Keywords

Introduction

Friedrich W. J. Schelling was a philosopher of a wide range of interests and although generally best known is probably his contribution to the theory of human freedom and the issue of evil, he also clearly deserves a place also in this book. This is for two main reasons: first, some of his insights regarding the disputes between a mechanistic and vitalist explanation of nature and his views on the subject of natural evolution exerted a lasting influence on the development of biology, especially in Germany; second, different scholars have found in his work anticipation of various approaches and concepts found in the current philosophy of biology, for instance, the theory of processuality or theory of self-organisation and reciprocal causality. But before we embark on introducing the basic outlines of Schelling’s concept of living nature, let us take a look at the contemporary context, at the situation Schelling had entered and which his views reacted to.

In Schelling’s time, that is, in the late eighteenth century, biology was fast developing as a science of classification (Linné, Buffon), but its ambition was also to be an analytical science capable of offering explanations. This was happening in a situation where on the one hand, the mechanistic explanation of the functioning of organisms, which was based on an analogy between organisms and mechanical machines (Descartes, La Mettrie, etc.) and worked within a conceptual framework of inert matter and impact force, was reaching its limits, while on the other hand, the discovery of irritability by Galvani (1791), which proved a connection between electricity and physiology, and the rapid development of chemistry all seemed to offer a novel direction that would still explain organisms fully in terms of the laws and principles that operate also in inorganic nature (see Küppers, 1992: 92). But this was also a time when numerous thinkers were pointing to phenomena which, in their view, demonstrated the shortcomings of even this more broadly conceived physicochemical explanation of the existence and functioning of organisms. This pertained especially to (self)reproduction in the sense of nourishment, reproduction, and regeneration ability of some organisms, but also to organs ‘taking over’ the function of another, damaged organ, and finally to the fact that body parts are existentially dependent on each other and contribute to each other’s continued existence (cf. Chap. 4; see also Kabeshkin, 2017: 1182). Another important direction of biological thought at that time, namely vitalism, was trying to explain these phenomena by positing that in living beings, there is at work also another type of causality and powers than merely the physicochemical ones, a ‘vital force’ (Lebenskraft) or ‘formative drive’ (Bildungstrieb). In the late eighteenth century, the most influential advocates of this approach in German-speaking lands were Georg Ernst Stahl, Joachim Dietrich Brandis, and Johann Friedrich Blumenbach.Footnote 1

Immanuel Kant occupied a specific position in the dispute between these two approaches: he showed that life sciences cannot rely only on physical and mechanical explanations of organisms and the processes which take place in them. Moreover, he was convinced that this is not just a temporary shortcoming that could be rectified over time, but an integral feature of our discursive thinking. He noted that in biological research, one must view living beings not only as the products of commonplace efficient causality but also see them as if they were formed according to a plan, i.e., as if final causes were also involved. In research, this implies, among other things, a study of the purpose of particular organs and processes. In other words, it leads to functional explanations. But that does not make Kant a vitalist, because this conception of living entities as if they were natural final causes is, he adds, merely a regulative idea, a heuristic principle that guides our investigation. Importantly, it does not mean that according to Kant this is how living beings are actually formed (Kant, 2000: 247; see Chap. 4).

Kant was perceived as an authority by physiologists and physicians of his time, but they did not know how to implement his epistemological considerations in practice, because it remained unclear to what extent Kant thought that biology can be a science sensu stricto. This is why it was so easy for Schelling to take over this line of thought with his Naturphilosophie, which, at least in the beginning, presented itself as an elaboration of Kant’s project, while offering a greater certainty regarding the status of biological research as such (Zammito, 2018: 323ff.). Still, as we are about to see, Schelling actually presented a separate position and one which went significantly beyond Kant’s views. This is the case despite the fact that Schelling dedicated to his Naturphiolosophie only a relatively short time, less than a decade (starting in 1797 and ending in 1806). He published his thoughts on the subject mainly in the Ideas for a Philosophy of Nature (1988 [1797]), On the World Soul (2010 [1799]),Footnote 2 First Outline of a System of the Philosophy of Nature (2004 [1799]) with the later added Introduction to the Outline (2004 [1799]), System der gesammten Philosophie und der Naturphilosophie insbesondere (1804).Footnote 3

In-Between Mechanicism and Vitalism

Let us first look at where Schelling identified the main shortcomings of both of the contemporary approaches to explaining the existence of living beings. A mechanistic explanation based on thrust and gravity is something he rejects as utterly insufficient with no further ado (Weltseele SW II 497f.; First Outline 57 = SW III 74). Explanation of life via chemical processes is an approach he viewed as more promising. The manner in which chemical – or, as he puts it, ‘material’ – physiology explains the form and function of living beings nevertheless in his view suffers from one-sidedness and incompleteness, because it seeks an explanation only in the chemical composition of living beings and in the effect of external forces. According to this approach, organisms and their activities are fully defined by external forces – and that does not correspond to the phenomena we actually encounter in the realm of the living, because organisms are able to modify, at least to some extent, the impact that external forces have on them (First Outline 59 = SW III 77). Another weakness of chemical or ‘material’ philosophy is, according to Schelling, its failure to account for the fact that, unlike organic processes, chemical processes are not self-sustaining and self-perpetuating: a chemical process stops as soon as all initial substances have reacted and transformed into the final products (Weltseele SW II 500–502; First Outline 109f. = SW III 150). Organisms, however, are characterised by disbalance (see Chap. 8), and that is a precondition of metabolism and life as such.

In contrast, the other prominent contemporary explanation of life claims that organisms have a certain vital force (Lebenskraft), and that determines the impact – or lack of it – of external forces; it influences the effect of external factors to such an extent that it can halt or change the laws of chemical processes. Such vital force would thus transcend the laws of material nature and would not be itself material. This is why Schelling calls this explanation ‘physiological immaterialism’ (First Outline 61 = SW III 81). Within this theory, however, it remains unclear why the vital force affects only certain kinds of bodies and not all of them, and eventually, what are the specific empirical conditions under which it can start functioning. At the same time, it seems impossible to find any laws of functioning of this vital force, laws that would explain all phenomena of organic nature and their regularities (First Outline 61 note *, 111 = SW III 80f., 152).Footnote 4

In his philosophy of nature, Schelling is trying to overcome the shortcomings of both of the theories described above and present a naturalist, but not reductive, explanation of life. In his view, life is something more than a physicochemical process but this ‘more’ cannot be an occult vital force. He does not want to assume any metaphysical forces or principles at work only in the realm of the living. His explanation aims at being monistic, i.e., such that assumes the same basic principles at work in both living and non-living nature. But that can only be achieved if the physicochemical character of nature is not assumed to be something basic and irreducible, but rather just a specific manifestation of certain more profound principles, which are at work in both living and non-living nature. We can arrive at a more concrete idea about this explanation of nature by following, one by one, Schelling’s philosophical writings on nature, because Schelling elaborates his conception gradually and his theory undergoes some development.

In his first book on natural philosophy, Ideas for a Philosophy of Nature (1797), the theory of biology is not yet developed. The exposition ends with chemistry and Schelling touches upon the concept of organicity only briefly, in an introduction which he wrote after completing the work on the treatise (Ideas 30–38 = SW II 40–51). A theory of organicity and living nature is developed only in his next writing, On the World Soul (1798), although some parts of the conception remain, in comparison to his later elaboration, somewhat raw and vague. In this book, Schelling is trying to explain the entire nature not just mechanically, i.e., using the principle of thrust and gravity. Instead, his approach is guided by the basic idea of nature as an interplay of mutually opposing forces (Weltseele SW II 497f.). In this, he was inspired both by Kant’s physical theory of repulsion and attraction and by Kielmeyer’s idea that even biological processes are based on the principle of balance of opposing forces (Kielmeyer, 1993). The most adequate explanation of natural processes is thus, according to Schelling, to be found in contemporary dynamic chemistry, which works with this contraposition of forces. Still, even that theory is not quite satisfactory (see Schelling’s objections above) and dynamic chemical processes themselves ought to be derived from something more general. Schelling claims that the world as a whole is organic and he defines organicity as a succession of causes and effects ‘that enclosed within certain limits, flows back on itself’ (World Soul 70 = SW II 349) – and thus forms a sort of loop, a feedback system. In contrast, mechanical and chemical processes that take place in the world are linear. According to Schelling, they are merely a specific, one could even say fragmentary, form of the original organic whole. In them, the initially organic forces manifest themselves only in their extremely simplified, non-complex form. For that reason, we should view a chemical process as merely an ‘incomplete process of organisation’ (Weltseele SW II 499).

What then does the initial duality of opposing forces which constitute the organic whole of the world (which, as noted above, returns to itself), and all the phenomena in it, look like? The first force is expansive: if unchecked, it would keep on expanding into infinity. This force is to be understood as the original positive principle. The second force is negating, limiting, and it is this force that creates empirical phenomena, i.e., something finite. All individual entities thus share a positive force, while their individuality and multitude are constituted by their boundaries, i.e., by restriction (World Soul 73f. = SW II 381ff.; Weltseele SW II 502ff.). The positive principle shared by all phenomena is not, in itself, a part of any concrete phenomenon. Schelling calls it a ‘formative force’ (Bildungskraft) or ‘formative drive’ (Bildungstrieb) (Weltseele SW II 565ff.),Footnote 5 noting that in antiquity, it was known as the ‘common soul of nature’ (SW II 569). The negative precondition of natural phenomena then takes the form of material and chemical processes, which in general take place as mutually antagonistic effects of various negative forces. On the level of living beings, they must reach a certain level of complexity to be able to integrate the ‘vivifying’ effects of the positive principle (Weltseele SW II 567). Still, Schelling views only the positive principle as the cause or source of life, while the negative principles constitute only its necessary conditions (Weltseele SW II 505). The positive principle continuously stimulates and sustains the processes of life by upsetting or disrupting the balance of powers in the body (Weltseele SW II, 568). We have already seen that without this disbalance, living entities would not be alive. They would sink to the level of mere chemical processes and enter a state of ‘rest’ (Weltseele SW II 514) and ‘general neutralisation’ (Weltseele SW II 493).Footnote 6

The main problem of this approach is that the formative force or drive is transcendent, i.e., it is not part of the material world. That takes Schelling perilously close to vitalism, although – unlike the vitalists – he admits that the negative material/chemical processes are a necessary precondition of all manifestations of life. Schelling was aware of this shortcoming, which is why he tried to reformulate the conception in his following book on the subject, namely in the First Outline of a System of the Philosophy of Nature (1799) and in the Introduction (1799) which belongs to it.

The main starting point of the explanation of nature presented here is a theory of productivity. According to Schelling, we should not view nature as a mere sum of things or facts, but as constant transition and conversion between infinite productivity and its fixation in the form of products. Theories that start with the existence of fixed entities, such as atomism, must explain how and where change and development enter nature. Schelling’s starting point is the opposite: in his view, nature is constant movement and change, and what is to be explained is how stable and permanent entities enter the picture (First Outline 202 = SW III 284) (see Chap. 8). In Schelling’s scheme, particular entities can emerge only if, within the infinite productivity of nature, there is also the opposite tendency, one that tends to inhibit this productivity. Even that, however, merely places certain boundaries on productivity since on its own, this limiting tendency does not create individual entities. These emerge only when the initial productivity once again works against this limitation. At that point, a re-production takes place, and that fills the by now limited sphere by what we call reality. Schelling tries to elucidate this insight using the metaphor of a stream that runs into an obstacle which creates a whirl in it. Such whirl is not something fixed: it arises because new water (i.e., productivity) constantly rushes in to fill the space outlined by the obstacle. In this way, the whirl is constantly renewed (First Outline 18 note, 206 = SW III 18 Anm. 2, 289). In nature, particular things are thus not something absolutely constant and passive. Rather, they are just inhibited productivity and they come into being by an interplay of limitation and re-production. In this sense of the word, one could call Schelling a vitalist, because in his view nature is active, productive, and, indeed, vital. But it is not vitalism in the sense of the existence of some principles acting only and solely in living nature (e.g., see Kabeshkin, 2017: 1189, note 21). As Schelling puts it: ‘… the difference between organic and inorganic nature is only in Nature as object, and […] Nature as originally productive soars above both’ (First Outline 232 = SW III 326), that is, both realms are governed by the same principles.

All natural entities and phenomena are thus just limited manifestations of one and the same productivity. According to Schelling, one can use philosophy to reconstruct a certain mutual link between them, and thus find the ‘sequence of stages in nature’ (First Outline 6 = SW III 6) which take the form of various degrees of development (First Outline 215 = SW III 302f.).Footnote 7 The progressive character of this development then consists in the primary opposition between infinite productivity and limitation being potentised or heightened in the sense of gradual objectification of the subjective moment. In other words, the active, productive element of nature becomes increasingly more explicit in the product itself (First Outline 226–232 = SW III 317–326). In the second and third division of the First Outline, Schelling thus reconstructs the development of nature from matter, through magnetism and electricity to chemical processes, and from there to the organic powers (the power of reproduction, sensibility and irritability). The higher forms of natural phenomena and processes are irreducible to the lower forms and their description requires a specific conceptual apparatus that does not make sense at the lower levels of nature. Moreover, the levels or stages are mutually linked, because they are different forms of the same primary dualism of nature: the dualism of productivity and limitation. Schelling engages in attempts to reconstruct the several degrees of nature from the foundational ontological duality also in his later works, most notably in the System der gesammten Philosophie und der Naturphilosophie insbesondere (1804), without, however, making further substantial changes to the ontological framework.

The Conception of Living Beings

Once Schelling leaves the general approach to nature and the place of life in it and focuses on a conception of living entities and their specific way of existing, he largely follows Kant’s theory of organism (see Chap. 4). The main difference between his and Kant’s approach is that Schelling does not view his theory of living beings as merely a regulatory heuristic principle but rather as a description of their actual formation. In his view, a living being is specific above all by its organisation, that is, by the fact that it consists of a multitude of organs that have different functions and perform different activities, which are nonetheless united (see Chap. 3 for Aristotelian view and Chap. 10 for contemporary conception). We can view this unity as existing in two distinct senses: according to Schelling, there exists in organisms both a reciprocal final and reciprocal efficient causality between organs (the term Schelling uses to describe this reciprocity is Wechselbestimmung). The latter, efficient causality rests in the fact that organs mutually create and maintain each other in existence. One could thus say that an organism is its own efficient cause, it exists due to itself, and undergoes spontaneous self-organisation (First Outline 51ff. = SW III 65–68). Nevertheless, as Michelini (2020) correctly notes, that on its own would not be a sufficient explanation of the nature of living entities, because such cyclical link between the cause and effect can be found for instance even in the water cycle. What is also at hand are comparisons between Schelling’s theory and current theories of self-organisation (e.g., Kauffman, 1993), but if what those theories mean by self-organisation is that upon exceeding a certain threshold the system spontaneously starts establishing a certain order, it does not describe the core of Schelling’s explanation of living beings. This is because at the core of Schelling’s concept is the process of constitution of a self, a kind of active subject which aims at maintaining itself in existence and is thus its own purpose. In this context, one can therefore say that particular constitutive parts (organs) are present not only thanks to other constitutive parts (efficient reciprocal causality) but also because of the whole and because of other organs (reciprocal final causality). This conception is closer to current theories of autopoiesis and agency than to the abovementioned theories of self-organisation and theories of chaos (e.g., Maturana and Varela, 1980).

How does this self-constitution of the self which is its own purpose take place? We saw above that Schelling’s aim is not to explain the emergence of movement and change in nature but the opposite: how, in the infinite stream of productivity of nature, there arises something stable and permanent, in other words, how do particular entities emerge. On the level of living beings, this constitution of entities happens in a specific manner different from what we find in inorganic nature. Only on the level of living entities can we speak about individuals sensu stricto, that is, entities which do not dissipate in the processes they enter. Instead, they actively sustain their current identity. A living individual maintains its identity and reproduces itself by resisting the effects of external physicochemical forces and by separating or singling itself out from the external environment. Unlike inorganic entities, living beings actively sustain themselves by dynamically and continuously maintaining the difference between the self (Selbst) and the external world (First Outline 54 = SW III 70). Such self-sustenance by self-delimitation vis-à-vis what is outside is, however, not ‘innocent’. It amounts to more than mere resistance to external influences in the form of, for instance, thermoregulation in warm-blooded animals (First Outline 63 = SW III 83). Importantly, Schelling adds: ‘No individuality in Nature can, as such, maintain itself, unless it begins […] to assimilate everything for itself, to encompass everything within its sphere of activity. In order that it not be assimilated, it must assimilate; in order that it not be organised, it must organise.’ (First Outline 54 = SW III 70) Every living being is thus trying to maintain and sustain itself via external agency and active self-assertion (see Chap. 10) which takes the form of negating the independence of external things, and thereby also at the cost of those external things. A paradigmatic example of this is nourishment as a process of decomposition and assimilation of external substances and other living beings.

One consequence of the fact that living individuals actively keep themselves in existence is that – in contrast to non-living things – they do not merely occur. Their existence is based on activity and without activity a living individual ceases to exist. As Schelling says: ‘The organic distinguishes itself from the dead simply in that the existence of the first is not an actual being but rather a continual being-reproduced (through itself).’ (First Outline 107 = SW III 146)Footnote 8 Another specific feature of living individuals is that their identity is not based on the identity of the matter from which their bodies are built, because that keeps on changing through life. The identity of a living entity can thus be based only on the identity of its form, that is, its shape or likeness, and its specific manner of acting with respect to itself and the external world (e.g., System der gesammten Philosophie, SW VI 393). The abovementioned self-constitution of individuals by active setting of boundaries vis-à-vis the external environment involves a degree of self-determination and autonomy such as we do not encounter anywhere in non-living nature. Nevertheless, this autonomy does not imply any self-sufficiency of living beings or their independence of the environment. All living beings have some requirements and needs that can be met only from the other, in relation to what is outside (see Chap. 7). Later, Schelling, along with Hegel, called this basic feature of life desire (Begierde).Footnote 9

So far, in relation to characteristic activities of living beings, we spoke only about self-constitution and self-reproduction. According to Schelling, however, organisms exhibit also two other basic activities: irritability and sensibility. Schelling adopts this pair of concepts from Albrecht von Haller (1771), who means by sensitivity the ability to feel for instance pain and links it to nerves. By irritability, he means reactions to stimulation, which consists in the contraction or expansion of the relevant organ and is linked to muscles.Footnote 10 Schelling adopts this distinction and tries to derive these two activities from the internal dialectics of the abovementioned process of self-constitution of organisms. Within his system, irritability is viewed as an aspect of the differentiating relation of organisms to what is external to them, i.e., as an aspect of relation to other things as other things (System der gesammten Philosophie, SW VI 408ff.). Sensibility, on the other hand, is an aspect of organisms’ assimilation of what is outside. In this case, however, it is not a material assimilation, as in digestion where the other was disappearing due to organism’s action. Sensibility preserves the other as other while placing it into the organism. It is thus an ideative assimilation, where matter is transformed into its representation, into an immanent image of the other (System der gesammten Philosophie, SW VI 409).

Let us now return to the primary activity of organisms, which in a certain sense includes also irritability and sensibility, that is, to self-reproduction of organisms. So far, we spoke about self-reproduction only in the sense of organisms’ self-maintenance and active assertion of boundaries vis-à-vis the environment. But part of the phenomenon of self-reproduction is, according to Schelling, also reproduction, which brings us to the subject of the origin and development of individuals on the one hand and the issue of development of species on the other.

Development of the Embryo and the Development of Species

Let us start with a brief outline of the chief contemporary theories of reproduction and origin of new individuals, since they form the context within which Schelling formulated his concept. On the one hand, there were the proponents of the so-called preformism, a theory called in Schelling’s time – for us somewhat confusingly – ‘evolution theory’. Preformist theories assumed that embryos are in fact fully developed miniatures of adult individuals, including their pre-prepared, albeit miniature, organs. A version of this theory formulated in antiquity usually claimed that embryos, or rather ‘germs’, are all around nature (e.g., Hippocrates and Heraclitus). Later, in the Modern Era, they were already situated into adult individuals: according to some into the father, according to others, into the mother. These Modern theories then also had to assume that embryos are in effect encapsulated in one another (Einschachtelung) ad infinitum, so that an adult contains an embryo, which contains another embryo, etc. The other camp consisted of proponents of epigenesis, who supposed that the formation of new individuals takes place by the development of organs from an unstructured embryonic substance. But this formation of organs had to be stimulated and directed by some force, which for instance Caspar F. Wolff called vis essentialis. Blumenbach (1799), who had an immediate influence on Schelling, then spoke about nisus formativus or Bildungstrieb, that is, a force acting towards a certain goal that is present in living nature and completely absent in non-living matter. At most, one can find some hints of it for instance in crystallisation. Dominant in the seventeenth and eighteenth century was, however, preformism, because it better met the desideratum of a mechanistic explanation of nature, while advocates of the epigenetic theory with their assumption of a vital or essential force leading to the formation of matter were in a minority. A new form of the epigenetic theory made more substantial inroads only in the nineteenth century together with the development of the cellular theory (cf. Casetta, 2020).

Schelling’s contribution to this debate consisted in an effort to find some middle ground. He rejected the traditional theory of preformation, because it amounted to a mechanistic and strongly deterministic explanation incompatible with the productive character of nature (see above). At the same time, though, he was convinced that nothing in nature can arise completely anew and by accident. Schelling argued against the theory of preformation by pointing to the metamorphosis in insects, where for instance a caterpillar has a completely different organ of respiration than an adult butterfly and a completely different digestion apparatus, which corresponds to the different kind of food it seeks. Moreover, according to Schelling it does not make good sense to assume that one kind of organ of digestion is in a fully developed, though miniature, form present in another. ‘All of these phenomena prove that the metamorphosis of insects does not occur by virtue of the mere evolution of already preformed parts, but through actual epigenesis and total transformation.’ (First Outline 38 note = SW III 47 Anm.) On the other hand, epigenesis does not take place accidentally. There is a kind of predetermination, although it takes the character of preformation not of organs but rather of directions of the formative drive, which regulates the development of particular organs and which specifies given species (First Outline 37 note, 47ff. = SW III 46 Anm., 60ff.). It is important to note that these directions of a formative drive or natural predispositions (natürliche Anlage)Footnote 11 exist, according to Schelling, within a particular species always in multiple forms: only some of these predispositions are actualised, while others are not. The trigger that decides which of these tendencies will be realised takes the form of influence of the external environment (First Outline 44 = SW III 56).Footnote 12 Within a species, depending on differences in the environment, there can therefore exist various subspecies and varieties, which then persist by heredity (First Outline 46 = SW III 58). Schelling uses the term ‘species’ sensu lato, so that for instance wolves and dogs or horses and donkeys are varieties of the same species. According to Schelling, the defining feature of individuals belonging to the same species is the ability to have offspring – whether the offspring are fertile is then not relevant (First Outline 43, 45 = SW III 55, 57). But it seems he is not quite certain about absolute validity of this criterion: he notes that in many particular cases, it is difficult to tell whether there are two distinct species or just varieties of one species present, and one can decide only based on a thorough biological investigation of identity or difference of innate disposition (First Outline 49 = SW III 63). It is also important to bear in mind that Schelling’s approach to species is inclusive, so that each individual embodies a different aspect of the ideal of a given species, while no individual expresses the species in full and the ideal is embodied only in the sum of all individuals belonging to it. This conception differs from the reductive concept of species, represented for instance by Linnaeus, according to whom a species is characterised by a shared set of features which fully apply to each individual belonging to the species (for more on this, see Richards, 2002: 302). Schelling’s inclusive understanding of species also implies that there is no ‘original’ representative of a species embodying all future possibilities, a representative from which all other varieties had developed. Instead, each variety is a different, separate, and necessarily incomplete embodiment of the original predispositions of a given species whose particular realisation depends on the varying influences of the external environment.

These thoughts about changes within a species bring us to the subject of the origin of species. Schelling was the first to use the term ‘evolution’ – which, as we saw above, originated in embryology, where it referred to the development of preformed organs – in the sense of a particular process within the whole of nature, a process that has certain stages during which the complexity of organic forms increases (First Outline 42 note † = SW III 53 Anm. 1). Let us first revisit the basic ontological framework of Schelling’s theory of nature. We saw above that, according to Schelling, nature is infinite productivity and particular living beings are merely fixed and temporary manifestations of this productivity. Nevertheless, production does not take place chaotically: in nature, we can find particular degrees or ‘potences’ of this productivity and its products. They vary in the complexity at which the original opposition integral to all there is had developed. On the level of living nature, which is what we investigate now, ‘organisms overall are to be seen as only one organism inhibited at various stages of development’ (First Outline 43 = SW III 53), whereby particular stages correspond to the particular species of living beings. Schelling probably found inspiration for this conception, according to which particular species are just stages and points in the development of one general organism, in contemporary embryology. It posited that within a single individual we can distinguish various developmental stages and – as already Kielmeyer (1993) had noted, and Haeckel later famously expressed in his law of biogenetics – the stages of ontogenetic development are strikingly similar to some existing species or rather higher taxa.Footnote 13

In our attempt to reconstruct a particular sequence of the individual degrees, however, we cannot take as our starting point the individual ‘products’, that is, particular existing species, because it would be very difficult to find a continuity of development at this level (First Outline 43 note * = SW III 53f. Anm. 2). Instead, we should focus on the productivity of nature and its particular stages and forms, meaning we ought to investigate the functions and activities of living beings, by which Schelling means above all the abilities of self-reproduction, irritability, and sensibility.Footnote 14 Mutual proportions and consequently also the concrete forms of these functions can be, according to Schelling, at least in broad outlines derived a priori. In particular, in this way one can derive the basic classes of living beings roughly on the level of plants, fish, amphibians, insects, mammals, etc., where for instance plants display a clear dominance of the reproductive power but lack sensibility, while in mammals, sensibility is dominant, but the reproductive potence is relatively low (First Outline 52f., 147f. = SW III 68, 203f.). A more detailed investigation should be, according to Schelling, left to comparative physiology (see Chap. 12), not to comparative anatomy, since that focuses only on the shape, which is merely an outer manifestation of organic functions (First Outline 43 note †, 50 = SW III 54 Anm. 1, 65).

What does Schelling say about the evolution of particular stages of life? In his earlier book, On the World Soul, Schelling admits that the development of nature might have the character of transformation (Umgestaltung), where one species is transformed into another and this leads to the emergence of new species, although due to the vast length of period over which such processes take place, it is very difficult to show (On the World Soul 69 = SW II 348ff.). In the First Outline, he abandons this notion and instead claims: ‘The assumption that different organisms have really formed themselves from one another through gradual development is a misunderstanding of an idea which actually does lie in reason.’ (First Outline 49 = SW III 63) Development in nature thus should not be viewed in terms of descent and transformation in the sense that all higher species evolved from a shared ancestor, some primitive kind of organism. According to Schelling, we should instead endorse a traditional view according to which a once ‘fixed’ species characterised by a specific mutual relation of organic functions cannot change into another. Instead, by procreation it reproduces further ad infinitum (First Outline 49 = SW III 62ff.). In that case, does Schelling believe at all in successive development that leads from simpler forms of life to more complex ones? How do new species appear in nature? This is somewhat unclear, and two interpretations are possible.

According to the first, all species appeared simultaneously, at a point when one and the same power of productivity stopped, as if frozen in one moment, at various degrees of development dictated by the various possible mutual relations between organic forces. If that were all there is to it, all manners of predispositions which define particular natural species would come into being at the same time. There would be an ideal-typical hierarchical order among species, but no new species could appear. They could at most die out due to geological disasters or climatic changes, about whose existence Schelling had no doubt (this interpretation is advocated, among others, by Engelhardt, 1984). In that case, any more widespread change in the composition of living beings on Earth could take place only if Schelling understood the ‘species’ within which variation takes place in a very broad sense (with, e.g., quadrupeds or fish forming a species), and moreover, if he did not assume that a species is defined by its members’ ability to produce offspring together. This broad definition of species is ascribed to Schelling for instance by Richards (2002: 311), although he does not adduce any passage in Schelling’s writings to directly support this claim.

The second, and in my view more plausible, interpretation runs as follows: according to Schelling, there appear in the history of the Earth successively new and higher species. They do not, however, emerge via a transformation of older species. Instead, ‘in order to bring forth a new product, Nature would have to begin again from the start.’ (First Outline 49 note * = SW III 63 Anm.)Footnote 15 By this, Schelling probably means to say that new predispositions, which consist in new mutual relations of organic functions and are specific to the nascent species, appear because after the stage of inhibition of productivity, which corresponds to one particular species of living beings, nature’s productivity is renewed, and with it comes also a new and higher form of inhibition of this productivity, characterised by new mutual relations of the organic forces. This leads to the formation of a new species, which then maintains itself by reproduction, while the free productivity of nature is once again renewed. On the one hand, one can thus say about relations between species that ‘one product contained the ground of the subsequent one. The product C could not arise before B, and this not before A had arisen.’ (First Outline 49 note § = SW III 63 Anm. 2)Footnote 16 On the other hand, it is not so that a new species arises by direct transformation of a previous species. Individuals of the new species do not originate in individuals belonging to the previous species genealogically, and individuals of the previous species are thus not their real ancestors. Although it remains somewhat hard to grasp how, according to Schelling, individuals of a new species come into being, it seems rather clear that his thoughts proceeded in this direction, and he did actually assume the succession of new species in nature. One piece of indirect evidence can be found in the fact that he aimed the criticism contained in the First Outline against the theory of descent,Footnote 17 but voiced no objections against the more basic theory of successive development and formation of new species, which are both implied in the descent theory.

Conclusion

Schelling’s philosophy of nature influenced nineteenth-century German biology mainly in three areas. First of all, it offered a monistic theory of nature. This, in turn, enabled contemporary biologists to abandon materialism, which reduces living nature to physicochemical reactions, without adopting dualism of the vitalist kind. At the same time, it formulated a view of nature as a productive process, thus enabling a conception of living beings as self-organising subjects who actively maintain their identity by asserting their boundaries vis-à-vis the external world while engaging in reciprocal causality among their constituent parts. This processual conception of nature eventually led to the idea of development, which on the ontological level takes place epigenetically and on the phylogenetic level takes the form of a sequence of stages, in which an order of ideal types can be distinguished. We also saw that many of these views are inspiring to this day and resonate with some of the subjects of current philosophy of biology that formed in late twentieth century and are the main topic of this book (as attested by cross-references to other chapters). Closeness to especially the theories of autopoiesis and agency is mentioned above, but Gare (2013) goes even further. He argues that Schelling, with his striving to overcome the Newtonian paradigm and find a more adequate ontology that would help us grasp the physical world in a way that makes intelligible the emergence of life, provided both direct and indirect inspiration to anti-reductionist thinking in twentieth-century mathematics and theoretical biology. He identifies and reconstructs in detail this fragmented tradition involving mathematico-physico-chemical morphology (J. Needham, C.H. Waddington et al.), biosemiotics movement (J. Hoffmeyer, K. Kull, M. Barbieri, H. Pattee et al.),Footnote 18 and relational biology focused on anticipatory systems (R. Rosen).