Liberty and representation in Hobbes: a materialist theory of conatus

ABSTRACT The concepts of liberty and representation reveal tensions in Hobbes's political anthropology that only a study of the development of his philosophical materialism can fully elucidate. The first section of this article analyses the contradictory definitions of liberty offered in De cive, and explains them against the background of Hobbes's elaboration of a deterministic concept of conatus during the 1640s. Variations in the concepts of conatus and void between De motu and De corpore will shed light on ideas of individuality, unity and agency that carry direct political relevance. The second section explains why the concept of representation that Hobbes elaborated at the end of the decade in Leviathan cannot be interpreted within an exclusively political and juridical framework. Rather, I will claim that it should be explained in the light of Hobbes's materialist theory of the power exerted by the sovereign persona on human imagination.


Introduction
Hobbes's political concepts, while formulated using terminology and presented in a framework that are mainly political and juridical, are imbued with the underlying materialist assumption that the reality they describe is ultimately 'nothing but' matter in motion. 1 This often produces a conceptual tension that is difficult to explain within the limited boundaries of what is usually classified as Hobbes's political thought, and which becomes particularly evident when one studies his political anthropology. Natural freedom, conceived as the materiality of human natural motions, poses the problem of having to generate the citizens' artificially ordered exercise of liberty within the body politic, the unity of which is realised through the mechanism of representation. The simplicity of this formula, however, hides problems related to the concepts of 'liberty' and 'representation' that only an accurate analysis of the parallel development of Hobbes's natural and civil philosophy can disentangle. How can human liberty and political representation be conceptualised and how can they even be thematised in a mechanical universe made exclusively of matter in motion and ruled by the laws of physics? My intention here is not to show that Hobbes ultimately answered these questions, but rather to analyse how some of their implications influenced the development of his political thought, in which materialism played a crucial role that is still to be fully elucidated. 2 The methodological assumption of this paper will be that all the concepts present in Hobbes's political theory were meant by their author to be compatible with a materialist ontology and with the overall purpose of founding a system of sciences based on the model of geometry. This does not mean that I will consider Hobbes's political concepts to be directly dependent on his physics of motion, but I will oppose Tom Sorell's conclusion that Hobbes's civil science 'does not depend on knowledge of physics and geometry'. 3 The reason for this is that, as Noel Malcolm admits, while there is no single underlying pattern of scientific method connecting Hobbes's natural and political philosophy, Hobbes consistently believed that, at least in principle, human nature could be described in mechanical terms. 4 This poses a quite remarkable problem of interpretation that becomes particularly acute when Hobbes explicitly places political theory within the framework of his systematic attempt to found all sciences on mechanical materialism, as he does most notably in De cive, the political treatise he embeds within the lifelong philosophical project that he names Elementa philosophiae. 5 In De cive Hobbes openly commits himself to founding a new scientia civilis as the third pillar of a system of sciences, and is therefore obliged to elaborate a philosophical anthropology compatible with both the descriptive aim of natural philosophy and the normative purpose of civil philosophy. 6 Because of the peculiar collocation of De cive, this article starts by exposing the tension implicit in the contradictory definitions of liberty offered by Hobbes within it. De cive provides both a purely mechanistic and a deterministic definition of liberty as a 'corporal' 'absence of impediments to motion', and a more traditional reference to the role played by 'accident' or 'choice' in human behaviour (DC, IX.9; OL II.259). This patent contradiction is no mere mistake, it is the symptom of a crucial problem implicit in the task Hobbes assigned to his research, namely to make political theory compatible with the mechanical world view that was being elaborated in the light of the Galilean revolution. Hobbes's attempt to achieve this task proceeded through a reformulation of many traditional concepts that political and legal thought had usually grounded on human agency and responsibility, and pushed him to privilege certain aspects of traditional materialisms over others. In this sense, Hobbes's system was in fact a work in progress, entailing philosophical choices that had at the same time ontological and political stakes.
In this vein, I will argue that the changes in Hobbes's natural philosophy during the 1640s had far-reaching implications for the coherence of his political thought that cannot be fully understood within the context of the 'political agenda' considered in Quentin Skinner's analysis of the development of Hobbes's political theory between The Elements of Law and Leviathan. 7 My aim is to show how the conceptualisation of liberty as well as the introduction of the idea of representation in Hobbes's political works interacted with the materialist 'philosophical agenda' he was pursuing over the same timeframe, the core of which was the elaboration of the concepts of conatus and void, and the development of a radical form of determinism. By doing so, I will show how the study of Hobbes's political ideas can be illuminated by issues that, strictly speaking, extend beyond the field of political thought.
In the first part of my essay I will describe the changing conceptions of liberty in Hobbes's political thought within the wider context of his system: the absence of a definition of liberty in The 2 This article adds layers of historical complexity to the analysis of ontological themes explored by other materialist readings of Hobbes's political thought (e.g. Frost, Lessons from a Materialist Thinker). 3 Sorell, 'Hobbes's Scheme of the Sciences', 56-7. 4 Malcolm, Aspects of Hobbes,155. 5 This was the title of the 1668 collection that included De corpore, De homine and De cive as well as the Latin version of Leviathan. Although De cive was written in 1641, before the completion of the other parts of the system, its original title -Elementa philosophiae Sectio Tertiatestifies to the systematic design to which it belonged. 6 Bardin, 'Materialism and Right Reason in Hobbes's Political Treatises'. 7 Skinner, Hobbes and Republican Liberty.
Elements of Law when Hobbes's mechanics was still at its inception, the problematic elaboration of the concept in De cive while Hobbes was pursuing his work on mechanics at the court of Mersenne in Paris, and its inclusion within a mature form of ontological determinism in Leviathan. The concept of conatus will be perfectly suited to the purpose for two reasons. Firstly, because it spans both Hobbes's natural and civil philosophy, serving as the explanation for all kinds of bodily motion, natural and artificial. 8 Secondly, because its development can be consistently connected to subsequent changes in Hobbes's political theory. Variations in the concept of conatus will be studied specifically in relation to the concepts of void and necessity theorised in Hobbes's natural philosophy, in order to show how these concepts connected with ideas of individuality, unity and agency that have direct political relevance.
In the second part, I will explain the central place that Leviathan's concept of representation occupies in Hobbes's later political theory by moving away from an exclusively political and juridical reading of the concept and focusing specifically on the materialist basis of Hobbes's theory of imagination. 9 I will maintain that the concept of representation set out in Leviathan can be interpreted as an attempt to solve a problem implicit in De cive's political treatment of the concept of liberty, and is therefore strictly related to Hobbes's elaboration of the concept of conatus during the 1640s. At the end of the decade, Hobbes deemed the concept of conatus to have been satisfactorily integrated within a deterministic theory of matter in motion. The term conatus referred to both the epistemological 'principle' [principium] and the ontological 'beginning ' [principium] that could explain and cause the unity of a body. 10 Correspondingly, the concept of representation, the radical theoretical innovation of Leviathan, was able to serve Hobbes's dual intention of establishing the principle of the unity of the body politic and of describing how within it the causal power of the artificial or 'fictitious [ fictitia]' persona of the sovereign exerted itself over human imagination. 11 Hobbes's concepts of liberty and representation thus came together in the theorisation of the effective 'Fiat' that was meant to institute, through the material power of imagination, the 'artificiall life' of a body politic.

Liberty as conatus: the issue of determinism
In De cive Hobbes felt it necessary to define explicitly the liberty he had previously conceived in The Elements of Law as 'nothing else but [a man's] natural power' (EL, II.1.18). In De cive liberty was connotated, as indeed it had been in The Elements of Law, as the characterising feature of the state of nature, but it was also specifically defined by Hobbes as one of the founding concepts of his entire political theory. Because of this, 'liberty' was forced to incorporate both the dangerous libertas of the multitude in the state of naturethe natural, 'disordered' motion of uncivilised humans unsuited to the body politicand the ordered motion characterising the political liberty of those subject to imperium, as depicted on De cive's frontispiece up to the third edition. 12 These two kinds of human 'motions' were in tension because they could not, in Hobbes's monistic materialism, be assumed to belong to different ontological domains. Human liberty had to be explained 8 Barnouw, 'Le vocabulaire du conatus', 103-24. The physical concept of conatus can also account for human psychology and political anthropology. See Jesseph, 'Hobbes on "Conatus"', 78-82; Van Apeldoorn, 'Rationality and Freedom in Hobbes's Theory of Action', 620. 9 The school of Padua's version of 'conceptual history' takes Hobbes's concept of representation as marking the beginning of a specifically modern political science that would reduce the 'political' to the 'juridical' (Chignola, 'History of Political Thought and the History of Political Concepts', 534-41). I am instead exploring the tension between the 'physical (or quasi-physical)' terminology and the 'juridical' anthropology displayed in Hobbes's political theory (Balibar, 'What is "Man" in Seventeenth-Century Philosophy?', 223-4). 10 The ambiguity in Hobbes's use of the term 'principium' in both the epistemological and the ontological sense should not be taken as an inaccuracy, but rather as a proof of his materialist understanding of geometry as well as of physics. See Jesseph, Squaring the Circle, 73 ff.

11
In this sense, the 'link' between Hobbes's natural philosophy and his political theory certainly 'has to do with fiction' ( as one of the causes concurring with the physical formation of the body politic and at the same time studied as an element of the body politic's theoretical construction. This tension generated different definitions of liberty in De cive, the problematic, if not contradictory, nature of which has been a shared assumption in Hobbes scholarship. 13 Hood is perhaps the first to point out clearly that, in general, Hobbes's concept of a 'liberty to do or to forbear' in accordance with one's own last appetite depends on a 'corporal' concept of 'liberty in the proper sense'. 14 This is what eventually allows Hobbes in Leviathan to univocally conceive liberty as 'the absence of externall Impediments' (Lev,XIV.198), which 'may be applyed no lesse to Irrationall, and Inanimate creatures, than to Rationall' (Lev, XXI.324). Despite believing Hobbes's conceptual development as a whole to be consistent with his materialist framework, Hood cannot avoid noting an anomaly in De cive, which also defines human liberty in terms of an absolute absence of arbitrary impediments, making explicit mention of the possibility of choice [electionem nostram] and conceding implicitly that chance [accidens] might also play a role in the process (DC, IX.9; OL II.259). Hood, however, limits himself merely to registering the anomaly, and concludes that, following the dispute over the issue of liberty and necessity in which he and Bramhall first engaged in 1645, Hobbes realised his mistake and corrected it by restricting Leviathan's definition of liberty to the absence of external impediments. 15 Jackson also considers the revisions added by Hobbes to De cive's 1647 edition, 16 which had a new Praefatio ad lectores and some new explanatory notes, but he does so only in order to underline the surprising lack of additional thoughts on the topic of liberty in the treatise. 17 All these additions had already been made by early 1646, 18 meaning that Hobbes could have included a response to Bramhall's attack of his doctrine of liberty and necessity but did not do so. Indeed, the 1647 edition does not contain even a single passage dedicated to clarifying the issue of liberty, and the only action ever taken by Hobbes to correct this comes in Leviathan, in which he provides his final definition: 'LIBERTY, or FREEDOME, signifieth (properly), the absence of […] externall Impediments of motion' (Lev, XXI.324).
In Skinner's more wide-ranging argument, theoretical reasons and political motives are intertwined. While he accepts Hood's thesis that the definition of liberty presented in De cive is simply an error later amended in Leviathan, Skinner sees the development of Hobbes's political thought in the 1640s as a path marked by his distinctive 'political agenda', the strategic defence of absolutism against republican theories of liberty. In Skinner's reconstruction this path was marked by Hobbes's progressive abandonment of the dream of providing a politically effective civil science still held in The Elements of Law and De cive, which subsequently led him in Leviathan to endorse fully the use of rhetorical strategies for political purposes. It is therefore for reasons of logical coherence as well as political motives that, according to Skinner, Hobbes modifies the concept of liberty throughout his three political treatises: liberty is initially 'described' and 'circumscribed' in The Elements of Law, 'defined' in De cive, and eventually 'redefined', that is reduced to 'liberty from external impediments', in Leviathan. 19 The natural liberty described in The Elements of Law as the undesirable alternative to the obedience completely lost by political subjects becomes, in De cive, a natural power absorbed, but not erased, within the citizens' libertas civilis. Finally, the rediscovery of humanist rhetoric in Leviathan allows Hobbes to 'redefine' liberty so that it can at the same time be recognised as a natural fact and radically denied as a political right of subjects facing absolute sovereign power. 20 In other words, while in The Elements of Law natural liberty continued to lurk dangerously 13 Scribano, 'La nozione di libertà nell'opera di Thomas Hobbes', already counted three contrasting definitions. 14 Hood, 'The Change in Hobbes's Definition of Liberty', 155-6. 15 Ibid., 155, 159. 16 This 'second' edition, published in the Netherlands in 1647, was in fact the third: it followed the publication of few copies circulated among friends by Mersenne in 1641, and the 'first' edition published in 1642. 17 Jackson, Hobbes, Bramhall, 123. 18 Malcolm, 'General Introduction' in Lev, vol. 1, p. 2. 19 Skinner, Hobbes and Republican Liberty, 157. 20 Ibid., 162-4.
behind the scenes of political order, in Leviathan it was fully absorbed within the mechanisms of sovereign power. 21 Even taking into due consideration the anomaly represented by the contrasting definitions of liberty offered by De cive, all the aforementioned explanations appear unsatisfactory for at least two reasons. Firstly, they ultimately fail to account for why, in De cive, Hobbes provided a definition of liberty as the 'absence of arbitrary impediments'. Secondly, they fail to question the lack of explanatory notes on the topic of liberty in the second edition of De cive, in which Hobbes did clarify other problematic issues that emerged from his dispute with Bramhall. More generally, the scholarship tends to focus on Hobbes's political agenda, and does not question the changing conception of liberty in Hobbes's ontology and epistemology. By contrast, a specific focus on Hobbes's philosophical agenda is instead crucial to my reading. Since De cive was intended to provide a systematic and definitive foundation for the new civil science within the context of the Elementa philosophiae project, a conception of liberty suited to describing the political stakes of human nature also found its way into a broader explanation of the natural motion of material bodies.
The theoretical problem Hobbes was facing at this stage may be formulated as follows: How can multiple natural human liberties be made to converge into the artificial unity of a single body politic? In the 1640s this theoretical exigency helped push Hobbes to reconsider the very concept of conatus (in English endeavour), the ultimate foundation stone of the mechanical (i.e. scientific) explanations present in all areas of his philosophy. A whole set of ontological and epistemological issues connected to this concept was in fact relevant to the theory of the body politic, and this is worth taking into account when analysing the crucial changes that Hobbes's political theory underwent over the same period. Evidence for the shifting meaning of conatus can be found in the different understanding of the concept in De motu (1642-43) and De corpore (1655). 22 An analysis of these texts reveals a changing conception of the individuality of a body, and therefore of its agency, which is of relevance to Hobbes's concept of conatus and to his adoption of an increasingly open deterministic ontology during the 1640s.
In De motu, which was written soon after De cive, the term conatus carries both an ontological and an epistemological meaning. Conatus is the 'actual motion [motus actualis]' of a whole body, or of its inner parts, and at the same time ambiguously 'identical to the principle of motion [motus principium]' that explains it. At the ontological level, conatus refers to the local motion that is continuously transferred from one body to another: 'conatus lies in the fact that a body that tends [conans] is moved [moveatur]'. 23 This uninterrupted chain of local motions makes it quite difficult to distinguish individual bodies, thus calling into question the very concept of individual agency. The ontological homogeneity of the matter involved in the flow of a river, human life, and the body politic [civitas], is assumed to be more or less self-evident. Only the 'actual motion' of a body, its uninterrupted 'flux [fluxus]', can define, despite the changing elements of the matter composing it, the persistence of an individual being [Ens], whether a person or a body politic: When the motion and the flux are one and the same, the river will also be one and the same. Likewise if one asks whether a man, when old and young, is the same Being, or body, in number it is clear that, because of the continual casting of matter and the acquisition of new, it is not the same matter, and hence not the same body; yet because of the unbroken nature of the flux by which matter decays and is replaced, he is always the same man. The same must be said of the body politic [de civitate]. When any citizen dies, the matter of the body politic is not the same, i.e. it is not the same Being. Yet as long as the order [ordo] and motion of government [regiminis], whence the body politic is named, remain as one, the body politic is the same in number. 24

21
Piccinini, Corpo politico, 76-7. 22 Hobbes wrote the MS just after completing De cive, as an analytical critique to Thomas White's De mundo. The book covers most of the physical doctrine Hobbes later included in De corpore (Schuhmann,Hobbes,une chronique,76). Evidently the element that makes it possible to individuate (homogeneous) matter at the epistemological level is the specific kind of motion characterising each individual. However, how motion works at the ontological level more generally is far less clear, as is the question of how a specific motion can be separated from others and hence how an individual body can actually 'be', independently of others. Perhaps the Epicurean concept of an empty space separating different bodies could have made full sense of the individuality of bodies and their agency, but Hobbes always refuted the idea of a macroscopic void. 25 As a matter of fact, in De motu the unity of an individual being can certainly be determined on the basis of the consistency of its motion, but the ontological 'cause' of its individuality is hardly explained, meaning that the epistemological and ontological levels of analysis remain somewhat detached.
Some years later in De corpore, however, Hobbes solved the problem by shifting the very focus of his understanding of the concept of conatus and its relation to the individual being. A version of the passage from De motu cited above is included in De corpore, but with some notable variations. The term 'principle [principium]' now also refers to conatus as the 'beginning of motion' in an ontological sense. The individuality of an ens is no longer defined by the consistency of the 'flux [ fluxus]' or of 'government [regimen]', but specifically by 'the beginning of individuation [principium individuationis]' (DCo, XI.7; OL I.120), that is by the first 'generative' motion on which all subsequent motions depend, whether we are referring to a 'fountain' or the 'institution' of a 'city [civitas]': [I]f the name be given for such form as is the beginning of motion, then, as long as that motion remains [manente eo principio], it will be the same individual thing; as that man will be always the same, whose actions and thoughts proceed all from the same beginning of motion [eodem principio (scilicet eo quod fuit in generatione)], namely, that which was in his generation; and that will be the same river which flows from one and the same fountain, whether the same water, or other water, or something else than water, flow from thence; and that the same city [civitas], whose acts proceed continually [continuo derivantur] from the same institution [institutione], whether the men be the same or not. (DCo, XI.7; OL I.122) Conatus, conceived as an imperceptibly small 'first motion' can thus both cause the individuality of a body and be the principle of its knowledge. A body's conatus is, in short, the 'principium' that provides both its ontological unity and its epistemological definition. 26 However, this is only possible because all the subsequent motions of that body are the effects of the initial conatus that 'institutes' it, and therefore the knowledge of the former is the sufficient and necessary condition of the knowledge of the latter. Only a deterministic conception of matter in motion, human and civil matter included, can legitimise a view in which conatus is a 'principle' both in the sense of being an ontological cause and an epistemological explanation of the individuality of a body.
At this point, few scholars would refuse to describe Hobbes's materialist mechanics as deterministic. However, by accepting this label they would risk perceiving as an invariant determination of Hobbes's philosophy something that was in fact the result of a process full of hesitations and contradictions. This path runs from The Elements of Law, through the violent epistolary dispute with Descartes on optics and metaphysics and the writing of the first version of De cive in 1641, to the quarrel with Bramhall in May to July 1645. It was at that final point that Hobbes openly formulated his theory of necessity, after which he was also forced to deny consistently the existence of void as such, something that he accepted the need to do in around 1646-1648. 27 Once void had been eliminated, the chain of causes connecting the initial conatus to all subsequent motions in each individual body was closed, and a body's conatus, conceived as the 'first motion', could unfailingly become the 'principium' of that body, that is both the 'beginning' of its existence and the 'principle' of its 25 Hobbes long hesitated on the subject of void, particularly in his optical and physical writings, at times adopting the concept of a microscopic void (vacuum disseminatum), but he always rejected the idea of a macroscopic void (vacuum coacervatum) (Shapin and Schaffer, Leviathan and the Air Pump, 82-91). 26 See note 10 above. 27 Bernhardt sees this turn as accomplished only after 1649 (Bernhardt, 'La question du vide chez Hobbes', 225), while Sergio situates it between February-April 1648 (Sergio, Contro il Leviatano, 227-43).
knowledge. At that point this series of philosophical assumptions signalled the full integration of determinism into Hobbes's mechanical philosophy.
In the dispute with Bramhall, Hobbes had to clarify his radical stance on determinism and draw all its implications for the relation between natural liberty and political power. When challenging Bramhall's concept of liberty, Hobbes had to develop a definition that would suit both his materialism and his political theory. Hobbes's materialism did not allow for any ontological difference between the 'last deliberation'that is the individual 'will'of men, animals, children, and 'fools and madmen' who 'manifestly deliberate no less than the wisest men' (LN,II.8.19). 'Election' or 'choice' follows from the process of deliberation as an effect, and it precedes the action as a cause, and there can be no ontological difference between the actions (that is motions) of different kinds of bodies. From this perspective, vacuism was not only politically dangerous because 'speech on vacuum was associated' with a subversive subculture, 28 but it was also ontologically dangerous because it surreptitiously introduced the possibility of a metaphysical liberty that would make human behaviour slip beyond the grasp of science, and most notably political science. Only in a voidless universe made exclusively of matter in motion could the issue of human liberty and agency be firmly inscribed within the more general knowledge of natural necessity (LN,II.11.20).
The case, however, is not as simple as it might seem. Hobbes's universe is indeed a complex one made up of an 'innumerable number of [causal] chains joined together' and concurring as the 'whole cause of an event' (LN,II.11.20). This totality, however, always remains beyond the grasp of human knowledge because truth can only be verified 'by every man's own sense and memory' (LN, II.33.39), and no individual can experience the totality of the universe. 29 Thus in principle universal determinism should be no more than a hypothesis responding to the need to theorise a reality which is, as a whole, by definition inaccessible. But this was not the case. At the time of the Treatise the die was cast, and Hobbes rejected the concepts of fortune and contingency as merely the marks of imperfect knowledge, doing so on the basis of an unyielding ontological belief: 'by contingent, men do not mean that which has no cause, but that which has not for cause anything that we perceive' (LN, II.16.28). In the radical form of determinism being adopted by Hobbes at that moment, the whole set of 'joined together' causes led back to the 'first link God Almighty' that was their first cause. This 'concourse of causes' could thus be conceived in a way that closely corresponded to the suggestion that Descartes had long been making, namely that the 'laws of nature' in a physical sense were attributable to 'the decree of God' (LN,II.11.20). 30 As such, De cive's concept of 'arbitrary' impediments no longer made sense.
From The Elements of Law onwards Hobbes had made clear that he would not allow any theological solution (either positive or negative) to the question concerning free agency and natural necessity to become part of his materialist framework. 31 In De cive he made clear that he did not believe that the philosophical issue of free will had been solved by either the Stoics or the Epicureans (DC, XV.14; OL II.178), while in De corpore he continued to deny that a 'philosophical belief' in God as 'first cause' could be transformed into rational demonstration. 32 In the latter work, however, he did incorporate an accomplished form of ontological determinism into his materialist framework. It is perhaps legitimate to conclude with Leijenhorst that Hobbes maintained in De motu an 'epistemological autonomy' of the secondary causes, although he could not conclude their 'ontological autonomy' from a supposed first cause. 33 While in De motu he had only accepted the hypothesis of determinism, in the Treatise he reduced contingency to a mere limit of knowledge 28 Shapin and Schaffer, Leviathan and the Air Pump, 91. 29 Even 'the foreknowledge of God' 'cannot be truly said' a cause. LN, II.11.20. 30 Descartes, 'Letter to Mersenne ', 145. 31 What is 'under the name of fate and contingency, disputed between the Epicureans and the Stoics' should 'not [be a] matter of faith, but of philosophy' (EL, II.VI.9). 32 He explicitly denies such an argument can be demonstrated 'by reason' in DCo, XXVI.1; OL I.335-6. 33 Leijenhorst, 'La causalité chez Hobbes et Descartes',116. Indeed, Hobbes eventually rejected many of the concepts he had provisionally adopted as working hypotheses in De motu, such as the 'plausible hypothesis' of astrology (Paganini, Introduzione, 41).
(LN, II.16.28), and in De corpore he finally assumed natural determinism as a fact by means of the concept of the unity of the 'whole cause [causa integra]' (DCo, IX-X; OL, I.106-17). This progressive shift, completed at the end of the 1640s, from the hypothetical assumption of natural necessity as a postulate driving philosophical inquiry to a fully-fledged and ontologically consistent adoption of determinism, may not be at the foreground of Hobbes's first philosophy or crucial to the understanding of its development. It is, however, particularly relevant to the ruminations on the political concept of liberty that he published in the same decade.
The dispute with Bramhallin which the themes of natural necessity and human liberty were debated openly and systematicallycan be interpreted as the catalyst that allowed Hobbes to change his thinking and solve the problem brought to light by the contradictory definitions of liberty provided in De cive. Aside from assuming a general definition of liberty as the 'absence of impediments to motion [absentia impedimentorum motium]', in De cive Hobbes conceded that certain arbitrary impediments might exist that would impede motion 'non absolutely [non absolute]' but 'accidentally [per accidens]' and usually 'on our choice [per electionem nostram]' (DC, IX.9; OL II.259). This definition seems at least in principle to imply the idea of some sort of human free self-determination, and to contradict a rigorously deterministic ontology. The inconsistency was left unresolved by the revised edition of De cive written by Hobbes in 1646, precisely when, and perhaps because, he was already conceiving and maybe even working on a new political treatise, Leviathan, 34 in which any possible reference to free determination would eventually be discarded. In this sense, I am assuming that the political theory of Leviathan should be interpreted as dependent on Hobbes's full adoption of determinism, in conjunction with his rising awareness of the political relevance of the concept of conatus. 35 Only after the theoretical development that eventually led Hobbes to abandon the idea of void and fully embrace determinism was complete could the physical concept of conatus as the 'beginning of motion' fully and consistently serve the explanation of all the motions of natural as well as artificial bodies, and become a crucial aspect of his political thought. The problem that Hobbes's materialist ontology of conatus posed to his political theory related to the compatibility between the (natural) liberty of the individuals comprising the multitude and the (artificial) unity of the body politic. If the 'life' of a body is the same as the persistence of its motion, and the very 'life' of a body politic lacks the internal conatus of natural bodies, 36 it will be necessary to provide an adequate artificial substitute for that internal conatus. Because the body politic's (artificial) life will rely on the persistence and coherence of the various (natural) individual lives of which it is comprised, understanding what kind of conatus could possibly transform these independent motions into a generally coherent and unitary motion was a crucial task for political theory. This principium had both to work as a central explanatory principle of the body politic and to indicate the primary cause of its unity. In Leviathan Hobbes believed he had been able to do so by connecting the traditional concept of persona to an entirely new way of understanding political representation that would explain how the institution of an adequate first cause would keep the political 'automaton' indeterminately in motion, as if it were, however 'Mortall', a god. 37 34 Hobbes was revising De cive in the spring of 1646 in view of the 1647 edition, which may have contributed to his decision to write a new political treatise: Leviathan (Skinner, Reason and Rhetoric, 330-1. See also Malcolm,in Lev,12). As a matter of fact, the text of De cive underwent no further revision after the writing of Leviathan.

35
I am assuming here that Hobbes's decision to embrace a radical form of determinism is far from the inevitable outcome of his materialist premises. On the contrary, I am suggesting that there is an internal tension between determinism and materialism, because determinism implies the existence of eternal and unchanging truths (the 'laws' of nature) that a materialism of matter in motion cannot easily admit (Bardin, 'The Monstrosity of Matter in Motion'). 36 Hobbes's ontological explanation for what we call 'life' is not very detailed. Although, in general, 'vital' motion specifically takes place in the heart, Hobbes ultimately assumes that the particles of all kinds of bodies provide their specific, inherent motion (Leijenhorst, The Mechanisation of Aristotelianism, 166). 37 Hobbes famously names the 'COMMON-WEALTH' or 'CIVITAS' a 'Mortall God' in Lev, XVII.260.

A material principium for the body politic: representation and imagination
Hobbes's use of the theological-juridical concept of persona as a means to explain how 'A Multitude of men, are made One Person' is the core of Leviathan chapter XVI (Lev, XVI.248). However, the concept was not an original element of Hobbes's final political treatise. Although it underwent noteworthy variations, the concept had in fact been present even in the first draft of his political theory. 38 In the second part of The Elements of Law, Hobbes had clarified that its purpose was to explain 'how a multitude of persons natural are united by covenants into one person civil or body politic' (EL, II.I.1). As in Leviathan, in this earlier text a 'civil person' could be either a 'man', in which case the sovereign would be a natural person, or a 'council', that is an artificial person whose will would include 'the will of every one in particular', and there was no differentiation between the two (EL, II.II.11). Moreover, it was clear from the beginning of Hobbes's political theory that the ability of a person's 'will' to make a multitude of individual motions converge in the collective motion of a body politic did not depend on the nature of the person (i.e. natural or civil) but relied instead on its unity (EL, II.I.18). 39 In short, Hobbes's first political treatise already included most of the elements commonly linked to his concept of persona. More specifically, it also implied the existence of a physical nexus between the unity of the person and its 'power', conceived as a motion that can govern further motions, human actions included. The unity of the civil person's 'will' was therefore explicitly connected to its actual power. Yet despite this, the material dynamics of the forces that bring about the unity of that person in the first place were hardly questioned in The Elements of Law.
In De cive the concept of persona entirely substitutes the classical concept of a 'body politic' largely employed in Hobbes's former work, 40 but this does not mark a change of approach as far as the physical mechanism is concerned. Notwithstanding the more frequent use of the concept of persona, which appears quite reasonable given the book's exclusive focus on politics, De cive still lacks any physical explanation of how the individuation of the artificial person comes about. The aim of chapter V, On the Causes and Generation of a Civitas, remains that of explaining how 'a number of natural persons from fear of each other have coalesced into one civil person to which we have given the name of commonwealth' (DC, V.12; OL II.215). However, this passage explains that, rather than how, the natural powers of individual persons converge into the artificial power of a collective person whose 'will' provides it with the legitimacy to use its 'strengths and powers [viribus et facultatibus]' in order to grant peace (DC, V.9; OL II.214). De cive's primary interest lays in legitimising the juridical unity of the will rather than in explaining the appetites that come together to bring it about. There is no physical explanation of how 'multiple wills are contained [continetur] in the will of one' (DC, X.5; OL II.268), and no analysis of the material mechanisms of the natural and artificial powers involved in the process is provided. Indeed, the incumbent civil war drove Hobbes to publish De cive prematurely, at a time when his system of sciences was still a work in progress, as was his materialist framework. Notably, as Hobbes openly admitted a few years later in De cive's new Praefatio ad lectores, which he wrote in 1646 while planning Leviathan, 41 he realised ('I saw') that the new civil science could be built 'upon its own principles known by experience [experientia cognitis]' (DC, Praef.; OL II.151). As a matter of fact, in De cive Hobbes did not provide an ontological explanation of the mechanisms underlying the collective agency that characterised the body politic. What I am suggesting here is that Leviathan was his attempt to do so through the concept of 'representation'. In Leviathan Hobbes injected the polysemic term 'representation' (at the same time optical, theatrical, epistemological and juridical 42 ) into the traditional theological-juridical concept of persona. The originality of this combination has induced many scholars to overlook the physical meaning that the two concepts joined together acquire in Leviathan if they are looked at through the lens of Hobbes's materialism. The use of the word 'to represent' to mean 'to bear the person of the People' (Lev, XXIX.512), that is to act in the name of a group of individual bodies under the condition that there be no more than one person, is certainly a novelty introduced in Leviathan. 43 While a natural body is a person endowed with a will, the collective artificial body must be 'personated' to acquire a unitary motion, in other words a unitary will. Thus the political body requires the power of a sovereign representative in order to be able to will and act coherently (and therefore to exist as an individual body): 'a Common-wealth, without Soveraign Power, is but a word, without substance, and cannot stand' (Lev, XXXI.554). 44 The subject taking action is the 'Persona civitatis, the Person of the Common-wealth' (Lev, XXVI.414), but the civil person can only act through the sovereign person. In other words, a Commonwealth (like any other 'thing personated' 45 ) can only become such because of the ontological power of the sovereign's act of representation. By making civil law, that is 'the Will and Appetite of the State', the 'measure' of good (Lev, XLVI.1090), the sovereign provides juridical qua physical unity to individual liberties and wills, transforming them into the unitary will and motion of the civil person.
The concept of 'representation' certainly responded to a problem of legitimation, while the concept of 'authorisation' helped shift juridical imputability from the sovereign to the citizens, and both no doubt proved crucial to the emerging theory of the impersonal power of the modern state. 46 However, these concepts were also meant to solve a series of problems related to the material production and continuation of the unity of the sovereign persona and hence of the body politic. For this reason, seen from the perspective of Hobbes's materialism the concept of representation appears to be Leviathan's true innovation. In Hobbes's materialist framework 'representation' can only refer to a coherent motion, an act of representation, rather than to a unitary representative body. That is why a satisfactory explanation of the concept of political representation in Leviathan should not be limited to the conceptual framework provided by its juridical form but should also take into account its physical meaning. From this perspective, although many scholars see the concept of authorisation as one of Hobbes's most original contributions to the theory of the state, 47 I interpret it as the translation into formal and juridical terms of a physical understanding of representation. My reading therefore focusses on the concept of representation as the key to the unification of natural human powers into one conatus, that is into a coherent motion and indeed into the 'life' of the body politic. As I will demonstrate in what follows, this interpretation relies on establishing how Hobbes's conception of conatus as the 'first cause' of the unity of a body and his conception of imagination as a material power were relevant to his political anthropology.
As explained in the first part of this article, at the same time as Hobbes was conceiving Leviathan, as early as 1646-1647, he was also elaborating his deterministic theory of conatus. As a result, he established that the unity and coherence of a body's motion depended on the unity of its principium, conceived as the first cause, and the civil body, of course, could be no exception. The body politic, however, is a peculiarly artificial automaton, given that it is an artificial assemblage of pre-existing natural bodies into an artificial self-moving machine whose conatus is neither exclusively given and inherent, as it is in animals (humans included), 48 nor exclusively artificial and dependent on human construction, as it is in machines. Human 'matter' is so complex that its motions can be somewhat limited by 'external impediments', but its internal motions, and therefore its will, can scarcely be controlled. Hobbes was perfectly aware that no lawwhether civil or naturalcould cover the whole range of prescriptions needed for the purpose. In other words, no law could ever become 'the whole cause' driving each individual conatus to contribute to the overall functioning of a body politic. Even if 'to make the law is […] to make a cause of justice and to necessitate justice' (LN, I.14.25), civil laws relate only to 'the will and no other precedent causes of action' (LN, I.14.24). In some cases, laws may therefore be a 'sufficient and therefore necessary cause' (LN,I.16.29) of justice, but certainly not the complete and permanent cause needed for a well-established commonwealth. Reason and the sciences also cannot be a sufficient cause, as long as they remain a 'small Power, because not eminent' (Lev,X.134). None of these forces can work as a universally effective principium driving human natural motions to converge into the unitary motion of the body politic. Civil laws and civil science can only work as partial causes of the unity of the body politic, but never as the whole cause [causa integra]. A more powerful artificial principium must therefore be set in motion in order for the body politic to be granted stable unity.
When Hobbes wrote Leviathan he was fully aware that an effective 'whole cause' for the unification of a body politic could only be provided by adequately compelling human actions and thoughtsi.e. by regulating human natural motion both externally and internallythrough violence, persuasion, fear and hope. As the two pillars supporting the sovereign person featured on the book's frontispiece perhaps suggest, civil power could use two types of tools to enforce natural laws and make individual liberties compatible with the functioning of the body politic. These tools, which traditionally belonged to temporal and spiritual powers, had to be unified in a single 'Common-wealth Ecclesiasticall and Civill' in order to make the individual citizen unable to stand against it and willing to submit even when the rationality of such obedience was not acknowledged. On the one hand, civil laws could externally work as partial impediments to human actions, either by opposing or guiding them, depending on the situation: The use of laws is not to bind the people from voluntary actions, but to direct and keep them in such a motion as not to hurt themselves by their own impetuous desires […] not to stop travellers, but to keep them in the way. (Lev,XXX.335,italics added) On the other hand, political power also had to overcome the internal resistance of individual wills, 'For the Actions of men proceed from their Opinions; and in the well governing of Opinions, consisteth the well governing of mens Actions, in order to their Peace, and Concord' (Lev,XVIII.272). Only the joint exercise of power over the external and internal motions defining natural human conatus could 'reduce all their Wills, by plurality of voices, unto one Will' (Lev, XVII.260).
As some scholars have perceived, there are Tacitean undertones in Hobbes's project of 'governing' human imagination by grounding 'the authority of […] Princes […] on the Consent of the People' (Lev, XXXL.740), 49 and many share the view that a unique use of rhetoric defines the peculiar style of Leviathan, revealing its author's unusual view of the purposes of civil science. 50 Hobbes's task, however, was to rework the arcana imperii to fit his materialist framework and find an artificial equivalent of the ancient wisdom of the sovereign for his political automaton. He needed something that could prove to be a less arbitrary yet equally effective conatus, in other words a first cause similar to the principle of the generation of natural living bodies capable of giving the body politic 'artificiall life' (Lev,Introduction.16). Finding such a solution required a solid materialist theory of imagination as causal 'power'. In Hobbes's mature anthropology imagination is 'sense decaying' whose products -'phantasms' called 'fancy and, in Latin, imaginatio' (DCo XXV.7) 51are the physical continuation in human 'organs' of the motion of the senses. More precisely, imagination is an internal motion of bodies, a 'perpetual arising of phantasms' within human beings and other animals, and it has no less causal power than the senses, despite being 'commonly called the discourse of mind' (DCo XXV.8; OL I.325). In short, imagination is part of the physical causes on which will -'the last deliberation', that is the final effect in the chain of internal motions, which, in turn, is the first cause of the (external) motion of a living bodydepends. As Hobbes wrote in Leviathan, 'Imagination is the first internall beginning of all Voluntary Motion' (Lev, VI.78, italics added). With this concept of a causal power of imagination in mind, Hobbes's idea of a unity of the 'feigned' person acquires a meaning that is rather more physical than merely 'linguistic', as he openly claims in relation to the word 'soul' (LN, II.20.32), 52 which in the introduction to Leviathan famously describes the sovereign's role in the political 'automaton'.
It is only through these materialist lenses that Hobbes's conception of imagination is shown to be fully compatible with, and even implied by, the concept of representation that Hobbes elaborated in Leviathan. A materialist interpretation of the 'act' of representation might seem to have been contradicted by Hobbes's claim that representation always works, whether the actor is a 'natural' person acting 'Truly' or an assembly acting 'by Fiction' as a 'Feigned or Artificiall person' (Lev, XVI.244). In the final systematisation of his theory in De homine, however, he clearly restates that the nature of the person does not affect its representative function because, whether the person be 'natural [naturalis]' or 'fictitious [fictitia]', the action should always be attributed to the 'civil [civilem]' person (DH, XV.1; OL II.130). This claim has obvious juridical implications, but a careful consideration of the concept of a 'fictitious' person demonstrates that it must also be understood as a physical explanation. While it is true that the sovereign person is a 'fancy', fancies and their effects are nevertheless actual motions and can be quite powerful ones. It is therefore clear that an 'artificial person' is 'imagined' in a sense that should not be understood as being opposed to 'real'. In fact, a person is 'fictitious [fictitia]' in the same way that political bodies are 'artificial, and fictitious Bodies' (Lev, XXII.352) that actually exist and 'act'. In Hobbes's materialism 'fictitious' bodies are endowed with the same physical causality as any other artificial body. This is why in the English Leviathan he uses the term 'person' to refer without discrimination to both the representer (as in Lev, XVI) and the represented (as in Lev, XLII). It is also the reason why he distinguishes between persona 'raepresentativa' and 'propria' in the Latin Leviathan, just as he does between persona 'fictitia' and 'naturalis' in De homine, always without undermining the underlying materialist assumption of the 'fictitious' person's capacity to act. 53 In the case of the sovereign person this capacity, however, depends on a specific kind of causality achieving its effects by the mediation of the motions of the mind and, more specifically, through human imagination.
The fact that Hobbes conceives imagination as a material power is precisely the reason why a fictitious person's act of representation can be understood in material terms as an adequate cause capable of providing unity to the body politic. Hobbes's materialist theory of imagination and representation thus explains the twofold power embodied in the persona fictitia: the power it derives from the individual powers it 'personates', and the power it exerts on the citizen's 'internal' motions (wills) and hence on their external motions (actions). As is the case with the principles animating living bodies, the sovereign person's 'office' is undoubtedly the establishment and continuation of the body politic, but this should not be identified with its 'bare Preservation'. On the contrary, Hobbes openly relates the salus populi to the citizens' active participation in 'all other 51 'Phantasmate, phantasia, et Latinis imaginatio' (OL I.323). 52 Here Hobbes clearly opposes the actual existence of the group (a commonwealth or a family) to the linguistic status of the human soul. Contentments of life, which every man by lawfull Industry, without danger, or hurt to the Common-wealth, shall acquire to himselfe' (Lev XXX.520). These individual motions cannot be suppressed without killing the body politic, and yet their convergence can only be granted in the first place by the overwhelming causal power exerted by the person's unitary act of representation. Representation should therefore be conceived as a physical qua imaginary cause that can make a plurality of natural 'liberties' (i.e. wills and therefore actions, that is necessary motions 54 ) converge in an artificially unitary and coherent motion governed by a single conatus.
The study of representation conceived as a principiumthe explanatory principle as well as the first cause of the body politicbecame a crucial purpose of Hobbes's civil science at the end of the 1640s. Leviathan took fancies seriously in pursuit of that purpose, even going so far as to, as it were, to theorise its own power as fancy. Along with the fittingly celebrated rhetorical use of the frontispiece and the abundance of biblical sources exploited in parts III and IV, Hobbes's theory of representation certainly contributed to the invention of a 'sign of the state' 55 capable of understanding and directing the actions of the subjects from within thanks to the material power of imagination.

Conclusion
Students of the political Hobbes often overlook the fact that he never abandoned the materialist assumption informing his whole philosophical project, which implied that everything should, at least in principle, also be comprehensible in terms of local motion. However far Hobbes's political thought may be from a merely physical explanation of the functioning of the body politic, interpretations of his scientia civilis can be furthered by the assumption that all its concepts should as far as possible be explored in terms compatible with the overall materialist framework he adopted in his system of sciences. On the basis of this, I have assumed that explanations of Hobbes's concepts of liberty and representation should neither be limited to the exigencies dictated by his political agenda nor formulated within the boundaries of the language he uses in his political philosophy. These and other concepts in Hobbes's political theory should also be explained in the light of the wider philosophical agenda that drove his research for a relatively long part of his remarkably long life. The need to conceive of liberty in terms ontologically compatible with the geometric imagination of material motion established by the Galilean science created a tension in Hobbes's political theory, and notably also in his political anthropology, since the latter was meant to be at once descriptive of human natural motions and normative for the purpose of their domestication in view of the construction of an artificial body politic. This tension was first evidenced by the contradictory definitions of liberty offered in De cive (1642).
During the 1640s Hobbes's natural philosophy underwent a transformation that had remarkable consequences for his political theory. Hobbes came to adopt a radical form of ontological determinism, ruling out the existence of void and consequently re-elaborating his own concept of conatus. He shifted from defining the conatus as the consistency of a body's motion to specifically using the term to refer to the small 'first motion' that causes a body and its subsequent motions. This concept of conatus could thus be taken as a principium that provided the key to understanding the functioning of all bodies in light of their first cause, human individuals and the collective body politic included. Once a radical form of ontological determinism was established in Hobbes's natural philosophy, no space remained for the 'arbitrary impediments' evoked in De cive's problematic political anthropology. In Leviathan (1651) the purpose of political theory became the institution of an adequate cause that would make each individual conatus coincide with the unitary functioning of the body politic's collective conatus, unifying the natural 'liberties' of the citizens by driving them from within. This principium was formulated there in terms of 'representation'.
The image of the representative person theorised in Leviathan was deemed capable of driving the dangerous natural liberty of humans into a necessary element of the institution of sovereign power. Far from abolishing individual agency, the concept of natural determinism allowed Hobbes to insert a materialist concept of liberty into his political theory. The need to explain the foundation, production and preservation of political order was thus solved by joining the concepts of determinism and liberty through the mediating function of the representative person. While representation established sufficient cause for the unity of the body politic, determinism provided political agency with consequentiality by connecting the sovereign representative to the citizens' internal motions. The genuine efficacy of this chain of cause-effect relations came through the material power of imagination, which was alone in being able to produce effectively the unity that the concept of persona was staging. As a result, the mechanism of representationworking as a sort of self-fulfilling prophecywas meant to explain both the power that the body politic derives from the active participation of its members, and the power it exerts on their will to participate.