Power, Harmony, and Freedom: Debating Causation in 18th Century Germany Corey W. Dyck As far as treatments of causation are concerned, the pre-Kantian 18th century German context has long been dismissed as a period of uniform and unrepentant Leibnizian dogmatism. While there is no question that discussions of issues relating to causation in this period inevitably took Leibniz as their point of departure, it is certainly not the case that the resulting positions were in most cases dogmatically, or in some cases even recognizably, Leibnizian. Instead, German theorists explored a range of positions regarding the nature of causal powers, the appropriate system to explain the observed agreement between the states of substances, and the ground of free actions, or so I will argue in this chapter. Focusing on these three issues, I will here sketch the development of the debates relating to causation and trace the evolution of positions among the philosophers within the so-called Leibnizian-Wolffian philosophy as well as among its many opponents. In the first section, I will briefly outline the interconnected background in Leibniz to the German discussion, focusing on his account of substance in terms of a power, his system of pre-established harmony, and his account of freedom, as they are presented in the texts most readily available at the outset of the 18th century. In the second section, which makes up the bulk of the chapter, I survey three debates that emerged from Leibniz's original treatment, namely, the debate concerning whether substances (and the soul in particular) have only a single power or multiple fundamental powers, the controversy between defenders of the pre-established harmony and the champions of physical influx, and the debate regarding whether freedom can be accounted for in terms of mere spontaneity. In the third and final section, I turn to Kant's discussion of these same topics in order to show that and how he continues to engage with these three issues in his Critique of Pure Reason. 1. The Background in Leibniz Theories of causality in 18th century Germany, as is so often the case in the period, take Leibniz's thought as the point of departure. Indeed, given that much of Leibniz's work was not available until the two editions of Leibniz's works (by Raspé and then Dutens) were published in the 1760's, the German discussion of causality is framed by a relatively small (and comparatively manageable) set of his texts: the essays "On the correction of substance" of 1694, "Specimen dynamicum" of 1695, and "On nature itself" of 1698; the tract "A new system of the nature and the 2 communication of substances" of 1698 and the ensuing exchange with Bayle; the Theodicy of 1710; and the "Monadology" which, along with the correspondence with Clarke and the "Principles of Nature and Grace" became available in the next decade.1 While these texts represent only a (diminishingly small) portion of all the Leibnizian texts on these topics, taken together they nonetheless offer an original and influential perspective on causality. We might begin with Leibniz's novel conception of substance in terms of an active power. Leibniz's reflections on this score arguably have their origin in his recognition of the inadequacy of the modern conception of body which, at one point, he also conceived merely in terms of extension and impenetrability. According to his own account (see Leibniz 1989: 453-4), Leibniz came to recognize that conceiving bodies in this way yielded results that were incompatible with the acknowledged laws of motion; so, conceiving bodies in merely mathematical terms would imply that "it would be no more difficult to move a large body than a small one, and hence there would be action without reaction" (Leibniz 1989: 440). Leibniz was thus convinced of the necessity of positing something over and above these qualities, namely, a power or force (vis).2 The significance of power or force, thus understood, is not limited to physics, however, since as something in addition to the mechanical properties of bodies, power is properly identified as a metaphysical concept. The derivative power or force in bodies is grounded in a primitive power which Leibniz understands as a principle of activity that is characterized in terms of a continual "striving or effort which has its full effect unless impeded by a contrary striving" (Leibniz 1989: 435). Indeed, this metaphysical concept of power becomes central for Leibniz's conception of substance as such, in which context it is identified as the source of the various changes that take place in a given substance: "I say that this power of acting inheres in all substance and that some action always arises from it, so that the corporeal substance itself does not, any more than spiritual substance, ever cease to act" (Leibniz 1989: 433). Significantly, Leibniz will contend that all change in a given substance is to be accounted for through its primitive active power. This is due in large part to Leibniz's rejection of any real influence of one substance upon another as incoherent given that it would require the migration of an accident from one substance to another, in the course of 1 Wolff provides a list of Leibniz's texts that were available to him as of 1719, in his autobiography; see Wolff (1841: 141). See also Wilson (1998: 442-43). 2 See Garber (2009), especially chapter 3, for a detailed treatment of Leibniz's criticism of the Cartesian conservation principle and conception of body. 3 which the accident would either belong to two substances or to none, either of which is incoherent (Leibniz 1989: 643-4 [§§7, 11]). Even so, this denial of real influence or interaction between substances undermines the most natural account of why it is that the states of the body (a composite of substances) and the soul (a single simple substance) agree with one another as we observe to be the case. Leibniz was not the first to recognize this problem as he credits Descartes with having come upon it, on the basis of his acknowledgement of the radical heterogeneity of thinking and extended substance, though Leibniz claims that he "gave up the struggle" (Leibniz 1989: 457). Thinkers in Descartes' wake, such as Malebranche, had proposed an alternate, so-called "occasionalist" account that acknowledged the impossibility of any natural influence but contended that an appropriate change in, for instance, the body was the occasion for God's activity in bringing about the appropriate state in the soul. Leibniz finds the occasionalist explanation to be lacking, however, given that, among other things, it would seem to require perpetual intervention in the events of the world on God's part, which intervention Leibniz contends is inconsistent with God's supreme wisdom.3 Leibniz offers his own alternative for accounting for the agreement between the states of the soul and the body, namely, the pre-established harmony. According to this view, the agreement or harmony between the states of the respective substances was established by God in such a way that, for instance, the bodily state involved in the stimulation of the sense organs agrees with the soul's state of representing some object of sensation (Leibniz [1710] 1985: I §66). The pre-established harmony is consistent with Leibniz's account of substance, since each substance is the active cause of its own changes, and it avoids the difficulties associated with the occasionalist account; so it does not require continuous miraculous intervention inasmuch as the principle of change remains located within the individual substances. In the end, the harmony between the soul and the body is only an instance of the universal harmony that Leibniz contends obtains among all substances in the world: "we must say that God has originally created the soul, and every other real unity, in such a way that everything in it must arise from its own nature with a perfect spontaneity with regard to itself, yet by a perfect conformity to things without" (Leibniz 1989: 457; cf. also Leibniz 1989: 651 [§78]). Leibniz's contention that the order of the world has been pre-established by God obviously raises a question about whether all events in the world are necessitated to take place as they do. Leibniz's response is rather subtle as he argues that while events in the actual world are in fact 3 Leibniz's arguments against occasionalism are helpfully catalogued in Watkins (2005: 28-32). 4 determined to take place, and that we can therefore be certain of them in advance of them happening (Leibniz [1710] 1985: I §36), this does not imply that they are necessitated. This is because the actual world is not the only possible world as there are infinitely many other worlds in which different events occur or events are differently ordered. Since other worlds are possible, Leibniz thinks it perfectly sensible to hold that the actual world is not absolutely or metaphysically necessary (which would be the case if it were the only world possible) but rather only hypothetically necessary inasmuch as it depends upon God's (only morally necessary) decision to choose to bring this world, the best of all possible, into existence (Leibniz [1710] 1985: I §37). While Leibniz thinks that the foregoing suffices for distinguishing his view from the necessitarian system of, for instance, Spinoza, he also claims that the sort of determination he endorses is entirely compatible with human freedom. The actions of the human soul, as a substance in the world, are likewise only hypothetically necessary inasmuch as it remains the case that for each action it was not absolutely necessary that the agent performs it.4 Nonetheless, Leibniz goes further to offer a specific account of the freedom of the will. As he writes in an oft-quoted passage, the contingency of the world is only one (necessary) condition for such freedom: I have shown that freedom, according to the definition required in the schools of theology, consists in intelligence, which involves a clear knowledge of the object of deliberation, in spontaneity, whereby we determine, and in contingency, that is, in the exclusion of logical or metaphysical necessity. Intelligence is, as it were, the soul of freedom, and the rest is as its body and foundation. The free substance is self-determining and that according to the motive of good perceived by the understanding, which inclines it without compelling it: and all the conditions of freedom are comprised in these few words. (Leibniz [1710] 1985: I §288) So, in addition to contingency, human freedom requires "intelligence" and spontaneity, where the possession of the former is what distinguishes souls, as minds, from the simple elements of nature, and involves a capacity to act in accordance with its (clear or distinct) knowledge of what is good (Leibniz 1989: 645 [§29]; Leibniz [1710] 1985: I §289). This already serves to distinguish Leibniz's account of freedom of the will from indifferentist accounts, such as Descartes', as rather than taking freedom to consist in the will's unconstrained choice between two actions, Leibniz takes freedom to involve the will's determination by (the right sort of) reasons since no event, including the determination of the will, is without a sufficient reason (Leibniz [1710] 1985: Prelim. §69). Finally, spontaneity has to do with the fact that the actions of some agent are determined by itself rather than by external causes, a condition which Leibniz claims the soul fulfills simply in virtue of the fact 4 A detailed treatment of these issues can be found in Adams (1994: 9-52). 5 that, as a simple substance endowed with a power, it contains the source of all its changes in itself, which is to say that "true spontaneity is common to us all and simple substances" (Leibniz [1710] 1985: §290, see also §291).5 2. Causation between Leibniz and Kant It would hardly be an understatement to claim that Leibniz's treatment of causation in terms of a power internal to substances, his denial of natural interaction between substances, and his account of freedom in terms of a substance's contingency, intelligence, and spontaneity proved foundational for German philosophers in the first half of the 18th century. These doctrines, particularly as they were adopted and defended by Christian Wolff and his followers, were among the most controversial for his Pietist opponents, and Wolff's (qualified) endorsement of the preestablished harmony apparently even proved decisive in his exile from the Prussian lands by King Friedrich Wilhelm I in 1723.6 However, debates regarding these issues outlasted this controversy and continued to be debated up to (and in some cases after) the publication of Kant's first Critique in 1781. In this section, I will trace the development of some of the key debates in this period regarding these questions. a. Power vs. Powers Significantly, Leibniz's reconceptualization of substances in terms of a power to act gained widespread acceptance among German thinkers with even those who opposed, for instance, his system of pre-established harmony, nonetheless accepting the essentials of this characterization of substance. What was, in any case, heavily contested was whether a single power was sufficient to explain all of the alterations of a given substance, a question which became a particularly important issue in psychology but was also significant for physics through the ascription of (apparently contrary) repulsive and attractive powers to bodies.7 The parties to this debate divided along the expected lines, with single-power theorists adhering to the Leibnizian-Wolffian philosophy, and the 5 See Rutherford (2005) for a nuanced defense of the role of spontaneity in a Leibnizian account of freedom of the will. 6 The most detailed accounts of Wolff's exile from Prussia are presented in Zeller (1894), and Beutel (2001). 7 So Kant claims in the Physical Monadology that "we can already in a way understand that anyone who is able to deduce these two principles [i.e., the two forces of attraction and repulsion] from the very nature and fundamental properties of the elements will have made a substantial contribution towards explaining the inner nature of bodies" (AA 1:476). 6 multi-power theorists comprised of its critics. And while the initial discussion was driven by metaphysical worries, such as the unity of simple substance, epistemological concerns eventually replaced these as foremost. Unsurprisingly, this debate gets its start in Wolff who, like Leibniz, understands a substance primarily in terms of the possession of a power. A substance, or a "thing that persists for itself [vor sich bestehendes Ding]," is something that is possible, which is to say, it contains nothing contradictory (Wolff [1719-20] 1751: §§12, 16). Among the features that it contains, some of these constitute the essence of that thing (inasmuch as they are grounds of some of the others properties-§§33, 44). The essence of a thing thus consists in features that serve as the initial grounds of the rest of what pertains to that thing (§34), and which Wolff further contends are necessary (§38), eternal (since the necessary is eternal-§39-40), and thus unchanging (§42). Since an essence cannot change, any change in a thing must consist merely in the alteration of the limitations (Einschränckungen) of its essence (§107). On the basis of this account of change, Wolff further distinguishes between things which persist of themselves, or substances, and things that persist through other things, or accidents: the former are taken to have the source ("Quelle") of alterations within themselves whereas the latter do not and are nothing more than the limitations of the former (§114). It is this source of alterations that Wolff proceeds to identify with the metaphysical concept of power (Kraft-§115), where this power is characterized as a "striving to do something" (§118). The close connection Wolff establishes between substance and power is clearly Leibnizian (even if presented in Aristotelian-Scholastic dress), yet Wolff does not follow Leibniz in every respect. Most notably, Wolff rejects Leibniz's characterization of the power of all substances as representative in nature. So, while Leibniz claims in for instance the "Monadology" that "all simple substances or created monads can be called souls" inasmuch as they are endowed with perceptions that represent states of the world (Leibniz 1989: 644 [§19]), Wolff contends that Leibniz has simply not provided us with any reason to hold that the elements of nature must be endowed with such a power (Wolff [1719-20] 1751: §599).8 Even so, Wolff accepts the characterization of the human soul as fundamentally a power of representation, contending that its essence and nature consists in "a power of representing the world in accordance with the position of the body in the world" (§745). The soul is identified as such a power in spite of the fact that it is capable of a wide variety of alterations, including sensations, imaginations, memories, and higher representations (§747). As 8 For Wolff's differences from Leibniz on this score, see Corr (1975: 255-56). 7 Wolff argues, however, all of the soul's representations find their source in this power of representing the world inasmuch as all such alterations have their source in sensations, where sensations are just representations of the world (Wolff [1719-20] 1751: §§749-51, Wolff [1724a] 1740: §271). Indeed, Wolff contends that the soul could not possibly have more than one power given that as a simple thing (Wolff [1719-20] 1751: §742), it cannot have any parts and multiple powers would require the posit of multiple parts of the soul, just as a body cannot be taken to endeavour to move in different directions at the same time (§745).9 As is clear, Wolff's insistence (not to mention Leibniz's) that substance in general, and the soul in particular, can be endowed with only a single power has its basis in his assumption that the simplicity of substance entails the singularity of a power.10 However, Wolff's grounds for taking all of the soul's alterations as having their source in a single (representative) power were immediately disputed by his Pietist and Thomasian critics who challenged the general metaphysical assumptions behind Wolff's argument. Joachim Lange, for instance, claimed that Wolff's argument against the possibility of multiple powers involves a conflation of a power with a part of a substance since, as Lange objects, this assumption would imply that body, which is correctly taken to have a single power (of motion), does not consist in parts (Lange 1724: 116).11 Along similar lines, Andreas Rüdiger contends that Wolff errs in taking all powers that merely differ in some way to be contrary powers. Accordingly, while it is clear that contrary powers cannot belong to the same (simple) substance, Wolff has not shown that the same substance cannot be endowed with merely different powers (Rüdiger 1727: 27-8). In addition to showing that Wolff has not ruled out the possibility of multiple powers of the soul (and by extension of substances in general), these critics take issue with the sufficiency of the power of representing the world to account for all of the soul's states. So, Lange finds that such a power cannot account for the activity of the higher intellectual power (which is not bound to representing states of the world-Lange 1724: 112), and both Lange and Rüdiger contend that it cannot account for the alterations in the soul that stem from the will, which should therefore be recognized as a power distinct from that power responsible for cognition which they identify simply as the understanding (Lange 1724: 115-16; Rüdiger 1727: 37-8). 9 See the detailed treatment of Wolff's distinction between faculty and power in the within the general context of his metaphysics in Hessbrüggen-Walter (2004: 57-61). 10 Wolff also claims the converse, namely, that the singularity of the soul's power implies that it is a simple substance; see Wolff 1724: §265. 11 Compare Hessbrüggen-Walter (2004), 61-2. 8 In an effort to break this impasse, Alexander Baumgarten offers what he intends as a conciliatory account in his Metaphysica. He begins by arguing, like Wolff, that the soul's nature consists in "the power of representing the universe according to the position of the human body in it" (Baumgarten [1739] 2014: §741), and he demonstrates this in much the same way as Wolff had. So, the soul is identified as a power on account of the activity in displays in bringing about alterations in itself (§505), these alterations are representations (§506), and in particular, are representations of other things in the universe through states of my body (§507-8), and therefore "my soul is a power for representing the universe according to the position of its body" (§513). While Baumgarten can thus be seen to follow Wolff concerning the nature of the soul's power, he nonetheless concedes to an extent that Wolff does not that the soul might be allowed to have different powers, albeit only in a broader understanding of that term where it is roughly synonymous with 'faculty' (§197). Accordingly, desire can be allowed to constitute a ground for certain alterations of the soul (§216); yet, Baumgarten is clear that there can be but a single power, taken in the narrow sense, in the soul which constitutes the sufficient ground of all of its alterations (§744). While Baumgarten's intervention on this issue appears to offer little more than a semantic concession to Wolff's opponents, it does succeed in illuminating the basis for the Wolffians' resistance to admitting more than one power. In addition to the original metaphysical worry stemming from the simplicity of substance, the admission of multiple powers threatens to undermine the possibility of any useful account of the causal grounds for changes in the soul. For Baumgarten, the consequence of rejecting a single power of the soul is that all of the soul's alterations could only be accounted for through reference to the faculties (or powers in the broad sense) that ground their possibility. This, however, would make such explanation all but pointless since arbitrarily many (and possibly overlapping) faculties might be posited as grounds of the alterations in the soul.12 Accordingly, when it comes to the soul at any rate, causal explanation is conceived by the Wolffians as an all-or-nothing affair-either a single ground is posited for the various alterations of the soul, or we cannot exclude a bewildering multiplicity of possible powers in the soul. Given the significance for Wolff of the reduction all of the soul's representations to a single 12 This point is made by Rüdiger, for instance, who claims that we can abstract multiple distinct powers from various objects: "Indeed, I would go so far as to say that it is no great art to abstract a common genus from various distinct things, as [Wolff] has done when he abstracts a common power of thinking from the various powers of the soul" (1727, 39). 9 causal power (since it allows abstract concepts to be traced back to sensations, thereby demonstrating their possibility13), this would be a disastrous result. This worry seems to have been recognized by Christian August Crusius who attempts to offer an alternative to the Wolffian dilemma. Specifically, Crusius introduces the notion of a fundamental power (Grundkraft) which is intended to distinguish those powers in a substance that serve as fundamental explanatory grounds for its various alterations from the manifold of other, merely derivative powers. Having recognized that one could posit a distinct power for every "positive property" of a thing (Crusius 1745: §29),14 Crusius like Baumgarten distinguishes between a broad and a narrow sense of power, where the broad sense is equivalent to a faculty (§69) and the narrow sense is strictly identified with a fundamental power. Moreover, Crusius provides a list of 8 characteristic marks proper to fundamental powers, among the most important of which are: "A true fundamental power must constantly pertain to a thing" (§71); "As long as one cannot intelligibly derive the effect from the supposed fundamental power, then one either does not yet have a fundamental power, or one does not have a completely distinct understanding of it," (§72); "A finite fundamental power always has the same proximate effect, and from this the more remote ones must be understood" (§73); "The conditions to which the action of a fundamental power are bound must lie in the same subject [as that power]" (§74); and "A fundamental power must not permit of being causally derived from other powers" (§76).15 Crusius applies these criteria to distinguishing explanatorily primary fundamental powers from "mere faculties and arbitrarily-abstracted general powers" (§70). Thus, he denies that a power of attraction could be fundamental in bodies (since its conditions lie in other bodies-§74), and he argues that in addition to a distinct fundamental power of willing (§446), there must be multiple fundamental cognitive powers to account for effects as diverse as sensations and consciousness which are as different as "the sun itself and the idea of the sun" (§444). Significantly, Crusius' treatment lent a distinctive slant to the ensuing discussion as his notion of a fundamental power was widely adopted, and his claim that the understanding consisted in multiple such powers was taken up by Johann Georg Sulzer in an essay of 176316 and provided the topic of an Academy prize question announced in 1773, which provoked extended treatments by J. A. Eberhard and J. G. Herder.17 The last significant contribution to this debate before Kant's 13 On the ways of demonstrating the possibility of concepts in Wolff, see Kuehn (1997). 14 See also Crusius 1745: §70: "Since one can generally put any given thing, effect, property, or capacity together with the idea of a power to make a single concept [...] [yet] through all of this nothing is explained at all." 15 Crusius' notion of a Grundkraft is also discussed in Watkins (2005: 81-5), and Hessbrüggen-Walter (2004: 96-100). 16 Published in Sulzer (1773). 17 For specifics regarding the prize question, and Eberhard's entry, see Grove (2012). 10 Critique was supplied by Johann Nicolaus Tetens. Like Crusius, Tetens rejects the Wolffian reduction of the soul's powers to a single representational power, instead proposing that the cognitive power consists of a fundamental power of feeling or sensation, a fundamental power of representation (albeit understood in a sense different than Wolff's), and a power of thought, all of which were in turn distinct from a power of willing.18 While Tetens proceeds in much the same way as Crusius had in distinguishing these fundamental powers, he also actively denounces the temptation to reduce these discovered fundamental powers to a further, original power. Tetens thus objects that the posit of a single power of the soul lacks any grounding in experience since "we have no idea of the first, original effects of [the soul's] natural power" (Tetens 1777: XI.i.3; vol. I, p. 737). Moreover, Tetens dismisses the urge to organize the multiple fundamental powers of the soul with respect to a putatively more original power as the product of a bias towards systematicity that only has the effect of interfering with our observation; he writes that the idea of a single fundamental power is such a natural and probable idea that I have to fear that it has functioned surreptitiously as a prejudice that I have found subsequently confirmed in observations. Nowhere does one have reason to exercise more caution, lest one is deceived by the systematic spirit [dem Geist des Systems], than where nature seems to present itself in just the form that one had previously imagined he would find it in (Tetens 1777: X.i.1; I, 619) Accordingly, Tetens rejects it as mere "supposition" or a "conjecture" (X.i; I, 618) that the dissolution of all remaining expressions of the soul will lead the investigator back to the same, single fundamental power. b. Pre-Established Harmony vs. Physical Influx As we have seen, the debate concerning the number of fundamental powers of the soul broke down roughly along Wolffian lines; however, the same is not the case for the most active discussion of the first-half of the 18th century in Germany, namely the dispute regarding the highly contentious system of pre-established harmony. Leibniz's system attracted early (if sometimes qualified) support among those most directly influenced by his thought, yet a growing number of thinkers came to oppose it on recognizably Leibnizian grounds. And while Leibniz had clearly viewed the occasionalist system as the most obvious competition to his own system, the critics of the harmony uniformly opted instead for the system of natural, or physical influx. Indeed, it is a peculiar, and as yet unexplained, feature of the German discussion that no widely influential 18 Tetens (1777: X.ii; I, 625). Beck (1969: 415-20) offers a detailed account of Teten's classification of powers and faculties of the soul. 11 proponent of the occasionalist system emerged. What is in any case distinctive about the treatments in this period are the sophisticated interpretations and defenses of both the pre-established harmony and physical influx. Largely on the basis of his difference with Leibniz concerning the nature of the powers of the elements, Wolff adopted a rather nuanced position on the pre-established harmony. The fact that we do not know what the nature of the power is that is possessed by the simple substances that compose bodies implies that we cannot determine precisely what grounds the agreement that obtains among their states.19 For this reason, Wolff limits his consideration of the pre-established harmony, and the underlying issue of what grounds the agreement among events in the world, to the relation between the soul and the body, a topic he situates within his psychology. As Wolff notes, anyone can observe for themselves that the representational states of the soul agree with the nonrepresentative states of the body (Wolff [1719-20] 1751: §§527-35), though Wolff makes the (later recognizably Humean) point that the underlying cause of this agreement is not likewise available to observation (§535; cf. Watkins 1998: 141). As a result, it is left to reason to determine how this agreement is best accounted for, and to this end Wolff compares the systems of physical influx, occasional causation, and pre-established harmony. Focusing on Wolff's criticisms of the first system, Wolff notes that physical influx finds no special purchase in experience, since we cannot directly perceive the causation involved (Wolff [1719-20] 1751: §761), and also that the system is contrary to the laws of motion inasmuch as the soul's influence on the body violates the conservation of motive force by generating a new motion. Wolff ultimately settles upon the preestablished harmony as consistent with experience and with the laws of motion, but also as the only system consistent with the fact that the soul is endowed with a power (§765).20 As noted above, Wolff's defense of the pre-established harmony proved enormously controversial with his Pietist opponents, and particularly Joachim Lange who engaged in the most protracted debate with Wolff on the subject.21 Lange's criticism was wide-ranging and opportunistic, charging Wolff with variously endorsing idealism, atheism, Spinozism, and fatalism through his support of the harmony. While Lange raises specific objections to the definition of spirit and conception of the nature of the soul that the harmony presupposes and contends that it undermines 19 "However, since we do not yet want to fix what it actually consists in that the inner state of simple things relate themselves to everything else in the world, so we will leave open for now as to what the universal harmony of things consists in" (Wolff [1719-20] 1751: §600). 20 See Watkins (2005: 45-50) and Fabian (1925: 32-47), both of whom present Wolff's version of the pre-established harmony with special attention to its differences from Leibniz's. 21 A convenient summary of the vigorous and protracted exchange is presented in Watkins (1998: 145-50). 12 any genuine (physical) union between the soul and body,22 the bulk of his criticisms concern the consequences of the harmony for morality (such as the denial of true freedom and resulting impossibility of the imputation of actions) and religion (such as understanding God in terms of infinite wisdom rather than goodness, and denying him power to intervene in the pre-established order).23 In response to these broader charges, Wolff offers a striking qualification of his endorsement of the system of pre-established harmony as he claims that each of the three systems amounts merely to an hypothesis, none of which finds decisive confirmation or disconfirmation in experience (Wolff [1724a] 1740: §280).24 Accordingly, those who claim that the pre-established harmony has negative consequences for morals and theology, Wolff simply recommends adopting another system as nothing substantial in his own philosophical edifice rests on it (Wolff [1724a] 1740: §289).25 Lange's campaign against Wolf focused on offering arguments against the pre-established harmony rather than defending and arguing for his own preferred view of physical influx. Instead, a robust defense of physical influx (if not exactly on terms that Lange would approve) was left to Rüdiger. Rüdiger diagnoses what he takes to be a longstanding prejudice at the root of the widespread rejection of physical influx, namely, the conception of body in terms of extension (or as having partes extra partes). On the basis of this narrow conception of body, philosophers were led to sharply distinguish the soul (as lacking parts) from body, where the evident heterogeneity between the two generates the inconceivability of any direct influence of one upon the other (Rüdiger 1727: §12). Against this Rüdiger argues that in fact there is no such conceptual obstacle to influx since both the (subject of the) soul and the body are in a sense extended, thus eliminating the heterogeneity. With respect to the body, Rüdiger denies that extension constitutes its proper essence, taking this rather to consist in elasticity (Rüdiger 1727: §11; cf. Watkins 1998: 156-9); concerning the soul, Rüdiger distinguishes between the soul as a metaphysical abstraction, or Aristotelian form, and the "subject of the soul" or the concrete particular from which the soul is abstracted (Rüdiger 1727: §6-7). As opposed to the soul, the subject is "extended" and even material 22 For representative presentation of these points see, for instance, Lange (1724: 110-18 and 125-29). See also Dyck (forthcoming) and Watkins (1998: 150-3). 23 For these criticisms, see Lange (1723b: 121), and Lange (1724: 130-67 and 196-7). For a detailed discussion of these larger issues raised by Lange concerning the harmony, see Bianco (1989: 120-6). 24 In doing so, Wolff likely picks up on Leibniz's own designation of the pre-established harmony as an 'hypothesis' (Leibniz 1989: 458). 25 See Wolff (1724b: 96-8) where Wolff notes that of the 550 sections devoted to psychology in his Deutsche Metaphysik, only 22 are devoted to its defense. 13 inasmuch as it consists of parts, albeit imaginary ones.26 With the heterogeneity of (the subject of) the soul and body thus shown to be merely apparent, Rüdiger no longer sees any obstacle to accepting physical influence.27 These early defenses of physical influx proceeded from a general opposition to the Leibnizian-Wolffian philosophy, and gained little traction outside of the narrow circle of Wolff's critics. Yet, given Wolff's own characterization of the pre-established harmony as a mere philosophical hypothesis,28 it was not long before philosophers within that tradition turned a more sympathetic eye towards physical influx.29 Among the most important of these was Martin Knutzen, whose case for physical influx proceeds on the basis of substantive agreement with Leibniz.30 Knutzen offers two arguments for physical influx which primarily concern the simple elements of bodies, contending that assigning a moving power (vis motrix) to a simple element is conceptually equivalent to assigning it a power to move other things around it (Knutzen 1745: §28), and that the impenetrability of simple substances cannot be conceived otherwise than as a power to resist the motion of other substances (§29).31 In turning to the relation between the soul and the body, Knutzen argues first for the possibility (or bare conceivability) of physical influx against its Wolffian detractors,32 claiming that there is nothing inconsistent in the notion that the soul, a simple perceiving substance, should act on bodies given that, on the one hand, simple things (namely the elements) have already been shown to act upon one another and, on the other, that the power to act on other things is evidently a perfection (and so consistent with other perfections) inasmuch as it can be ascribed to God (Knutzen 1745: §34).33 Knutzen proceeds to defend the comparative probability of physical influx as an explanation of the observed agreement between soul and body, contending that among other things it provides the most efficient explanation of such agreement and is therefore most consistent with divine wisdom (§35). Knutzen also replies to a number of the objections against physical influx, 26 For more on Rüdiger's argument here, see Dyck (forthcoming) and Fabian (1925: 218-19). 27 Additional responses by Rüdiger to Leibnizian-Wolffian objections to physical influx, as well as his novel objections against the harmony, can be found in Watkins (1998: 162-65). 28 Wolff's closest disciples likewise characterized the pre-established harmony in this way; cf. Thümmig (1725-6: 197-98), and Bilfinger (1725: §CCCLVI). For a discussion of the latter's views, see Kintrup (1974). 29 Other important influxionists in the Wolffian school are discussed in Fabian (1925: 86-137) and Watkins (1998: 16774). 30 For instance, Knutzen agrees with Leibniz (and against Wolff) that the elements of bodies have representational states (Knutzen 1745: §31). Knutzen's "return" to Leibniz is stressed by Erdmann (1875: 84-94). 31 See Watkins (1995: 309-17), and Watkins (2005: 54-63). 32 So, Wolff had objected that the "system of physical influx does not permit of being intelligibly explained" (Wolff [1724a] 1740: §277). 33 For discussion, see Watkins (1995: 317-22) and Watkins (2005: 63-67). 14 particularly its rejection as inconsistent with the laws of motion, countering that for instance the law of the conservation of motion has only been proven for inelastic bodies and not for interactions between soul and body and, citing the example of the law of inertia, that there is good reason to think that these laws do not hold for these interactions.34 The work of defending the pre-established harmony was taken up by Baumgarten (along with his student G.F. Meier35). Baumgarten's treatment of the issue clearly takes its bearings from that of Leibniz, rather than Wolff, as he makes a case for a universal pre-established harmony obtaining among all substances in the world on the basis of which the specific harmony between the soul and body follows (Baumgarten [1739] 2014: §463, §762). Even so, recognizing the shift in the debate towards physical influx, Baumgarten characteristically attempts to re-interpret the preestablished harmony in a way that acknowledges the possibility of influence between substances. Key to Baumgarten's efforts is a distinction between real and ideal influence, where the latter involves a suffering on the part of an individual substance undergoing a change that is also an activity and where this is not the case in the former sort of influence (§212).36 Baumgarten thus contends that endorsing the pre-established harmony is consistent with holding that all substances "mutually influence" each other (§409), and accordingly that the system of physical influence and pre-established harmony are not to be distinguished in terms of one upholding and the other denying the interaction of substance but rather in terms of the kind of influence this interaction is taken to involve, that is, real (in the former case) or ideal (in the latter-§448).37 Significantly, Baumgarten uses this notion of ideal influence to mount a response to the Pietist concern that the pre-established harmony undermines the union of the soul and body. So, Baumgarten contends that every instance of external sensation provides an occasion to observe the mutual influence of the body and the soul inasmuch as the alteration of the body contains the ground for the representational state of the soul which state is likewise an activity on the part of the soul (§736), thus concluding that the soul and its body constitute a union (§739). Despite these efforts, however, the tide had turned against pre-established harmony, which could only claim a few prominent holdouts (such as Moses Mendelssohn38), and decisively in favour 34 These objections are canvassed in Watkins (1995: 324-27). 35 Meier's discussion is presented in Meier (1743). For a comparison of Meier's and Baumgarten's endorsements of the pre-established harmony, see Watkins (2005: 78-81), and Fabian (1925: 82-6). 36 On this see Watkins (2005: 75-7). 37 For discussion of Baumgarten's conception of interaction and whether it constitutes a departure from Leibniz in particular, see Erdmann (1875: 95-6) and Fabian (1925: 81-2). 38 Mendelssohn offers a defense of the pre-established harmony in (1761), see especially 183-217. 15 of physical influx within the Leibnizian-Wolffian school. A final (at least for present purposes39) contribution to the debate was provided by Crusius, who offered a rather more sophisticated, and influential, take on the Pietist-Thomasian case for physical influx. In contrast with previous critics of Wolff, Crusius situates his defense of physical influx within a novel metaphysical account of causality.40 Crusius introduces, for instance, the notion of a "real ground" which, in contrast to a merely "ideal ground," does not only bring about the thought or cognition of some thing but actually brings something about outside of our thoughts (Crusius 1745: §34).41 This notion plays an important role in Crusius' conception of the world which he considers as a system of things that are really connected, that is, connected by means of real grounds rather than merely ideal grounds as he takes to be the case in Wolff (Crusius 1745: §359). Turning to the specific problem of accounting for the real connection between soul and body, Crusius follows Rüdiger in viewing the primary obstacle to a defense of an influxionist account to lie in the apparent heterogeneity of the two substances. To remedy this, Crusius draws on his notion of a fundamental power and defense of the possibility of multiple such powers, contending that while body and spirit (or soul) are distinct, they do have the capacity for movement (of bodies), in common. What accounts, then for how spirit can move the body is the fact that like all finite substances it is impenetrable and, as a result, it has the capacity to move matter by displacing it (§364). And while spirit, in virtue of its impenetrability and consequent occupation of space, is thus capable of moving bodies, Crusius denies that this has the consequence of reducing spirit to matter since spiritual substances are additionally endowed with the powers of thought and will, and so remain essentially distinct from matter (§364).42 c. Spontaneity vs. Freedom A final debate, and one that has received comparatively less attention, concerns the contrasting accounts of the freedom of the will that emerged on the basis of Leibniz's brief treatment in the Theodicy. While the debate regarding this issue was initially driven by the controversy surrounding the harmony and its alleged necessitarian consequences, it quickly took on a life of its 39 For further developments in this debate in the second half of the 18th century, with an emphasis on Tetens' defense of physical influx, see Wunderlich (2014). 40 The following summary of Crusius' views on causation follows Watkins' presentation in (2005: 82-9). 41 On this difference, and its significance (particularly for Kant), see Beck (1969: 396-402). 42 The success of Crusius's efforts on this score are considered in Dyck (2016b). 16 own, with theorists moving beyond the crude contrast of freedom and fatalism to explore a variety of, in some cases, rather sophisticated compatibilist and incompatibilist alternatives. Here, Wolff's discussion once again provides the initial salvo. Despite superficial resemblances with the brief account of freedom in the Theodicy, such as his hostility to the indifferentist account of freedom and his analysis of freedom into similar components, a closer look reveals key differences from Leibniz. Indeed, Wolff construes freedom primarily in terms of the soul's spontaneity (spontaneitas) which he opts to render through the (not obviously equivalent) German term 'Willkühr' (frequently translated as 'will' or even 'freedom of choice' in English).43 Just as Leibniz had, Wolff takes spontaneity to constitute a central element of freedom: "freedom is nothing else than the capacity of the soul to choose through its own spontaneity [Willkühr] that of two possible things which pleases it most" (Wolff [1719-20] 1751: §519). Considered in light of Leibniz's account, what is immediately notable is that Wolff makes no mention of contingency (and specifically that of the world) as a presupposition of free action. In fact, Wolff had previously emphasized that, for any free action, the opposite of that action (i.e., its omission or acting otherwise) is possible (§516); however, 'possibility' here is understood only in a weaker sense of our (psychological) awareness that the opposite is equally possible (§515-16) rather than as a kind of metaphysical contingency (in Leibniz's sense).44 Similarly, Leibnizian "intelligence" plays little more than a token role in free actions for Wolff; so while he indicates that "reason" or the capacity for insight into the connection of things serves as the "ground of freedom" (§520), it is not clear what this amounts to as Wolff proceeds to claim that we are necessitated to act in accordance with what appears to us as best anyway (§521). Accordingly, for Wolff, freedom is understood primarily in terms of the spontaneity of an action, that is, that an action has its ground in the soul (§518) though, and again unlike Leibniz, this is not taken in broader metaphysical but in psychological terms, that is, as proceeding from some internal motive (Bewegungsgrund). Wolff's virtual identification of freedom with spontaneity did not escape the notice of his dogged Pietist critics. This issue is clearly of central significance for Joachim Lange, who claims that the proper dignity and nobility of the human being consists in freedom (Lange 1723a: 11), and makes an influential case for distinguishing freedom from spontaneity.45 Following Wolff, Lange 43 See the first register of Wolff ([1719-20] 1751) and Kawamura (1996: 40). 44 Along these lines, it bears noting that Wolff's discussion of freedom is presented before his case for the contingency of the world in Wolff ([1719-20] 1751: §§565-76). 45 For more on Lange's criticism of Wolff on this score, and on its wider significance see Bianco (1989), esp. 116-20 and 129-36. 17 takes spontaneity to pertain to those actions which proceed from an agent without external coercion but also without any internal direction or source in the will (Lange 1724 [Einleitung]: 71). As Lange observes, this includes actions that proceed in accordance with an internal but "necessary drive of nature," such as that which operates in natural causes and automata (Lange 1724 [Einleitung]: 71). Identifying spontaneity with freedom, then, has the effect of reducing human agency to the working of a clock which likewise has an internal (and necessary) principle for its actions, and so subjecting human action to the same causal principles that govern natural events in the way the Stoics, and Spinoza had (Lange 1724 [Einleitung]: 71-2). Against this, Lange claims that what it means for an agent to act freely is that he is able to determine himself to do something on the basis of his own will, such that the beginning of the action lies in him and specifically in his will, and is directed by the understanding (Lange 1724 [Einleitung]: 70-1). What is, then, important for Lange, and what is evidently missing in both Leibniz's and Wolff's accounts, is that in order for an action to be free there must be some causal contribution on the part of the will to the action, which contribution must also be independent of the intellect and the senses (Lange 1723: 8-9). In response to Lange's criticisms, a number of theorists influenced by Pietist concerns but sympathetic to Wolff sought to distinguish freedom from spontaneity and determine more precisely the way in which they are related. The trailblazer in this respect was Friedrich Wagner, a Pietisttrained pastor but who attended classes by Wolff. His treatise (Wagner 1730) aims at clarifying the notion of freedom as it concerns actions,46 to which end he distinguishes what he terms mere spontaneity, which has to do with an internally necessitated action such as the working of a clock or the circulation of the blood, from freedom (Wagner 1730: §26). The latter involves spontaneity inasmuch as it is an action proceeding from powers and drives internal to a being, but among these internal powers is the will which is not internally necessitated in the same way (i.e., physically) as these other process but instead amounts to the capacity to act according to one's desires (which contra Wolff is now identified with Willkühr-Wagner 1730: §27), and where such an action is free when it is additionally performed knowingly (Wagner 1730: §28). Wagner's conclusion, that "freedom is more than a mere spontaneity" (§29), accordingly responds to Lange's concern on this score, though the resulting account bears a distinct resemblance to Wolff's. Significantly, Wagner's analysis of the notion of freedom was taken up by Baumgarten, who similarly distinguishes between spontaneity and freedom in his Metaphysica, where only those (spontaneous) actions are free which involve our 46 Wagner's contribution to this discussion, and importance for its later developments are detailed in Kawamura (1996: 47-52) and Schröder (1938: 57-60). 18 will, as opposed to sensitive desire, in accordance with our preference (Baumgarten [1739] 2014: §719).47 Unsurprisingly, it was Crusius who offered the clearest and most sophisticated alternative to the Wolffian view. As Crusius recognized, the deeper issue with the Wolffian account is not just that it fails to recognize the causal contribution on the part of the will in any free action, but that it fails to exempt the activity of the will from the necessity that governs natural events. Accordingly, Crusius not only distinguishes the will as a separate, fundamental power (distinct from the understanding), but also denies that its activity is governed by the principle of sufficient reason as Wolff conceived it.48 So, Crusius contends that the actions and effects of the understanding and the will are not the same since something must be added to representations in the understanding in order to constitute an instance of willing (Crusius 1745: §73). Even so, Crusius identifies both the activities of the powers of the understanding and the will as "fundamental actions," that is, actions immediately grounded in the essence of their respective power, but which depend on certain circumstances obtaining in order to take place (Crusius 1745: §82). However, Crusius distinguishes two sorts of actions of this sort, namely those that must occur under certain circumstances and those which are only rendered possible under given circumstances (§82), where the actions of the understanding are examples of fundamental actions of the first sort, and the fundamental actions of the will provide examples of the latter sort (§79; cf. also Crusius 1744: §41). Significantly, Crusius contends that, while both the actions of the understanding and the will are grounded in the essence of their respective fundamental powers, they are nonetheless grounded in different ways. That there is a ground for these actions follows from Crusius' claim that all actions can be understood to have a "sufficient cause" for their activity. While this looks to be an endorsement of the Leibnizian principle of sufficient reason, Crusius is quick to differentiate his principle from the Leibnizian version that holds that every occurrence has a cause or ground why it is so and not otherwise, which Crusius refers to as a 'determining ground' (Crusius 1745: §84). In the case of the fundamental actions of the understanding, the understanding is the sufficient and determining ground of those actions,49 but in the case of the fundamental actions of the will, the will 47 For more detail on Baumgarten's distinction between spontaneitas and arbitrium, see Kawamura (1996:, 53-7), and for a presentation of his account of freedom as a response to the conflict between Wolff and the Pietists, see Schwaiger (2011: 79-95). 48 That the principle of sufficient reason governs the "free" actions of the will is clear in Wolff's rejection of indifferentist accounts; see Wolff ([1719-20] 1751: §510): "The comparison of the scale that tilts to one side with the will goes no further than the fact that the former as well as the latter must have a sufficient reason." 49 For an account of this in Dyck (2016a). 19 serves merely as the sufficient cause of such an action, which is to say that such an action does not rule out the possibility of other actions taking place, and so the sufficient cause falls short of also determining that the activity had to be so and not otherwise.50 A fundamental action of the will is free, then, because in the very same circumstances at a given time we can act or refrain from acting, or act in either of two contrary ways (Crusius 1744: §38), a conception that Crusius contrasts with that "spiritual spontaneity" which involves being determined to an action through internal representations and desires (Crusius 1744: §40). While both Wolff and Crusius attracted their defenders in the ensuing debate (with the preCritical Kant notably siding with the Wolffians in the Nova dilucidatio), a number of thinkers sought to find common ground between these opposed positions,51 with perhaps the most notable attempt being that of Tetens. Tetens lays the blame for the apparent intractability of the debate between the "determinists" (Wolffians) and "indeterminists" (Crusians) on both sides' abandonment of experience in favour of sheer speculation and indeterminate universal concepts (Tetens 1777: XII.i; II, 2-4). The account that Tetens proposes on the basis of our observation of ourselves amounts to something of a hybrid between the two accounts. So, Tetens endorses key planks of the Wolffian conception, claiming that spontaneity is at the very least a necessary condition of free action, as it pertains to all of the soul's activities (XII.iii.1; II, 25).52 In the case of free actions in particular, Tetens claims that these are brought about in whole or in part though the soul's determination to act through its power over itself (Selbstmacht) in accordance with the will (XII.ii.1; II, 5-8), and so freedom amounts to a "higher level" of spontaneity (XII.i; II, 5).53 Nonetheless, what makes such an action free in the proper (Crusian) sense54 is that alongside the power of the soul to determine itself to activity there as an unrealised (mere) capacity to act otherwise, which capacity is disclosed by experience (albeit not infallibly).55 So, while Tetens agrees with Leibniz and Wolff when he claims that experience discloses that every free action has a sufficient and even determining reason in the external and internal circumstances preceding the action (XII.vii; II, 41),56 and so that "nothing happens 50 For more detail on Crusius' criticism on this point, see Heimsoeth (1956: 175-6). 51 These include Joachim Georg Darjes and J.G.H. Feder; see Schröder (1938: 106-8) and Kawamura (1996: 69-77). 52 Tetens' account of spontaneity in general is explored in detail in Dyck (2016a). 53 Tetens also claims, in agreement with Wolff that such action involves reason albeit not without exception; cf. XII.v.2, II 32-4. 54 See Tetens (1777: XII.ii; II, 5): "Freedom is here a capacity of not doing what one does, or of doing something other than what one does." 55 Tetens (1777: XII.ii.2, II, 8 and XII.v.1, II, 32). For the possibility of deception in this experience, see XII.ii.2, II, 9-10 and for discussion, see Hahmann (2014: 202-3). 56 Tetens arguably qualifies this later, claiming that these circumstances might not amount to a "fully determining" reason (XII.vii, II, 43), though he does not explain what this might amount to. 20 without a sufficient reason, " he nonetheless denies, given the presence of the faculty for acting otherwise, that this implies (as Wolff clearly thinks it does) that "nothing could happen without a sufficient reason" (XII.xv.4, II, 144). 3. Kant on Causation A comprehensive overview of Kant's views on causation in the Critique of Pure Reason, much less over his entire philosophical career, obviously cannot be undertaken in the space remaining here.57 Accordingly, in this third and final section I will offer a focused presentation of Kant's treatment of causation in the first Critique pertaining to the three debates considered above. My aim is simply to show how and where Kant engaged with his contemporaries on these issues and to highlight his original contributions on these topics. The issue of whether the soul has a single power or multiple fundamental powers crops up in a number of places in the Critique, though it is discussed in the most detail in the Appendix to the Transcendental Dialectic. Kant sets out from the challenge, implicitly acknowledged by Baumgarten, that faces any attempt to trace the observed changes in the soul back to powers: "At first glance the various appearances of one and the same substance show such diversity that one must assume almost as many powers as there are effects" (A648/B676). Like Crusius, however, Kant distinguishes a number of fundamental powers which provide the causal ground of the innumerable other faculties and powers of the soul that might be posited, where what distinguishes these "comparatively fundamental powers" is that the cannot be derived from one another nor from another power of the soul (A94). Indeed, Kant also follows Crusius in contending that the cognitive power, the understanding, rests on multiple "powers of cognition" (Axvi) inasmuch as these powers supply distinct and mutually irreducible a priori contributions to our cognition (A115-16).58 Even so, Kant does not reject out of hand Wolff's claim that the soul has a single fundamental power (though he does reject that this is grounded in the simplicity of substance59), as Kant identifies the notion of "a single radical, i.e., absolutely fundamental, power" (A649/B677) as an idea of reason. This is, of course, reminiscent of Tetens' characterization of a single fundamental 57 Watkins (2014) provides such an overview of Kant's pre-Critical and Critical views on causation. 58 For a detailed consideration of Kant's argument for this conclusion, see Dyck (2008). 59 See A650/B679: "it is not only, as in the case cited, on account of the unity of substance that reason presupposes systematic unity among manifold powers, but rather reason does so even where many powers, though to a certain degree of the same kind, are found, as with matter in general." 21 power as a misleading conjecture, and indeed Kant accepts that, as an idea of reason, the representation of an absolutely fundamental power "pretends to objective reality" (A650/B678). Nonetheless, Kant contends against Tetens that we could not begin to trace the effects of the soul back to even comparatively fundamental powers independently of such an idea.60 The idea of a single, fundamental power is thus a transcendental presupposition needed for introducing a systematic unity into inner appearances, but where the resulting unity is only projected by reason rather than grounded in those appearances. Where Kant's discussion of the soul's fundamental power thus offers criticism but also a measure of vindication for both sides of the dispute, his position in the Critique concerning the question of what system best accounts for the ground of the agreement in the changes of substances is less even-handed as he sides unambiguously with the defenders of physical influx. Opting to focus on Leibniz's presentation of the pre-established harmony in the context of his doctrine of monads, Kant offers a diagnosis of his error in the Amphiboly of the Concepts of Reflection. Kant claims that Leibniz commits an amphiboly insofar as he takes the comparison of objects in terms of the concepts of reflection (such as identity/difference, or inner/outer) to yield objectively valid judgments, where this amphiboly (and its resulting errors) is grounded in Leibniz's rejection of the sensible conditions of cognition. In the case of the pre-established harmony, Leibniz is led first to his account of monads through his comparison of objects considered merely as intelligibilia, which led him to prioritize the internal determinations of these objects (that is, those determinations had antecedent to any composition-A274/B330). This yields the conception of the monad as a simple, non-spatially located substance, but also implies the pre-established harmony as the only account for the possible community of substances: "For since everything is only internal [...] the state of the representations of one substance could not stand in any efficacious connection at all with that of another, but some third influencing all of them had to make their states correspond to one another" (A275/B331). However, Kant claims that Leibniz's amphiboly, and consequent transcendental misuse of the understanding, can be avoided through the acknowledgement of the independent contributions of sensibility to our cognition (which is to say, the endorsement of transcendental idealism), and the act of transcendental reflection, in accordance with which we distinguish what cognitive power a given representation belongs to (i.e., sensibility or the understanding) before engaging in a (putatively) objective comparison. 60 See Dyck (2014: 199-225) for detailed discussion. 22 In addition to diagnosing the error behind Leibniz's endorsement of the pre-established harmony, Kant also offers a full-blooded defense of physical influx. In the Third Analogy, Kant argues for the principle (in its B edition version) that "All substances insofar as they can be perceived in space as simultaneous, are in thoroughgoing interaction" (B256). The thoroughgoing and reciprocal interaction of substances, which is to say, their "real community" (A214/B261) follows from the consideration of the conditions for cognizing their simultaneity. Very briefly, to perceive two substances as co-existing through the same time requires the reciprocal orderability of the perceptions of their respective states, but this reciprocal orderability is only possible insofar as each substance determines the temporal ordering of the other's states, which is to say, insofar as they really interact.61 In addition to defending the real influence among (corporeal) substances, Kant also contends that his transcendental idealism removes any obstacle to maintaining the real influence between the soul and the body. Evidently agreeing with Rüdiger that the primary difficulty is occasioned by the apparent heterogeneity between the soul (as non-extended, thinking substance) and body (as extended, non-thinking substance), Kant argues that the transcendental idealistic conception of the objects of outer sense (bodies) and inner sense (the soul and its states) as mere appearance, which is to say representation, renders them homogeneous and, accordingly, removes the alleged incomprehensibility of their mutual interaction (A385-6).62 Transcendental idealism supplies Kant's most important contribution to the last debate as well, namely that concerning spontaneity and freedom. In the Third Antinomy, Kant takes up the question as to whether there are any events, such as the action of the human will, that are not subject to the principle of natural causation (as expressed in the Second Analogy). The thesis of the antinomy, which corresponds to the Crusian (and Pietist) position, holds that there is another causality, namely transcendental freedom, which is exempt from natural causality, whereas the antithesis of the antinomy, which corresponds to the Wolffian position, contends that there are no events in the world that do not occur in accordance with the principle that governs natural occurrences. Kant contends that this dispute remains intractable from the perspective of the transcendental realist and only admits of a resolution from the vantage of transcendental idealism's distinction between appearances and things in themselves. In brief,63 the transcendental idealist can hold, with the proponent of the antithesis, that all natural occurrences or events in the world take 61 Watkins (2010) contains a convenient overview of the main argument of the Third Analogy, with Watkins (2005: 21729) offering a more detailed treatment. 62 See Powell (1988) for a discussion of Kant on the soul-body problem in the Paralogisms. 63 Allison (1998) provides a detailed account of how transcendental idealism offers a resolution of the Third Antinomy. 23 place in accordance with the causal principle insofar as these are considered as appearances; consistent with the proponent of the thesis, however, the transcendental idealist can at the same time maintain that a non-natural causality or transcendental freedom is not ruled out insofar as we consider things as they are in themselves and, indeed, that the idea of such freedom is even necessary for the sake of reason's search for completeness in the series of conditions. As it applies to the specific issue of the freedom of the will, this "cosmological" idea of transcendental freedom provides the basis on which the "practical concept of freedom is grounded" (A533/B561). Again, we can only sketch Kant's conception here,64 but the resulting conception of the will as "a faculty of beginning a series of successive things or states from itself" (A448/B476) serves to distinguish its activity from that of the understanding, the action of which depends upon the availability of a sensible manifold (cf. B423n). This aligns Kant's conception of the will with that of Crusius and the Pietist opposition to Wolff, and while Kant clearly conceives of the action of the will as likewise exempt from the law that governs natural occurrences, in broad agreement with the Wolffians he views this freedom as ultimately compatible with causal determination. Lastly, but significantly, in spite of these contentions Kant denies that we can have insight, empirical or otherwise, into the reality or even possibility of transcendental freedom (A557-8/B585-6);65 rather, freedom is only presupposed as an idea of reason necessary for our conception of ourselves as moral agents, a point which Kant stresses in his subsequent treatments of moral philosophy (see, for instance, Groundwork 4:448). 4. Conclusion Having thus considered the development of three debates concerning causation, from their origin in Leibniz through to Kant's discussion in the first Critique, a number of things should be clear. First, we have confirmed Leibniz's importance for the debates regarding causality in the 18th century German context. Second, in spite of this, the positions canvassed by thinkers in this period hardly represent Leibnizian orthodoxy but in many cases significantly develop or starkly deviate from this, and indeed this is not only the case for thinkers like Lange, Crusius, and Tetens, who professed no loyalty to Leibniz, but also for thinkers like Wolff and Baumgarten who represented 64 For a discussion of Kant's views on freedom of the will which also takes into account some of the context supplied above, see Allison (2016). 65 While Tetens' Philosophische Versuche exercised an important and largely positive influence on Kant as he laboured on the first Critique, his appraisal of Tetens' treatment of freedom in Essay XII is rather negative; see Kant's letter to Herz of April 1778, AA 10:232.. 24 the mainstream of the Leibnizian-Wolffian philosophy, a fact that attests to the originality and complexity of this tradition. 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