The 1860s seemed to mark the dawn of a new age in Germany.1 The liberal hopes for greater democracy, for constitutional government and national unity, which had been defeated in 1848, began to stir again. After the oppressive atmosphere of the 1850s, when the forces of reaction bore down heavily on German lands, the air began to clear. Several developments of the late 1850s created this change of atmosphere. Some German states (viz. Baden and Bavaria) were forced to make concessions to liberal parliaments; more liberals were elected to local parliaments; more enlightened reform-minded ministers came to power (viz. Radowitz in Prussia and Schmerling in Austria); and the new Prussian monarch, Wilhelm I, seemed more amenable to reform and liberal ideas than his predecessor, Friedrich Wilhelm IV, a figurehead of the reaction. As the repressive policies of reactionary forces began to weaken, so political activity among liberals began to strengthen. With renewed hopes, the old leaders of 1848 again began to agitate for their cause. They would now proceed more slowly and prudently than in the past, however, calculating that gradual reform could succeed where revolution had failed.
The 1860s was also the breakthrough decade for neo-Kantianism. The calls for a return to Kant now became more vocal and frequent. The few disparate voices of the interim years grew in number and seemed to speak in unison. Some of the most dynamic young philosophers in Germany wrote articles, manifestos, essays, and even whole books, championing the cause of Kant’s philosophy. No longer seen as obsolete or dated, Kant’s philosophy was now deemed not only worthy of study in its own right but the best solution to the crises and controversies of the day.
It was no accident, of course, that the 1860s witness both the Kant revival and a new political atmosphere. While Kant never advocated, let alone foresaw, German national unity, he was famous for his advocacy of liberal ideals, such as constitutional and representative government. He was no less well-known for his critical project, according to which all political institutions, “whether the state in its majesty or the church in its holiness”, had to submit to the tribunal of critique. No one had done more to secure Kant’s reputation as a fearsome critic of the political and religious establishment than Heinrich Heine, who, in his Zur Religion und Philosophie in Deutschland, had portrayed Kant as “this great destroyer in the realm of thought who surpassed the terrorism of Maximilian Robbespierre”.2 To some liberals, the “old destroyer” (der alles Zermalmende) would be just the man to invoke against those reactionaries who wanted to return to the old alliance of throne and altar.
This connection between the new political atmosphere of the 1860s and the rise of neo-Kantianism is very plain in a very timely and symbolic book published in the beginning of the decade, Ludwig Noack’s Immanuel Kant’s Auferstehung aus dem Grabe.3 Writing in 1860, Noack made a plea for Kant’s resurrection, for a return to the original more radical Kant, whose critical spirit had been buried by the forces of reaction. “The romantic foxes”, who populated the theological faculties at the universities, Noack charged, had tried to render Kant harmless by building a foggy metaphysics on his philosophy; but the young Hegelians led by Feuerbach, and “the buddhist saint and pessimist Schopenhauer”, had now smoked them out of their refuge. “It is time to get away from the Kantian foxpelt, which is how the philosophical romantics bring him to market, and to return to the true spiritual form and heroic armor of the old man from Königsberg”.4 We should have our Kant neat and straight, Noack advised, and that means pushing his critical project to its limits, whatever the consequences for state and church. What the critical philosophy stands for above all, in the realms of science as well as religion and politics, is free enquiry, the right, indeed duty, to free our minds of all prejudices and superstitions. Doubtless, Noack’s pleas expressed the standpoint of many liberals in the early 1860s. The prophecy expressed in the title of Noack’s book was becoming true: slowly but surely, Kant’s spirit was rising from his grave.
Of course, there were more than political reasons for the Kantian revival of the 1860s. Political reasons alone cannot explain why Kant became the head of a philosophical movement. The philosophical reasons for Kant’s resurrection lay, as we have already seen,5 in his power to solve the crises and controversies of the interim decades. The neo-Kantian writers of the 1860s advocated the critical philosophy because, in their view, it alone could solve the materialism controversy and the identity crisis.
There were five major figures who helped to re-establish Kant in the 1860s: Kuno Fischer (1824–1907), Eduard Zeller (1814–1908), Otto Liebmann (1840–1912), Jürgen Bona Meyer (1829–1897) and Friedrich Albert Lange (1828–1875). All of them published their chief writings on Kant some time during the 1860s, and so, despite their different ages, they still belong to the same period from the standpoint of neo-Kantian history. Several themes unite these authors. All saw Kant as a bulwark against materialism; all made criticism the central vocation of philosophy; all advanced a psychological interpretation of Kant; and all, with one complicated exception, repudiated the neo-rationalism of speculative idealism.
Our task in the following five chapters will be to provide an introduction to each of these thinkers, determining their contribution to neo-Kantianism, and retracing their intellectual development up to their conversion to Kant. Before we turn to that larger task, though, we will provide a brief overview of some of the main themes of the 1860s.
The neo-Kantian thinkers of the 1860s were by-and-large the heirs of the psychologism of Helmholtz and the lost tradition. Meyer and Lange were wholehearted advocates of this tradition; and while Fischer, Zeller and Liebmann had some doubts about it, they still affirmed its fundamental tenets. All these thinkers saw Kant’s epistemology essentially as psychology, as an investigation into the basic mental activities behind human cognition. Although they were perfectly aware of Kant’s distinction between the quid juris? and quid facti?, they still saw his epistemology primarily as a first-order account of the causes of human cognition rather than a second-order evaluation of the reasons for it. They reaffirmed Herbart’s and Beneke’s view that Kant’s psychology was simplistic and archaic, in desperate need of modernization to meet the standards of the new empirical sciences. They stressed therefore the value of empirical method in epistemology, whether it is a form of introspection, in the manner of Fries and Beneke, or a form of experiment and observation, in the manner of Helmholtz. Although they upheld Kant’s thesis of the a priori dimension of the mind against empiricism, most still believed that the proper way of knowing this a priori dimension is through empirical means.6
By the standards of contemporary Kant scholarship, the psychological tradition itself seems archaic and obsolete. We are today the heirs of the Marburg and Southwestern schools, which saw Kant’s epistemology in logical rather than psychological terms, and which regarded it as a second-order evaluation of the evidence for beliefs instead of a first-order causal enquiry into their origins. We should not assume, however, that the neo-Kantians of the 1860s were guilty of simple confusions between logic and psychology. They were well aware of the distinction between the normative and natural, the logical and psychological; but they still chose to read Kant in psychological and natural rather than normative and logical terms. The reason for this lies chiefly in the extraordinary pressure to bring epistemology in line with the empirical sciences, which had set the intellectual standards of the 19th century after the decline of speculative idealism. It was hard for the mid-century neo-Kantian to detach a purely logical and normative epistemology from the scholastic enterprise of Wolffian psychology, or even worse the speculations of the idealist tradition.
During the 1860s, however, cracks began to form in the wall of the psychological tradition. Serious doubts arose whether Kant’s epistemology could or should really be simply a form of psychology. Fischer and Liebmann, for example, asked whether Kant’s epistemology could be a form of psychology if its task were to examine the necessary conditions of all empirical knowledge. Since psychology is supposed to be a form of empirical knowledge, it should be more the object rather than mode of investigation. It should be the business of transcendental philosophy to investigate the possibility of empirical psychology, to examine its conditions and methods, so that it cannot be reducible to empirical psychology. Fischer and Liebmann raised these doubts, even though they, on the whole, continued to uphold the psychological ways of thinking about epistemology. But their doubts were not forgotten: they became the rationale for a complete break with the psychological tradition later in the 1870s.
There were more than just cracks in the foundation of psychologism. There was also a deeper crisis looming in the background, one that became evident only by the end of the 1860s. The source of the crisis lay in two clashing ambitions of the neo-Kantians: on the one hand, they wanted to psychologize philosophy, so that its methods were more in accord with the empirical sciences; on the other hand, however, they wanted philosophy to have autonomy vis-à-vis the natural sciences, for it to have its own distinctive methods and standards. Clearly, though, the neo-Kantians could not have it both ways. But this impossibility seemed possible in the murky context of the 1860s because the status of psychology was still very much unsettled and undefined. It was not clear then whether psychology was a unique kind of science having its own methods, or whether it was just another empirical science with methods like those of physiology and biology. The more psychology progressed in the later half of the century, however, the more it seemed to be just another empirical science, reaching its results through observation and experiment, and having as its goal the formulation of general causal laws. If this were so, then the identification of philosophy with empirical psychology meant surrendering philosophy’s claim to autonomy. Rather than avoiding the danger of obsolescence, philosophy fell prey to it; it became redundant, becoming just another empirical science, empirical psychology.
Another fraught theme of the 1860s was the status of the Kantian thing-in-itself. This had been the major stumbling block to the critical philosophy ever since Jacobi’s famous criticism in his David Hume, which made affirming the existence of the thing-in-itself the chief reason for both entering and exiting the Kantian system. The 1860s generation continued to wrestle with this dilemma, though it remained unresolved. This generation did not explicitly affirm the existence of the thing-in-itself, as the lost generation once had; but nor did it attempt to eliminate it entirely, turning it into a regulative ideal, as the Marburg and Southwestern schools will later do. Initially, Fischer, Zeller, Liebmann and Lange attempted to remove the thing-in-itself; but, ultimately, they reluctantly admitted its ineliminability. Since, as good Kantians, they stressed the role of the subject in creating the form of its experience, and since, as good students of Helmholtz, they also emphasized the active role of sensibility in conditioning the content of experience, they had to admit that we could not know the object in itself, as it exists apart from and prior to the workings of our cognitive faculties. None of the neo-Kantians were willing to accept a complete Fichtean idealism, which derives all the content of experience from the knowing subject; they insisted that, to some extent, the matter of experience, the content of sensation, is given. They were loyal Kantians in accepting the dualisms between form and content, the posited and given, even if they did not always formulate it in the Kantian manner. If, however, we accept a given content to experience, and if we insist that all objects of knowledge are conditioned or determined by the activities by which we know them, it becomes impossible to avoid the unknowable thing-in-itself. This was the bitter lesson learned by the neo-Kantians of the 1860s.
Still another major theme of the 1860s was the tenability of the epistemological conception of philosophy. Though entrenched, salient and prevalent, this definition came under increasing stress during the decade and thereafter. Granted that this definition is very strategic in helping philosophy overcome its crisis of obsolescence, nagging doubts remained whether it is too narrow. If philosophy is simply epistemology in the strict intended sense, that is, the second-order examination of the logic of the sciences, then it has to forfeit its traditional role as a worldview, as an attempt to answer basic questions about the meaning and purpose of life. These questions had been placed at the centre of philosophy since antiquity. How, then, could they be ignored? Is it not the purpose of philosophy to answer them, to try to resolve “the riddle of existence”?
There was no unanimity about how to answer these questions in the 1860s. There was a positivist strand to neo-Kantianism that wanted to get rid of old fashioned worldviews, which smacked too much of metaphysics; this attitude appears most strongly in the work of the early Liebmann and Lange. There was also, however, an anti-positivist strand to neo-Kantianism in the 1860s, which grew stronger as the century grew older. This anti-positivist strand reaffirmed the value of a worldview and stressed the need to answer the traditional questions about the meaning of life. In other words, philosophy should be not just epistemology but also metaphysics. We find this view best represented in the older Liebmann; but it also appears in Meyer, Zeller and Fischer, who all insist upon the importance of metaphysics. But revitalizing metaphysics was always a testy matter for any neo-Kantian who had taken on board the hard lessons of the first Kritik. How could philosophy be a worldview without violating Kant’s strictures against metaphysics?
One of the most important and striking intellectual events of the 1860s—one crucial for the development of neo-Kantianism—was the famous dispute between Adolf Trendelenburg and Kuno Fischer regarding Kant’s Transcendental Aesthetic.7 This bitter controversy began in the early 1860s and continued until the end of the decade. After Trendelenburg and Fischer, battered and bruised, withdrew from the fray in 1870, a younger generation took over, which debated the issues well into the 1880s. When the dust finally settled at the end of the century, Hans Vaihinger counted some fifty books, brochures and articles devoted to the dispute.8
The immediate issue behind the Fischer–Trendelenburg dispute was a question of Kant scholarship. Namely, do Kant’s arguments in the Transcendental Aesthetic of the first Kritik permit or prohibit the possibility that the a priori forms of space and time apply to things-in-themselves? It was Kant’s central thesis in the Transcendental Aesthetic that space and time are a priori forms of sensibility, that is, they are the universal and necessary manner in which the human mind perceives the matter given to it by sensation. In other words, the human mind, by the necessary laws of its operation, must perceive things in some space and at some time. These forms, Kant argued, cannot be abstracted from experience because they are necessary conditions of experience; before we abstract anything from experience, they must already be in operation. Since these forms are therefore subjective, arising from our own mental activity, Kant concluded that they are valid only for how we perceive things, that is, only for appearances and not things-in-themselves. But the question arose whether Kant’s arguments really give this conclusion. Are the forms of space and time, simply because they arise from the mind, valid only of appearances? Or is it still possible that they are also valid of things-in-themselves? Even though these forms arise directly from the mind, it should still be possible, so it seemed, for them to apply to things-in-themselves.
In Chapter VI of his Logische Untersuchungen, Trendelenburg raised just these questions and claimed to have found a gap in Kant’s reasoning.9 All Kant’s proofs for the subjectivity of space and time in the Transcendental Aesthetic, he insisted, do not exclude the possibility that they are also true of things-in-themselves. Trendelenburg did not dispute Kant’s intentions. He realized that Kant intended to argue that space and time are only subjective, and that he had expressly stated that they are valid only of appearances. But the crucial question was not about Kant’s intentions or statements but the logic of his arguments, that is, does admitting the a priori status of space and time logically entail that they are true of appearances alone? Trendelenburg insisted that there is no such implication at all: although the forms of space and time are a priori and not derived from experience, it is still possible for them to apply to things-in-themselves.
In a later article Trendelenburg laid out the issue as follows.10 There are three possibilities regarding the ontological status of space and time: 1) they are only subjective, that is, forms of intuition valid for only how we perceive the world or for appearances alone; 2) they are only objective, that is, the structure of things that exist whether or not we perceive them; and 3) they are both subjective and objective, that is, though they are forms arising from our mental activity, they are also true of the objective structure of things-in-themselves. It was this third possibility that Trendelenburg embraced and that he believed Kant’s reasoning had failed to exclude.
It was just this third possibility that Fischer adamantly rejected. He could see no gap in Kant’s argument whatsoever. In the second edition of his Logik und Metaphysik, which appeared in 1865, Fischer mounted two arguments against Trendelenburg’s third possibility.11 First, he makes the exegetical point that Kant’s arguments, when read in context, do demonstrate that space and time cannot be properties of things-in-themselves. Fischer points out and underlines one of Kant’s crucial background assumptions: that if space and time were objective qualities of things, they would have to be derived from experience; but in that case they would be empirical concepts, so that mathematical propositions would have to forfeit their universality and necessity. Second, he makes the philosophical point that Trendelenburg’s position does not avoid scepticism but reinvokes it, for it raises the inevitable problem of how we know that our representations of things in space correspond to things in objective space (175). The sceptic will answer that we have no means of ever establishing a correspondence between our representations and things-in-themselves, so that all the difficulties return about the possibility of a mathematical knowledge of nature (176–177).
Though much of the dispute got bogged down in details of textual exegesis, it is important to see that much more was at stake than issues of Kant scholarship. Underneath the dispute lay fundamental philosophical issues. The chief issue was formulable in terms of that classic Kantian question: How is mathematical knowledge of nature possible? Trendelenburg and Fischer had conflicting views about the necessary conditions of such knowledge. Both accepted Kant’s arguments for the a priori status of our representations of space and time; both rejected an empiricist account of the origins of these representations because they feared it would undermine the universal and necessary validity of mathematics. But they were at odds concerning the question: Under what conditions do these a priori forms give knowledge of nature? Trendelenburg adamantly affirmed a transcendental realism, according to which these forms give knowledge of nature only if they are true of things-in-themselves, that is, for reality independent of how we perceive it. If these forms apply only to appearances, he argued, then we are caught inside the circle of our own representations, given that these appearances are, as Kant says, “only representations in us”. An empirical realism, which would hold only within the realm of appearance, was not an option for Trendelenburg, because, in his view, appearance (Erscheinung) is not far removed from illusion (Schein).12 “It is the vital nerve in all knowing”, he wrote, “that we want to reach things as they are; we want the thing, not only us.”13 Fischer, however, passionately defended transcendental idealism, insisting that transcendental realism is unnecessary for an objective knowledge of nature. All that is necessary, and indeed possible, for objective knowledge of nature, Fischer contended, is a Kantian empirical realism, according to which objectivity is possible within the realm of appearances. According to empirical realism, objectivity means not the correspondence of representations with things-in-themselves—an impossible standard to meet, as Kant had argued—but simply the conformity of representations with universal and necessary norms of consciousness.
The dispute between Fischer and Trendelenburg also raised the broader issue of the comparative merits of transcendental versus absolute idealism. The question at issue concerned which worldview bests explains the possibility of mathematical knowledge of nature: transcendental or absolute idealism? Fischer’s transcendental idealism states that the subject is the first condition of all knowledge, that all knowledge is limited to appearances, and that empirical realism is sufficient to account for the possibility of mathematical knowledge of nature. Trendelenburg’s absolute idealism, on the other hand, claims that there is a single ideal structure equally instantiated in the subjective and objective realm, that empirical realism is insufficient to account for the mathematical knowledge of nature, and that it is instead necessary to assume something like transcendental realism, that is, the doctrine that our knowledge is about nature in itself. Like all absolute idealists, Trendelenburg assumed that there is a single activity of reason that manifests itself in both the subjective and objective realms, and that this activity manifests itself as space and time both in consciousness and nature. In making such as assumption, Trendelenburg had returned to an older position once championed by Schelling and Hegel. Fischer, like Fichte before him, rejected that absolute idealism because, in postulating knowledge of nature in itself, it transcends the limits of knowledge, and so lapses into “dogmatism”. The dispute between Fischer and Trendelenburg was therefore more than a bit déjà vu. It was a repeat of the old battle between Fichte’s “subjective idealism” and Schelling’s “objective or absolute idealism” which took place in the early 1800s.14
That the key issue involved a choice between absolute and transcendental idealism was often obscured in the thicket of Kantian exegesis. Nevertheless, it was stated clearly by Trendelenburg later in the dispute. In his 1869 Kuno Fischer und sein Kant he wrote that the question of the third possibility is not only of historical but also of philosophical importance.15 If Kant’s arguments prove exclusive subjectivity, then transcendental idealism is true; but if they do not, the possibility is open “to show the ideal in the real”. “To show the ideal in the real”—that was the absolute idealist’s catch phrase for demonstrating how nature, which exists independent of consciousness, manifests the intelligible or intellectual form of things. In other words, Trendelenburg saw the third possibility as opening the door for his own version of absolute idealism, according to which the subjective and objective manifest one and the same intelligible activity. Schelling, in his battle with Fichte in the early 1800s, had made a similar argument on behalf of his own absolute idealism.
Though it raised substantive philosophical issues, the dispute between Fischer and Trendelenburg eventually degenerated into a personal brawl. By the late 1860s the quarrel had become a notorious spectacle. Here were two of the most eminent philosophers in Germany, professors at two of its most prestigious universities—one in Berlin, the other in Heidelberg—locked in a bitter personal feud over a question of Kant interpretation. The dispute attracted such attention chiefly because of the animosity it aroused between its contestants. They began by discussing Kant interpretation; but they ended by abusing one another. Each cast doubt on the ability of their adversary to discuss exegetical or philosophical questions in an honest and impartial manner. Both quit the field bristling with indignation and nursing wounded vanity. Not surprisingly, the dispute was widely reported in the press and heavily discussed in lectures, reviews, articles and books. Battle lines were drawn, and parties rallied around one contestant or the other.
If the Trendelenburg–Fischer dispute showed anything, it was how important Kant had become to German philosophy. It was not only that Kant interpretation could be seen to arouse intense passions and heated controversy; it was also that so much seemed to depend upon it philosophically. Whether personally or philosophically, Kant mattered; he was now at the centre of attention.
Our list of the leading neo-Kantians of the 1860s in Section 1 seems to commit a major oversight. For it does not mention a man who claimed to be Kant’s sole legitimate heir, and who did probably more than anyone else for his revival in the 1860s. I mean, of course, Arthur Schopenhauer. Although his major work, Die Welt als Wille und Vorstellung, was published in 1819 and neglected for decades, it was rediscovered in the 1850s, and had even become popular by the 1860s. Its rediscovery and popularity was of the greatest importance for the revival of Kant. For Schopenhauer, long before the 1860s, had stressed the revolutionary importance of Kant’s philosophy, and he had made it very clear that it was the foundation for his own. In the preface to the first edition of his book he made a special request to the reader: that he study “the most important publication that has appeared in philosophy in the past two thousand years”, namely, “the main writings of Kant”.16 The effect of reading Kant’s writings Schopenhauer compared to the results of a cataract operation: where once there was blindness, now there was sight.
There are features of Schopenhauer’s philosophy that make his exclusion from the neo-Kantian canon seem puzzling. For, no less than the neo-Kantians, Schopenhauer was an opponent of the neo-rationalism of the speculative tradition, and he too insisted on returning to Kant’s critical teachings. All knowledge, he stressed, had to begin with, and to be verified through, experience; the attempt to gain knowledge through a priori reasoning alone is futile. Schopenhauer was also an opponent of the foundationalism of the speculative tradition, which he too regarded as an attempt to squeeze blood from a stone.17 Like Herbart, Fries and Beneke, Schopenhauer championed an empirical method for philosophy, a procedure that would begin with experience and determine through analysis its content and necessary conditions. It was chiefly on these grounds that he claimed the right to ascend Kant’s throne. While the speculative idealists flaunted Kant’s limits on knowledge and indulged in a priori reasoning, he alone remained loyal to Kant’s critical doctrines.
For these reasons historians of philosophy before the 1860s were often inclined to include Schopenhauer within the neo-Kantian movement. Thus Karl Rosenkranz added a section on Schopenhauer in his 1840 Geschichte der kant’schen Philosophie, and Carl Fortlage had a chapter on him, right along with Herbart, Fries and Beneke, in his 1852 Genetische Geschichte der Philosophie.18 Yet later historians ceased to place Schopenhauer in the neo-Kantian tradition. The one-time pretender to the throne had been completely cast out of the Kantian palace. It is as if all Schopenhauer’s claims to the Kantian title were spurious, as if all his suffering in the wilderness during the reign of speculative idealism counted as nothing. How could this be?
The more we consider Schopenhauer’s relations with the neo-Kantians, the more we find solid grounds for his exclusion from the club. Understandably, the leading neo-Kantians of the 1860s saw Schopenhauer not as an ally but as an enemy. They did so for two reasons: one is political, which we will consider below;19 and the other is philosophical, which we need to look at now.
The philosophical issue is simple: the neo-Kantians cast Schopenhauer into the very speculative tradition that he had so vocally opposed. To be sure, Schopenhauer had opposed the rationalism and foundationalism of the speculative tradition no less than the most orthodox neo-Kantian. But the problem was that his conception of philosophy ran completely counter to that of the neo-Kantians. Philosophy, for Schopenhauer, is not simply an analysis and investigation into the logic of the sciences; it is first and foremost a metaphysics, and metaphysics in the grand old traditional sense: knowledge of reality in itself and as a whole. Despite his claim to observe Kantian limits, Schopenhauer insisted that philosophy should provide us with an immediate knowledge of ultimate reality, reality in itself as opposed to mere appearances.20 The thing-in-itself that the neo-Kantians wanted to eliminate or make into a limiting concept Schopenhauer wanted not only to keep but to know. Philosophy was for him “unconditional knowledge of the essence of the world”, knowledge of “the in-itself” (das An-sich), just as it had been for Schelling and Hegel.21 Though Schopenhauer pretended to know this reality through more cautious empirical methods, that hardly detracted from his metaphysical ambitions.
Schopenhauer’s affinities with the speculative tradition, and his differences with later neo-Kantianism, are especially apparent from his Naturphilosophie. Although Schopenhauer strived to distance himself from the methods and worst excesses of the Naturphilosophen, his arguments for a metaphysics of nature, and for the limits of empirical science, seem to come straight out of the pages of a Schelling, Oken or Steffans. Schopenhauer argues repeatedly and emphatically that empirical science can know nature only as appearance, and that it presupposes a metaphysics, which alone grasps the ideas and inner nature of things. This was the very doctrine that physicists, chemists and physiologists had rebelled against and rejected by the 1830s. In this struggle the neo-Kantians sided with the empirical scientists against the Naturphilosophen. They accepted the autonomy of the sciences, and they disputed the need for a metaphysical foundation for them. Schopenhauer, however, was claiming the kind of priority and privilege for philosophy that had become discredited and unfashionable by the 1830s. This was not the least reason why Die Welt als Wille und Vorstellung was neglected for so long in the first half of the 19th century. To the empirical scientists, and the neo-Kantian philosophers sympathetic with them, Schopenhauer seemed to be calling for the revival of a dead cause.
Nowhere are Schopenhauer’s metaphysical intentions, and his differences from the neo-Kantians, clearer than in his theory of ideas in Book III of Die Welt als Wille und Vorstellung. Here Schopenhauer makes it perfectly clear that his philosophy is essentially a version of Platonic idealism. The thing-in-itself, Schopenhauer informs us, is nothing more nor less than the Platonic idea (I, 247; §31). He stresses the great affinity between Kant and Plato: that both distinguish between appearance and reality in itself, that both think that the realm of appearances is subject to space and time. Where Kant needs to go a step further, Schopenhauer avers, is in making his things-in-themselves into ideas. With that extra step, the philosophy of Plato and Kant, the two greatest philosophical systems, are joined in holy matrimony. Schopenhauer admits that there is an obvious difference between Kant and Plato: Kant’s thing-in-itself, unlike Plato’s form, is in principle unknowable (I, 252; §32). Still, he thinks that this difference is only the result of Kant’s unnecessary restriction of all forms of experience to sense perception. What Schopenhauer does not mention, or refuses to recognize, is Kant’s own sharp distinction in the Prolegomena between his own critical idealism and Plato’s idealism: that critical idealism limits knowledge to appearances while Plato’s idealism strives to transcend it. And what he also conveniently ignores is Kant’s withering criticism of the possibility of immediate and intuitive forms of knowledge. It was not least for these all-too Kantian reasons that the neo-Kantians were never ready to accept Schopenhauer’s conflation of Platonic with transcendental idealism; that to them grossly flaunted Kant’s restrictions on metaphysics. Following Kant, the neo-Kantians reject the possibility of an intuitive or immediate knowledge of reality in itself, and they insist upon a regulative reading of the Platonic ideas following the guidelines of the Transcendental Dialectic.
Thus the neo-Kantians’ interpretation of Schopenhauer, which they will develop gradually throughout the 1860s and 1870s, strategically place him in the tradition of speculative idealism, which, by the 1850s, almost everyone saw as surpassed and antiquated. All Schopenhauer’s bluster and tirades against this tradition only disguised his real affinity with it. The Schopenhauer revival of the 1860s therefore seemed to the neo-Kantians a step backwards, both philosophically and politically, a call for a return to the bygone Romantic age.
Yet in an important sense it was Schopenhauer who had the last laugh, and who ultimately trumped the neo-Kantians. For the old grouch showed them, and made them admit, that he was ultimately more timely and relevant than any of them. One reason for Schopenhauer’s enduring popularity throughout the last half of the century is that he placed one fundamental question at the front and centre of his philosophy: “the question of existence”. By this he meant not only why the universe exists at all, but also whether life is worth living. The big question, to which his entire philosophy is an answer, is whether we should affirm or deny the will to live (I, 423; §56). Schopenhauer insisted that these questions had always been at the heart of philosophy, and that no philosophy worth the name could ignore them. Man was a “homo metaphysicus” and he would pose the question of the purpose and value of his existence as long as he was an intelligent being at all. “To be or not to be”, that was the crucial question for Schopenhauer, as it is indeed for all of us.
It was no accident that later in the century the neo-Kantians would be accused of neglecting this all-important question, of coming too close to an arid positivism in their insistence that philosophy should be primarily epistemology and the investigation into the logic of the sciences. This criticism, and the continuing popularity of Schopenhauer, put great pressure on the neo-Kantians to revise and broaden their own conception of philosophy. Neo-Kantianism could survive in the intellectual marketplace only by showing that it too could provide a plausible answer to this basic question. Thus, by the 1880s, such neo-Kantians as Wilhelm Windelband, Friedrich Paulsen, Otto Liebmann and Alois Riehl moved away from their original positivism, towards a more practical philosophy that reflected on the value and purpose of life. The thinker pushing them in this direction—let us give credit where it is due—was that old pessimist, Arthur Schopenhauer. He was an educator not only for the young Nietzsche but for the entire neo-Kantian generation!
1 See James Sheehan, German History 1770–1866 (Oxford: Oxford University Press, 1989), pp. 863, 869, 876.
2 Heinrich Heine, Zur Religion und Philosophie in Deutschland, in Sämtliche Schriften, ed. Klaus Briegleb (Munich: Hanser, 1976), V, 595. This work was first published in 1834.
3 Ludwig Noack, Immanuel Kant’s Auferstehung aus dem Grabe (Leipzig: Wigand, 1861).
4 Noack, Immanuel Kant, pp. 27–28.
5 See the General Introduction, Section 2.
6 Fischer was an exception to this generalization, holding that the a priori had to be known through a priori means. See Part II, Chapter 8, Section 4.
7 For a detailed analysis of the dispute, see my Late German Idealism: Adolf Trendelenburg and Hermann Lotze (Oxford: Oxford University Press, 2013), pp. 107–120. For a survey of the course of the dispute as a whole, see Christopher Adair-Toteff, ‘The Neo-Kantian Raum Controversy’, The British Journal for the History of Philosophy II (1994), 131–148.
8 Hans Vaihinger, Kommentar zu Kants Kritik der reinen Vernunft (Stuttgart: Deutsche Verlags Anstalt, 1922), II, 545–548.
9 Friedrich Adolf Trendelenburg, Logische Untersuchungen (Leipzig: Hirzel, 1862), I, 155–232.
10 Trendelenburg, ‘Ueber eine Lücke in Kants Beweis von der ausschliessende Subjektivität des Raums und der Zeit’, in Historische Beiträge zur Philosophie (Berlin: Bethge, 1867), III, 215–276.
11 Kuno Fischer, System der Logik und Metaphysik oder Wissenschaftslehre, Zweite umgearbeitete Auflage (Heidelberg: Bassermann, 1865), §66, pp. 175–178.
12 Trendelenburg, Logische Untersuchungen, I, 160.
13 Trendelenburg, Logische Untersuchungen, I, 163.
14 On that dispute see my German Idealism: The Struggle against Subjectivism, 1781–1801 (Cambridge, MA: Harvard University Press, 2002), pp. 491–505.
15 Trendelenburg, Kuno Fischer und sein Kant: Eine Entgegnung (Leipzig: Hirzel, 1869), pp. 2–3.
16 See Schopenhauer, ‘Vorrede zur ersten Auflage’, Die Welt als Wille und Vorstellung, in Sämtliche Werke, ed. Wolfgang Freiherr von Löhneysen (Stuttgart: Insel, 1968), I, 10. All references in parentheses are to this edition. A Roman numeral indicates a volume number, an Arabic numeral a page number; and ‘§’ a paragraph number, which is standard in all editions.
17 See Schopenhauer, ‘Über das metaphysische Bedürfnis’, §17 of Die Welt als Wille und Vorstellung, Werke II, 229.
18 See Karl Rosenkranz, Geschichte der kant’schen Philosophie (Leipzig: Voß, 1840), pp. 475–481; and Carl Fortlage, Genetische Geschichte der Philosophie seit Kant (Leipzig: Brockhaus, 1852), pp. 407–423.
19 See Chapter 10, Sections 1, 3–4.
20 See Schopenhauer, Die Welt als Wille und Vorstellung, Werke I, 160, §18; 170, §21; and ‘Anhang. Kritik der kantischen Philosophie’, I, 675.
21 Schopenhauer, Die Welt als Wille und Vorstellung, I, 190, §24; I, 135, §15.