Power and Substance
An ontological extension of dispositional essentialism is proposed, whereby what is necessary and sufficient for the dispositional causation of events is interpreted realistically, and postulated to exist. This ‘generative realism’ leads to a general concept of ‘substance’ as constituted by its more fundamental powers or propensities appearing in the form of some structure or field. This neo-Aristotelian view is reviewed historically, and in respect to quantum physics.
It is now widely argued that dispositions have a leading role in all kinds of natural processes. Dispositional properties of objects—also called propensities or causal powers—appear to be a crucial part of any kind of causal explanation, whether we talk about the fragility of complex objects, or about the mass and charge of an individual electron. Since Ellis and Lierse (1994), many have supported this argument. It has been given the name of ‘dispositional essentialism’, which asserts that that each object has some properties that are inherently dispositional, and that these include the causal base properties that enter into scientific laws.
This dispositional essentialism, however, leaves unanswered two important questions. The first question is whether all, or only some of an object’s properties are dispositional. We would naively think that structural properties, such as shapes, sizes and arrangements of parts, are not dispositional properties, but Bird (2005) argues that we cannot be sure of this. It would be useful to have clear understanding how (or whether) dispositional and non-dispositional properties can be simultaneously instantiated in an object. The second question concerns ontology: what is the relation between dispositional properties and the being (or substance) of the object with such properties? Menzies (2009) doubts, for example, that properties are correctly construed as causal powers: surely, he say, it is objects rather than properties which are the correct bearers of enduring causal powers.
In section 2, I look again at how science analyzes and constitutes dispositional properties, and see how those properties are explained as forms of some essential more-fundamental dispositions or propensities. (Propensities are those dispositions which have probabilistic manifestations.) We can now philosophically generalize that analysis, to formulate a new view of the constitution of objects, such that dispositional essentialism logically follows. This new constitution is to take powers or propensities themselves as the persisting ‘stuff’ of which objects are made. That is, I argue that we should identify ‘propensity’ and ‘substance’, so that natural objects, as ‘forms of propensity’ are then ‘forms of substance’ in nearly the manner of Aristotle.
It is admittedly a large metaphysical leap to identify propensity as substance, but I argue in sections 4-7 that the identification is grammatically correct, philosophically sound, historically defensible, and physically correct, even helping to clarify interpretations of quantum physics. It furthermore agrees with the Eleatic Principle: that existence should only be given to that which has causal power. In a more modern age, this would be called a ‘pragmatic’ view of substance, again as attributing significance not to what it merely is, but to what it can do. The identification of substance and propensity is claimed in the same sense that while the morning star and the evening star are initially known independently, they turn out to refer to the same (ontological) being. This identification should usefully be the next development for those who adhere today to dispositional essentialism. Instead of worrying about ‘ungrounded dispositions’, we will see that dispositions are able themselves to be grounds.
2. Scientific Analyses
Let us consider how science might analyze fragility of a glass vase, namely the disposition to break after small external pressures. The very first analysis would be to treat the vase as a whole with mass, shape, rigidity and fragility. The fragility is then a property of the vase, which is therefore an object with dispositional properties directly, as well has having a shape and orientation. The second analysis would be to consider the vase made of glass, where the glass is a continuous solid with various mass, elastic and fracture properties. A computer finite-element model of the vase may perhaps then explain its fragility in terms of the stress and fracture properties of the constituent material. In this case, the glass is the dispositional material, to be arranged in the shape of the vase and thereby to explain the properties of the vase. A third level of analysis may be a molecular simulation, where elasticity and fractures are properties derived from the strengths of interaction potentials between molecules. Now, the molecules are the substance constituted by those interaction potentials, which are dispositions, and they are arranged to make macroscopic glass-material. And so on: a fourth level may consider the potentials between individual electrons and nuclei, where now those electrons and nuclei are constituted by mass, charge, spin, magnetic moments, etc.: all dispositional properties. Surely quantum mechanics is also needed, which introduces its own set of probabilistic dispositions (propensities).
We see that at each stage of microscopic analysis, the presented objects are diagnosed as structural forms of some more fundamental disposition. Whether the stages reach the most fundamental level is not the issue here. Rather, we note that at each level, the result of the analysis is to attribute existence to some ‘stuff’ with some causal powers held essentially. First, vase as a whole was the existing stuff; in the second analysis the glass with stress-strain powers is taken as the stuff of the glass; later it is electrons, etc., with electric charges; and the final stage listed here we have electrons with propensities to emit or absorb virtual photons. Note that, following Thompson(1988), we never avoid dispositional properties: this is to support the claim of dispositional essentialism.
3. The Proposal
On the basis of the above scientific analyses, I want to claim first that every natural object is composed of some underlying stuff or substance with some given set of causal powers or propensities, and moreover composed according to some form or structure. We may think of those forms as being spatial arrangements or fields. This can be done at any stage of scientific analysis, wherever we believe we have a complete set of the causal powers exhibited by an object, not just when (we think) we have knowledge of some fundamental level.
Let us make a second philosophical step, by considering that substance itself. What is it? Its essence is some set of causal powers. Therefore, from the Eleatic and pragmatic points of view, all we can (and need) to say is that the substance is that set of causal powers. This is to identify complete sets of causal powers as substances, and substances as complete sets of causal powers.
We are thus making an ontological move, as powers are no longer all properties, or properties of properties, but those more fundamental of them are taken as substances of which objects can be made. This will also suggest a grammatical move of the powers, from being adjectives within predicates, to being subjects and objects: we have now to envisage powers and propensities as nouns, as discussed in section 4.
But are propensities (powers, etc.) the right kind of thing to be substance? One might object that propensities do not appear to have enough being, as they appear instead always to point to an incipient state of becoming. Are they, as Armstrong (1997) claims, always packing but never arriving? Would such substances as proposed here actually exist, or only potentially exist, or (perhaps) exist potentially? Bird (2007) responds to this objection by pointing out that this objection assumes that powers or dispositions are not fully actual. Rather, he says, we should insist that powers are actual full-blooded features of objects, and that what is merely potential are their manifestations. Now, however, I would respond slightly differently: that powers are the actual full-blooded substance of objects, not merely the ‘features’ or ‘properties’ of objects.
But perhaps we wonder whether such substances are really ‘full-blooded’. Do such substances persist as substances persist? How do they have being? Can they be individuated as substances can be individuated? Can they be individuated properly? Are they simple units, or can they be divided? Could elementary particles be of such substances? Could we be such substances, and still feel our own reality? Let us discuss some of these issues.
Do these new substances persist? There is certainly no need for them to persist forever, but can they persist through accidental changes while maintaining their essential nature? To answer the question about persistence, we simply note that dispositions are possessed even when they are not being manifested. A vase is still fragile when it is not breaking. The fragility, then, precisely persists for a finite duration: at least from one contact event until the next. All I am now asserting is that the corresponding substance of the glass persists for exactly the same duration. In that duration its may change its position, orientation or illumination: these are the variable accidental properties that vary while the underlying substance (fragility and the other dispositions) remains the same. Whether the underlying substance persists forever is the same question as whether the fragility (etc) persists forever. That can only be answered by looking at the future adventures of the vase in the world. If the fragile glass ends then the substance ends, perhaps by being changed into another kind of substance. That substances might persist only for a finite time does not render them any less enduring or persistent substances during that time.
How do these substances have ‘being’? The recent dispositional essentialists have taken all properties as ‘powers, and nothing but powers’, so we wonder if we can take all substances similarly. That claim was taken, in the strong dispositional essentialism of Bird (2009), to include all properties, including all those previously thought categorical such as position, shape and structure. On the present view, we do not take such a strong view, since particular objects have both dispositional and categorical properties. The dispositional properties are instantiated by the underlying (dispositional) substance, whereas the categorical properties are instantiated by the form or structure of that substance which makes up this specific substance. In this way we have what Martin (1993) calls a ‘Janus-faced’ or ‘dual-aspect’ view, but of objects rather than of properties. We are thereby constructing a notion of substances whereby substantial objects legitimately have both dispositional and categorical aspects. We do not follow Jacobs (2008) in having powerful qualities that have both dispositional and qualitative sides, but rather it is the substances that have both. This constitutes a kind of ‘weak dispositional essentialism’, where some but not all properties are dispositional. We do not deny the semantic distinction between dispositional and categorical properties, but rather reinforce it. Neither do we have a ‘neutral monism’ whereby the dispositional and categorical are ‘modes of presentation’ (Mumford,1998) of the same instantiated properties.
Many philosophers (since Prior et al., 1982, and recently Rives 2005) have argued that dispositions are ‘causally impotent’ following the argument that ‘if dispositions are distinct from their categorical bases, and their bases are efficacious, then the dispositions themselves are impotent.’ Rives carefully assumes that ‘the causal efficacy of categorical properties is not in question’, but that is precisely what I now deny. Categorical properties such as size, shape, structure are by themselves never causally efficacious, as we saw in section 2. Such properties are only ever efficacious when they are shapes or structures of some substantial object, and this requires the participation of dispositional properties. That is, a ‘base’ can never be a structure per se, and hence never purely categorical. Psillos (2006) also makes this mistake, when he argues that “fundamental properties [..] flow from some fundamental symmetries”, for symmetries, as purely mathematical structures, can never physically ‘flow’, and can never produce physical objects. Rather, on our Aristotelian basis, they describe the properties of objects, and here relations between those properties. It cannot be that “elementary particles are the irreducible representations (irreps) of a group,” again because groups (or even their representations) have no causal powers.
A summary of the new position is thus to say that specific objects are unions of form and power, of qualitative and dispositional aspects. They are structures of propensity, namely forms of substance, in a good Neo-Aristotelian manner. Forms may be examined in great deal by form-al sciences such as mathematics and logic, but no natural changes can be generated by formal constructions. For example, contemporary attempts in physics to construct ‘it from bit’ (to derive existence from form) can only produce a static (timeless) universe without changes or causes of change. We may instead say generously that forms are the means by which dispositional powers operate, since the power-substances can only operate if they are arranged in some form or structure that allows for interaction and movement. Conversely, forms can only have an impact on the world if they are the forms of some propensity, as thereby a physical object in the world is in existence, one that has powers to influence others. This is the basis for saying that objects in the world are required to be unions of form and power: they require powers to be in some form, and require forms to be of some power: the resulting union has an existence that goes beyond either ingredient by itself. In a natural object, the power and form are actually inseparable, and only abstractly distinct. We can (and should) intellectually distinguish them—as recent philosophers have emphasized—but that does that mean that they can ever exist apart.
But can these substances be individuated as appears to be needed here? Can we identify individual substances? It certainly does not seem that we can divide powers or propensities themselves into parcels, with some for each individual object in the world. I can only see individuation proceeding via the specific forms that the substance-stuff has in specific object-substances. That is, identifying individual substances, as forms of the underlying substance-stuff, can only proceed by identifying those particular forms used in each individual object. We may say that even the individual and specific existence of an object depends on the specific forms that inform the essential underlying powers/propensities of the substance.
Finally let us consider the logical and philosophical plausibility of this proposed identity. Grammatically, nouns in sentences are the agents of actions, and at least refer to the bearer of causal influences. The object of an action must also cooperate in the operation of those influences. This is entirely consistent with the present claim that subjects and objects are themselves forms of propensity. It is the nature of powers and propensities to be causal influences, so any thing constructed from them will be the bearer of causal influences. We thus must agree to a grammatical move of powers from being adjectives within predicates to being the substance of subjects and objects, and to envisage as nouns the forms of such powers and propensities. This seems to me to be easily feasible.
5. Historical Comparisons
To clarify the content and consequences of the present proposal, we may examine a short list of historical comparisons and brief contrasts.
The Pythagoreans held that the principles of mathematics are the principles of all things; in other words, the basic structure of Being is mathematical. We find this difficult to understand precisely because we do not understand how a mathematical object (a form) could constitute the entirety of a physical object that is concrete and changeable. In other words, the Pythagoreans have forgotten about the powers of objects, and hence they can have no concrete underlying substance.
Aristotle named the underlying stuff as hyle, or matter, as that of which objects are formed, just as the statue is formed of clay. He certainly recognized that the resulting objects had potentialities for changing themselves or others, but unfortunately he attributed that ability to added forms, rather than to the substance. Vegetative or animal forms when added, for example, entitle the bearer to act as vegetable or animal.
This neglect of underlying powers became more critical in Thomism, when hyle (matter) was reduced in capability to the ‘pure potency’ that is only capable of receiving forms. No non-trivial or active powers or dispositions were attributed to the matter, only to the added forms. This is a mistake that has long persisted, and is only now, with the revival of interest in dispositions and powers (witness this volume), being remedied in a thorough manner. Today the underlying matter or substance is being recognized for its more active role in nature. We insist that structure or forms, qua form, have themselves no active powers or dispositions. Indeed, they can never exist by themselves in nature.
Another deeply held philosophical idea of substance was held by Spinoza and Leibniz, who defined substance as ‘that whose nature requires its separate existence’. On this view, substances are self-sufficient beings that contain within themselves the complete source of all their changes. Leibniz claimed, for example, that all natural changes of his monads come from within, as ‘an external cause can have no influence upon its inner being’ (Leibniz, (1714) para. 11). The difficulty then, as Kant realised, is that on this account ‘it is not necessary for [a substance's] existence that it stand in relation to other things’ (Kant, (1747) §7). It is then a puzzle why substances even have positional relations that might enable the acting of one substance on another. The possibility of interactions of substances can only be regained by denying that substances are self-sufficient beings. They persist, not autonomously, but for interactions.
Descartes is famous for his dualism of two substances: the mental that is essentially rational, and the material that is essentially extension. On this view of nature as that which is extended, extensiveness is a geometrical form, and Descartes is known in mathematics for his new coordinate analyses of geometry. But something is missing, we now realize: there is no component of power, and hence no idea of natural substance.
Boyle, Locke and Newton, by contrast, did have both the necessary ingredients. Their ‘solid corpuscular substances’ had both form (spherical or other shapes) and powers (hardness, impenetrability, mobility, and inertia of parts, according to Bk. III of Newton’s Principia). This union of form and power means that they enable complete explanations in the sense of Section 3 above. Their explanations were logically coherent by my proposal, but the existence of gravity, with its action at a distance, was still puzzling. Did the corpuscles have power at distances where they had no substance? That seemed to violate some principle, but which? I rejoin that it is precisely the then-tacit acceptance of a power=substance principle that gives rise to the unease.
These difficulties became more severe with the further discoveries of magnetism, electric fields and (astonishingly) propagating electromagnetic waves. Boscovich wanted to accept that substances had powers extended away from a mass point in space, but Faraday, accepting the present proposed identity, argued that these fields were ‘real’ in their own way—just as real as atoms. They must have some kind of ‘substance’ of their own, since they have persisting powers.
The puzzle about the substantiality (or otherwise) of electromagnetic fields is resolved in modern physics. According to quantum field theory, these fields are composed of propagating photons. These photons carry momentum and energy, so, according to the relativistic E=mc2, they have gravitational mass as well, so there can be no objection to identifying them as substances. The only problem is the probabilistic nature of virtual photons and their quantum behavior. Such quantum phenomena are discussed in the next section. Other fields (nuclear and gravitational) are posited to be composed of their own field quantum particles (gluons and gravitons, respectively).
The philosophical implications of physics are still being assimilated. At the start of the twentieth century there was a denial of ‘substance’ altogether, and of any sense of continued identity, in favor of pure process. We then would have a purely event or flux philosophy. Reasons for this repudiation varied. Sometimes it has been the alleged unknowability of the real constitution of substances. At other times it was a preference for ‘flux’ or ‘creativity’ as against the ‘Parmenidean influence’ that was seen to pervade much of Western philosophy. Hume and Whitehead were perhaps the two most prominent influences here. As well, between the World Wars last century, an ontology of ‘events’ became popular, especially under the influence of a common interpretation of relativity theory and a positivistic approach to metaphysics. Russell’s The Analysis of Matter (1927) was a good presentation of this position, wherein events are fixed in space and time. Paradoxically, they become then like fixed substances, and the understanding of event as change often faded.
After the Second World War, Rescher (1962) noted that there was a general reaction to such an extreme event-and-no-continuant ontology, and many writers were repudiating ‘events’ in favor of substances and their relations. In the reaction, however, a very uncritical idea of ‘substance' was taken over, practically identical with ‘material object’. This has the result that there could be no very precise understanding of either the fact or the dynamics of real change. Recent work on powers and dispositions is well on the way to remedying these failures, so now the program of dispositional essentialism should take its next step, and discover how it can reconstitute a good account of substance based on dispositions.
6. Quantum Physics
In the above sections, power and propensity have been included generically, where propensities are those powers that manifest themselves with some probabilities of different outcomes. To allow for quantum physics and its probabilities, we need specifically these propensities. The question whether propensities are in fact needed for describing nature is linked to the accuracy of quantum physics. I do not decide on that question now, but only wish to argue that quantum processes may yet be described by means of propensities, and how it is still possible that quantum substances can be identified with those more fundamental propensities as appearing in some form or structure.
Quantum mechanics describes the probabilities of actual outcomes in terms of a wave function, or at least of a quantum state of amplitudes that varies with time. The public always asks what the wave function is, or what the amplitudes are amplitudes of. Usually, we reply that the amplitudes are ‘probability amplitudes’, or that the wave function is a ‘probability wave function’, but neither answer is ontologically satisfying since probabilities are numbers, not stuff. We have already rehearsed the objections to the natural world being made out of numbers, as these are pure forms. In fact, ‘waves’, ‘amplitudes’ and ‘probabilities’ are all forms, and none of them can be substances. So, what are quantum objects made of: what stuff?
According to Heisenberg, the quantum probability waves are “a quantitative formulation of the concept of ‘dynamis’, possibility, or in the later Latin version, ‘potentia’, in Aristotle’s philosophy. The concept of events not determined in a peremptory manner, but that the possibility or ‘tendency’ for an event to take place has a kind of reality—a certain intermediate layer of reality, halfway between the massive reality of matter and the intellectual reality of the idea or the image—this concept plays a decisive role in Aristotle’s philosophy. In modern quantum theory this concept takes on a new form; it is formulated quantitatively as probability and subjected to mathematically expressible laws of nature.” Unfortunately Heisenberg does not develop this interpretation much beyond the sort of generality of the above statements, and the concept of ‘potentiality’ remains awkwardly isolated from much of his other thought on this subject. It is unclear even what he means by ‘potentia’.
Herbert (1985), in describing Heisenberg’s ideas, imagines them to describe world more ephemeral than substantial, imaging that “the entire visible universe, what Bishop Berkeley called ‘the mighty frame of the world,’ rests ultimately on a strange quantum kind of being no more substantial than a promise.” We rather argue that, far from being ‘as ephemeral as a promise’, the propensities of the physical world are perfectly real and substantial, and may in fact be the very substance of all things.
We now propose, according to generative realism, that propensities can be the stuff of quantum objects. Furthermore, we may describe those objects as having the forms of wave functions spread out in space and time. Such forms, with a spatiotemporal range, are best viewed as fields. Quantum substances themselves can then be conceived as ‘fields of propensity’, according to the general manner of this paper. This concept of substance is similar to Nicholas Maxwell’s notion (1988, 2009) of smearon or propensiton. Substances with such natures are particularly relevant, since it is now found that the concept of a corpuscle with definite extension, hardness, etc., is markedly inadequate, yet for which no philosophically adequate replacement has been generally accepted.
With the help of the new proposal of ‘propensity fields’, we can try to understand some of the more puzzling quantum features, such as the nature of ‘measurements’ and a reason for ‘non-localities’
One feature of the present account of substances is that they need not be necessarily located in small fixed volumes of space, as, for example, the corpuscles or ‘particles’ of classical physics would be. The propensity fields that have been defined do not need to have any special ‘center’ distinguishable from all the other places in the field. They may have no center that could be regarded as the ‘true substance’, whereby the surrounding field could be regarded as just the ‘sphere of influence’ of the central substance.
It is commonly believed (e.g. by Molnar (2004), and by many physicists) that high energy scattering experiments allow us to conclude that fundamental particles like electrons, quarks, etc are point particles, like real objects of zero size. However, this is inference is incorrect. What the experiments show is that there is no lower limit to the size that the wave packet of an electron (etc.) may be compressed. They never show that there is actually a point particle, as this would contradict the Heisenberg Uncertainty Principle by requiring infinite energy to construct. Some other objects (e.g. atoms, or nuclei) do have a lower limit of compression, and this is interpreted as arising from a composite internal structure. No matter how small we then compress the wave packet for an atom’s centre of mass motion, the atom as a whole cannot be made indefinitely small. At all times, therefore, both fundamental particles and composite objects have some varying finite size that depends on time and circumstances, and may be legitimately said to occupy the volume of this size in space. Whether they also fill that volume depends on the probabilities of interaction with instruments, which may be small or large, so is a matter of degree in a similar manner to the way that air ‘fills’ a room according to its pressure.
A substance-field of propensities may have a variable spatial size: sometimes it behaves more like a spread-out wave, and when at other times it interacts, it behaves like a localized particle. In fact, propensity fields can have practically any extensive shape over the places that are possible for it. We can allow that propensity fields are described by some kind of field equation, such as the Schrödinger or Dirac equation including interaction potentials. They would be subject to boundary conditions set by the results of past actions, and this gives continuous and wave-like propagation into the future, and allows them to propagate as wave packets around obstacles or potentials which would stop any classical atoms. They can even tunnel through barriers, as the probability for a definite interaction may be reduced but still non-zero. It becomes reasonable to expect the diffraction, interference and tunneling effects we know in quantum physics from the solutions of Schrödinger’s equation, even though we have no general grounds yet for choosing any particular equation.
We do not now need to believe that somewhere, as it were hidden away behind the propensities, there really exist particles waiting to appear. This is not the case. Questions like ‘Where is the electron and what is its speed?’ have no answer, because there never exists such a thing as a small corpuscular electron. The only things that exist are propensity fields and the inter(actions) they produce. Propensity fields are not like vague, indeterminate or smeared-out particles, but are perfectly definite entities in their own right. It may not be determinate in advance which actions a propensity field will produce, but that does not mean that the propensity field is any the less real or definite when considered as a thing in itself. Its field structure can be described using perfectly definite mathematics. Its existence is as real and substantial as any existing object. In fact propensity fields are the very substances out of which all things are made! Nothing can be more substantial than them.
Kaempffer (1965), for example, after pointing out the ‘erosion of naive pictures of particles’, goes on to suggest that the word particle stand for a quantum mechanical state [a wave field], characterized by a set of quantum numbers, which is associated, in principle, with an identifiable event such as the momentum transfer in a “collision”. We can therefore follow him as he redefines the meaning of the word ‘particle’ to refer to (something like) propensity fields.
The concept of substance as dispositional contains the essential idea that they do something: that the dispositions are for some kind of event. Such events are characterized generically as ‘actual events’, because they have definite properties once they exist, and are selections between distinct possibilities that are arrayed like a field. In quantum mechanics, these actual events are just the process of ‘reduction of the wave packet’ that physicists and philosophers have long discussed and sought for both theoretically and experimentally. The conception of substance-dispositions implies that such reduction or selection events do occur.
In cognitive psychology it is a common starting point that mental activity consists of functions of information processing modules, engaged for example in signal or symbol processing. We see, however, that this description refers only to the structural or formal aspects. Admittedly, structural changes are described, but no specific powers or dispositions for those processes are admitted. This is clearly inadequate from the point of view of our generative realism. The least that can be allowed is that even computers are made of substances with powers, as then physical symbol processing is thereby consistently possible.
The interesting question is what impact the true human substances have on cognitive processing, since they will have their own characteristic powers and propensities not necessarily present in computers. For example, it now common to remind us that mental processes are embodied (in brains, bodies or even the environment), and the influence of the powers of those embodiments are precisely the details which need to be examined in psychology.
A more general issue in psychology is whether the dispositions and powers that constitute the substances for mental processing are related to the dispositions and powers manifest in the mind itself. I am thinking specifically of the emotional and motivational dispositions that make up the apparent life of mental feelings and intentions. These are powers that appear on first phenomenological analysis, so psychology should well consider whether they could be the first ‘more fundamental’ underlying ‘stuff’ of which cognitive and symbol processing is the activity.
8. Further Research
This short paper is to introduce the ontological possibility of identifying propensities/powers with substance-stuff, so that particular objects are unions of dispositional powers and categorical forms. Much work remains to be done to flesh out this proposal. More work is needed to see how to individuate such objects, both within one world, and between possible worlds. The objects may be simple or complexes; the powers may be truly fundamental or everyday: we still have to see how the proposal works in all cases. We need more details about the manifestation of such underlying powers—whether in classical physics, quantum physics, or generically—and what happens to the objects after such changes. These details should help us localize objects in space, if that is possible. After those details are investigated, we can begin to discuss how long such substances may endure, and whether they are Aristotelian individuals or Parmenidean ones, to use the terminology of Harré and Madden (1975). I have not here addressed the puzzling ‘Problem of Fit’ between interacting objects, as highlighted by Williams (2010). Some of these issues have straightforward resolutions, while others are more difficult, but I recommend nevertheless the proposed ontological identification as fitting successor metaphysics to the dispositional essentialism now widely discussed.
In conclusion, this paper gives a simple summary of a ‘pragmatic’ or Eleatic approach to ontology, whereby what is necessary and sufficient for the dispositional causation of events is interpreted realistically, and postulated to exist. This development, following on from dispositional essentialism, leads to a general concept of ‘substance’, Aristotle’s underlying ‘matter’, as being constituted by dispositions, and not just being the ‘bare subject’ for those dispositions. We may call this ‘generative realism’, and advocate a slogan such as “No process without structure, no structure without substance, no substance without power, no power without process.” We see how to understand objects as made of propensity-substance in the form of some structure or field, so that things in the world may consistently be bearers of both dispositional and formal properties.
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 Note that the word substance has two useful meanings in this paper. The first, as Aristotle’s ousia, refers to specific objects, as in this substance and that substance. The second, as in hyle, refers to the underlying stuff, as in the underlying substance of which objects are formed.
 I talk of ‘natural’ objects to refer to those that undergo changes, in distinction to mathematical or formal objects, which do not.
 Spatial relations are needed since (after Kant) they appear to be the pre-requisites for any possibility of interaction.
 I would doubt that vases are eternal. I not believe that electrons or nuclei are necessarily eternal either.
 A hammer and a vase must have powers to interact with each other, if fragility is to be manifested this way.
 W. Heisenberg, ‘Planck’s discovery and the philosophical problems of atomic physics’, pp. 3-20 in Heisenberg (1961).
 Heisenberg, for example, brings into his thought on quantum physics the Kantian phenomena/noumena distinction, as well as some of Bohr’s ideas on ‘complementarity’ in experimental arrangements.
 Herbert (1985), p. 195. Note that he here uses Ryle’s (1949) account of dispositions as ‘inference tickets.’
 This was Boscovich’s conception, and it slowly percolated into physics, resulting in the ‘dynamic matter’ of the mid-nineteenth century. This view is best summarized by the aphorism “No matter without force, no force without matter”.
 The present proposal could be called ‘dispositional substances’ or ‘substantial dispositionalism’, but I prefer a more general ‘generative realism.’