This chapter considers the place of Jacobi’s thought within the history of philosophy. Despite the prominent dismissal of his thought as unsystematic, misologist, and effectively incompatible with scientific philosophy, Jacobi’s critique of rationalist philosophy aptly situates him within the tradition of philosophical skepticism.

This chapter considers how Jacobi’s philosophy of mind distinguishes itself by ascribing a resolutely realist intuition to sensibility, the intellect, and reason. The key to this difference is Jacobi’s personalism, or self-feeling – an awareness of the finite nature of one’s existence – which reveals itself as an unmediated, pre-discursive, non-sensuous actuality.

This introduction offers an account of Jacobi’s importance for intellectual history and describes how he positioned himself at the centre of critical debates in a way that would shape the intellectual terrain for coming generations.

Jacobi played a determinative role in shaping the landscape from which German Romanticism would emerge. His critique of the philosophies of both Spinoza and Fichte, and his advocacy of transcendent realism, would deeply influence Early German Romantics such as Schlegel, Novalis and Hölderlin and would go on to shape the thought of Samuel Taylor Coleridge.

Jacobi argues that although Spinoza produced the most consistent rational system, its complete rational explanation leads to fatalism, mechanism, and atheism. The concern in this chapter is with how Jacobi stimulates Kant on issues of faith in relation to autonomy and practical reason (ethics), and how Kant’s “moral faith” seeks to avoid the pitfalls of mechanism while integrally linking faith with reason.

The chapter provides a study of François Hemsterhuis’ affinities with and influence on Jacobi’s Über die Lehre des Spinoza in Briefen an den Herrn Moses Mendelssohn. Both Hemsterhuis and Charles Bonnet significantly influenced Jacobi’s thought and the development of German idealism while providing the foundation for an alternative understanding of Spinoza.

Jacobi famously contended that Fichte’s transcendental philosophy ultimately leads to metaphysical nihilism, while Fichte himself continued to see a close harmony between the Wissenschaftslehre and Jacobi’s thought. This chapter explores a middle path between these positions in the writings of the two philosophers.

This chapter outlines the relationship between Johann Georg Hamann and Jacobi, demonstrating its significance for their respective reception within the history of ideas. Despite Jacobi and Hamann’s affinity in friendship, there were significant differences in the very foundation of their post-enlightenment thought.

Jacobi’s claims concerning the relationship between philosophy and religion are complex and often expressed in varied ways. This chapter sorts out the arguments Jacobi brings in support of his conception of epistemic realism, the opening of reason to suprasensible reality, as well as the relationship between Jacobi’s philosophy and Christianity.

Jacobi’s influence on the founder of so-called existentialism, Søren Kierkegaard, has rarely been examined. This chapter explores Kierkegaard’s critical and somewhat polemical discussion of Jacobi’s notion of the “leap” in Concluding Unscientific Postscript, which not only shows that Kierkegaard was acquainted with Jacobi’s major work, Concerning the Doctrine of Spinoza but how it shaped Kierkegaard’s own particular development of the salto mortale.

This chapter addresses Jacobi’s literary contributions, Edward Allwill’s Collection of Letters and Woldemar, in the context of his critique of both Enlightenment reason and feeling. Both, Jacobi argues, undermined human individuality and freedom.

Jacobi’s central role in the Spinoza controversy opened the eyes of the young Schleiermacher and shaped his development as a theological thinker. Probably even more influential, however, was Jacobi’s philosophical concept of intuition as a source of the evidence of God, which this chapter explores both for Schleiermacher and Rudolf Otto.

Jacobi’s criticisms of some key issues of Kantian transcendental philosophy have been very influential with respect to the further development of Kantian ideas by the young students in the Tübingen Stift. This chapter explores Kant’s understanding of causality, Jacobi and Tübingen philosophy professor J. F. Flatt’s role in shaping the revision of Kantian transcendental philosophy by the Tübingen students.

This analysis of Jacobi’s pivotal Spinoza Letters illustrates that the driving force behind his innovative altercation with Spinoza lies not in religious motives, but rather in motives derived from the philosophy of action. By putting into effect the contradiction between system and freedom in the practical sphere, Jacobi opened up new perspectives in modernity’s own self-understanding.

Moving beyond Hegel's critique of Kantian general logic and the logic of the Aristotelian tradition, this chapter considers his critique of Kant's transcendental logic: specifically, the Analytic of the Critique of Pure Reason. It offers an account of Hegel's famed swimming objection, going beyond previous ones by arguing that the objection has a more specific target than is often realized: the Metaphysical Deduction of the Categories. It further explains Hegel's dissatisfaction of the efforts of two of Kant's successors (Reinhold and Fichte) to overcome the dilemma the swimming objection presents. Some attention is given here to Fichte's project of deriving the categories from a version of the cogito, that is post-Kantian rather than the one familiar from Cartesian rational psychology. In my view, it is Jacobi and Romanticism who furnish Hegel with the possibility of deriving the categories from a post-Kantian version of the ontological proof – though he rejects their irrationalism. This explains Hegel's provocative claim that the ontological argument, and its rigorous distinction between the modes of thinking appropriate to finite and infinite entities, constitutes the true self-critique of reason.

This chapter reviews how the early post-Kantians perceived the need of reforming Kant’s Critique in order to complete the philosophical revolution it had initiated. In 1785, Jacobi had brought Spinoza to the discussion, claiming that his monism undermined human freedom and personality. He further claimed that this monism was the logical conclusion of all philosophy. The post-Kantians’ task was thus threefold: (1) to demonstrate that personalism is consistent which monism, which they in principle accepted as the necessary standpoint of reason; (2) to show that Kant’s idealism could be the basis for the desired personalism; and (3) to overcome what they took to be the formalism of Kant’s system that stood in the way of it. All this came down to ridding the system of its presumed unknown “thing-in-itself” while finding a principle that would unify it internally, not just by means of external reflection. Fichte had attempted this with his “I.” Even more important, however, was his analysis of feeling, which he considered the concrete counterpart of the “I” and which, as in the feeling of guilt, brought reason and nature together. This was the synthesis that the post-Kantian idealists explored in their different ways.

Also Schelling – by 1802 a declared Spinozist – altered his methodology, adding to it a phenomenological dimension. In 1807 he portrayed the philosopher as an artist singularly gifted with an intuitive sense for nature as issuing from the Oneness of the Absolute, equally substance and subject. Jacobi attacked him for this. Chapter 4 details Schelling’s ensuing controversy with him but is otherwise dedicated to Schelling’s seminal Freedom Essay (1809). In the essay Schelling again portrayed the philosopher as a divinely inspired artist. He now conceived his work, however, as one of remembering the event at which God manifests himself in the form of a world that reflects in its manifold the internal economy of the divine being. This event is shrouded in the human unconscious but can be brought to light through the philosopher’s imaginative representations. The warrant for these is that they resonate with humankind’s belief, embodied in mythology, that its history is also the history of God’s realization in space/time. Schelling was thus adopting a rich metaphysical position, the direct contrary of Fichte’s ontological quietism, which the monism the two shared nonetheless also made possible. Evil comes up as an important issue for Schelling

Prior to Hegel’s portrayal of the French Revolution’s “fanaticism for destruction,” F. H. Jacobi criticized the impoverished, abstract conception of reason that he sees realized in the politics, philosophy, and broader intellectual culture of the era.Inaugurating a tradition of reflection in German thought, Jacobi labels this conception “nihilism.” While Jacobi identifies and analyzes both the theoretical and the practical sides of nihilism, its basic sense is practical.Practical nihilism equates ideal rationality with the realization of a pure form, minus the “way of sensing [Sinnesart]” that allows us to see what is at stake in any situation. Jacobi further argues that one’s “way of sensing” is the source of individuality and so of one’s irreplaceable value as a person. For Jacobi, the otherwise diverse group including the French philosophes, Kant, and Fichte all exemplify practical nihilism in some manner or other.This account starts from Jacobi’s initial reactions to the French Revolution, eventually captured by the letter “To Erhard O.” (1792). This discussion establishes the core of Jacobi’s objection to his era’s dominant conception of rationality.The open letter “To Fichte” (1799) in which the charge of nihilism first appears is explicable against this decades-old concern on Jacobi’s part.

Kant is critical of many of the practices of Christianity in his time. But when we appreciate the dynamic relation between rational and revealed religion as Kant conceives them, the apparent opposition becomes more questionable and raises more questions than it answers. Kant’s project in the Religion bears important affinities with the religious philosophy of Moses Mendelssohn. Mendelssohn’s philosophy of church and state and their relation involve a number of radical proposals expressive of Enlightenment religious consciousness. Mendelssohn’s concept of enlightened Judaism bears interesting comparison to Kant’s enlightened reflections on Christianity. Mendelssohn defends a form of evidentialism even more radical that Clifford’s. He also defends a conception of the freedom of religious conscience that inspires Kant’s treatment of that topic in part four of the Religion. Conscience is an important theme in Kant’s moral philosophy, which has special application to religious conscience and the freedom of conscience Kant and Mendelssohn both defend.