The Metaphysics of Development and Evolution: From Thing Ontology to Process Ontology Open Access

The idea that metaphysics could assist rather than hinder the scientific study of life has only recently become respectable again. After the ground-breaking advances of molecular biology and genetics during the second half of the 20th century led biologists and philosophers of biology alike to dismiss traditional metaphysical investigations into the nature of life as unscientific and, hence, obsolete, there is now a growing realisation that metaphysics might do something good for biology and, perhaps, science in general. The spectrum of views ranges from somewhat reserved rapprochements that confine metaphysics’ raison d’être to its use as a conceptual toolbox for philosophy of science (French, 2018) to euphoric calls for adoption of particular metaphysical ideas to foster scientific progress. All agree, however, that a constructive dialogue would be of mutual benefit for the disciplines involved (Meincke, 2020a; Meincke & Dupré, 2021).

Kuhn (1970) has famously argued that scientists predictably turn towards philosophy in times of crisis. Anomalous results of scientific investigation demand reflection on – and possibly revision of – the underlying paradigm. This paradigm comprises, besides an agreement on values and methods, basic metaphysical assumptions about reality. This is to say that metaphysics is at work in science also when it is not attended to explicitly. It shapes the basic way a scientific enterprise proceeds: the questions formulated, the perspective from which these questions are pursued, the methods applied. Obviously, different sets of metaphysical assumptions shape science in different, possibly even incommensurable ways, as Kuhn suggested. Yet, he insisted that science does make progress, implying that some paradigms are better than others. We may conclude from this that the same, then, is true also of metaphysics: some metaphysical assumptions are better than others.

It is fair to say that evolutionary biology finds itself in a state of crisis. Received views of evolution have come under attack for their one-sided focus on genes as evolutionary agents. According to these views, commonly subsumed under the heading “Modern (Evolutionary) Synthesis,” evolutionary change amounts to heritable change in gene frequencies in populations, which is thought to be produced primarily by natural selection acting upon random genetic mutations (with genetic drift and cumulative effects of [nearly] neutral genetic mutations being further relevant factors). However, in the light of new data in particular from developmental biology, evolutionary change no longer always seems best explained by random genetic mutations, if at all. At the very least, there seem to be more causes, most importantly, the individual development of organisms and its interactions with the environment. Of course, conceiving of development as a major driver of evolutionary change only makes sense if development is more than the automatic unwinding of a predetermined, fixed genetic “programme.” Proponents of what has become known as the “Extended Evolutionary Synthesis” accordingly stress the genuinely creative nature of development (Laland et al., 2014), echoing parallel claims made by evolutionary developmental biologists (Gilbert, 2006, 2019; Moczek, 2023).

There is currently no agreement on whether the Extended Evolutionary Synthesis, as its name suggests, is indeed a mere extension of the original Synthesis (Richards & Pigliucci, 2020), or whether it rather presents a “distinctively different framework for understanding evolution” (Laland et al., 2015, p. 3). The latter would explain the occasional communicative breakdown between the two parties. It is characteristic of historical situations of paradigm shifts, Kuhn observed, that the advocates of the old and the new paradigm talk past each other: “Though each may hope to convert the other to his way of seeing science and its problems, neither may hope to prove his case. The competition between paradigms is not the sort of battle that can be resolved by proofs” (Kuhn, 1970, p. 148). In such a situation, it may be wise to enter into a philosophical reflection on the very foundations on which the respective paradigms rest, i.e., on the metaphysics involved.

Very briefly put, this is what I will be doing in this paper. I want to uncover the metaphysical paradigm shift at stake in the competition between the Modern Synthesis and the Extended Evolutionary Synthesis. As I shall show, the former relies on what I call thing ontology: the idea that the world, most fundamentally, is populated by things, i.e., by entities for the identity of which change is not essential. The latter, on the other hand, makes best sense within a process ontological framework, which gives the ontological priority to processes, i.e., to entities for the identity of which change is essential (with the term “entity” in both cases serving as a placeholder for whatever it is that satisfies the definition). Explicitly adopting process ontology, I will argue, would strengthen the case for the Extended Evolutionary Synthesis and, more generally, improve our understanding of development and evolution.

As it happens, there is a new movement in the philosophy of biology that takes itself to be inspired by process ontology: so-called process philosophy of biology or, short, process biology (Dupré, 2012, 2020, 2021; Meincke, 2018c, 2019a, 2019c, 2021, 2022a, 2022b, 2022c, 2023c; Nicholson & Dupré, 2018). The key claim of process biology is that organisms are processes rather than things or substances; and this claim is motivated by the intention to capture the all-pervasive dynamicity of biological reality: “[A] scientific metaphysics of biology ought to do justice to the all-pervasive dynamicity of biological reality. […] Life […] is a process and so are living beings: processes rather than things or substances” (Meincke, 2022a, p. 432). Or as Dupré & Nicholson (2018, p. 3) put it: “[T]he world – at least insofar as living beings are concerned – is made up not of substantial particles or things, but of processes. It is dynamic through and through.” The process view is beginning to gain traction also among biologists (Gilbert & Epel, 2009, pp. 403–420, 2017; Jaeger & Monk, 2015). Furthermore, developmental science has recently seen a similar push towards what is called relationalism as a new scientific paradigm or metatheory that “includes process, activity, dialectic change, emergence, and necessary organization as fundamental defining categories” (Overton, 2013, p. 98; see also Lerner, 2011; Lerner & Overton, 2017). Relationalism and kindred metatheories in developmental science, such as interactivism (Bickhard, 2009), explicitly draw on process ontology.

Here, I will focus on the philosophy of biology and ask how process ontology can constructively inform respective debates on development and evolution. This will require clarifying the notion of process ontology. Historically, process ontology has always been overshadowed, if not marginalised, by its adversary, thing ontology. Systematically, both are interrelated in that they devise opposing strategies to conceptualize change and its relation to identity. The notion of process ontology can therefore be elucidated only in conjunction with that of thing ontology, and I will do so by tracing the broad developments of both through the history of western metaphysics.

Understanding the history of the antagonism between process and thing ontology will help us identify their respective metamorphoses in contemporary philosophy of biology, something that indeed turns out to be critical when it comes to applying process ontology to biology in general and to development and evolution in particular. Applying process ontology to biology is the programme of process biology, and – in the light of history – we will find that not every self-proclaimed version of process biology actually can count as such, just as much as not every processual sounding claim about development and evolution in fact invokes process ontology, properly (I contend) understood as an ontology that takes processes to be ontologically fundamental.

It is against this backdrop of disguised thing ontological patterns of thought still permeating both developmental and evolutionary theory that we can start working towards a concrete alternative processual approach. However, while I will give some hints as to what this could look like, the aim of this paper is not to deliver a fully developed process theory of development and evolution, but only to lay the foundations for such a theory by advancing the necessary conceptual framework. Given the metaphysical paradigm shift involved – from thing ontology to process ontology – this objective may seem ambitious enough.

The first process philosopher on record in the western sphere was Heraclitus from Ephesos (5th century BC). According to him, reality is dynamic at all levels. Most fundamentally, matter is engaged in continuous substantial transformation by way of the four elements – fire, water, earth, and air – continuously changing into one another. Each such change amounts to the “death” of the one and the “birth” of the other element, i.e., to a radical kind of change involving the instantiation of contraries. Passages from Heraclitus’s writings that appear to grant ontological priority to fire over the other elements are best understood not as expressions of material monism but as invoking fire as a symbol of change to emphasise that “the process of change is more real than the material substances that undergo change” (Graham, 2021, ch. 3). The same features – radical change and the “war” of opposites – apply to higher levels of reality, as shown by Heraclitus’s probably most famous (putative) statement that one cannot step into the same river twice (we will come back to this). For Heraclitus, “everything flows” (“πάντα ῥεῖ”). The cosmos is in motion and becoming from tip to toe.

However, Heraclitus had a rather powerful adversary: Parmenides of Elea (first half of the 5th century BC). Parmenides argued for exactly the opposite of Heraclitus’s view: for the thesis that nothing moves or changes. There is no motion, no becoming; instead, everything is stationary and unchanging being. For Parmenides, there cannot be any becoming or change because becoming or change involves nonbeing – something comes into being from nonbeing – and nonbeing, according to Parmenides, does not exist: Being is; nonbeing is not (ἔστι γὰρ εἶναι, μηδεν δ′οὐκ ἔστιν [Parmenides, 2009, Poem, fragment 6]). Thus, the very concept of change, Parmenides thinks, is incoherent and, hence, the appearance of change is illusory. Those who, trusting sensory experience, choose the “way of opinion” fall prey to it and mistake illusion for reality. In contrast, those who follow the “way of conviction” as devised by pure reason understand that nonbeing cannot be known because being and knowing are the same. They will therefore recognise being as one unchanging, non-generated, indestructible, coherent, and unified whole – a sphere.

The fight between the pro change and contra change stances has been going on in western metaphysics ever since up until today, with the contra change party (“the no-changers”) having the upper hand (over the “changers”). Parmenides’s students, the so-called Eleatics, launched a concerted campaign against the supposed illusion of change. The most prominent among them is Zeno of Elea. By means of a series of paradoxes, he purports to show that the assumption of motion and change leads to contradictions, from which he then infers that motion and change cannot be real. Well known is the paradox of Achilles who allegedly is unable to overtake the tortoise that started ahead of him on account of the infinite number of points in space separating him from the tortoise.

An attempt to find a compromise between Heraclitus’ and Parmenides’ stances on change was atomism. Renowned proponents were Leukippos and Democritus (both 5th century BC). Based on the materialist presumption that everything results from natural laws, the atomists held that all that exists are tiny indivisible particles, so-called atoms. Bodies are aggregates of atoms and change consists in the differences between arrangements of atoms. For atoms actually move – which is the Heraclitean element in the theory – while, however, not changing themselves – this is the Parmenidean part: atoms are Parmenidean objects. Thus, atomism seems to explain change without invoking the supposedly unintelligible notion of nonbeing. Atoms neither come to be nor do they go out of existence. Our senses are right about the existence of motion and change; but they are wrong insofar as they suggest the existence of becoming and destruction.

Atomism leaves open the question of how atoms bond together to form objects. In fact, one might wonder if, in the atomist picture of reality, there are any objects at all other than the atoms themselves. Objects, we tend to think, are not mere aggregates of things; they possess coherence and unity. Atomism fails to tell us how such coherence and unity could come about.

Aristotle provided an answer to this question that effectively refuted atomism, thereby offering an alternative middle ground between Heraclitus and Parmenides. According to Aristotle, the world is populated by so-called substances. A substance (οὐσία) is a concrete particular that is neatly bounded and ontologically independent of anything else. Examples are a house, a rock, a bronze statue, Socrates and Socrates’s dog. More specifically, Aristotle defends what is known as hylomorphism, i.e., the idea that a substance is a composite of matter and form (see especially Aristotle, 2018, Physics, Book I, and 2004, Metaphysics, Book VII). A substance is not a mere aggregate of things, let alone atomic things. It is rather unified by its form, be it the shape given by an artist to a lump of bronze or be it the soul as the organising principle in the case of Socrates, Socrates’s dog and other living substances. The form imposes structure on matter, thereby actualising certain potentialities inherent in matter (such as a lump of bronze’s potential to be moulded into a statue, or a body’s potential to be alive). It defines what kind of thing a given substance is.

This entails that, thanks to its form, every substance possesses a set of immutable properties: essential properties it cannot lose without ceasing to exist. Only so-called accidental properties it can change, i.e., gain or lose, while retaining its identity. Thus, if Socrates were to see the hairdresser to have his hair dyed, he would still exist afterwards – he would just look different. But if Socrates suddenly started barking and walking on four legs, this would mean, Aristotle thinks, that it is actually not Socrates but a numerically distinct entity – a dog – doing these things. Socrates would have ceased to exist because his essence – that he is a bipedal rational animal – would have been destroyed.

Unlike Parmenides and the atomists, Aristotle believes becoming and going out of existence are real. The house in which Socrates lives did not exist before it was built; and Socrates himself did not exist before he was conceived and born. Yet, Aristotle concedes to Parmenides and the atomists that whatever comes into existence does so not from nothing. Substantial change does not involve being emerging from nonbeing. Instead, just as in accidental change the substance – for instance, Socrates – persists through the change, so does in substantial change matter persist through the change: the matter the substance is made of and which itself is hylomorphically constituted, such as the bricks used to build Socrates’s house. This is true even for living substances, whose bodies neither predate nor outlive them. Here, some less structured, lower level matter underlies the change: the matter that is transformed into Socrates’s body through the living form, i.e., through Socrates’s soul.

For Aristotle, everything is ultimately made up of different proportions of the four elements, where changes of these proportions are themselves supported by an even more fundamental material substrate: so-called prime matter (Aristotle, 2004, Metaphysics, VII.3 1029a20-26). Qua pure potentiality, prime matter lacks any essential properties; it is completely indeterminate, thus being capable of assuming any form. Importantly, prime matter is also eternal. It must be; otherwise the question would arise what underlies its coming- or ceasing-to-be, and so on ad infinitum. Thus, Aristotle’s hierarchical vision of reality, although more welcoming towards change than the atomists’ and even more so Parmenides’ vision, still rests upon a changeless foundation. For there cannot be any change without an unchanging substratum.

Aristotle’s theory of substance lives on in contemporary substratum theories of objecthood. According to these, an object (or concrete particular) is made up of its properties and an underlying substratum, comparable to a bundle of balloons tied to a rug. This corresponds with the way we speak: we attribute properties to a thing that bears them (e.g., “The rug is green, soft and rectangular.”). So, the properties and the thing that bears them are distinct, which implies that we can apprehend the bearer independently of its attributes. The substratum’s identity is independent of the properties attributed to it, which is why it is often called a “bare particular” (Benovsky, 2008; Sider, 2006). We can then conceptualise change as a change of the composition of the bundle of properties, the balloons, while holding fixed our rug, the bare particular.

Unfortunately, the concept of a bare particular is incoherent: it is something that has no properties while bearing properties; and likewise: it is something that does not change while bearing change (Geach, 1979, p. 46f.). We could try to avoid this problem by switching to another type of theory of objecthood discussed in contemporary analytic metaphysics: the bundle theory. This theory claims that objects are constituted exclusively by the properties attributed to them; there is no underlying substratum. We keep the balloons but get rid of the rug. Objects are bundles of properties – an idea that can be traced back to David Hume. However, we run again into problems here: Bundles are subject to so-called mereological essentialism: their identity is defined by their elements. Take one of these balloons away and you have a different bundle. In other words, whereas the substratum theory gives us a self-contradictory, incoherent account of change, the bundle theory eliminates the possibility of change altogether. On top of this, the problem already faced by atomism returns: how do the properties bond together? Is there a single object at all? Whoever has tried to handle a bundle of balloons knows how little it behaves like an object.

Now, we could attempt to address these issues by imagining our bundle of properties to be stretched out not only in space but also in time, with time being strictly analogous to space. The bundle is thus conceived of as a four-dimensional object extended across a particular region of spacetime. Then we chop it up into different spacetime chunks or slices each of which is a different bundle of properties, and we claim that the object “changes” in the sense of having different spatiotemporal parts with different properties. Furthermore, we postulate that there is some kind of continuity relation (“unity relation”) that links the different spatiotemporal parts. Quine (1960, 1986) and Lewis (1986) have offered accounts in this spirit – also known as four-dimensionalism (see also Sider, 2001). Lewis in particular has argued that only this so-called perdurance account of persistence allows to evade the looming contradiction inherent in change, namely that one and the same entity has different intrinsic properties (so-called problem of temporary intrinsics). Change appears to be incompatible with numerical identity, which, according to Leibniz’s Law, requires identity of intrinsic properties.

Four-dimensionalism has continued to fascinate analytic metaphysicians ever since – despite its serious problems. Thus, we must accept that change is in principle no different from spatial variation. Being sad today and happy tomorrow, according to four-dimensionalism, means having a sad temporal part and a happy temporal part, which just is like having a nose-shaped spatial part and a leg-shaped spatial part. But, more serious even, it is not clear of whose variation we are speaking. The binding relations are notoriously weak and fail to turn the four-dimensional entity into anything more than a mereological sum. But then, if all we have is different things with different properties (Lewis, 1986, p. 204), what does actually change? Recall our bundle of balloons. A juxtaposition of a red, a blue, a green, and a yellow balloon does not make up an object, and so there simply is nothing of which we could say that “it” changes from red to blue, from blue to green, and from green to yellow. It is not clear how putting a time-index on each balloon is supposed to solve this problem. In fact, just as little as anything changes does anything persist through time – this running counter perdurantism’s claim to be a theory of persistence (Meincke, 2019b).

Our brief walk through the history of counter-reactions to Heraclitus reveals a shared pattern: appeal to things as the ontologically primary building blocks of reality. A thing in the technical sense that I deploy here is an entity for whose identity change is not essential – a thing need not change in order to exist. Setting aside Parmenides’s special notion of being as one undivided whole, we have found that two kinds of things are typically invoked: (i) complex things (“substances”) or (ii) elementary things (atoms, properties, events, matters of fact). These two kinds of thing correspond with two versions of thing ontology: (i) substance ontology and (ii) atomism/(neo-)Humean ontologies (Meincke, 2018c, 2019b, 2019c, 2020b, 2021, 2022a). Both versions consider change and process as parasitic on the identity of things: either it is assumed that change is borne by an unchanging bearer (a substance or substratum, possibly also prime matter) or change is reconceptualised as variation between different things (atoms or different temporal parts of a four-dimensional object). In each case, it is change that presumably requires explanation, whereas the identity of the thing is taken for granted. This reflects the underlying conviction that change and identity are incompatible. Therefore, change is downgraded or in effect eliminated altogether (Meincke, 2019b).

Thing ontology is driven by a deeply entrenched fear of change. Thing ontologists suspect that if one does away with things, as process ontologists propose, the world turns into a chaotic place without structure. However, this assumption is the result of misrepresentation, or even deliberate slander. Here is how Plato paraphrases Heraclitus’s doctrine: Heraclitus taught “that all things pass and nothing stays, and comparing existing things to the flow of a river, he says you could not step twice into the same river” (Plato, 1997, Cratylus 402a). But what Heraclitus actually said was: “On those stepping into rivers staying the same other and other waters flow” (Graham, 2021, ch. 3.1). Processes change and, through changing, remain the same over time. Change is a constituent of the identity of processes – which would thereby possibly qualify as what metaphysicians call “continuants”: entities that continue to exist through time while changing (Meincke, 2022a, forthcoming a). There is thus certainly identity in the Heraclitean universe; however, not as something pre-given and primitive, but as the result of continuous interaction of processes. Accordingly, identity is never static but rather inherently dynamic.

A modern version of process ontology that shares many features with Heraclitus’s original vision was developed by Bergson (1946, 1998, 2004). Bergson insists that change – contrary to what language and perception seem to suggest – does not require an unchanging substratum: “There are changes, but there are underneath the change no things which change: change has no need of support. There are movements, but there is no inert or invariable object which moves: movement does not imply a mobile” (Bergson, 1946, p. 173). Change is never mere alteration, i.e., the superficial “accidental” qualitative change of an unchangeable core, as Aristotle tried to show ultimately for all change, including so-called substantial change (which, in his analysis, turns out to be the alteration of [prime] matter). To speak in Aristotle’s terms, for Bergson, in contrast, all change is substantial change. This, however, does not mean that there is no identity. On the contrary, change, according to Bergson, “is the most substantial and durable thing possible” (Bergson, 1946, p. 177). And it is exactly because of the “substantiality of change” (Bergson, 1946, p. 175) that change does not need a substratum.

How is it that we usually overlook both the ontological priority and the ontological robustness of change? Bergson gives an interesting and rather compelling explanation. He thinks the reason lies in our tendency to spatialise time. Instead of realising that time is duration (durée), i.e., an indivisible continuation of change and movement, we treat time like space, i.e., as infinitely divisible.

The contemporary metaphysical doctrine of four-dimensionalism is a striking manifestation of this tendency: it programmatically treats time like space. Four-dimensional spacetime does not move and lends itself to being cut up into an infinite number of immobile slices or portions. However, as Zeno’s paradoxes show, it is impossible to reconstruct change and movement from a series of unchanging things: if time were to coincide with the infinitely divisible space lying between Achilles and the tortoise, Achilles could not even dream of overtaking the tortoise. “If movement is not everything, it is nothing; and if to begin with we have supposed that immobility can be a reality, movement will slip through our fingers when we think we have it” (Bergson, 1946, p. 171f.). According to Bergson, the attempt to reconstruct the dynamic continuity between these hypothetical immobilities by basing them on an unchanging substratum is no less bound to fail: “this immobile substratum of immobility, being incapable of possessing any of the attributes we know – since all are changes – recedes as we try to approach it: it is as elusive as the phantom of change it was called upon to fix” (Bergson, 1946, p. 184). Bergson concludes that it is in fact immobility that is not real. What appears to be immobile amounts actually to a relative stability of movements, comparable to two trains travelling on parallel tracks in the same direction at the same speed (Bergson, 1946, p. 169). Time is movement, and “movement is reality itself” (1946, p. 169; see Meincke, 2022b).

The name most commonly associated with process philosophy is of course Alfred North Whitehead thanks to his book Process and Reality (1978). There he claims: “[T]he actual world is a process, and […] the process is the becoming of actual entities” (Whitehead, 1978, p. 22) What Whitehead calls “actual entities” (or also “actual occasions”) are completed processes and, that is, events, which implies that their being cannot be understood without taking into account how they became what they are. Being is to be explained in terms of becoming. More specifically, Whitehead distinguishes two kinds of becoming or “fluency.” On the one hand, there is the microscopic process of a “concrescence” of feelings into a unified experience, which is the actual entity (Whitehead endorsed panexperientialism: whatever exists is at least minimally experiential). On the other hand, there is the macroscopic process of “transition” in which an actual occasion, as a fully determinate existent, becomes a datum or element for the becoming of another actual occasion (Whitehead, 1978, p. 210). We thus end up with a dynamic universe of interdependent experiential events. Whitehead accordingly called his process philosophy also a “philosophy of organism.”

Drawing on the historical models provided by Heraclitus, Bergson, and Whitehead, we can characterise process ontology as an ontology that takes processes to be ontologically fundamental (see also Rescher, 1996). A process, as I technically define it, is an entity for whose identity change is essential (“entity” here to be understood in the most neutral way as a placeholder for whatever satisfies the definition): a process must change – and move – in order to exist, as opposed to a thing (in the technical sense defined earlier), which may but need not change, or which, actually (as we have found in our discussion of both historical and contemporary versions of thing ontology), must not change (at least not in certain ways) if it is to continue existing. Being qua becoming, as understood by Whitehead, is a process, and so is time qua duration, as understood by Bergson.

Besides such, as it were, primordial, metaphysical processes like being and time, there are arguably more mundane processes, those that populate our everyday lifeworld, those that constitute nature, and so on. Heraclitus’s river is an example, the Alpes’ deglaciation and Peter’s riding a bike to his grandmother’s home might be others, not to forget Peter and his grandmother themselves. Processes may come in all shapes and sizes – they may be material, immaterial, simple, complex, dependent, independent, etc. The generic definition of a process provided above, that is, may be satisfied by different categories of entity, which then would constitute different kinds of process, distinguished by ontological features which a given process ontology may describe further.

As indicated by my definition of process, for the process ontologist, change is not only compatible with, but in fact constitutive of identity. Identity, accordingly, is to be understood not as a given but as a product: a product of processes and their interactions. It is itself genuinely processual and never static. This is not to say that processes cannot be stable over time – indeed, their stability is what facilitates tracking them, as self-identical entities, through time and space. We must not confuse stability and stasis, the latter being an (alleged) absence of movement and change, the former being a dynamic equilibrium of movements and changes. Process identity is stability over certain periods of time and relative to certain time scales. In each case, it is stability, not change, what requires explanation.

A process ontology need not deny the existence of things, understood in some weaker sense. One could, for instance, decide to call “things” those processes that are particularly stable at a time scale relevant in a particular context and/or particularly stable in particular relevant respects. Perhaps one could also imagine that processes produce things, that things supervene upon processes or that things are the precipitates of processes [the latter view has been proposed by Simons (2018)]. However, in any case, i.e., even if things are assumed as entities ontologically distinct from processes, processes – being what, in some sense or another, brings things about – remain ontologically primary. Reality, for the process ontologist, is fundamentally processual.

We are now ready to turn to process biology. What exactly is it? Very briefly put, process philosophy of biology is process ontology applied to the biological domain, i.e., to life and the living. While this sounds straightforward, there is more to the story. Just as there are different versions of process ontology – I highlighted here only three, those of Heraclitus, Bergson, and Whitehead – so are there different versions of process philosophy of biology. Thus, it is worth mentioning that while some authors take a Whiteheadian stance on biology (Koutroufinis, 2014; Koutroufinis & Araujo, 2023), most contributions to what is known as process biology do explicitly not draw on Whitehead (see, e.g., Dupré & Nicholson, 2018, p. 7; Meincke, 2018c, p. 373). Process biology is far from homogenous. This is often overlooked, especially by critics. To be clear: to say that there are different versions of process biology is not to say that any theory that somehow incorporates processes in the explanation of biological phenomena is therefore to be regarded a process philosophy of biology. In fact, some of what is currently advertised as process biology is actually no process biology. Against the historical background just presented, it is easy to see why.

Let’s have a look, for example, at so-called New Mechanism, a movement in the philosophy of biology popular since the turn of the 21st century. The New Mechanists’ agenda is to understand the complexity of living systems by identifying mechanisms. What are mechanisms? As Peter Machamer, Lindley Darden and Carl Craver (commonly abbreviated as “MDC”) in their landmark 2000 paper put it: “Mechanisms are entities and activities organized such that they are productive of regular changes from start or set-up to finish or termination conditions” (Machamer et al., 2000, p. 3). Other New Mechanists speak of “parts” and their “interactions” (Glennan, 2002) or of “component parts” and “component operations” (Bechtel & Abrahamsen, 2005). All emphasise the need to assume activities/interactions/operations as a distinct ontological constituent of mechanisms, on a par with entities/parts/component parts. This is motivated by the conviction that mechanisms are genuinely active: “Mechanisms do things. They are active and so ought to be described in terms of the activities of their entities, not merely in terms of changes in their properties” (Machamer et al., 2000, p. 5). Activities/interactions/operations are therefore sometimes identified with “processes” as assumed by declared process biologists (Illari & Williamson, 2013), suggesting that New Mechanism was compatible with process biology – or perhaps even identical. Is this true?

Mechanistic explanation, as Bill Bechtel and Robert Richardson first pointed out in their 1993-book Discovering Complexity (2nd ed. 2010), works by decomposition and localisation: a living system is decomposed into its structural parts, and the sub-tasks performed by the parts are located; the guiding assumption being that by putting it all back together, one gets an explanation of the overall phenomenon just as with a machine: “the behavior of the machine is a consequence of the parts and their organization” (Bechtel & Richardson, 2010, p. 17). This implies that the parts of a mechanism are identifiable independently of the mechanism in which they are found, and, i.e., independently of the activities in which they are involved. Stuart Glennan, another mechanist, explains:

But there’s a problem: what works for machines might not work for organisms. Where are the robust parts whose identity is context-independent in, say, metabolism? Metabolism appears to qualify as “mechanism” in the MDC-sense: “Mechanisms are entities and activities organized such that they are productive of regular changes from start or set-up to finish or termination conditions.” Intuitively, one would identify the cell’s membrane boundaries as “entities” as opposed to the “activities” of exchange of matter and energy they engage in. However, this is much less straightforward if one considers properly what metabolism is. To wit, a cell’s membrane boundaries through which an exchange of matter and energy with the environment takes place facilitate the bounded dynamics of a metabolic network which then produces the metabolites that constitute the membrane boundaries. Thus, while the membrane boundaries prima facie may appear robust, they are in fact totally dependent on the context: they both contribute to and result from the process of metabolism. The metabolites do not even exist long enough to be called robust, let alone can one have any without metabolism. The only thing that could be called robust is the dynamic and self-recursive organisation of metabolism itself (see also Jonas, 2001, esp. chapter 5).

Maturana & Varela (1980) have described this kind of interdependent processual organisation under the title “autopoiesis” which translates to “self-production” or “self-constitution” (Meincke, 2019a). According to Maturana & Varela, any system exhibiting autopoietic organisation counts as a living system – no matter what its matter is. An autopoietic system

There are material components only as part of the network of processes of production of components; hence, one can never isolate them as thing-like “entities” from “activities” other than by conceptual abstraction – any attempt to do so in concreto would result in the components’ destruction. Likewise, it is inappropriate to think that dynamicity in organisms reduces to the activities of entities, as the New Mechanists believe. The assumption that there cannot be any activity without a thing performing it – that processes always need things as their bearers – is, as we have seen earlier, a key assumption of thing ontology; but it is refuted by the fact that, at least in dynamical systems such as organisms, we only get “entities” – i.e., relatively stable structures – thanks to processes. An organism as a whole is an organisation of processes.

Recently, a more refined version of the autopoiesis theory has been proposed by Alvaro Moreno and colleagues under the title of biological autonomy (Arnellos et al., 2014; Barandiaran & Moreno, 2008; Moreno & Mossio, 2015). Biological autonomy is defined as a living system’s ability to actively maintain itself, and it has two different dimensions: (i) the constitutive dimension, also called “basic autonomy,” which is the system’s metabolic self-constitution or autopoiesis; and (ii) the interactive dimension: the system’s adaptive interaction with the environment (“agency”). The interactive dimension, while being entailed in autopoiesis, deserves recognition in its own right given the fact that it, evolutionarily, has stepwise been decoupled from the basic processes of metabolic self-constitution. Agency in a more interesting and robust sense for a living system means to maintain its self-constitution through interactively promoting favourable environmental conditions, in particular by means of bodily behaviour.

My own version of process biology builds on the conceptions of autopoiesis and biological autonomy, while also being inspired, especially with respect to the general ontological foundations, by elements in Bergson (1946, 1998, 2004) and Jonas (2001). I take it that organisms, ontologically speaking, are higher-order autopoietic processes that stabilise themselves through constant interaction with surrounding processes. There is no organism beyond this process of autopoietic interactive self-stabilisation. Just think about it: if the organism stops metabolising, i.e., exchanging matter and energy with the environment, it can no longer maintain its delicate stability far from thermodynamic equilibrium and ceases to exist. Change is all-pervasive; there is no unchanging core or substrate.

That organisms are higher-order processes means that there are lower level processes on which organisms, qua higher-order processes, depend from the bottom up and which they, at the same time, modulate according to their needs from the top down. There is a dynamic causal interdependence within and across levels of organisation; and because of that, reductionist approaches, such as the one advocated for by the New Mechanists, are bound to fail (besides New Mechanism not being a process account because it regards processes as dependent on thing-like “entities” rather than as fundamental). One cannot build organisms from “parts” or “components” like a house from bricks because what material parts an organism has depends on its overall processual organisation, including – and, arguably, most fundamentally – its metabolic organisation (Dupré & Nicholson, 2018, p. 28ff.; Meincke, 2018c, 2019a, 2021, 2022b, 2023b, forthcoming b).

Biological identity, then, both is processual and has organisational depth: biological identity is a matter of ongoing stabilisation efforts at all organisational levels. As such, it comes in degrees, as opposed to strict and primitive substance identity, which is an all-or-nothing affair. Yet, this processual identity is more robust than the stitched-together identity of a four-dimensional bundle of things ever could be. Metaphysically, we may say: Organisms are processes that are continuants – processual continuants (Meincke, 2018c, 2021, 2022a, forthcoming a). This is quite a heretic claim given that, traditionally, so-called continuants were equated with substances; but, as we have seen, the concept of processual continuants was already envisaged by Heraclitus and, as I have argued elsewhere (Meincke, 2022a), also by Bergson. The special metaphysical status enjoyed by organisms, and the robustness it implies, has to do with the fact that organisms enact their own identity, that they are – at least minimally – agents (Meincke, 2022b, 2023c, forthcoming a).

In lieu of a comprehensive presentation (for which there is no space here), my version of process biology may be characterised by the following seven key claims:

• 1.

  Biological organisation is autopoietic interactive self-stabilisation;

• 2.

  Biological causality is multi-directional, working both from the bottom up, and from the top down;

• 3.

  Biological identity is processual and inherently temporal; complex rather than primitive; and gradable, yet robust;

• 4.

  Biological time is internal, indivisible, directional and irreversible;

• 5.

  Biological subjectivity is a basic feeling of existence and rooted in the self/world distinction brought about by organisms through autopoietic interactive self-stabilisation;

• 6.

  Biological agency is the sensorimotor mode of autopoietic interactive self-stabilisation;

• 7.

  Biological freedom is entailed by biological agency and consists in the choice between possibilities in the face of attraction/repulsion.

These seven key claims can guide us when we now try to determine how a process biology that deserves its name – a process philosophy of biology that is committed to process ontology properly understood – should aim to conceptualise development – and how it shouldn’t.

What is development? Here is what Dupré and Nicholson, in their “Manifesto for a Processual Philosophy of Biology” (2018), say: “[A]ll organisms undergo a characteristic series of morphological and behavioural changes over the course of their lifetime” (Dupré & Nicholson, 2018, p. 18). Development refers to a particular type of change: the change of an individual organism during what is called its ontogeny, literally meaning the coming-to-be of an organism, its growth to maturity. Ontogeny forms a part of an organism’s life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring. The stages of a life cycle, however, can differ radically from one another – potentially calling into question that we are really dealing with one and the same individual here.

Consider animals that undergo metamorphosis, such as butterflies or frogs. A chrysalis looks and behaves rather differently from the caterpillar that preceded it; it does not move, it does not eat, it just sits somewhere, hosting, however, dramatic changes in body structure happening inside. The same holds true for the adult butterfly as compared to both the chrysalis and the caterpillar: it flies, it mates, it feeds on nectar, none of which can be seen in pupal and larval stage of development, let alone in the embryonic stage. Development, hence, poses the challenge to reconcile identity with change.

James DiFrisco has made a suggestion as to how to handle this problem. He says:

Is this really what process biologists think, or should think? No. It is false packaging. The packaging says “process”; but it is no actual process inside.

DiFrisco deploys what one could call the “4D-trick”: in order to avoid violation of Leibniz’s Law (according to which numerical identity requires identity of properties), attribute the troublesome different properties not to the same thing but to different things which themselves do not change and which you then label “parts” of some bigger four-dimensional thing. DiFrisco, following the example of Quine and others, addresses this bigger four-dimensional thing – here the mereological sum of developmental stages – as a “process.” However, as also powerfully argued by Bergson, a juxtaposition or aggregate of static things is not a process, i.e., an entity for whose identity change is essential. Such an aggregate does not need to change in order to persist any more than a bundle of balloons needs to change in order to persist. For the same reason, it fails to form a unified entity. In contrast, biological processes, especially those that are organisms, do possess an identity, which, as we have found, was already emphasised by Heraclitus.

While denying numerical identity to processes, DiFrisco is, however, prepared to grant them causal cohesion, i.e., some sort of demarcation through an interaction gradient such that the interactions among the entity’s parts are stronger than the interactions with the environment (DiFrisco, 2018, p. 84). He even declares that the cohesion of biological processes, such as the cohesion of a living cell, “occurs by means of the recursive organization of chemical reactions whereby the material constraints on the dynamics of these cells (e.g., membranes, enzymes) are continually regenerated by those dynamics” (DiFrisco, 2018, p. 84). But if this is the case, i.e., if a living cell is a unified, autopoietic network of interdependent processes, how could this ever go together with the four-dimensionalist understanding DiFrisco proposes for processes?

What this understanding gives us are at best static snapshots of an ongoing process of (supposedly) interactively bringing about causal cohesion – a process whose complex multi-level organisational structure is fundamentally at odds with the one-dimensional, linear atomism of four-dimensionalism. To the extent that these snapshots are assumed to be ontologically basic, i.e., to compose a process ontologically rather than just being products of conceptual analysis, DiFrisco’s view falls short of being a version of process biology. Process biology, properly understood, is committed to process ontology, which, as we have seen, is an ontology according to which processes are ontologically fundamental – and this appears not to be the case here. A piece of thing ontology is being sold to us as process ontology.

When it comes to the question of identity in development, it could seem as if substance ontology had a point – or at any rate, it seems like this to Dupré & Nicholson. They say: “[O]ne could attempt to retain the commitment to substance ontology by arguing that, despite the developmental transformations that organisms undergo, they nevertheless remain the same thing – or substance – throughout.” However, they insist that substance ontology is actually not up to the task of making sense of development:

Is this a successful way to attack substance ontological takes on development? No, it is not. Helen Steward, a prominent contemporary advocate of substance ontology, has an easy time with refuting this attack. Steward simply rejects the idea that substance identity must be grounded in some “interesting” property predicable of the developing organism throughout the life cycle. She suggests an alternative approach:

More specifically, Steward suggests two criteria of identity: “(i) the spatiotemporal continuity of the material elements involved in the changes; and (ii) the consistency of the form of these changes” across species members (Steward, 2020, 49ff.). So, according to Steward, the substance ontologist need not deny that organisms change, also drastically change, in the course of their development. On the contrary, these changes exactly provide a criterion of identity insofar as they are characteristic of all members of a species. That a butterfly starts out as a larva, then turns into a chrysalis, before continuing life as a flying insect – i.e., its particular “form” of change – is what makes a butterfly a butterfly.

The mention of “form” in this context is significant. Steward appeals to a (neo-) Aristotelian version of substance ontology. According to Aristotle, in the case of living beings, which are the paradigmatic substances for him, form amounts to “a principle of change and of staying unchanged” (Aristotle, 2018, Physics I, 192b8-12) and as such grounds an organism’s diachronic identity. Only living substances, Aristotle thinks, have a principle of change in themselves – their soul; whereas non-living substances need to be moved and changed from without. The metaphysician David Wiggins calls this a “principle of activity”: “a distinctive source of development and change” that is expressed by sortal terms, such as cat, dog, tree, etc. (Wiggins, 2012, p. 8; see also Wiggins, 2016, p. 272). Indeed, neo-Aristotelians love to point out on this basis how sympathetic they are towards processes.

Now, there is a sense in which Dupré and Nicholson are still right about the substance ontologist being committed to the idea that at least some properties or property stays the same throughout an organism’s lifetime: the property of having a particular principle of activity or form. The substance ontologist, of course, will be quick to point out that form is not a property like any other; it is rather the property that brings the organism into being. So, there is an essentialist assumption here which one might want to reject, it is just a more sophisticated one than that targeted by Dupré & Nicholson’s argument.

One may want to reject essentialism while actually holding on to the idea of identity. In fact, unlike DiFrisco, Dupré & Nicholson do want to keep identity. They agree with the substance ontologist that development does not undermine identity (which would indeed sort of go against the very idea of development – there needs to be something that develops), in the sense that the butterfly life cycle is one numerically self-identical process and not different processes. In my view, what they should have criticised about the substance ontologist’s take on development is not an alleged inability to accommodate drastic changes, but rather that organismal identity is conceptualised as something primitive and unchanging that underlies the change happening during development.

Let’s get clear about the ontological role the substance’s so-called form or principle of activity plays. The form or principle of activity determines what kinds of changes a substance can undergo, and in what kinds of activities it can engage, in accordance with its identity. But, note, this is a one-way dependence relation. Form or principle of activity, respectively, is not themselves determined by change or activity. Therefore, they also do not change themselves. A substance’s identity is primitively and unchangeably given with its form. Change and activity come second. In other words, identity precedes change and activity, rather than resulting from it, as the process ontologist wants to have it (Meincke, 2019c). Steward’s and Wiggins’s proposals thus bear all the marks of thing ontology: change is grounded in something unchanging, in an organism’s identity-constitutive form.

Grounding development in an unchanging form comes at the price of explanatory disappointment. Development – and movement in general – is for Aristotle the actualisation of a potential or entelechy determined by a living substance’s form or soul. It is like winding up a clock, which then runs until the momentum is used up. This corresponds with the literal meaning of the word “development”: unrolling, unfolding of something that is already there. So, if we ask: “Why does a frog egg or butterfly egg develop into a frog or butterfly?”, all we get as an answer is this: “A frog egg or butterfly egg develops into a frog or a butterfly because this development is predefined by the form of a frog or a butterfly, respectively, including the characteristic stages of the development.” There is no explanation of why these developments follow particular trajectories, and of why they differ from one another. As to the latter, Aristotle simply tells us: “A frog develops and moves differently than a butterfly because it has a frog soul rather than a butterfly soul.” Why do organisms have the form or soul they have? How do these forms come to exist?

Well, forms, according to Aristotle, do not come into existence; they are eternal and unchangeable. And animal organisms have the form or soul they have because they inherit it from their fathers, as Aristotle explains as part of his hylomorphist theory of the generation of living substances. The form, Aristotle thought, is contained in the male semen. Once the male semen is placed in a female womb, it supposedly creates from menstrual blood present in the womb an embryo, which then – thanks to and in accordance with its form – develops by itself into a recognisable exemplar of its species, receiving from the female no more than nourishing matter in the form of menstrual blood (Aristotle, 1963, De Generatione Animalium, books I–II).

Strikingly gendered as it is, this story has continued to shape western theorising about reproduction. Although with the discovery of female gametes it has become clear that, at least in mammals, the paternal and the maternal organism each contribute half of the genetic makeup of the foetus, it is still common to regard the female womb as a mere container for the embryo (Meincke, 2022c; see also Gilbert, 2023). The embryo is believed to develop largely independently of external circumstances by virtue of its essential form, entelechy or intrinsic active potential (Meincke, 2015, 2018b, 2022c). This deeply engrained Aristotelian legacy is especially manifest in ongoing debates on the moral status of human embryos. Massimo Reichlin, for instance, claims:

Contemporary anti-abortionists typically locate the alleged potential towards personhood in the human embryo’s genes. Thus, Alfonso Goméz-Lobo declares: “All living things have within themselves an active potentiality that scientists today view as encoded in their genome.” (Gómez-Lobo, 2005, p. 106) and “[P]ersonhood is a function of our DNA” (Gómez-Lobo, 2007, p. 333). Genes are treated as fixed essences that determine phenotypic characters with little or no contribution by environmental factors. Any ultimate explanations of developmental outcomes are considered to be genetic explanations.

I will come back to the role of genes as heirs of Aristotelian essences and exponents of a modern variant of thing ontology in the following section. For now, let me outline briefly what a (proper) processual account of development, as opposed to both four-dimensionalist and neo-Aristotelian approaches, would look like and how it is supported by scientific findings. The idea here is not to present a fully developed view but only to highlight key points and to indicate directions for further thought, thereby taking guidance from the seven aforementioned aspects of my version of a process view of life and living beings.

We meanwhile know that development does not work as advocates of a species-specific principle of activity or intrinsic active potential imagine. Instead, available empirical evidence corroborates the process view of biological organisation as orchestrated autopoietic interactive self-stabilisation: there is no development without environment (Moczek, 2015). Mammalian embryogenesis is highly dependent on extrinsic, successively generated information, such as positional information, maternal hormonal and cytoplasmatic information and on epigenetic information (Meincke, 2015, 2018b). The Containment View of pregnancy is false – mother and foetus form what I call a “hypercomplex process” that is in a process of asymmetric bifurcation (Meincke, 2022c).

Interaction with the environment is pivotal to embryogenesis also in other taxa. For instance, avian embryogenesis is dependent on temperature, humidity and on the eggs being turned. There is also so-called developmental symbiosis: the ubiquitous phenomenon that organisms (both plants and animals) are constructed, in part, by the interactions that occur between a host and its persistent symbiotic microorganisms. Organisms are therefore best understood as multi-species composites, so-called holobionts (Gilbert, 2023a; Chiu & Gilbert, 2015; Gilbert et al., 2012). Furthermore, during both the embryonic and the juvenile phase, development is influenced by nutrition, parental care and the ecological niche in which the developing organism lives. There is just no way for an organism to develop without being dynamically entangled with myriads of surrounding processes of various kinds and origin. Autopoiesis is interactive (Meincke, 2019a), it takes place embedded in sympoiesis (Clarke & Gilbert, 2022; Gilbert, 2023b; Haraway, 2016) or, as I would prefer to say, in a sympoietic interactive space.

Autopoietic interactive self-stabilisation involves, as we have seen, a dynamic causal interdependence between the whole organism and its parts. In accordance with this, we find that also in development causation does not travel in one direction only, namely, as within the predominant mechanistic paradigm is mostly assumed, from the genes to higher levels of organisation. Quite the contrary, genes themselves need a very specific environment in order to do anything at all. As the systems biologist Denis Noble puts it:

Within a process framework to emphasise – contra mechanist approaches – the action of downward causation (see also Meincke, 2018c, p. 371f., forthcoming b; Dupré & Nicholson, 2018, p. 27; Dupré, 2021, p. 7ff.; Jonas, 2001, p. 79ff.) is therefore exactly not to endorse the traditional myth of a primitive form (be it an Aristotelian soul or the genome) that develops an organism all by itself without any help from outside. On the contrary, biological form is processually constituted during development-through interactions at all levels of organisation and working from the bottom up just as much as from the top down (Meincke, 2018c, forthcoming a; Pezzulo & Levin, 2016).

Its multi-directional, context-sensitive causality proves development to be the product of ongoing concerted effort, something predicted by a process view of biological identity: what is being produced did not already exist beforehand – “potentially” – in some minimal form, be it an Aristotelian form, a homunculus or a “genetic programme.” Instead, development is a genuinely creative process, a process of strong emergence (Goodwin, 2001; Meincke, forthcoming b; see also Witherington, 2011), with different players taking part in it. The possible directions this co-creation can take are as diverse as the possibilities for interactions of the partners involved.

Over evolutionary time, organisms have managed to canalise their development along particular trajectories through hereditary mechanisms. This cross-generational stability serves the purpose of maximising the chances of survival for subsequent generations by maintaining those phenotypic characteristics that proved beneficial in the past. Genes are part of this internalised species memory, though perhaps not the most important part; patterns of bioelectric signalling seem to be just as important (Levin, 2021) (see also point 5 below). However, (to repeat) this does not mean that the outcome of developmental processes is “predetermined,” as illustrated impressively by unpredicted morphological novelties emerging from targeted manipulation. The morphospace of life is bigger than the life forms evolution has (so far) produced (Clawson & Levin, 2022; Davies & Levin, 2023). The relative cross-generational stability of phenotypes that we see is the result of ongoing interactive efforts, which remain open to change.

Essentialism, Aristotelian and genetic, is unable to make sense of the plasticity of life and the genuine creativity of development. Just as much does it struggle to explain why organisms age and die. From a process perspective, the common focus on an organism’s mature form as telos and final result of development is inadequate. Development does not stop with maturity: ageing (senescence) and dying are developmental stages too. The process view takes the entire life cycle into account, conceiving of it as one continuous process whose dynamics are driven by a complex network of intrinsic and extrinsic factors.

One of these factors is time. Biological time, according to my process view, is internal to organisms, indivisible in a Bergsonian sense, directional and irreversible. What does this mean and why does it matter? To start with, biological time is something that organisms, through their inner workings, bring about, rather than being an external container in which organisms are located. In a sense, there is no time for inanimate things other than “abstract” or “mathematical time,” as (Bergson, 1988, p. 21 and p. 9) says. Inanimate things can be disassembled and reassembled without any harm to their identity (Bergson, 1988, p. 8), whereas for a living process its past continuously shapes its present as it moves towards the future. “Duration is the continuous progress of the past which gnaws into the future and which swells as it advances” (Bergson, 1988, p. 4) and: “Wherever anything lives, there is, open somewhere, a register in which time is being inscribed” (Bergson, 1988, p. 16). In other words, unlike inanimate things, biological processes have a history: they age, thus being unable to “go through the same state twice” (Bergson, 1988, p. 5). The arrow of biological time is stretched out irreversibly between birth and death of an organism (see also Jonas, 2001, p. 86; and Meincke, 2023a, on Heidegger’s (1962) parallel observation concerning human persons).

From a process perspective it comes as no surprise that the timing of environmental clues and their synchronisation with the organism’s internal temporal profile of developmental processes is indeed key to development. Scientists speak of intrinsic and extrinsic “timer mechanisms” that “work together to reproducibly time developmental events in the embryos of a given species” (Busby & Steventon, 2021, p. 12). For example, in mammalian embryogenesis it matters when and for how long the embryo is exposed to morphogens. Moreover, we know that changes in developmental timing of events relative to an ancestral form can give rise to new species by changing the morphology. This has, for instance, been shown for emu versus chicken wing development (and has been discussed under the title of “heterochrony” since Ernst Haeckel and Gavin de Beer). In addition to the absolute timing of developmental events their ordering, directionality and speed are critical too (Busby & Steventon, 2021, p. 1).

Organisms, as conceived by my Process View, are (at least minimal) biological subjects as a result of their processual organisation. Interactive self-stabilisation means a constant effort to maintain integrity contra “the equalizing forces of physical sameness all around” (Jonas, 2001, p. 84). Biological identity, as a stability far from thermodynamical equilibrium, is always at risk of falling prey to entropy. Paradoxically, the only way for a living process to prevent collapsing and being assimilated to surrounding processes is to interact with these very surrounding processes, by exchanging matter and energy with them so that entropy within is decreased by decreasing it without (metabolism). It is through this paradox that a biological self emerges: a perspective from within on a world without, from which it demarcates itself as much as it depends for its existence on this world. The self-world relationship is, as Jonas puts it, one of “needful freedom”; biological identity is “internal identity” (Jonas, 2001; Meincke, 2018c, 2022b, 2023c) [which becomes more articulate and sophisticated in humans as “personal identity” (Meincke, 2019c, 2021, 2022b, 2023a)].

Characterised by need and effort, biological subjectivity is essentially affective (Meincke, 2023c). Biological selves are driven and drive themselves towards the fulfilment of their needs (Heidegger, 1995; Meincke, 2023b); they care about the world to the extent that they care about their survival. Cognition in living beings (as we know them) is a means towards achieving this end and as such embedded in affectivity. This is underpinned by current research on basal cognition, which “includes the fundamental processes and mechanisms that enabled organisms to track some environmental states and act appropriately to ensure survival (finding food, avoiding danger) and reproduction long before nervous systems, much less central nervous systems, evolved” (Lyon et al., 2021, p. 4; see also Baluška & Levin, 2016; Lyon, 2015; Piedra & Frohlich, forthcoming; Smith-Ferguson & Beekman, 2020). Basal cognition is intertwined with valence: “the biological impetus of attraction or repulsion to a state of affairs based on an assessment of value relative to an individual’s goal structure” (Lyon and Kuchling, 2021, p. 2). Valence is the ““building block” of affect” (Lyon and Kuchling, 2021, p. 5; see also Meincke, 2022b, 2023c).

The creativity at work in development (see point 3 above) must be understood against this background. It is an instance of affectively driven cognition. How do cells “know” what to build and how? The answer given by biologist Michael Levin and colleagues is: collectives of cells display swarm intelligence. Cognition is not hard-wired to a specific body architecture, e.g., to a brain sitting in a skull. On the contrary, the development of a particular body architecture is itself guided by cognition. Cells act together drawing on memory that is stored not in the genes but in the patterns of the bioelectric signals by which cells communicate with one another (Clawson & Levin, 2022; Levin, 2014a, 2014b, 2019, 2021; Levin & Dennett, 2020; Levin & Yuste, 2022).

To say that in development cells act together in intelligent ways is to say that they are agents. Biological identity is agential at all levels of organisation. As indicated in the previous section, I consider agency to be entailed by the basic organisational structure of interactive self-stabilisation that is constitutive of organisms, just as subjectivity is entailed by it (see also Meincke, 2022b). Indeed, both biological agency and biological subjectivity are two sides of the same coin: only a being that must act in order to persist has needs whose satisfaction or frustration feels like something to it; and only a being that has needs whose satisfaction or frustration feels like something to it is driven to act upon these needs. Ultimately, this interdependence is itself rooted in the purposiveness of living organisation (Meincke, 2023b, 2023c; Jonas, 2001).

This view is in stark contrast to the view prevalent in metaphysics and the philosophy of mind since Descartes that agency is an intellectualist skill reserved to humans. However, an inclusive biological notion of agency is supported by emerging scholarship in the philosophy of biology (Arnellos & Moreno, 2015; Meincke 2018a, 2022b; Moreno & Mossio 2015; Sultan et al. 2022; Walsh 2015; but see Potter & Mitchell, forthcoming, for some caveats). It is increasingly also invoked to explain the efficiency of developmental processes. Thus, Levin & Yuste (2022) “call on biologists to embrace the intentional stance: treating circuits and cells as problem-solving agents.” Development, according to them, is a goal-directed process enacted by intelligent agents. Cell collectives, Davies & Levin (2023, p. 46) argue, ought to be modelled as “as agential materials, with their own goals, agendas and powers of problem-solving” to make better sense of cell cooperation in development and to devise new therapeutical intervention techniques.

My process view of life regards freedom as an implication of agency. To act means to choose between possibilities, however limited these possibilities may be in number and however rudimentary or primitive the character of choice may be. Importantly, choice need not be rational; it can be – and both most fundamentally and most commonly is – (purely) affective in nature. Biological freedom, thus, comes in degrees just as biological agency does, depending on three main factors: (i) the more possibilities there are to choose from, (ii) the more control the agent has about their choice, and (iii) the longer the response can be delayed, the higher is the degree of freedom of agency. The function is in each case the same, namely to ensure a flexible and thus maximally adaptive response to environmental cues as opposed to rigid hard-wired reflex mechanisms. Plasticity, therefore, is the characteristic that runs through all degrees of freedom of agency.

This includes developmental plasticity, which, I contend, is enacted by the behavioural plasticity of cells exhibited in plastic interactive networks. As agents, cells in a developing organism make choices between different possibilities in the face of environmental factors, as depicted by Conrad Hal Waddington’s well-known epigenetic landscape (Waddington, 1940, 1957). According to Waddington, cell fates are settled during development in a so-called process of canalisation just as marbles roll down a particular valley (see also Waddington, 1942). This explains why development is both robust and highly plastic. While a cell, as Huang (2012, p. 7) puts it, is typically subject to an “intrinsic downward force imposed by the interactions hard-wired in the network,” it may “jump” out of a basin of attraction over a sufficiently low hill into a neighbouring valley (attractor)” in response to gene expression noise or random external events.

The structure of the epigenetic landscape can be manipulated. Michael Levin and colleagues have shown, in a number of rather mind-blowing experiments, that manipulation of bioelectrical patterns of cell signalling in salamander, frog, and planarian flatworm embryos prompts the development of entirely novel anatomies (Davies & Levin, 2023; Levin, 2021). Levin speaks of “somatic plasticity” (Levin, 2019, 2021). Also under “normal” circumstances (i.e., without targeted experimental manipulation), the epigenetic landscape may change its topography through processes of genetic assimilation, as Waddington (1953, 1959) has argued.

Note the striking parallel with what one could call, in the context of a process theory of the human person (Meincke, 2018c, 2019c, 2023a), the epigenetic landscape of personalities. Whether through psychotherapeutic intervention or prompted by life-changing events, we are able to leave well-trodden pathways of behaviour, feeling and thinking and to create new ones. Biological freedom encompasses all levels of organisation, from the primitive plasticity of cells to the sophisticated plasticity of human minds.

What about evolution? How can process ontology help us understand evolution? Putting the question like this suggests that evolution so far has not been understood – or, at least, not been understood well enough. That this is indeed the case is being claimed by ecological developmental theorists and proponents of the Extended Evolutionary Synthesis. We shall see that this claim is true to the extent that the received view of evolution, the Modern Synthesis, relies on thing ontology. Admittedly, this diagnosis may cause surprise. Is a thing ontological view of evolution not a contradictio in adjecto? Thing ontology, we have found, is a view of reality which, driven by a fear of change, emphasises sameness and permanence. Evolution, however, abounds with change. Species change over time, new species emerge, others become extinct. Evolutionary theory as such started out by questioning the Aristotelian world view, on which species are fixed and eternal. And with the discovery of evolutionary change arose the challenge to account for this change.

To get a better grasp of current debates, it is worth recapitulating the most important steps in the history of evolutionary theory. As is well known, the first to defend the so-called transmutation of species in form of a comprehensive theory of evolution was the French botanist and zoologist Jean-Baptiste Lamarck. Species, he argued against Aristotelian essentialism in several writings (Lamarck, 1802, 1809, 1815–22), do not have immutable essences but change over time. He also offered explanations as to how this change comes about (mainly by postulating a complexifying and an adaptive force). In particular, Lamarck formulated the idea that characteristics organisms acquire through their interactions with the environment are heritable, so-called soft inheritance. Thus (to recall his famous example), when giraffes, triggered by environmental conditions, stretch their necks to reach leaves high in trees, they would strengthen and gradually lengthen their necks. These giraffes would then have offspring with slightly longer necks.

Fifty years later Charles Darwin, in his ground-breaking book on The Origin of Species by Means of Natural Selection (Darwin, 1859) presented a different explanation of the transmutation of species: so-called descent with modification. Darwin proposed that all present-day species have descended from a common ancestor through branching – much like branches sprout from the trunk of a tree. More specifically, new species arise through a gradual accumulation of inheritable variation within populations. However, not just any heritable variations but only those heritable variations accumulate, according to Darwin, which are most favourable to survival within the environment of a population. Just as breeders select individual plants or animals for certain desirable traits to reproduce, so nature selects those individuals that are the fittest in the ongoing struggle for existence. Natural selection thus explains both the emergence of new species and the adaptation of species to their environments.

Darwin managed to convince his contemporaries of the existence of evolution. However, people remained sceptical about natural selection as the driving force of evolution. This scepticism had to do with the fact that Darwin could not explain how the variations, on which natural selection was supposed to act, came about, and how inheritance actually works. For Darwin, it was enough to know from observation and experiment that breeders were able to select certain variations and produce huge differences in many generations of selection. But Darwin’s contemporaries were not satisfied with this.

A big step towards the understanding of heredity was made with the rediscovery of Gregor Mendel’s work in 1900. Mendel hypothesised that there are units of heredity (he called them “factors”), which come in pairs, are segregated in the gametes and randomly recombined in reproduction while retaining their identity through this process. For multiple reasons, Mendel’s work was perceived as incompatible with Darwin’s theory of evolution (most importantly, the tension between Mendel’s commitment to particulate inheritance and saltationalism and Darwin’s endorsement of blended inheritance and of gradualism was believed to be irresolvable). This delayed the further development of evolutionary theory.

It took another 50 years until finally Darwin’s theory of evolution and Mendel’s theory of inheritance could be reconciled (thanks, among many other things, to the discovery that purported mutants actually simply were recombinant genotypes, leading to an appreciation of the potential of variability inherent in sexual recombination). This is known as the Modern Evolutionary Synthesis. It was developed 1930–1950 by scientists of different disciplines. The key claim is: evolution occurs through “gradual, cumulative change in gene frequencies in populations, brought about by selection acting on the variation among individuals that results from random gene mutation and recombination” (Jablonka & Lamb, 2020, p. 2). The ideas of gradual, cumulative change and of natural selection go back to Darwin, whereas the focus on gene frequencies in populations and the idea of random gene mutation and recombination are Mendelian in spirit.

Whose ideas, however, are strikingly absent from the Modern Synthesis are those of Lamarck: the Modern Synthesis does not include environment-induced variation as a source of evolution. This is in line with the so-called Central Dogma of Molecular Biology, which was formulated by Francis Crick in a famous lecture given in 1957 (Crick, 1958; see also Crick, 1970) after he had discovered the double helix structure of DNA together with James Watson. Crick (1958) described the two-step process, in which DNA is transcribed into RNA, and RNA is then translated into the proteins that build the cell, as unidirectional: genetic information flows from the DNA to proteins but not vice versa. Adaptive changes undergone by an individual during its lifetime thus cannot be coded into heritable information.

The Central Dogma (basically a biochemical reformulation of the so-called Weismann barrier, i.e., the idea first put forward by August Weismann (1892) that hereditary information exclusively travels from the germline to the soma) facilitated the view that what matters in evolution and biological life in general is genes, not organisms. Thus, Theodosius Dobzhansky, one of the architects of the Modern Synthesis, identifies heredity with the self-reproduction of genes and declares organisms to be a mere “by-product” thereof:

Similarly, British biologist Richard Dawkins, in his 1976 book The Selfish Gene, explains that organisms are “vehicles” of “replicators,” i.e., of genes as the fundamental units of natural selection (Dawkins, 2016, e.g., p. 254). The evolution of organisms results from the strive for endless self-replication – for “immortality” – of selfish genes (Dawkins, 2016, e.g., p. 44f.).

Given these key assumptions, the Modern Synthesis faces a problem of disappearing change. If inheritance happens only through self-replication of genes, with no input from the environment, how can there be any evolutionary change? Proponents of the Modern Synthesis appeal, as mentioned, to random gene mutation and recombination as sources of variations for natural selection to work on. These mechanisms, however, imply strikingly weak and contorted notions of change.

Recombination, as viewed by Dobzhansky, Dawkins, and others, equals the shuffling around of themselves unchanging things – just like the shuffling around of Leukippos’s and Democritus’s atoms. Atomism, we have seen, is unable to account of the unity and, thus, existence of complex objects. It thereby also excludes the occurrence of any true novelties. All there is at any point in space and time is the very same things assembled differently. Change remains superficial, parasitic upon the unchanging identity of atoms – or genes, respectively. Unless – and here the Modern Synthesis transcends the bounds of atomism – something goes wrong, that is, a gene mutates resulting from errors in DNA replication or other DNA damage.

The assumption that genuine change can happen only by accident or, more accurately, by mistake is an impressive proof of how deep thing ontology’s fear of change goes. To be sure, viewed from a metaphysical perspective, the key commitments of the Modern Synthesis align with thing ontology, with genes functioning as things in the technical sense introduced above of entities whose identity does not depend on (and may even be incompatible with) change. Genes are seen as things with virtually immutable essences which they confer on their vehicles (organisms). This is manifest in three widely shared beliefs about genes, which are nicely summarised by Kostas Kampourakis in his 2017 book Making Sense of Genes:

Dawkins is aware of the fact that biologists traditionally deemed the dependence relation between genes and organisms to be the other way around: “The individual organism came first in the biologist’s consciousness, while the replicators – now known as genes – were seen as part of the machinery used by individual organisms” (Dawkins, 2016, p. 343). But he insists that this traditional view, according to which organisms use genes rather than genes use organisms, is illusory and turns upside down the true reality of life. Therefore, he invites us to make “the mental effort to turn biology the right way up again, and to remind ourselves that the replicators come first, in importance as well as in history” (ibid.).

There is, however, a growing number of scholars who think that what proponents of the Modern Synthesis like Dawkins dismiss as being upside down is exactly right. Thus, geneticists Eva Jablonka and Marion Lamb claim that more recent scientific discoveries about inheritance require us to move away from gene-centrism and to return “to an earlier, development- and organism-oriented view” (Jablonka & Lamb, 2020, p. 1). In other words, we need to turn the right way up again what the Modern Synthesis turned upside down: the order of priority between organisms and their genes.

One of the ventures to spell out the theoretical implications of this move is called the “Extended (Evolutionary) Synthesis”. What is “extended” about the “extended synthesis”? Briefly put, the claim is that there is more to heredity than genes – there are other “inheritance systems” (to use Jablonka & Lamb’s term), which need to be included in our theory of evolution. According to Jablonka & Lamb (2014, 2020), evolution happens in (at least) four dimensions, via genetic, epigenetic, behavioural, and symbolic means. Kevin Laland, director of the recently completed research project “Putting the Extended Evolutionary Synthesis to the Test,” stresses in particular the importance of developmental processes:

Development drives evolution insofar as it is shaped by environmental factors, whether these be abiotic or biotic, agential, social, or cultural (for more details, also see Chiu, 2022). Novel phenotypes frequently are environmentally induced (West-Eberhard, 2003, 2019), not least as a result of organisms’ own active modification of the environment (Piaget, 1978; Lewontin, 2000; Odling-Smee et al., 2003; Laland et al., 2016; Chiu, 2019; Aaby & Desmond, 2021).

Note the stark contrast to the view of development as an intrinsic process isolated from and not to be affected by the environment, as to be found in traditional (neo-) Aristotelian substance ontology and modern thing ontology of genes alike. Indeed, the rehabilitation of Lamarck’s concept of an inheritance of acquired characters (see also Danchin et al., 2019) prompts the question of whether the Extended Evolutionary Synthesis is not merely an “extension” of the Modern Synthesis but a “substantial revision” (Jablonka & Lamb, 2020, p. 1). This question is subject of ongoing controversy (see, e.g. Laland et al., 2014, 2015; Wray et al., 2014; Richards & Pigliucci, 2020).

My hypothesis is that what is ultimately at stake in the competition between the Modern Synthesis and the Extended Evolutionary Synthesis is metaphysics. Switching from the Modern Synthesis to the Extended Evolutionary Synthesis amounts to a Kuhnian paradigm shift, namely from a thing ontological to a process ontological framework. The Extended Evolutionary Synthesis, I contend, requires a process ontological framework in order for its key tenets to make sense. Or put differently, if the Extended Evolutionary Synthesis, compared to the Modern Synthesis, delivers the more convincing account of evolutionary change (a matter ultimately to be decided by biologists on the basis of empirical evidence), and then this is facilitated by preceding process ontological assumptions. Accordingly, our task now is to explicate those assumptions. What does it mean to think of evolution in process ontological terms?

Evolution is the evolution of new species. Species, therefore, cannot be natural kinds with fixed essences, as Aristotle thought. What species are then, if not natural kinds or classes, i.e., groups of entities subject to universal laws, is a matter of ongoing debate. However, since the seminal contributions by Ghiselin (1974) and Hull (1978), most philosophers of biology have come to view species as individuals. The reason is that in order for species to be units of selection, they must be spatiotemporally continuous, which is not the case with classes. Organisms, accordingly, are regarded as parts rather members of species; that is, a part-whole relationship instead of a class-member relationship is invoked.

But there is a problem: How can an individual be made up of discrete and independent parts? Dupré & Nicholson (2018) argue that a process view of species can solve this problem. Species, they explain, are in fact lineages and, that is, temporally extended processes. If so, we may try to establish the identity of species lineages via postulating causal links between temporal stages:

While it is certainly right to conceive of species in temporal rather than merely spatial terms, the question remains whether the particular approach taken by Dupré & Nicholson aligns with the spirit of a process account of evolution envisaged here. This is because their proposal seems to suggest that species lineages are four-dimensional spacetime worms. However, assuming there is such a process as a lineage, we as process ontologists must think of it as being indivisible and dynamic, not as being composed of itself unchanging parts, which only ex post are bound together. Four-dimensionalism, we have learnt from process philosophers such as Bergson, will not give us a true understanding of process and change, let alone provide us with a robust enough notion of identity or “integrity.”

But the problems do not end here. For in what sense could one reasonably claim a lineage process to exist at all? Dupré & Nicholson make a rather strong and, to my mind, puzzling point:

This seems to attribute some kind of active self-perpetuation to lineages, based on an analogy with the metabolic self-perpetuation of organisms. I do not think this analogy holds. Ontologically speaking, species lineages are nothing over and above the organism lineages of which they consist. Conceptually it makes sense, of course, to conceive of speciation as a process involving species as individuals, if only because it simplifies things. However, the true individuals that realise any such process of speciation are individual organisms as they descend from one another. Thus, to the extent that species lineages can be said to exist at all, they are both brought into existence and being sustained through the efforts of individual organisms insofar as these organisms work towards their own persistence and reproduction. Lineages are chains of life cycles of individual organisms. If anybody acts here, it is organisms, not lineages (whether lineages of organisms or lineages of species).

To say that lineages evolve is in effect to say that there is, as Maturana and Varela put it, a history of change in sequentially realised autopoiesis. To be sure, the autopoietic organisation (or biological autonomy, or autopoietic interactive self-stabilisation) is the same in every living system; however, the ways it is realised are subject to change:

For Maturana and Varela it is therefore clear that ontogeny and evolution must be sharply distinguished:

Taking into account the proviso that ontogeny and evolution belong to different domains, what would our process view of evolution be, broadly speaking? To start with, we should conceive of evolution as a higher-order dynamical process embodied and enacted by individual processes of different, albeit lower, levels of organisation. Evolution, lacking an identical subject (as Maturana and Varela rightly observed), refers to the relational change between sequential individual processes of autopoietic interactive self-stabilisation. It is, as it were, a “meta-meta change,” made up from individual changes in the realisation of the kind of change that is autopoietic interactive self-stabilisation.

A key question for evolutionary theory is at what level or levels of biological organisation natural selection works. What are the so-called units of selection? Given the dynamic entanglement of biological processes both within and beyond hierarchies, I surmise that there are multi-level units of selection. The most important is that of organisms qua holobionts; however, also cells within organisms or groups of organisms are relevant drivers of evolution to the extent that they exhibit agency. How these factors relate to one another is a complex matter and needs to be assessed individually for any given cases. Given the critical role of organism-environment interactions, we ought to consider ecosystems to be subject to natural selection too.

Species, on the other hand, are not to be included in the list of units of selection because they fall short of constituting entities in a sufficiently strong ontological sense. Species, or species lineages, are conceptual divisions of a continuum of chains of life cycles of organisms or, to use Bergson’s phrase, “mental views of an indivisible process” (Bergson, 1998, p. 29) (Bergson thought this to be true for all elements in the domain of life; I disagree with him on this point). To repeat, if species can be said to exist at all, they in any case lack agency and cannot bring about evolutionary change by themselves. Strictly – and, that is, ontologically – speaking, it is not species but such-and-such specified organisms, or groups of such-and-such specified organisms, that compete with one another for survival in a given ecological niche.

Likewise, I doubt that genes are units of selection. In accordance with the Extended Evolutionary Synthesis, a process view ought to regard genes as a means used by organisms to survive individually and to facilitate continuation of the lineage: as a means of cross-generational stabilisation. Genes are the (deep-seated) memory of the lineage that shapes individual processes of development but can to some extent be deployed flexibly as is seen fit in a given environment and situation; genes must not be reified into essences. Speaking of reification, natural selection should not be reified either. There is no invisible breeder walking around, selecting some individuals for breeding, while dismissing others. It is just organisms doing stuff that either does or does not contribute to their fitness.

Ultimately this means that evolution is as it is because organisms, including their constitutive parts, are as they are and behave as they do, taking additionally into account geological conditions on Earth as well as generic physical constraints acting upon development (Goodwin, 2001; Newman et al., 2006). Organisms bring about the changes on which (as evolutionary biologists like to say) “natural selection acts,” or which (as we should perhaps better say) make up, over evolutionary time, the change that is called evolutionary change. Organisms bring about these changes in at least the seven ways highlighted earlier as key characteristics of living systems according to my version of process biology: through their processual organisation, i.e., autopoietic interactive self-stabilisation, their multi-directional causality, their processual identity, their temporality, their subjectivity, their agency and their natural freedom. As we have seen, these seven aspects are also critical for the development of organisms as a major source of evolutionary change. Development and evolution intersect in the processuality of organisms.

Let’s sum up.

We started with an excursion into the history of western metaphysics, in order to distinguish process ontology from its powerful opponent, thing ontology. Thing ontology, we found, is committed, in one way or another, to essentialism and is biased against change. This bias need not take the extreme form of wholesale denial of change and movement, as espoused by Parmenides and his Eleatic followers. It is equally manifest in the atomists’ endeavour to restrict change to a reconfiguration of themselves unchanging atoms and in Aristotle’s conviction that there cannot be any change without an unchanging substratum. The same holds for present-day versions of thing ontology: bundle theory and four-dimensionalism, which are descendants of atomism, on the one hand and substratum theory, which follows in the footsteps of Aristotle’s substance ontology, on the other hand. In contrast, process ontology, as first proposed by Heraclitus and prominently elaborated by Bergson and Whitehead, takes reality to be irreducibly dynamic, which is to say that processes, not things, are ontologically fundamental. An important implication of this, we have seen, is that change, rather than being a threat to identity (as suspected by the thing ontologists), is in fact constitutive of identity.

Against the historical background, it was possible to distinguish genuine versions of process philosophy of biology from putative ones. New Mechanism, while assuming both so-called entities (things) and activities (processes) as ingredients of mechanisms, still regards processes as dependent on things, thus revealing itself to be a version of thing ontology. Process biology proper must acknowledge that it is just the other way around: any identifiable parts of a mechanism or living system are dependent on the processual organisation to which they belong and to which they themselves contribute, being, in fact, themselves processes, just slower ones. Both the autopoiesis theory of life and the more recent theory of biological autonomy aim to capture this interdependent (“circular”) processual organisation. So does, too, my own version of process biology that centres around the notion of autopoietic interactive self-stabilisation and metaphysically construes organisms as processual continuants.

When it comes to ontological conceptions of development, I argued that four-dimensionalist proposals which construe development as a series of numerically distinct stages linked through mereological relations, if to be taken seriously in ontological terms, cannot rightfully claim to belong to process biology because four-dimensionalism puts things first: atomic and themselves unchanging stages or temporal parts. Just as much, however, should we stay clear of substance ontological accounts of development given their commitment to essentialism and primitive identity, which leads to a view of development as the environment-independent realisation of an intrinsic active potential, possibly located in the developing embryo’s genes. In response, I have outlined the central tenets of an alternative process account of development. Looking at seven key aspects – organisation, causality, identity, time, subjectivity, agency, freedom – I have shown how a process perspective makes development comprehensible as being environment-dependent, both upward- and downward causal, creative, intrinsically temporal, minimally cognitive, enacted and plastic, this in line with recent scientific findings.

Finally, we turned to evolution and discussed theoretical proposals, both historical and present, of how to account for evolutionary change. We found that the appeal to genetic recombination alone won’t do the job, something unsurprising in the light our earlier critique of atomism. Interestingly enough, neo-Darwinism incorporates, at the same time, a (neo-) Aristotelian heritage, by positing genes as unchanging essences that provide a blueprint for development. Given these strong thing ontological roots, the neo-Darwinist idea that genuine change may occur only as a random mistake, i.e., in the form of gene mutation, makes sense, without thereby becoming any more convincing. The alternative approach is to start with the assumption that change is not an exception but the default, by invoking a process ontological framework. In this vein, I have offered a reconceptualization of evolution as a higher-order process of historical change of the ways autopoietic interactive self-stabilisation is realised by individual organisms.

From a process perspective, there is no question about how evolutionary change is possible. Change is the daily bread of life. Development is a particular type of organismal change, one that is especially productive. Surely, a plausible theory of evolution must put development back into evolution, thereby putting organisms back in power, too. Here, I have argued that such a move indeed calls for a fundamental paradigm shift: from a metaphysics that views reality in terms of things to a metaphysics that views reality in terms of processes. I also have sketched how a process ontological framework can improve our understanding of both development and evolution. This, I hope, will encourage future work towards a fully developed process view of development and evolution, besides sparking further dialogue between metaphysics and biology more generally.

This paper was first presented on June 2, 2022, in a keynote talk at the 2022 meeting of the Jean Piaget Society, “Putting Development Back Into Evolution,” in Philadelphia, PA, USA. I thank the organisers, Robert Lickliter, David Moore and David Witherington, for inviting me and the audience for stimulating discussion. I am also indebted to Don Frohlich, Scott Gilbert, Dan McShea and two anonymous reviewers for helpful comments on earlier versions of this paper.

No ethical approval was required for the preparation of this manuscript, as no human or animal subjects were used.

The author has no conflicts of interest to declare.

This research was funded in whole by the Austrian Science Fund (FWF), grant agreement number #V714-G30 (“Bio-Agency and Natural Freedom,” PI: Anne Sophie Meincke).

Anne Sophie Meincke conceived the ideas, reviewed literature, and wrote the entire manuscript.

No empirical study was conducted for this article. Any data referred to can be found in or via the literature cited. Further enquiries can be directed to the corresponding author.