no time of perhaps more than one time is relevant, and where this is the case, the analysis cannot be reduced to propositions true at just one time.

The Aristotelian distinction between actual and potential presence of a substance in a mixture forms part of a conception of mixture which stands in contrast to atomist and Stoic theories as propounded by the ancients. But the central ideas on which these theories are built need not be combined and opposed to one another in precisely the ways envisaged by these ancient theories. This is well illustrated by Duhem, who maintained the Aristotelian idea that the original ingredients are only potentially, and not actually, present in a mixture, but who sided with the Stoics and against Aristotle on the possibility of co-occupancy. I have argued that the Stoic theory cannot dispense with some such notion as the Aristotelian conception of potentiality in allowing the elements to be actually present in a mixture. Here I suggest that some such Aristotelian notion must be at work in a more modern atomic conception of matter if this is to allow elemental substances to be actually present in compounds, which I think is how compounds are usually understood. Analogous issues arise regarding the status of solutions and their components.

Despite all the criticism showered on Nagel’s classic account of reduction, it meets a fundamental desideratum in an analysis of reduction that is difficult to question, namely of providing for a proper identification of the reducing theory. This is not clearly accommodated in radically different accounts. However, the same feature leads me to question Nagel’s claim that the reducing theory can be separated from the putative bridge laws, and thus to question his notion of heterogeneous reduction. A further corollary to the requirement that all the necessary conditions be incorporated in an adequate formulation of the putative reducing theory is that the standard example of gas temperature is not reducible to average molecular kinetic energy. As originally conceived, Nagel’s conception of reduction takes no account of approximate reasoning and this failure has certainly restricted its applicability, perhaps to the point of making it unrealistic as a model of reduction in science. I suggest approximation can be accommodated by weakening the original requirement of deduction without jeopardizing the fundamental desideratum. Finally, I turn to briefly consider the idea sometimes raised of the ontological reducibility of chemistry.

This paper takes up issues related to the notion of chemical substances arising from their mereological and modal features. Related notions are elements and compounds, into which substances are sub-divided, and the general notion of mixture, which as a special case might involve several substances, but covers other cases too. These are essentially macroscopic concepts. Some of the chemical arguments for this claim have been presented elsewhere. The present paper is a metaphysical treatment of matter as categorised by the major chemical concepts bearing on distinctions between homogeneous and heterogeneous matter, and between a single and several substances.

According to microessentialism, it is necessary to resort to microstructure in order to adequately characterise chemical substances such as water. But the thesis has never been properly supported by argument. Kripke and Putnam, who originally proposed the thesis, suggest that a so-called stereotypical characterisation is not possible, whereas one in terms of microstructure is. However, the sketchy outlines given of stereotypical descriptions hardly support the impossibility claim. On the other hand, what naturally stands in contrast to microscopic description is description in macroscopic terms, and macroscopic characterisations of water are certainly possible. This suffices to counter the claim that microdescriptions are necessary. Whether it counters the impossibility claim depends on whether all macroscopic descriptions are stereotypical (stereotypical descriptions presumably being macroscopic). In so far as systematic import of “stereotypical” can be determined, it would seem not. But some macroscopic characterisations have definite affinity with everyday knowledge, which presumably stands in conflict with the spirit of the impossibility claim. Since what is characterised are properties expressed by predicates like “is water”, the necessity of identity has no bearing here, and matters of interpretation pose problems for claims to the effect that science fixes the extension of “water” as ordinarily understood

Two inter-linked theses are defended in this paper. One is the Duhemian theme that a rigid distinction between physical and chemical properties cannot be upheld. Duhem maintained this view not because the latter are reducible to the former, but because if physics is to remain consistent with chemistry it must prove possible to expand it to accommodate new features, and a rigid distinction would be a barrier to this process. The second theme is that naturally occurring isotopic variants of water are in fact distinct substances, and naturally occurring samples of water are mixtures of these substances. For most practical purposes it is convenient to treat protium oxide, deuterium oxide, and so on, as the same chemical substance, but to insist on this as a matter of principle would stand in conflict with the first thesis.

In a recent article in this journal (Foundations of Chemistry, 7 (2005), 125–148) Lombardi and Labarca call into question a thesis of ontological reduction to which several writers on reduction subscribe despite rejecting a thesis of epistemological reduction. Lombardi and Labarca advocate instead a pluralistic ontology inspired by Putnam’s internal realism. I suggest that it is not necessary to go so far, and that a more critical view of the ontological reduction espoused by the authors they criticise circumvents the need to resort to their radical alternative.

Robert Deltete and Anastasios Brenner have provided a thorough examination of my translation of Duhem’s Le mixte et la combinaison chimique (1902) and associated essays. I am very grateful for their efforts and gratified that such competent reviewers should be generally positive. They provide an overview of relevant aspects of Duhem’s life and work, which may serve to introduce him to readers of this journal and promote interest in Duhem studies. They also raise and answer some questions about the interpretation and evaluation of Duhem’s work, make some points of criticism of my choice of material and question certain points of translation. The editor has suggested that I make a response, and I shall take up some issues in these three areas. Since Duhem’s views play a central role in the development of the concept of chemical substance which I have worked on in recent years, I will make several references to my own publications.

A general analysis of reduction is as important to critics who deny reductionist claims as to their advocates. Nagel’s analysis continued to find favour amongst such critics after advocates sought alternatives—often attempted generalisations of perceived specific paradigm cases of reductive identification, such as temperature and mean molecular kinetic energy. The pros and cons of Nagel’s account are discussed, but the difficulties are not satisfactorily overcome by approaches advanced by Causey, Spector and Beckermann. Although no general account is settled upon, temperature is considered in some detail and found not to provide the paradigm case of reduction taken to motivate these alternatives.