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Paul Needham

Pages 141 - 147

Fundamental to elementary modern chemistry is the distinction between, on the one hand, chemical substances and, on the other hand, the different phases exhibited by substances. The most familiar phase properties are those of solid, liquid and gas. (Note that in scientific usage, ‘solidity’ is not a synonym for ‘impenetrability’). This distinction is muddled in Putnam’s project of delimiting the extension of the chemical kind water in terms of what bears the relation of being the same liquid to some sample. The significance of this distinction emerged with discoveries made in the latter part of the 18th century leading to a clear change in the extension of some substance terms such as ‘water’ with the development of modern chemistry, and was fully systematised in Gibbs’s chemical thermodynamics towards the end of the 19th century. For phases finer distinctions are made. ‘Ice’, for example, is a general term for the substance water in the solid phase, but investigations have led to several different solid phases of water being distinguished from ice I – common ice – and called ice II, ice III, etc. Calcium carbonate occurs as calcite and as aragonite, which are distinct solid phases of the same substance. As these examples illustrate, names of kinds of matter are not always simply names of a kind of substance, but may also include a phase determination. The term ‘water’ is ambiguous in this respect, sometimes denoting the chemical substance (when ice and steam are water) and sometimes denoting this chemical substance specifically in the liquid phase (when ice and steam are not water). But quartz is unambiguously a chemical substance, silicon dioxide, in a particular solid form, distinct from the other solid phases tridymite and cristobalite. The distinct phases of a single substance are related to one another in ways that depend on the prevailing conditions in accordance with general thermodynamic laws, but with many specific features characteristic of the particular substance, such as boiling points and freezing points. At normal pressure, quartz passes to tridymite at 870°C and this to cristobalite at 1470°C. Liquid sulphur, on the other hand, comprises a mixture of the clear, mobile Sλ form in equilibrium with the dark-red, viscous Sμ form, the proportion of the latter increasing with temperature.

1Department of Philosophy, Stockholm University

1 Bogaard, P. A., (1978), “The Limitations of Physics as a Chemical Reducing Agent”, Proceedings of the Philosophy of Science Association 2: 345-56.

2 Eisenberg, D.; Kauzmann, W., (1969), The Structure and Properties of Water, Oxford: Clarendon Press.

3 Gibbs, J. W., (1948), “On the Equilibrium of Heterogeneous Substances”, in The Collected Works of J. Willard Gibbs, Volume I, Yale University Press, New Haven.

4 Hendry, R. F., (2006), “Is there Downwards Causation in Chemistry?” in Baird, D.; Scerri, E.; McIntyre, L. (eds.) Philosophy of Chemistry: Synthesis of a New Discipline, Dordrecht: Springer, 173-89.

5 Hendry, R. F. The Metaphysics of Chemistry, Oxford University Press, forthcoming.

6 Hendry, R. F.; Needham, P., (2007), “Le Poidevin on the Reduction of Chemistry”, British Journal for the Philosophy of Science, 58: 339-53.

7 Hendry, R. F.; Needham, P.; Woody, A. J. (eds.), (2012), Handbook of the Philosophy of Science, Vol. 6: Philosophy of Chemistry, Amsterdam: Elsevier.

8 Needham, P., (2007), “Macroscopic Mixtures”, Journal of Philosophy 104: 26-52.

9 Needham, P., (2010a), “Nagel’s Analysis of Reduction: Comments in Defence as Well as Critique”, Studies in History and Philosophy of Modern Physics 41: 163-170.

10 Needham, P., (2010b), “Substance and Time”, British Journal for the Philosophy of Science 61: 485-512.

11 Needham, P., (2011), “Microessentialism: What is the Argument?”, Noûs 45: 1-21.

12 Needham, P., (2013), “Hydrogen Bonding: Homing in on a Tricky Chemical Concept”, Studies in History and Philosophy of Science 44: 51-66.

13 Roeper, P., (1983), “Semantics For Mass Terms with Quantifiers”, Noûs 17: 251-65.

14 Scerri, E., (1991), “The Electronic Configuration Model, Quantum Mechanics and Reduction”, British Journal for the Philosophy of Science 42: 309-25.

15 Scerri, E. R., (1994), “Has Chemistry Been at Least Approximately Reduced to Quantum Mechanics?” PSA: Proceedings of the Biennial Meeting of the Philosophy of Science Association 1994: 160-70.

16 Sutcliffe, B.; Woolley, R. G.; (2012), “Atoms and Molecules in Classical Chemistry and Quantum Mechanics” in Hendry et al., 387-426.

17 Timmermans, J., (1963), The Concept of Species in Chemistry, trans. by Ralph E. Oespar, Chemical Publishing Company, New York.

18 van, Brakel, J., (2000), Philosophy of Chemistry: Between the Manifest and the Scientific Image, Leuven University Press, Leuven. (Contains an extensive bibliography.)

19 Weisberg, M.; Needham, P.; Hendry, R., (2011), “Philosophy of Chemistry”, in: The Stanford Encyclopedia of Philosophy, Zalta, E. N. (ed.),

20 Woolley, R. G., (1988), “Must a Molecule Have a Shape?”, New Scientist, 120 (22 Oct.): 53-7.


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