Nineteenth-century philosophy witnessed the development of intellectual projects and movements for whose invention the eighteenth century deserves primary credit. It might even be said that it was largely constituted by the fruition of such projects. Both empiricism and German idealism were essentially products of the Enlightenment: empiricism was born of a creative reading of the moderately skeptical rationalist philosopher John Locke, mainly by French and Scottish philosophers such as Étienne Bonnot de Condillac and David Hume. Just as Condillac attempted to treat the theory of knowledge as a natural discipline based on the psychological investigation of the human senses, so Hume thought to apply to metaphysical and epistemological subjects the same method that had been seen to have such great success, applied to nature as a whole in Newton’s physics. German idealism was the attempt to fulfill – usually by “going beyond” – the project of transcendental philosophy invented by Immanuel Kant (1724–1804). But whereas Kant devised the transcendental approach as a way of responding to problems of the seventeenth and eighteenth centuries – problems about the roles of reason and experience in knowledge and the recognition of the limits of metaphysical cognition – his immediate followers saw this approach as opening up a new kind of philosophical method, a new and radical answer to an equally radical skepticism by which they felt knowledge was threatened, and at the same time as an invitation to a new and higher kind of scientific systematicity than philosophers had hitherto known.

The truly revolutionary figure here was Johann Gottlieb Fichte (1762–1814), who devised a new “synthetic method” of transcendental inquiry that overcame what he and his contemporaries viewed as the false and artificial “dualisms” – between sense and understanding, reason and empirical desire, theory and practice – that Kant had set up and had even attempted to mediate in his third critique, Critique of the Power of Judgment (1790). Fichte’s approach was the gateway to later “speculative” systems and also to a variety of criticisms of systematic philosophy, which also emerged out of Enlightenment and counter- Enlightenment approaches that arose in the middle to late eighteenth century.