Andrea Strazzoni

The present study aims to present a transcription and a commentary of three unpublished letters of the Dutch Cartesian philosopher Johannes de Raey, addressed to his former student Johannes Clauberg. Mainly containing suggestions concerning the defence of Cartesian philosophy and academic affairs, these letters, dating back to 1651, 1652 and 1661, bear witness of a steady friendship and of a certain cooperation in rebuking the critiques moved by Jacob Revius in his Statera philosophiae cartesianae and by Cyriacus Lentulus in his Nova Renati Descartes sapientia, refuted in Clauberg’s Defensio cartesiana. According to these letters, this cooperation had to be kept secret, not to provoke the reaction of Leiden theologians. However, the violation of the correspondence of Clauberg and De Raey occasioned the edition of Lentulus’s book and the rise of the polemics over the new philosophy. Eventually, such cooperation is to be noticed also in some crypto-quotations between the edited texts of Clauberg and De Raey.

Alsted was a foremost encyclopedist of the early seventeenth century. He provided both a complete presentation of all the subjects of philosophy (of which encyclopedia consisted) and a method to learn them. This method was an original synthesis of the dialectic of Petrus Ramus, the combinatorial art of memory of Raimond Lull and Giordano Bruno, and the method of presentation of philosophical disciplines of Bartholomäus Keckermann. Alsted’s encyclopedism was intended as a remedy to the postlapsarian condition of man and was functional to the pedagogical reform pursued at the Academy of Herborn; this was, in turn, an essential part of the Calvinist state reform of the county of Nassau-Dillenburg. In theology, the importance of Alsted consists of having introduced millenarianism in the Reformed Europe, though his early, optimistic views on the imminent end of the world would change to pessimistic as a consequence of the Thirty Years’ War.

Abstract: This article explores the medical theories of the Dutch philosopher and physician Henricus Regius (1598-1679), who sought to provide clearer notions of medicine than the traditional theories of Jean Fernel, Daniel Sennert and Vopiscus Plempius. To achieve this, Regius overtly built upon the natural philosophy of René Descartes, in particular his theories of mechanical physiology and the corpuscular nature of matter. First, I show that Regius envisaged a novel partitioning of medicine, intended to make it independent in exposition but conceptually grounded in natural philosophy. This served his overall purpose of making medicine a ‘clearer’ discipline. To this end Regius detaches the general notion of physiology as the study of the human body (which pertains to natural philosophy) from a medical physiology that concerns only health. Secondly, I show that Regius’s notions of health, disease, temperament and medicaments were the product of a Cartesian interpretation of traditional concepts, which was influenced by Santorio Santorio’s project of practicing medicine without occult elements. As a consequence, Regius’s classification of these notions is largely traditional. In conclusion, I show that Regius’s method of investigation in the area of natural philosophy consisted of a problem-solving procedure based on sensorial ideas. This approach can be traced back to Descartes, but was grounded on a purely empirical theory of knowledge, by which he rejected Descartes’s metaphysics. Regius’s order of exposition in natural philosophy and medicine, on the other hand, proceeds by definitions and divisions, and omits proofs. The reasons why Regius adopted this order were: 1) his rejection of Descartes’s metaphysical interpreta-tion of physics, and 2) his wish to emphasize the conceptual clarity and continuity of natural philosophy and medicine.

The philosophy of Francis Bacon was interpreted in various ways in the seventeenth century. In England, his utopian project and natural history became the basis for the projects of religious pacification, pedagogical reformation, and scientific cooperation of Hartlib, Comenius and Charleton. In the hands of Evelyn, Wilkins, and Wren, moreover, Bacon’s ideal of cooperative science engendered the birth of the Royal Society, and his natural history guided the experimental activities of Boyle and Hooke. In France and the Netherlands, attention was paid to Bacon’s natural history especially within the circle of friends of Descartes. In the second half of the seventeenth century, though Bacon’s historical approach was gradually supplanted by mechanical-mathematical science in Europe, Baconianism still served as a source of arguments in the Dutch Cartesian context, as to his theory of error and as a source of criticisms to Aristotelianism.

Bacon’s philosophy had a wide dissemination in Dutch Seventeenth Century context. This can be explained by the coeval diffusion of Cartesianism. Bacon’s project of a reformation of science was deemed by Heereboord and De Raey as the manifesto of a new philosophy. Along with Geulincx, moreover, De Raey borrowed Bacon’s arguments on the causes of error and on the replacement of Aristotelian natural history, aimed at integrating Descartes’s physics. Also in logic Bacon’s influence was noticeable, as the development of a new Organon had its accomplishment in the Cartesian logic of Clauberg and of De Raey himself. In theology, Heidanus relied on Bacon in order to confute Socinianism. The fortune of Dutch Baconianism had its end with the rise of Newtonianism: as a quantitative, experimental philosophy arose, Bacon’s works were no more regarded as a valuable source of arguments.

In this paper I provide a commentary on and edition of the unpublished and apparently incomplete Medicina contracta of the Flemish philosopher Arnold Geulincx (1624– 1669). This short treatise, dating to c. 1668–1669, was not included in the edition of Geulincx’s works edited by J.P.N. Land, on the ground of its apparent unoriginality. However, it reveals the attempt, by Geulincx, to develop a medicine based on a new account of disease (intended in Cartesian-Platonic terms of the impossibility of the mind using the body through animal spirits), and integrating avant-garde solutions typ- ical of iatrochemistry (in particular those of Franciscus Sylvius) and iatromechanics. The text, which I also consider in the light of Geulincx’s disputations in physiology, is moreover revelatory of his ongoing efforts in understanding the nature of respiration and its related diseases and conditions, such as apoplexy, and of his progressive, albeit not uncritical acceptance of Cartesianism.

This article offers an assessment of Henricus Regius’s (1598-1679) pre-Cartesian sources and their role in his appropriation of Descartes’s ideas, via two main questions: 1) Who was Regius, doctrinally speaking, before his exposure to Cartesianism? And 2) how did he use Descartes’s theories before his quarrel with Descartes himself in the mid-1640s? These questions are addressed by means of a textual analysis that concerns his theory of matter. In this article, I will show that 1) Regius started out with a scientific program he had found in Ramism and the medical theories of Heurnius and Santorio. 2) On this basis, he developed a physiology encompassing Descartes’s theory of blood circulation and sensory perception. 3) Regius completed the resulting physiology with a theory of matter more developed than Descartes’s, and which he appropriated from Santorio, Basson, and Gorlaeus.

The fifth chapter is a study of the emergence of ‘radical Cartesianism’ as an actor’s category in 1660s and 1670s, which prompted a further development of foundationalism as a reflection on the limits and proper method of philosophy. The key figure in this double process was De Raey, who in the late 1660s started to develop a new logic or metaphysics, intended to counter, on the one hand, the uses of Descartes outside natural philosophy and metaphysics itself, and on the other, the erosion of Descartes’s metaphysical tenets. His writings thus turn out to be relevant as he offers a mapping of the interpretations of Cartesianism covering its uses in theology (as by Meijer and Spinoza) and the spreading of Hobbes’s materialist philosophy in the Low Countries. Moreover, his logical-metaphysical theories embody a novelty in determining the aim of these disciplines, both with respect to the Cartesian tradition (i.e. to Clauberg and Geulincx) and to the Scholastic one, and start to assume a reflective role as they assess the limits of scientific knowledge. In his hands, logic and metaphysics become one discipline, as they have the same function, i.e. the definition of the principles of scientific knowledge (viz. the notions of physical and mental realities), and of its scope and applications. On the one hand, therefore, he can overcome the reduplication of metaphysics and ontology of Clauberg, and the introductory or didactic function that logic played both in Clauberg’s and Geulincx’s philosophy. On the other, his logical and metaphysical systematisation can be read as the result of a long-standing debate over the objects of these disciplines (either mere concepts, or entities existing outside mind), in which De Raey places himself by dealing with the theories of Burgersdijk and Ramus. This chapter thus works as a junction in the account of the establishment of Cartesianism as the philosophy of the university, and its challenges by emerging, alternative worldviews, interpretations and uses. Together, these converging theoretical and historical factors shaped a new, reflective function for logic and metaphysics.

In this article, I intervene in a long-standing debate over the alleged assumption and teaching of Spinozist ideas by the Dutch philosopher and scientist Burchard de Volder (1643–1709). I discuss De Volder’s position with respect to three main topics (necessitarianism, substance monism, and biblical interpretation), as well as the use his student Jacob Wittich made of De Volder’s ideas in Wittich’s highly controversial De natura Dei (1711). Eventually, I argue that De Volder was certainly a sympathizer of Spinoza, accepted necessitarianism, and considered Spinoza a reliable interpreter of Descartes in physics, even if he did not accept Spinoza’s monist metaphysics, nor his biblical hermeneutics.

The Quarrel over Swammerdam’s Posthumous Works reconstructs the vicissitudes of Johannes Swammerdam’s Biblia naturae, a pivotal collection of writings in the history of science. Bequeathed to the polymath Melchisédech Thévenot, the manuscripts and drawings of the treatises constituting this collection were instead kept by the editor Hermann Wingendorp after Swammerdam’s death (1680), triggering a quarrel over their publication. By analysing Swammerdam’s scientific legacy and by offering an edition of the correspondence testifying to the efforts towards such publication, this book sheds light on the editorial history and intellectual context of Swammerdam’s Biblia. This reveals not only an intricate plot of authorized and unauthorized attempts to publish it, but also an exchange of scientific texts and instruments in the late seventeenth century.

The third chapter gives an account of the debates over Cartesianism outlined below, which shifted from the University of Utrecht to Leiden, where the new philosophy was introduced by Adriaan Heereboord in the early 1640s, and was carried on by Johannes de Raey at the end of the decade. In Leiden, the quarrels over Cartesianism were prompted by the intervention of the theologian Jacob Revius, criticising Descartes’s philosophy as a source of Pelagianism in 1647. This gave rise to a series of attacks, replies, and counter-replies which would dominate Dutch Cartesianism well into the 1650s: Revius’s Methodi cartesianae consideratio theologica (1648), Statera philosophiae cartesianae (1650), and Cyriacus Lentulus’s Nova Renati Descartes sapientia (1651) offered a full-blown critique of Descartes’s philosophy, focusing on his metaphysics, method and on their uses in academia. Such critiques are analysed in this chapter as they brought about the first foundation of Cartesian philosophy after Descartes himself, namely, the development of a ‘Cartesian Scholastic’ by Johannes Clauberg, professor at Herborn and Duisburg. In fact, Clauberg’s defence and foundation of a Cartesian academic philosophy was not the effort of one philosopher, but was coordinated with De Raey and with other members of the Cartesian network in the Netherlands and in Germany (including Abraham Heidanus, Tobias Andreae and Christopher Wittich), as a means to avoid the bans on Cartesianism and to provide a decisive answer to the theologians. This coordinated strategy of defence is revealed by two letters of De Raey to Clauberg: their contents shed light on the background of Clauberg’s foundation, which constitutes the first, Cartesian reworking of the academic curriculum. In his works, indeed, Clauberg maintained a metaphysical foundation embodying rational-theological arguments, while providing at the same time a logical theory of the method for natural philosophy, as well as for law, theology and medicine. Yet, his concerns with the traditional structure of the curriculum led him to develop, besides a Cartesian first philosophy, also an ontosophia, whose object is being as such. This is considered by Clauberg not only in the light of the ‘first notions’ of mind and body, but also of those abstracted from concrete realities, as ‘unity’, ‘goodness’, ‘truth’, and so on. This ultimately results in the reduplication of metaphysics, which will be reduced by Clauberg’s followers – dealt with in the next chapters.

Through a consideration of the philosophical debates occurring in the Dutch and Dutch-related intellectual framework in the early modern period, in the present study some alternatives in the foundation of philosophy and science have been highlighted and analysed. In conclusion, it is time to assess them in a more systematic manner. Each alternative entails a different view on foundational arguments, which may be grouped into theological, metaphysical, and logical ones. This research reveals the essential features of a philosophical milieu created by Descartes and constituting the framework for the dissemination of Newtonian science in Europe, leading to the birth of a philosophy of science as the study of the foundations, assumptions, methods, and limits of the study of natural realms. In fact, one can recognise several reasons for such foundation: on a general level, the need of providing philosophy with a secure foundation against the ‘sceptical crisis’ of the sixteenth and seventeenth centuries highlighted by Richard Popkin. More specifically, however, the foundation of Cartesian and Newtonian philosophy and science served to defend the conceptual premises of new ways of thinking in an academic context, demonstrating the validity of such new ways and rejecting the commonsensical and non-explanatory assumptions of Scholastic philosophy, and, in the case of ’s Gravesande, the speculative character of Descartes’s physics itself.

The fourth chapter analyses the establishment of Cartesianism at the University of Leiden in 1650s and 1660s. This was carried out by De Raey, who provided a defence and teaching of Descartes’s physics in his Clavis philosophiae naturalis (1654), although not based on Descartes’s metaphysics: physical principles, indeed, are presented by De Raey as self-evident truths, and consistent with Aristotle’s theory of scientia or universal and necessary knowledge. This was not the only peculiar characteristic of Leiden Cartesianism, as De Raey also provided a differentiation between philosophical and practical knowledge (including medicine and revealed theology), as these are based on different sources of knowledge, namely, intellect and sensory experience. In the hands of Christopher Wittich, the separation thesis became the standard in conceiving the place of Cartesianism in the university, which was confined to natural philosophy in 1650s and strictly secluded from revealed theology. At the same time, the need to develop a moral philosophy consistent with the Reformed creed became the centre of the debate between Revius and Heidanus, a Reformed theologian who saw in Cartesianism a philosophy more consistent with Calvinism than Scholasticism. Accordingly, he was eager to support the appointment in Leiden of Arnold Geulincx, who was developing a philosophical ethics independent of revealed theology but consistent with the Reformed creed. For this purpose, besides the relation of body, soul and world, Geulincx considered those relations of man, world, and God from which moral duties follow. Accordingly, he provided his ethics with a foundation in rational theology. In turn, this foundation entails a reflection on the type of knowledge that constitutes physics and determines its very method. Given the inscrutability of God’s reasons in creating the world, Geulincx could claim that physics has to proceed by hypotheses based on experience rather than by a deduction of natural laws from metaphysical principles. In this way, the epistemic consequences of his foundational theory refuelled a reflection on the method of natural philosophy itself, making his foundation a sample of the transformation of Cartesian foundationalism – dominated by Descartes’s metaphysical physics – into a reflection on physics itself. In other words, Geulincx provided, together with De Raey, a de-metaphysicisation of physics.

How did the relations between philosophy and science evolve during the 17th and the 18th century? This book analyzes this issue by considering the history of Cartesianism in Dutch universities, as well as its legacy in the 18th century. It takes into account the ways in which the disciplines of logic and metaphysics became functional to the justification and reflection on the conceptual premises and the methods of natural philosophy, changing their traditional roles as art of reasoning and as science of being. This transformation took place as a result of two factors. First, logic and metaphysics were used to grant the status of indubitable knowledge of natural philosophy. Second, the debates internal to Cartesianism, as well as the emergence of alternative philosophical world-views progressively deprived such disciplines of their foundational function, and they started to become forms of reflection over given scientific practices, either Cartesian, experimental, or Newtonian.

This monograph details the entire scientific thought of an influential natural philosopher whose contributions, unfortunately, have become obscured by the pages of history. Readers will discover an important thinker: Burchard de Volder. He was instrumental in founding the first experimental cabinet at a European University in 1675. The author goes beyond the familiar image of De Volder as a forerunner of Newtonianism in Continental Europe. He consults neglected materials, including handwritten sources, and takes into account new historiographical categories. His investigation maps the thought of an author who did not sit with an univocal philosophical school, but critically dealt with all the ‘major’ philosophers and scientists of his age: from Descartes to Newton, via Spinoza, Boyle, Huygens, Bernoulli, and Leibniz. It explores the way De Volder’s un-systematic thought used, rejected, and re-shaped their theories and approaches. In addition, the title includes transcriptions of De Volder's teaching materials: disputations, dictations, and notes. Insightful analysis combined with a trove of primary source material will help readers gain a new perspective on a thinker so far mostly ignored by scholars. They will find a thoughtful figure who engaged with early modern science and developed a place that fostered experimental philosophy.

The seventh chapter focuses on the aftermath of the decline of Cartesianism as a leading force in the Dutch academic context. After De Volder and De Raey, indeed, only Ruardus Andala in Franeker carried on the teaching of Cartesian physics (which he taught by commenting upon Descartes’s Principia) and metaphysics, mainly for the sake of contrasting Spinozism and other forms of radical Cartesianism. Thus, Descartes’s philosophy came a dead end on the eve of the eighteenth century. Yet, Leiden Cartesianism and the Leiden experimental tradition (which could include, after De Volder and Senguerd, the activities of Herman Boerhaave), favoured the introduction of Newtonianism as the standard in teaching natural philosophy. This was carried out by ’s Gravesande, who used logic and metaphysics (including rational theology), that is, the chief foundational disciplines in the Cartesian tradition, to introduce students to and justify the assumptions (methodological and ontological) of a Newtonian approach in natural philosophy. This had two outcomes. On the one hand, his arguments in metaphysics (i.e. ontology) have the function of clarifying which objects natural philosophy can investigate. These are natural laws, whose ultimate source in substances or modes cannot be ascertained by intellect alone, as they depend on the power of God. On the other, given the fact that experience is our only means of grasping such laws (which are then mathematically handled) he provides a rational-theological justification of experiential evidence, as capable of providing us with a degree of certainty equal to mathematical evidence. As for the Cartesians, this is still the paradigm of scientific knowledge. Accordingly, with the introduction of Newtonianism foundational disciplines such as logic and metaphysics (including rational theology) served as a justification for and a reflection on a given scientific methodology. Thus, philosophy started to be actually detached from the natural sciences, and to assume a subservient role with respect to them, as once it was the ancilla theologiae.

The second chapter is devoted to the analysis of the first introduction of and quarrels over Cartesianism at the University of Utrecht, as determined by the teaching of a Cartesian natural philosophy and physiology by Henricus Regius. First, it is shown how his teaching gave rise to the querelle d’Utrecht (1641), in which two main issues were debated: the rejection of substantial forms, and the characterisation of man as ens per accidens. During the quarrel, questions were raised about the consistency of the new philosophy with theology and – insofar as it raised the problem of the individuation of bodies and species by substantial forms – of the unity of man. Secondly, it is shown how Regius’s peculiar approach to natural philosophy (and physiology) led him to quarrel with Descartes himself in 1645–1648, with regard to two main questions: the nature of mind, and the method of natural philosophy, which Regius interprets in both cases from an empirical standpoint, as he maintains that the nature of mind may consist in matter (according to medical evidence), and that all knowledge has a sensory origin. Accordingly, he paved the way for ‘radical’ interpretations of Descartes which rejected his metaphysics, but also for an approach to a natural philosophy more open to the use of experience. In this chapter, I scrutinise the reasons behind Regius’s approach to physics and metaphysics by paying attention, on the one hand, to his quarrel with Descartes, and on the other to the sources of his methodology, which he largely borrows from medical authors. In conclusion, I show that Cartesianism, in the hands of Regius, might serve as the basis for medicine but could not yet become a full-fledged alternative to Aristotelianism.

The sixth chapter focuses on the evolution of Cartesianism in the last quarter of the seventeenth century in Leiden and Amsterdam, against the background of the emergence of alternative views in natural philosophy capable of replacing it as a dominant paradigm, namely, the experimental philosophy of Robert Boyle and the mathematical-experimental approach of Huygens and Newton. The last evolution of Cartesianism is reconstructed in this chapter by considering the ‘Cartesian empiricism’ of Burchard de Volder, and the reflections on the language of philosophy and practical disciplines by De Raey in Amsterdam, where he moved in 1669. In 1675 De Volder established the Leiden Theatrum physicum. There he performed experiments in order to teach the principles of a mechanical philosophy largely inspired by Descartes but open to the use of experimental and mathematical evidences in the formulation of natural laws. A similar approach was in fact assumed in the same years by Wolferd Senguerd, who used the Theatrum to perform experiments in pneumatics to teach some of the principles of his eclectic worldview, encompassing some Cartesian principles (such as that of the circularity of movement), but also rejecting the vortex theory. Yet, only De Volder developed a foundational theory for the basic principles of mechanicism, namely, the assumption that every phenomenon can be explained by the notions of matter and movement alone. This was the result of a movement internal to Cartesianism, as De Volder not only reacted (positively) to the emergence of an experimental-mathematical natural philosophy, but was also involved in the defence of Cartesianism against the Censura philosophiae cartesianae of PierreDaniel Huet (1689), in which Descartes’s metaphysics is rejected as inconsistent given its very foundation on doubt and cogito. The intermingling of these different issues resulted, in De Volder’s hands, in a further de-metaphysicisation of physics – as metaphysics cannot provide a justification for the laws of motion – and in the narrowing of the scope of foundationalism, which can only sanction the psychological character of clarity and distinction as a criterion for internal truth, defined in terms of indubitability only. Accordingly, for De Volder metaphysics cannot demonstrate, on a Cartesian basis, that phenomena are actually ruled by the principles of mechanism: insofar as, for him, metaphysics has a prominent reflective role, and loses its status as justification of the absolute truth of scientific statements. This process can be labelled as the transition from foundationalism to philosophy of science and does not characterise only his ‘Cartesian empiricism’. In Amsterdam, De Raey was, over the same years, developing his Cogitata de interpretatione (1692), embodying one of the first, self-standing philosophical considerations of language. Still maintaining his separation thesis, and attacking Hobbes and the radical Cartesians, in this text he aimed to clarify how words meaning sensory data and abstract notions (such as those of mathematics) can be used in philosophy. Rather than setting a method for how to use mental faculties, De Raey aimed, at the end of his career, to provide an updating of the linguistic meanings of scientific vocabulary, namely, a reflection rather than a justification of science.