Second edition of Paul Needham's book, Macroscopic Metaphysics, is now out!

With the publication of the 2nd edition of Paul Needham's book, Macroscopic Metaphysics: Middle-Sixed Objects and Longish Processes, Jargonium is honored to publish a short blurp by the author, where he explicates the main thesis of the book.

*Paul Needham, Macroscopic Metaphysics: Middle-Sized Objects and Longish Processes, 2nd. ed., Synthese Library, Springer, Cham, Switzerland, 2026.

The book can be ordered here.

The book seeks to bring together traditional metaphysical issues dealing with the nature of matter and the philosophy of science, and chemistry in particular. Traditional metaphysical concerns with matter fall within what science recognises as the macroscopic realm, and this is the primary vantage point from which chemical issues are taken up, although it inevitably makes call on details at the microscopic level.

I realise that this combination narrows the potential readership, perhaps excluding philosophically informed people uncomfortable with the chemistry and chemists uncomfortable with logic and the general modus operandi of philosophers. But this seems to be the inevitable price to pay for interdisciplinary projects.

Matter and processes are treated as continuants and occurrents, i.e. 3-dimensional objects enduring over time and fleeting processes with temporal parts. They are located within a framework of time and space with temporal intervals and spatial regions but no instants or points. Theories of temporal intervals and spatial regions are built up on the basis of classical mereology dealing with relations such as part, overlapping, being separate from (non-overlapping) and operations such as sum, product (common part) and difference, to which appropriate axioms are added yielding complete first-order theories. Mereology also lies at the heart of processes and quantities of matter, and their distinguishing features are explored with extra-mereological principles governing, for example, their relation to spatial regions and temporal intervals and to one another. Quantities of matter are continuants, but not the only ones. I distinguish them from the general class of individuals, which are material bodies that are constituted of quantities of matter. They too are continuants, enduring over time, but are constituted of different quantities of matter at different times due to their interaction with their environments. Biological organisms are a paradigm example, but non-living things such as comets, rivers and tectonic plates are also individuals in this broad sense.

Having distinguished quantities from individuals with variable constitution, the idea of matter as continuous is developed on the basis of the mereological understanding of so-called mass terms. The key ideas here are the distributive condition, that all parts of a given kind of matter are also of that kind, and the cumulative idea that mereological sums of matter of a given kind are also of that kind. These two themes call for nuances and stand in need of detailed formulation. On the latter point, there is a particular problem with the cumulative condition in connection with relational predicates. Substance properties, such as being water, are expressed by dyadic predicates applying to a quantity of matter at a time. This applies even to elemental properties, since elements too undergo substance-changing transformation in the course of their evolution in stars and radioactive decay. However, it is not necessarily true that the sum of two quantities, one of which was water all day yesterday and the other water all day today is water throughout the sum of yesterday and today. Some of what was water yesterday might participate in chemical reactions and change to other substances today. The correct generalisation of the cumulative condition incorporating relations calls for more careful consideration. There is a classical objection to the distributive condition, that as Quine put it, “‘water’ and ‘sugar’ are true of each part the world’s water and sugar down to single molecules, but not to atoms”, which must also be addressed and is taken up at several places in the book. But the generalisation to relational predicates shows that Quine’s suggestion of rejecting the distributive condition whilst retaining the cumulative condition is untenable.

Aristotle advocated the distributive condition as a criterion of a quantity of matter containing just one substance (i.e. as a criterion of purity). A discussion of key aspects of the historical development of the macroscopic understanding of matter gets under way with an account of Aristotle’s theory substances and mixture and the rival Stoic view, culminating in the account of mixture in Gibbs phase rule. An important feature of the transition from ancient to modern views of matter was recognition of the distinction between substance and phase, and the realisation that a substance like water is not necessarily liquid, as Aristotle thought (and some modern writers still think), but the same substance might be solid or gas too. The older view was surprisingly tenacious, and even Lavoisier had difficulty abandoning it completely although he prepared the ground for doing so. But the distinction was clear enough throughout most of the nineteenth century, and received its definitive formulation in Gibbs’ phase rule in the late 1870s. The import of this fundamental principle of chemistry is discussed, in particular the criterion it provides of being a single substance which replaces Aristotle’s.

With this background, the dyadic predicate “water” is discussed in some detail in Chapter 7 as illustrative of substance predicates. The familiar claim “Water is H2O” relates two predicates applying to the same things, and is naturally construed as a purely macroscopic claim applying to quantities concerning what chemists call the composition of water. Relating the macroscopic term “water” to microscopic constitution must take cognisance of the fact that the situation is a dynamic one and there is no fixed, unchanging microstructure. The continual restructuring renders macroscopic quantities effectively homogeneous for macroscopic times. What should we say about extremely small parts of a quantity of water for extremely short subintervals of a time? Infinite divisibility of time entails that intervals have proper subintervals without limit. A uniform treatment of quantities is less obviously appropriate in moving from the macro- to the microdomain of quantum mechanically indiscernible entities. Nevertheless, a uniform treatment is considered, bearing in mind that the parts are parts of a macroscopic quantity for the times at issue and not isolated from the bulk matter. But an alternative treatment is also developed on the basis of a criterion of belonging to the microscopic, and not the macroscopic, domain provided by French and Krause’s two-sorted interpretation. This treats identity as meaningfully predicated of macro- but not microentities, and the mereology of quantities is restricted to exclude microentities as parts.

This is consistent with the conclusion that might be drawn from the discussion in Chapter 4, that the quantity, time and space variables to which predicates at issue here apply range over macroscopic domains. Phase predicates don’t follow the same pattern, mereologically speaking, as substance predicates. The microscopic understanding of the dynamic equilibrium between the exchange of matter between abutting phases calls for a different mereological interpretation and an accumulation condition similar to that applying to the occupies and constitution relations comes into play.

Many issues raised up to this point bear on the discussion in the literature of so-called natural kinds. Some comments on these issues are drawn together in a final section of Chapter 7.

Processes are introduced in Chapter 8 in the wake of a discussion of the notion of change, which discounts any idea of introducing occurrents on the basis of a distinction between intrinsic and Cambridge changes in continuants. The understanding of occurrents as temporally extended processes—causings rather than relata of a dyadic causal relation—is based on the analysis of thermodynamics in the second half of the nineteenth century, which disposed of caloric in favour of distinguishing between warmth as a feature of the states of bodies measured by temperature and the process of heating, the magnitude of which is measured in units of energy. The chapter continues with a development of the mereological features of processes. Mereological properties include distinguishing temporal parts, parts arising from a consideration of the parts of bodies involved and parts of complex processes such as the elementary reactions underlying complex chemical reactions. The relational character of processes (arising from the several bodies typically involved in processes) and their modal character are taken up in the final sections.

This ontological commitment to the existence of processes is developed alongside the commitment to continuants (quantities of matter and individuals) without any call on the reduction of continuants to occurrents. But precisely this reductionist thesis has been advanced in recent years in the field of biology under the heading of processual philosophy (to distinguish it from the motivation and formulation of an analogous thesis in the wake of Whitehead’s process philosophy). Chapter 9 discusses processual philosophy, arguing for the rejection of the reductionist thesis. The argument hinges on the contention—the main theme of Chapter 3—that individuals, exemplified by biological organisms, are for a given period constituted of a quantity of matter which may well not be fixed over longer and shorter periods of time.

Modal features of quantities are taken up in Chapter 10, beginning with a discussion of how resilient being the same substance, in particular the same element, is to possible changes in states of combination. The chapter continues by pursuing the analysis of the idea of being possible for a quantity to be such-and-such. Claims difficult to capture with conventional sentential modal operators lead to the use of possible states to achieve appropriate expressive power. Incorporation of possible processes is a natural development, linking up with the discussion in Chapter 8. These ideas are developed further in Chapter 11, which relates modality to time and the mereological structure of states, in terms of which a notion of a possible world as a total sum of states is put forward that brings together the ideas about modality in Chapter 3 with those in these later chapters.

Finally, the last chapter takes up ideas of size and shape by developing the theory of spatial regions with the addition of relations expressing a notion of size, in terms of which congruence can be defined. This allows for the definition of shapes and the linear ordering of regions. Angles are subsequently introduced, allowing the further development of shape. Finally, the idea of regions being indistinguishable up to a certain level of discrimination is put forward by way of addressing an issue to do with precision raised at the end of Chapter 2.

Paul Needham