Idealism

In the years following its public promulgation, Kant's transcendental idealist philosophy was the object of widespread excitement but also much critical scrutiny. Three interrelated problems (or perceived problems) would prove to be significant for the subsequent development of German idealism. First, critics argued that Kant failed to derive or "deduce" the forms of intuition and the categories of the understanding in a systematic and rigorous way, and as a result his critical system could claim only contingent or inductive (as opposed to universal and necessary) validity for itself. Second, critics claimed that Kant's inadequate derivation of the forms of intuition and categories of the understanding committed him to a series of unacceptable dualisms, all of them rooted (directly or indirectly) in the dualism between sensibility and understanding (for example, the dualisms between intuitions and concepts, activity and passivity, receptivity and spontaneity, the a priori and a posteriori, knowledge and belief, theoretical reason and practical reason). Third, critics argued, Kant's strict separation of sensibility and understanding made it impossible for him to account for the receptive character of human knowing except by reference to "things-in-themselves" that allegedly exist apart from the human knower and thus render the activity of human knowing finite, dependent, and passive; but this postulation of things-in-themselves contradicts the spirit of Kant's own transcendental idealism, according to which we cannot know anything about things-in-themselves, including what role—if any—they play in rendering human knowing finite, dependent, and passive.

In the midst of ongoing debates about Kant's transcendental idealism, the young Johann Gottlieb Fichte (1762–1814) became convinced that the Kantian system was essentially correct but stood in need of a more systematic formulation and rigorous defense. First, Fichte argued that it was wrong to think of the "faculty of thinking" or the "mind" or the "self" as if these terms referred to a substrate that underlies our mental operations and persists even in the absence of actual cognitive activity. To think of the self in this way, he claimed, is to regard it as an unknown "thing in itself" that has existence even apart from its being known, and such a view is inimical to transcendental idealism. Fichte went on to argue that the self is nothing other than the free, uncoerced activity of "self-positing" or "self-awareness" and that this very activity can serve as the single, foundational principle from which one could rigorously derive all the other conditions of synthetic a priori knowing, including even the self's apparent dependence on things outside of it. More specifically, Fichte argued that the self would have no occasion to reflect back on itself, and thus it could never even be a self if it did not also take itself to be finite and partly determined by a "not-self" outside of it. In other words, Fichte held that even the apparent dependence of human knowing on supposedly independent, unknowable things-in-themselves could be explained on the basis of the necessary conditions of the self's own activity of self-positing. He went on to assert that the not-self, without which the self could not even be a self, must ultimately be understood as another free self, thereby arguing for the necessity of belief in other selves (or intersubjectivity) as a condition of the possibility of the self's own self-positing. In practical philosophy, Fichte also took a step beyond Kant, arguing that the idea of God is necessary for our moral purposes but also that this idea in fact signified nothing other than the moral order of the world itself.

Friedrich Wilhelm Joseph Schelling (1775–1854) was an early follower of Fichte but eventually distanced himself from the Fichtean claim that a properly critical philosophy can begin only with the activity of the self-positing self. By 1799 Schelling was arguing (along with Fichte) that one could derive the not-self (or "nature") from the self-positing activity of the self, but also (against Fichte) that one could equally derive the self-positing activity of the self from the not-self (or "nature"). In subsequent years Schelling departed even farther from Fichte, explicitly rejecting the Fichtean claim that the distinction between subject and object (self and not-self) is a distinction that can be made only by and within subjectivity itself. In effect Schelling argued that Fichte was right to relativize Kant's rigid distinction between subject and object (or correlatively, between understanding and sensibility, or concepts and intuitions) but wrong to achieve such relativization by locating the distinction within subjectivity alone. For Schelling, the distinction between subject and object is not merely subjective but arises only from within an "absolute identity" that is neither subject nor object but both at once. Furthermore, Schelling held, this absolute identity cannot be discursively demonstrated or conceptually articulated (because demonstration and conceptualization already presuppose a subject-object split) but can only be apprehended immediately in an intellectual intuition or (according to Schelling's later thought) an aesthetic intuition. According to Fichte, Schelling's appeal to immediate intuition and his claim that unconscious nature is continuous with and provides the conditions for the emergence of conscious subjectivity could only signal a return to pre-critical, pre-Kantian metaphysics. But Schelling insisted that his "identity philosophy" incorporated the truths of transcendental idealism, while also moving beyond Kant's and Fichte's "subjective idealisms" to a more comprehensive and satisfactory "absolute idealism." This absolute idealism, Schelling argued, did not uncritically presuppose any dualisms between subject and object, freedom and nature, or human agency and God, but rather explained all such dualisms as mere moments within the absolute's own process of internal self-differentiation.