I.i. The a priori status of nature and sound

Any excursion into Hegel's Philosophy of Nature must confront the vexed question of the a priori status of nature's intelligibility. How exactly does natural-scientific knowledge constrain Hegel's method of inquiry into nature? There are three main stances on offer: the a priori interpretation (Houlgate Reference Houlgate1998; Stone Reference Stone2005; Pinkard Reference Pinkard2012; Furlotte Reference Furlotte2018; Kabeshkin Reference Kabeshkin2019, Reference Kabeshkin2021; Sala and Kabeshkin Reference Sala and Kabeshkin2022), the a posteriori interpretation (Petry Reference Petry, Hegel and Petry1970; Webb Reference Webb1980; Burbidge Reference Burbidge1996), and one which aims to eschew the a priori/a posteriori distinction altogether (Rand Reference Rand2007, Reference Rand and Moyar2017).

The recent work of Anton Kabeshkin is helpful for navigating this debate. Against Rand, Kabeshkin argues that Hegel does not oppose the a priori/a posteriori distinction in general but only Kant's Manichaean deployment of it (Reference Kabeshkin2019: 204–205).Footnote ² Additionally, Kabeshkin shows that Rand inadvertently falls into an a posteriori reading, and further demonstrates that every a posteriori reading fails to provide a convincing explanation of Hegel's Philosophy of Nature due to its excessive focus on contingency—that which is least philosophically comprehensible for Hegel—as the very source of nature's intelligibility (Reference Kabeshkin2019: 201–206). In light of Hegel's repeated emphasis on the need for a philosophical proof of the laws of nature distinct from that provided by the natural sciences, Kabeshkin defends a uniquely broad a priori reading (Reference Kabeshkin2019: 206).

Kabeshkin's apriorism is broad because it is inclusive of what Alison Stone casts as strong and weak a priori interpretations of Hegel's Philosophy of Nature, its categories and transitions (Stone Reference Stone2005: 8; Kabeshkin Reference Kabeshkin2019: 206). According to Stone, strong apriorism first works out what nature is conceptually and then proceeds to compare this conception with empirical knowledge (Stone Reference Stone2005: xviii). Weak apriorism, on the other hand, begins with empirical knowledge, and then seeks to determine its conceptual necessity (Stone Reference Stone2005: 8). For Stone, Hegel's method is strictly, strongly a priori, and is incompatible with any weak a priori interpretation. However, recent Hegel scholars have not only launched trenchant criticisms of strong apriorism (Rand Reference Rand and Moyar2017; Kaufmann, Lyssy and Yeomans Reference Kaufmann, Lyssy, Yeomans, Stein and Wretzel2021), but explicitly defended weak apriorism against it (Furlotte Reference Furlotte2018; Kabeshkin Reference Kabeshkin2019).

In Kabeshkin's interpretation, Hegel employs a strong a priori method in certain circumstances and a weak one in others (Reference Kabeshkin2019: 196–97). Empirical knowledge need not challenge the validity of the conceptual derivation in question, nor need it imply a source of a posteriori justification, but it can still nevertheless guide Hegel's inquiry, just as a mathematician or logician might receive a ‘hint’ or a ‘certain step’ in a proof (Kabeshkin Reference Kabeshkin2019: 197). Such a broad and inclusive a priori interpretation is helpful for my introduction to Hegel's philosophy of sound because I believe that Hegel provides a weak a priori derivation of sound in his Philosophy of Nature, while still offering strong a priori justifications for other categories and transitions. That Hegel's inquiry into sound is not a strong a priori one is confirmed by Petry's a posteriori account: ‘In the treatment of Sound […] the major transitions demarcating the sphere as a whole were evidently suggested by the science of the day’ (Petry Reference Petry, Hegel and Petry1970: 89). As we will see, Hegel's view of the nature of sound was especially influenced by physicists of the eighteenth and nineteenth centuries, such as Ernst Chladni (PN: §300R, §301), Jean-Baptiste Biot (PN: §300R, §300A) and Johann Wilhelm Ritter (PN: §302). Significantly, however, his account is not simply justified by them. Rather, Hegel's metaphysics of sound celebrates the real contributions of the natural sciences, while also seeking to overcome their limitations.

I.ii. Hegel's Aristotelian ‘Physics’

Next to other spheres of Hegel's Philosophy of Nature, comparatively less has been written about Hegel's account of ‘Physics’ in recent years (exceptions include Petry Reference Petry1984; Halper Reference Halper and Beiser2008; Westphal Reference Westphal and Beiser2008; Winfield Reference Winfield2017). Famously, Hegel defines nature as ‘the Idea in the form of otherness’, as ‘external to itself’, and ‘externality itself’ (PN: §247). Yet, nature's externality comes in degrees and stages (PN: §252).

In ‘Mechanics’, Hegel is concerned with ‘matter and the ideal nature of the system of matter’ (PN: §252). There, ‘unity of form’ is only ‘implicit’, ‘merely sought after’ (PN: §252). At this stage, wholes are explained in terms of the causal interactions of their parts (Pinkard Reference Pinkard2012: 20). In ‘Physics’, on the other hand, ‘reality is posited with an immanent determinateness of form’ (PN: §252), and matter comes to participate in conditioned wholes which cannot be entirely reduced to their parts or causal interactions between them. Finally, with ‘Organics’, matter and form are most concretely unified in animals, in which parts are transformed into bodily members through functional roles in organic wholes (Pinkard Reference Pinkard2012: 20).

Multiple scholars have pointed to the Aristotelian influence on Hegel's concept of nature and ‘Physics’ (Findlay Reference Findlay2013; Santoro-Brienza Reference Santoro-Brienza1992; Ferrarin Reference Ferrarin2001; Halper Reference Halper and Beiser2008; Winfield Reference Winfield2017; Schuringa Reference Schuringa2022). Edward Halper submits that ‘when Hegel speaks of “Physics”, he has in mind the Greek term phusis and, in particular, Aristotle's understanding of phusis as an internal principle of motion’ (2008: 314). On this reading, whereas ‘Mechanics’ surveys the external motion of quantified matter, Hegel's ‘Physics’ aims to account for the inner motion and form of ‘qualified matter’ (PN: §271).

The greater ‘unity’ of form and matter found in Hegel's ‘Physics’ is suggestive of Aristotle's doctrine of hylomorphism. Though the concept of hylomorphism (from the Greek hyle matter and morphé form) is relatively recent, the meaning of the metaphysical doctrine has long been debated.Footnote ³ It is commonplace for Aristotle scholars to characterize the doctrine of hylomorphism as a mereological view that matter and form are elements or parts constituting the unity of any substance (Koslicki Reference Koslicki2008; Kelsey Reference Kelsey2010). Still, others have pushed back against this interpretation (Marmodoro Reference Marmodoro2013; Kosman Reference Kosman2013).

According to Marmodoro, the identification of a substance with its elements or parts reduces it to a kind of aggregate, and therefore cannot capture the unity of the substance that hylomorphism is supposed to explain in the first place (Reference Marmodoro2013: 15). To illustrate the problem, she points to Plato's distinction in The Theaetetus between a mereological and non-mereological whole (Marmodoro Reference Marmodoro2013: 5). While the former is construed as identical to its parts, ‘a non-mereological whole is identical to its enmattered form, and in this sense is partless’ (Reference Marmodoro2013: 5). Therefore, for Marmodoro and others, Aristotle's hylomorphism is non-mereological, since the unity of a substance does not simply result from combinations of form and matter as parts but from the functional and processual organization of matter by substantial form.

Significantly, Aristotle's doctrine of hylomorphism is a dynamic one: form is the activity of matter, and matter is a capacity for form (Kosman Reference Kosman2013: 70).Footnote ⁴ However, matter's capacity to take form does not simply exist independently of the form which actualizes it. What may have been separate material parts or elements in some static mereological entity cease to be those parts or elements in a hylomorphic process. For Marmodoro, material parts are ‘re-identified’, stripped ‘of their distinctness’, and endowed a functional role in the inner motion of the whole (Reference Marmodoro2013). Once the hylomorphic process is over form loses its internal hold over matter, which inevitably returns to its prior externality.

With Aristotelian hylomorphism in view, Hegel's ‘Physics’ can be understood as an inquiry into how matter begins to acquire substantial form. Accordingly, in the ‘Physics of Universal Individuality’, Hegel is interested in the most basic qualities individuating physical bodies beyond the mechanical sphere. In this chapter, where hylomorphic form is most inchoate, Hegel discusses the qualities of various astronomical phenomena (such as light, the sun, moons, comets and planets) (§§274–79), the elements as ‘subordinate moments’ of physical bodies (§§281–85), as well as certain meteorological occurrences (§§286–89). The ‘Physics of Particular Individuality’ then introduces a diverse set of qualities—‘Specific Gravity’ (§§293–94), ‘Cohesion’ (§§295–99), ‘Sound’ (§§300–302), and ‘Heat’ (§§303–307)—differentiating the constitutions of physical bodies and influencing their processual alterations. Lastly, the ‘Physics of Total Individuality’ constitutes the highest hylomorphic sphere in inorganic nature, since here, in the diverse shapes of magnetism (§§310–315), electricity (§§316–25), and the relative self-determination of what Hegel calls the ‘chemical process’ (§§326–46), form and matter are closer together than anywhere else in ‘Physics’.

Finally, it is important to bear in mind that when Hegel discusses individuality in these chapters, he is not referring to Einzelheit, the third moment of the Concept, but to Individualität (Kislev Reference Kislev2018: 2). According to Di Giovanni, this sense of individuality denotes ‘a special kind of individuality, one which is best realized in a person but for which we can see at least a first delineation in any internally organized object’ (Di Giovanni Reference Di Giovanni and Hegel2010: lxx). In my interpretation, the internal organization of ‘natural individuality’ in Hegel's Aristotelian ‘Physics’ is expressly hylomorphic.

I.iii. Specific gravity and cohesion in ‘Physics of Particular Individuality’

Hegel's ‘Physics of Particular Individuality’ charts how ‘matter is determined by immanence of form’ through the categories of specific gravity, cohesion, sound and heat, each of which comprises its four subsections (PN: §290). For Hegel, specific gravity and cohesion both concern the spatial organization of individual physical bodies, and sound and heat effectuate alterations of such organization in more or less permanent ways. In short, Hegel is arguing that all physical bodies have different specific gravities, degrees of cohesion, and resulting elasticities, which shape not only their capacity to be temporarily altered by sound, but more enduringly altered by heat (PN: §305A).

Specific gravity is the most abstract of these relational categories. It can be understood as the relation between the density of one substance and another ‘reference substance’ (Houlgate Reference Houlgate2022: 282), where density itself consists in the ratio of a body's weight and volume (PN: §293). Since bodies with the same volume can have different densities, they also have different specific gravities. To illustrate this difference in density and specific gravity, Hegel compares water and gold (PN: §293R). As Houlgate explains, water becomes a reference substance for most solids because it has a density of 1. Gold is 19.32 times as a dense as water and so has a specific gravity of 19.32 (Reference Houlgate2022: 282). In this way, specific gravity is a quantitative relation amongst qualities, a unifying ratio of independent measures, and thus a relation of real measure for Hegel.Footnote ⁵

Beyond density and specific gravity, bodies are distinguished from themselves and from one another through what Hegel calls cohesion, the formal spatial relationship that holds bodies together (PN: §292). Although every physical body possessing cohesion will have a specific gravity, Hegel is clear that a body's cohesion ‘bears no relation’ to its density (PN: §296A). For example, Hegel notes, gold is heavier than iron but nowhere near as cohesive or firm (PN: §296A). Further, Hegel stresses that it is ‘immanent form’ that ‘posits the spatiality of the separate existence of material parts’ in cohesion (PN: §295). This occurs in three different ways.

The first is what Hegel calls abstract, extrinsic ‘adhesion to another’ or ‘passive cohesion’ (PN: §296). Hegel often cites water as an example of this, and presumably he is thinking about fluids in general in this discussion (PN: §296A). Water's cohesion is ‘passive’ for Hegel because, though it is quite cohesive among non-metallic fluids, it lacks the active coherence of solids (PN: §300R).

In the second form of cohesion, matter is more active in its coherence, and therefore more solid. Active cohesion takes quantitative and qualitative forms, both of which are comparatively actualized in collisions with other bodies (Winfield Reference Winfield2017: 296). Quantitative cohesion is labelled ‘ordinary cohesion’ and is interpreted as the capacity of a homogenous mass to endure fragmentation (PN: §296). The qualitative cohesion of matter, on the other hand, discloses a body's ‘independence of form’ in response to ‘the pressure and impact of external force’ (PN: §296). This formal independence of a qualitatively cohesive body manifests itself in three tiers, which Hegel designates as ‘punctuality’ (brittleness), ‘linearity’ (rigidity) and ‘superficiality’ (malleability). His point is that brittle bodies cannot be stretched without breaking, rigid bodies continue to hold together when stressed, and malleable bodies, like certain metals, have greater ‘continuity’ still. In this way, qualitatively coherent bodies display ‘a specific mode of juxtaposition, i.e. a determination of space’ (PN: §296A), a conditioned form of spatial individuality.

The third and final form of cohesion, elasticity, consists in the displacement of a material body by a mechanical collision, and its oscillatory reformation in response. For Hegel, elasticity can be abstract and directed ‘outwards’, or more concretely ‘internal to the self-individualizing body’ (PN: §297A). Though density and cohesion are not dependent on each other, both directly influence the elastic body's capacity to deform and rebound, to move not just from one place to another but also in place (Winfield Reference Winfield2017: 302). In so far as this ‘giving way and preserving itself’ (PN: §296) is a necessary condition for the vibration of the body, elasticity marks the transition from cohesion to sound.

II.i. Hegel's ontology of sound

In this section I offer a close exegetical reading of the subsection on ‘Sound’ in the ‘Physics of Particular Individuality’. Despite the ambiguities surrounding Michelet's controversial arrangement of the additions to Hegel's Encyclopaedia, I agree with Stone that it would be ‘excessively restrictive’ to ignore these altogether (Reference Stone2005: xvi). My interpretation thus tracks Hegel's elaboration of the nature of sound from the main paragraphs of the subsection on ‘Sound’, while supplementing with the additions when helpful, and elucidating prominent influences on Hegel's weak a priori account when appropriate.

Hegel introduces sound in the final paragraph of the subsection on ‘Cohesion’ in the ‘Physics of Particular Individuality’:

In the ‘Quality’ section of the Logic of Being, Hegel defines ideality as a ‘process of becoming’ and as ‘the quality of the infinite’ (SL: 21.137). According to Bowman, ‘for something to be ideal is for it to be grounded in a process of which it is a moment and which it thus serves to realize’ (Reference Bowman and Moyar2017: 237). That which possesses ideality in Hegel is therefore either an ontologically dependent moment in a process, or a process with ontologically dependent moments (this multivocality of meaning is confirmed by Inwood (Reference Inwood1992: 126–27)). On my reading, such processes are hylomorphic, and the ideality of sound presents itself both as a ‘moment’ in a hylomorphic process and as the ‘individual’ form of one.

Why then does Hegel describe sound as a ‘double negation’?Footnote ⁶ Sound involves a double negation because the mechanical collision which results in it displaces the density and cohesion of the sounding body, which nevertheless resists this disturbance through its own internal elasticity. Sound's first negation thus arrives straightforwardly from mechanical impact, and its second negation consists in the sounding body's elastic pursuit of lost unity in vibratory response to this collision (Moland Reference Moland2019: 227, Sallis Reference Sallis, Houlgate and Baur2011: 375). The double negation of sound therefore serves to demonstrate the ineradicable embodiment of Hegel's concept of sound, designated here as: ‘the inner vibration of the body with itself’.

Hegel tell us more about sound's qualitative abduction of the physical body in §300:

In this passage, we are reminded that, for Hegel, bodies already have some degree of form through their density and cohesion, which sound liberates by articulating these qualities in time. Indeed, Hegel's claim that sound effectuates a transition from ‘material spatiality to material temporality’ announces his commitment to the temporal character of sound (Derrida Reference Derrida and Bass1982: 87; Hanly Reference Hanly2009: 360). Therefore, although sound is dependent for its existence on the temporal interactions of material objects, sound is unlike material objects in being essentially temporal for Hegel.

Hegel's hylomorphic view of sound comes to the fore in his emphasis on the ‘form’ of sound as ‘the ideality of materiality’ in §300. According to Hegel, sound transforms the material event in which it was a moment itself into a moment of sound. The qualitative process of sound negates the physical bodies, collisions and vibrations from which it derives and re-identifies these as sources of sound. Because sound sources cannot exist independently of the actual activity of sound, they only exist in potentiality for Hegel. Hence, sound is not just another moment alongside bodies, collisions, vibrations and propagations which connects them. It is the individual form of their relation. Hegel clarifies the hylomorphic character of this transformative event in the addition:

Accordingly, for Hegel, matter and form are included in the individuality of sound, but not as parts or elements. Rather, the ‘total form’ of sound brings unity—however finite and exterior—to the capacity of matter to sound in time. Once actualized, the hylomorphic event of sound negates itself, form and matter come apart, and sounding bodies and their juxtaposed parts are returned to their prior externality.

After explaining the ideality and negativity of sound, as well as its distinctively temporal and dynamic hylomorphic form, Hegel proceeds to explain how sounds are qualitatively individuated in the remark to §300:

Hegel describes this individuation of vibration as a kind of ‘ideality or subjectivity’ because, through it, sound becomes a subject in the sense of a substance, a locus of predication, a carrier of qualities.Footnote ⁷ Auditory properties—like pitch, volume and timbre—only come to belong to sound through its negation of the qualities of the physical bodies introduced in the ‘Physics of Particular Individuality’. Concretely, passive cohesion will sound quite different from active cohesion, and brittle bodies will sound different from malleable ones. Compared with solid bodies, Hegel notes that, ‘water has no cohesion and no tone’, and ‘gives rise only to a murmuring sound’ (PN: §300R). Glass and metal, on the other hand, ‘ring’, and instruments have their characteristic ‘tone and timbre’. Due to the ‘determinateness’ of vibration's ‘negation’ of the specific gravity, cohesion, and elasticity of sounding bodies, we might add that sounds are individuated not only by the qualities they possess, but by those that they exclude (Brandom Reference Brandom2019: 156), and by those excluded by the bodies, collisions and vibrations emitting sound.

To further illustrate the material specification of sound (Klang) by physical bodies and their qualities, Hegel introduces a distinction between noise (Geräusch) and sound proper, the latter of which he characterizes as tone (Tönen) (PN: §300R). For Hegel, we experience noise when a sounding body's vibration is posited by a body external to it, and the vibrations of both bodies subsequently disrupt one another (PN: §300A, 72, 15–17). Tone, on the other hand, is described as the ‘vibration of the body within itself’ (PN: §300A, 72, 15–17), and therefore exemplifies Hegel's definition of sound.

Hegel's differentiation of sound (as tone) from noise can be traced to Ernst Chladni. In his Treatise on Acoustics, Chladni argued that ‘If the vibrations of a sounding body are distinguishable, both in their frequency and in their change in shape, they are called distinct sound or sound properly called to distinguish them from noise, or indistinguishable vibrations’ (Chladni Reference Chladni and Beyer2015: 1). For Hegel after Chladni, noise involves interference between competing vibrations, whereas a (simple) tone, on the other hand, sustains only one frequency.

Complicating matters, in the addition to §300, Hegel offers a more formal tripartition of sound into 1) noise (Geräusch) 2) tone (Tönen) and 3) song (Gesang). Here, Hegel introduces song as the tonal, vocal, musical and lyrical sound of the human body: ‘There is also a third form in which external stimulation and the sound emitted by the body are alike i.e. human song’ (PN: §300A, 72, 24–29). Consequently, according to the main paragraphs, Hegel's concept of sound is illustrated by tone, but in the additions, it is typified by the tonality of human song. Since sound's concept must agree with itself (Pippin Reference Pippin2019: 96), we can conclude that noise is a form of sound that is not fully adequate to its own concept, tone is more adequate to the concept of sound, but the free articulation of the human body in song is the true concept of sound for Hegel, where sound most agrees with itself.

Another crucial feature of sound for Hegel is its propagation, whether that be air, earth, water, metals, etc. Importantly, this ‘transmission of sound’ is ‘soundless’ (PN: §300R), meaning that the propagation of sound is not itself sound because sounds are again necessarily indexed to the bodies which emit them for Hegel. Hegel's understanding of the propagation of sound was largely inspired by Biot, who, according to Hegel, proved that every body transmits sound, and moreover, that sound travels much faster and further in solid matter than in the air (PN: §300A).

If paragraphs §300 and §300R focus predominantly on the qualitative nature of sound, Hegel's understanding of the quantitative nature of sound becomes more explicit in §301 and thereafter. In these passages, we learn that the ‘inner motion’ of sound ought to be distinguished from other co-existent forms of mechanical motion, such as rotary or progressive motion, which involve an ‘external change of place’ (PN: §301).Footnote ⁸ Distinctively, Hegel argues that these two moments, of outer and inner motion, are both ‘identical’ and ‘different’ in sound.

Hegel then expands on the mechanical nature of sound in the addition to §300:

In this passage, Hegel is insistent that sounds belong to ‘the mechanical sphere’. Their ‘flight from materiality’ and ‘freedom from weighted matter’ remain ‘linked’ to it. Nevertheless, proclamations such as these also suggest that Hegel thinks of sound as a kind of emergent process (Döbereiner Reference Döbereiner2014: 27). In other words, while sounds belong to mechanical nature for Hegel, they do so as hylomorphic events conditioned by, but irreducible to, the lawful collisions they arise from.

With regards to the mechanical sources of sound, Hegel argues that the production of every sound requires two or more physical bodies. ‘Sound depends upon the striking of another body’ (PN: §323A) he exclaims, and these impacts constitute the causal sources of sound for Hegel. Furthermore, in the additions, Hegel informs us that sound can be produced in one of two ways: a) friction or b) vibration proper (PN: §300A). For Hegel, friction results from dry surfaces of bodies rubbing against each other, vibrating in contestation of one another. One example Hegel gives for friction is the scrape of a bow on a violin (PN: §300A, 72, 20). Another might be a pencil underlining its way across a piece of paper. Vibration proper is associated with the steady, distinguished vibration of tone, which Hegel refers to as ‘the elasticity of being-in-self’ (PN: §300A, 72, 8) since only certain bodies have the density and cohesion necessary to sustain it.Footnote ⁹ For Hegel, the specificity of tone thus depends entirely on the physical characteristics of the sounding body, as we hear, for instance, in the tone of a voice.

Though my focus in this essay is Hegel's philosophy of sound, it is worth acknowledging that Hegel articulates elements of his music theory in §301R (and the extensive addition to it). In the Aesthetics, Hegel claims that music treats sound as ‘an end in-itself’ (A: 899). Here, he provides a thorough account of the ‘specific numerical relationships’ involved in musical sound—defining ‘notes’, ‘key-notes’, ‘whole tones’ and ‘semi-tones’, ‘harmony’, and ‘melody’ in turn (PN: §301R). In passing, he also praises the violinist Giuseppe Tartini for his discovery of ‘terzo suono’, a third tone only made perceptible when two tones are played simultaneously, which implies that tone's qualitative character depends as much on auditory perception as it does on physical bodies and their qualities.

Finally, in paragraph §302, Hegel introduces his transition from sound to heat. Given that this is the paragraph that Popper casts as ‘gibberish’ (Reference Popper1950: 243), capturing its intelligibility will be important for my account. The paragraph begins with a reiteration of Hegel's view of the negativity of sound, before comparing sound and heat as distinct forms of ideality. Then, in the remark to §302, Hegel somewhat tersely asserts heat's conceptual origination with sound. Popper is not himself all that clear in his criticism here, but what appeared to bother him most was this latter claim (Reference Popper1950: 243). How are we to interpret it?

Hegel articulates the transition between the orderly motion of sound and the disorderly motion of heat by specific reference to the heat generated by sonorous bodies, a connection which Petry proposes was largely inspired by Ritter (Petry Reference Petry, Hegel and Petry1970: 297; Ritter Reference Ritter and Holland2010: 494–95). In doing so, he seems to be suggesting that the conceptual origination of heat in sound stems from the mere fact that sounds can generate heat. That said, in the specific context of the ‘Physics of Particular Individuality’, I think a deeper explanation of their co-origination stems from their shared ideality, understood here as the mutual and processual capacity of sound and heat to alter the density and cohesion of bodies. Hence, Hegel separates sound as an ideal form of ideality from heat as ‘real ideality’ in §302 because sound can offer only a momentary alteration of the density and cohesion of bodies, whereas heat may effectuate a permanent one.

Due to this ideality of sound and heat, Kabeshkin is correct to argue that neither sound nor heat are material objects for Hegel, but that both are instead moments of broader material processes (Reference Kabeshkin2021: 3). That said, in this section, I have also argued that Hegel conceives of sounds as metaphysical events or processes, the individual form of which remains irreducible to the mechanical matter which conditions them. In the next section we will see that, for Hegel, the form of sound is also that of hearing.Footnote ¹⁰

II.ii. Hegel on auditory perception

Though sounds are mechanical and physical processes for Hegel, auditory perception is not. Sounds are only heard by animals capable of hearing them. Further, they afford novel experiences for different species. Fully unravelling Hegel's views of auditory perception would take us well beyond the scope of this essay. Yet, no introduction to Hegel's philosophy of sound could ignore his insights into audition altogether.

In the Encyclopaedia, Hegel first discusses sensation in ‘Organics’. There, he divides the animal organism's sensory system into three categories: 1) the sense of feeling as such; 2) the sense of smell and taste; 3) and the sense of ideality, of sight and hearing (PN: §358). He tells us that ‘In sight, the physical self manifests itself spatially, in hearing it does so temporally’ (PN: §358). So, already for the animal, the contents of vision are spatial, whereas those of audition are temporal. While the objects of sight are ‘light’ and ‘colour’, the object of hearing is ‘sound’ (PN: §358). Further, Hegel defines sight and hearing as ‘theoretical’ senses, since in them animals do not sense themselves to the same extent that they do when they smell, taste or touch. Lastly, Hegel categorizes hearing as ‘a sense which belongs to the mechanical sphere’ (PN: §300A, 72, 32–34), since it (like touch) tracks external motion in the mechanical world.

Significantly, animals perceive not only sounds, but their own voices as well. Following Aristotle's account in De Anima (Reference Shields2016: 420b5–7), Hegel claims that sound is transformed entirely in ‘the animal's vocal faculty’, which reveals itself as ‘a free vibration within itself’ (PN: §351). In the additions, Hegel discusses this perception of the voice as ‘active hearing’ (PN: §358A), even suggesting that in nature ‘it comes closest to thought’ (PN: §351). For Hegel, the proximity of the animal voice to thought follows from its purpose of expressing feeling—‘pain’, ‘desire’, ‘contentment’, even ‘joy’ (PN: §351A). Intriguingly, Hegel contends that: ‘The theoretical emanation of the singing bird is a higher kind of vocal faculty however, and is so advanced that it has already to be distinguished from the general vocal power possessed by animals’ (PN: §351A). Hegel likely thought of bird song as a higher vocal faculty due to what sensory biologists refer to as its ‘temporal fine structure’, the combinatorial intricacy of its tonal arrangements in time (Yong Reference Yong2022: 225). Ethereal and language-like as bird song may be, the animal cannot raise its voice to thought for Hegel.

Turning now to human perception, in Hegel's ‘Anthropology’ we find that the threefold system of the senses has been inverted. Since the animal senses point towards human cognition and vice versa, this transposition speaks to Hegel's broader naturalism (Peters Reference Peters2016; Pinkard Reference Pinkard2012). Critically, for Hegel, human sensation is in part distinguished from animal sensation in being just one moment in human cognition (alongside consciousness, intelligence, etc). Furthermore, Hegel divides human sensation into two interdependent forms, ‘internal’ and ‘external’ sensation, rendering the former as sensation which enters the body through the mind (as in laughter or tears) and the latter as sensation which enters the mind through the body (as in sensory perception) (PS: §401). Consequently, external sensation is especially significant for interpreting human auditory perception in Hegel.

According to Julia Peters, external sensation is unique in Hegel because it ‘affords a bodily, sensuous form of self-awareness’ (Reference Peters2019: 167). In short, each sensory modality provides a form which shapes the content delivered through it. Sound is then the form of hearing as well as sounding, and the essence of sound, like colour, is equally manifested in the subjective realm of perception, and the objective one of ‘Physics’ (Peters Reference Peters2019: 183).

Building on Peters’ account of colour in Goethe and Hegel, we can conclude that the external sensation of sound has three important features. First, what we hear as sound is always determined by our finite human capacities for sensation in an environment (after all, we cannot hear frequencies below 20 Hz or above 20 kHz). Second, the sounds we do hear are also determined as unpleasant or pleasant (as noise or tone for instance), and this valencing is shaped by our broader goal-directedness. Third, what is most distinctive about the sensation of sound for Peters is its capacity to invoke specific moods in human beings. Hegel confirms, ‘it is tones in particular which evoke in us a corresponding mood’ (PS: §401A). Since, as Peters shows, moods are symbolic states for Hegel, tones beckon for a distinct kind of self-awareness in human beings.

The extent to which human auditory perception is saturated with conceptuality becomes more apparent in Hegel's ‘Phenomenology’ and ‘Psychology’ (McDowell Reference McDowell1994; Houlgate Reference Houlgate, Herrmann-Sinai and Ziglioli2016). Already in the ‘Anthropology’, Hegel intimates that mature human hearing is like other sense modalities, in so far as they unify ‘in one simple act the many determinations of sensation, consciousness, intuition and intellect’ (PS: §410R; see also Houlgate Reference Houlgate, Herrmann-Sinai and Ziglioli2016: 57). In ‘Phenomenology’, sensation is first introduced to thought through consciousness (Houlgate Reference Houlgate, Herrmann-Sinai and Ziglioli2016: 59). Yet, as we learn in the Phenomenology of Spirit—whether it be in the indexical episodes of sense-certainty, the happenstance predication of perception, or the lawful verdicts of the understanding—consciousness posits its objects without awareness of itself as doing the positing, hears without awareness of itself as hearing.

What Hegel calls ‘intelligence’ is self-conscious. It is divided into three phases of intuition, representation, and thought. Through intuition, intelligence concentrates its attention on what it hears. In representation, the self tracks duration, anticipates, and remembers. Yet, sound is fully comprehended in conceptual thought. Since, as Ikäheimo points out, such thought must take place in accordance with the judgemental forms outlined in the Doctrine of the Concept (Reference Ikäheimo and Moyar2017: 445), sound can be thought existentially or accidentally, ‘that sound is quiet’; or more reflectively, ‘but it has a tone’; or more essentially and necessarily still, ‘the tone of a voice’; or, finally, fully conceptually, ‘a beautiful voice’. We only come to appreciate the beauty of sound in thought for Hegel.Footnote ¹¹

III.i. Proximal, medial and distal views of sound

The central question for the philosophy of sound has been: what are sounds ontologically? If one is committed to sounds being located somewhere in space, and not, as Strawson believed, solely in time (Reference Strawson1959: 59–86), philosophers of sound have argued that there are three positions available: proximal, medial and distal theories. Proximal theorists treat sounds as mind-dependent phenomena, which are proximal to consciousness, and typically equated with sensations (Maclachlan Reference Maclachlan1989). Accordingly, on this view, if a tree falls in a forest and no creature is around to hear it, it does not make a sound. However, this theory of sound runs into ontological problems, since for any given sound there will always be as many sounds present as there are creatures hearing them (Casati, Dokic and Di Bona Reference Casati, Dokic, Di Bona and Zalta2020).

Medial theorists argue that sounds are mind-independent phenomena propagating from a source through a medium (Meadows Reference Meadows2018). The modern acoustic view of sound is the best example of a medial theory. In this picture, sounds consist of longitudinal pressure waves defined by frequency and amplitude travelling through a medium. Returning to our overfamiliar example, we can say that even if no creatures are present, the tree does make a sound from this perspective, and that this sound extends from the event of collision through a medium as far as soundwaves travel, since sounds and soundwaves coincide exactly.

Although the wave-based medial theory construes sounds as spatially and temporally extended events, philosophers of sound nevertheless argue that it fails to cohere with our experience of the locations and durations of sound. With regards to location, the problem is that we do not experience sounds to be travelling unless their sources do (O'Callaghan Reference O'Callaghan2007: 43). Rather, we hear them as occurring in or near their sources. With regards to duration, the medial theory conflates our experience of the spatial boundaries of sound with the temporal extension of sound, confusing our encounter with the duration of a soundwave bundle for that of a sound itself (Reference O'Callaghan2017: 20). Most contemporary philosophers of sound are thus convinced that the modern acoustic view of sound gives rise to ‘wholesale’ illusions (Pasnau Reference Pasnau1999; O'Callaghan Reference O'Callaghan2007; Casati, Dokic and Di Bona Reference Casati, Dokic, Di Bona and Zalta2020).

Finally, distal theorists claim that sounds are mind-independent phenomena located in the world near, at, or in their sources. According to this view, the falling tree again always makes a sound. However, whenever a sound is heard, it is also always heard from a distance and in a direction, close to its source.

There are three main camps of distal theories of sound: distal views of sounds as properties, dispositions or events. The property view proposes that we treat sounds as belonging to objects in the same way that colours, smells, or tastes do. Similarly, the disposition theory treats sounds as stable dispositions of objects to vibrate (Kulvicki Reference Kulvicki2008). The disposition theory can thus be understood as a version of a property view (Casati, Dokic and Di Bona Reference Casati, Dokic, Di Bona and Zalta2020). In these cases, the sound would belong to the tree, the forest floor, or both jointly. The problem is that, if sounds did permanently belong to objects as properties or dispositions in this way, we would be obligated to strip them of their temporal character, which conflicts with our perception of the duration of sounds.

Distal event theorists think of sounds as temporally extended events or processes, spatially located in, at or near their sources. Further, distal event theorists understand sounds as property bearing individuals, which ‘ground the grouping and binding of audible qualities’ (O'Callaghan Reference O'Callaghan2017: 17). There are two kinds of distal event theories—relational event theories and located event theories. In the former, represented most prominently by Casey O'Callaghan, sounds are ‘relational events’, which occur close to their sources, but necessarily relate sound sources and medium disturbances. In this case, sound is made by the tree only when its collision with the forest floor disturbs a surrounding medium, thereby sending soundwaves promulgating through the air, which transmit information about the distally located sound (without being that sound). In other words, for O'Callaghan, sounds are ontologically dependent on the transmission of soundwaves through a medium, which are included as part of the relational event of sound, even though sounds are not themselves soundwaves, and must remain situated near their sources.

Located event theorists, on the other hand, such as Roberto Casati, Jérôme Dokic, and Elvira Di Bona, construe sounds as ‘monadic events’ necessarily located in their sources in the vibrations of bodies. They describe their position as an ‘identity view’ because, for them, sounds are entirely equated with their sources and vibrations. In this perspective, the sound of the tree in the forest is not merely located near the tree's collision with the forest floor, but only in the collisions and vibrations of these sounding bodies (Casati, Dokic and Di Bona Reference Casati, Dokic and Di Bona2013). Hence, for located-event theorists, although sounds depend on soundwaves for their propagation and audition, sounds do not depend on soundwaves for their existence, and can in fact exist in a vacuum (Casati, Dokic and Di Bona Reference Casati, Dokic, Di Bona and Zalta2020).

III.ii. Hegel's hylomorphic located event view of sound

Since Hegel situates sound not only in ‘Physics’ but in the inner vibrations of physical bodies, we know he is not offering us either a proximal or a medial theory of sound. So, what kind of distal theory does Hegel provide?

Hegel clearly does not think of sounds as properties of objects like colours, smells, and tastes, or he would have discussed them alongside these in ‘The Particular Properties of Bodies’. One might still be tempted to consider Hegel's philosophy of sound as a disposition theory, however. Indeed, Kulvicki's claim that sounds result from ‘stable dispositions to vibrate in certain ways when thwacked’ (Reference Kulvicki2008: 6) appears quite close to Hegel's suggestion that ‘Bodies resound only when they are struck’ (§300A). However, disposition theorists deny that sounds are intrinsically temporal, and assert that though we perceive them this way, our perception of their transience is ultimately illusory (Casati, Dokic and Di Bona Reference Casati, Dokic, Di Bona and Zalta2020). Hegel's remarks on the temporality of sound are thus suggestive of a distal-event theory (PN: §291A, §300; A: 890). But of what sort?

Hegel's philosophy of sound shares a significant amount in common with both relational and located event theories. Beyond the fact that Hegel says nothing about the ontological dependence of sounds on soundwaves, his overt and repeated location of sounds within bodies (PN: §299), and his broader insights into the individuation of sounds by the density, cohesion, and elasticity of these bodies (PN: §300R), are straightforwardly expressive of some version of a located-event theory of sound.

That said, Hegel's located-event theory is clearly different from that of Casati, Dokic and Di Bona. Most importantly, Hegel does not simply equate sounds with their source collisions and vibrations. Rather, as we have seen, he explicitly characterizes the ‘inner motion’ of sound and the external change of place found in sound sources to be identical and different, and not simply identical. Accordingly, Hegel regularly distinguishes between vibration and sound: ‘this is why vibration is specified, together with sound itself’ (PN: §300R).

Ultimately, however, Hegel's account of sound is distinguished from all other distal-event theories of sound in not being mereological. O'Callaghan defends his philosophy of sound as mereological in two distinct senses, which he somewhat contradictorily runs together. First, sounds are construed as mereological parts of their sources: ‘such audible events audibly include sounds as constitutive parts. The sounds you hear audibly are mereological parts of such audible sources’ (Reference O'Callaghan2017: 4). Second, O’ Callaghan defines auditory objects themselves as ‘mereologically complex individuals—a collection of parts perceptibly belonging to a complex whole’ (Reference O'Callaghan2017: 113). How exactly are sounds both parts and wholes composed of parts? Without a broader metaphysics of nature, this problem is not fully explained by O'Callaghan.

In the end, the located-event theorists offer a mereological conception of sounds as well. They thus pose the question, ‘Is the mereological view the only possibility open to distal theories?’ (Casati, Dokic and Di Bona Reference Casati, Dokic and Di Bona2013: 463). Their response is, ‘In a sense, yes, but it can also be easily improved’ (Casati, Dokic and Di Bona Reference Casati, Dokic and Di Bona2013: 463). The proposed improvement lies in their ‘identity view’, which maintains that sounds are not parts of a distinct event but are rather identical to their event sources. The identity view then introduces a distinction between ‘event sources’ (the energy, collisions, vibrations, etc.) and ‘thing sources’ (the bodies, objects, thing, etc.) in order to discriminate ‘things’ involved in the event of sound without distinguishing sounds from their sources ontologically (Reference Casati, Dokic and Di Bona2013: 462). Casati, Dokic and Di Bona clearly clean up O'Callaghan's argument to some extent. Nonetheless, the unity they achieve remains abstract, since by their own lights they fail to answer the question of how sounds (as event sources) are related to the objects (thing sources) that produce them, a problem which itself hinges on the ‘metaphysical question of the relation between objects and the events involving them’ ((Reference Casati, Dokic and Di Bona2013: 462). Therefore, in the mereological metaphysics of distal-event theories of sound, we find either a disunified account of sounds as many, or an undifferentiated account of sounds as one, which attributes auditory qualities to event sources, and fails to explain the relation between sounds and the objects that produce them.

Though more remains to be said, Hegel's philosophy of sound points to some answers. As we have seen, Hegel describes sounds both as ‘moments’ and as ‘individuals’. Yet, in Hegel's non-mereological conception, sounds are neither themselves parts, nor are they composed of parts. Rather, Hegel's distinction between ‘moments’ and ‘individuals’ is expressive of his hylomorphic located-event view, in which physical nature is composed of nested and overlapping hylomorphic processes, and sounds appear, in one aspect, as dependent ‘moments’, and in another, as quasi-independent ‘individuals’ conditioned by the bodies, collisions, and vibrations that shape them. In this picture, there is only one event of sound, and yet sounds are both identical with and distinct from their ‘event sources’. Furthermore, sounds are explicitly related to ‘thing sources’ through a determinate negation of the density, cohesion, and elasticity of the bodies conditioning them. Hence, Hegel's non-mereological, distally located, hylomorphic-event view of sound is not only more unified than the relational event view but tells us more about how sounds are related to objects than the standard located-event view.