German idealism, commencing with Kant’s initiative to defeat Humean skepticism and determinism and culminating in Hegel’s efforts to ground philosophy in an unassailable base, simultaneously pursued rationality and freedom in ways overlooked by European Enlightenment and English empiricism.
Hume asserted metaphysics must be grounded in scientific demonstration (i.e., fact) not Spinozan geometry (relationship). Induction is circular and so lacks rational justification; causal inference must rest on custom (past experience). Empiricism shows the individual incapable of rational self-determination and also epistemological, moral, and political autonomy – freedom.

For Kant, matters of fact can be known by reason alone. His response to Hume is tantamount to Copernicus’ astronomical revolution: instead of knowledge conforming to the world as it is (noumena), the world conforms to the structure of the mind. Metaphysics is saved by reexamining the subject’s capacity for representation and experience, provided we are agnostic about that which transcends our experience. Such agnosticism is justifiable only in respect of free will: we cannot know, which creates license to act as if we are free. Hence freedom is the keystone to pure reason. Pure concepts of understanding do not derive from impressions, but their application in experience is legitimated (the transcendental argument), leading to synthetic a priori knowledge. A central claim of critical philosophy is arguments about the soul, freedom, and God cannot yield knowledge because they transcend experience and play no role in making it possible. Further, ideas of reason (‘pure’ ideas) which derive from the mind’s operation do not lead to knowledge but transcend illusion. Because we can’t know if there is immortality, freedom, or God, Kant considers the possibility that remains defeats skepticism. Rational willing for Kant is borne of the nature of reason, it cannot be contingent. Morality depends exclusively on what we do in full knowledge and motive. Doing one’s moral duty for its own sake establishes dignity and rationality of man, and therefore establishes freedom. The use of practical reason, especially in moral resolutions, both demands and generates ‘rational faith’, belief in God and a human soul, to which theoretical reason must agnostic. To appreciate aesthetics, we must abstract from cognition and sensory satisfaction. Only through disinterested appreciation of the object and its appeal to desires can we appreciate the form of qualities for their own sake. Nature is purposive only if we regard it as intelligently designed: God has arrayed matters seen of science is such a way that they orient toward the emergence of rational creatures. Seeing the world as governed by providence bridges the gap between nature and freedom: nature’s purpose is to create conditions for humanity exercising freedom for moral ends.

Transcendentalism distinguishes between the possibility of experience and of being (subjective idealism), seeking to define conditions of the former, the conditions of synthetic a priori. Transcendental idealism presumes experience can be explained only by supposing the external world. This was disputed: Jacobi asserted Kant’s philosophy is an idealism that makes all knowledge dependent on faith in the senses and is thus dependent on finitude of humanity. Reinhold, the bridge to Fichte, Schelling, and Hegel, each of whom argues over unconditional, self-determining starting points, sought to defend transcendental idealism; but concluded Kant’s foundation lacked an explanation of how cognition works (i.e., understanding the senses). He recognized Kant’s cognitive capacities – sensibility, understanding, reason – as well being modes of receiving or processing mental representations; but concludes Kant has not established a ‘science of representation’. Whereas rationalism commences from defined terms and axiomatic principles, but a lacks defensible starting point.

Fichte: the core problem is the basis of synthetic a priori, not explaining things-in-themselves, which we can’t know. Philosophy cannot take Reinhold’s representation as a foundation, but must deduce the necessity of representation from more basic self-consciousness. The former is contingent, the latter necessary. Philosophy is concerned solely with necessary operations of mind, making it a closed system, unlike all other senses: constitutive elements of consciousness are generated by the mind itself. This has the effect of rejecting transcendental deduction of categories, since the world of objects is constituted by the conditions which make experience possible. Fichte’s influence foundered on the difficulty of his argument. NB: it was Fichte, not Hegel, who invented the thesis-antithesis-synthesis dialectic, not Hegel.

The primary appeal of practical (political) philosophy is concern with freedom of the individual in a sociopolitical setting, as determined by individual use of reason. But Fichte substitutes Kant’s individual (uncaused cause) with a communitarian ideal: if rational agents are well-ordered among one another, then they are free. For Kant, by contrast, freedom is a metaphysical postulate which underpins moral obligations: politics serves morality, as does education and religion. For Fichte, freedom is not given but an end in itself, available only to certain communities (i.e., with certain characteristics): thus, economic resources and opportunities become involved in what we now call social justice. Fichte’s revision of the categorical imperative means there can be no truly human persons without just communities fostering the individual’s capacity for rationality. Sociopolitical relations are a prior condition to moral agency, a view embraced by Hegal and Marx.

Schelling changed his mind thrice, albeit honestly. Hegelians often him a waystation, while critics take his final rejection of metaphysics as a precursor to Kirkegaard, Marx, Heidegger, and postmodernism. He first sought epistemological grounds, then abandoned the search in favor of the ontological – from Kant to the Spinozan tradition. Kant has insisted we could not treat ideas of reason as if they can inform us of the world, asking the epistemological question ‘How is it possible to know anything to be true that is not an analytic, conceptual relation?’ Schelling replied asking an ontological question ‘How is it possible for there to be differentiated subjects and objects, without which there would be no need for a cognitive synthesis?’ Philosophy is to explain how anything emerges from an undifferentiated subject, and to reconcile this all-encompassing subject with the freedom of individual subjects, he thought, breaking with Kant and Fichte and anticipating Heidegger. That is, the objective is not understanding cognition but essence / being. Kant would have replied the ontological question is outside the scope of transcendental idealism, because it is beyond rational inquiry. In his middle period Schelling contrasted idealism which commences with the subject and ‘philosophy of nature’ which starts with objective or natural world to determine why self-conscious subjects should emerge. His paradigm of the object is math, such as the concept of triangles: science determines not merely how we think but how they must be. He tried to reconcile a philosophy of identity, but could not and so abandoned the a priori system. It was a pursuit akin to speculative physics, in which the first problem is to explain the absolute cause of motion.

More Schelling: latterly, he asserted the product (content) of true art is the absolute identity. It is the pinnacle of human activity, the unconscious element of acting and producing, generating identity via consciousness. His idea of freedom comes from Spinoza: that which is free acts according to laws of inner being, unimpeded by anything else. He tries to reconcile this freedom with the emergence of everything from the absolute being. (Whereas (to repeat) Kant’s assertion that the cognizing subject cannot conform to the object of cognition, if there is to be metaphysical knowledge, was transcendental idealism’s Copernican revolution, its point of departure. The object must be understandable by the subject.) The French Revolution theorists argued freedom is impossible if the populist must conform to ruling authorities, and so sought to establish an entirely rational polity with no such authorities.

Hegel, following Schelling, denies that Kant (and Fichte) established an identity of subject-and-object; Hegel calls true identity ‘reason’ – actuality must be rational. The Phenomenology claims rational cognition is possible only if the determinations of thinking and being can be established; this is to reject Kant’s view that philosophy is incapable of rational cognition; he joins Schelling in restoring metaphysics as queen of the discipline, rejecting Kant’s view that thinking cannot determine the truth of being. Therefore his project is ontological, an account of what it is to be.

For Hegel, ‘consciousness’ means self-understanding: knowledge requires the thinking subject to truly appreciate the realm of objectivity it confronts and distinguish itself from it. Dualism is suspended, one achieves knowing by result of the subject undermining one’s assumptions via synthesis achieving reason (‘science’). While Fichte and Schelling accepted selfhood (consciousness) as a fact, Hegel in Phenomenology describes how consciousness seems; how it can only be determined by dialectical reason.

To appreciate ancient skepticism is to suspend the Cartesian subject-object dualism. Presuppositionless knowledge (i.e., phenomenology), or presuppositionless philosophy is a systematic philosophy beginning with indeterminate being of thought and unfolding as logic, or what must be thought of being, and ontology, what must be of being. Thought can only be self-determining if it allows immanent dialectic to emerge; otherwise it is beholden to the subject. However, the natural world exists independent of thought and also thinking subjects; but Hegel is an idealist in that nature has a structure which thinking can comprehend. The rational is actual and vice versa, but all is implicit, not empirical.

There is a limit to systematic philosophy’s explanation of the natural world – we know there are contingencies, such as the form matter will take. Thus Hegel is not totalizing. The systematic philosophy provides an account of being and comprehends rational aspects of empirical phenomena but stops at contingency and chance. Hegel rejects Kant’s view that freedom transcends nature; freedom depends on thinking being the achievement of reconciliation with the natural world from which it differs. Hegel sees, as does Fichte, the moral will is self-certain and hence capable of evil by mistaken conclusion – there is no objective standard. It is not objective freedom. The will cannot reconcile with the natural world: ethics and purpose (of the subject) do not guarantee freedom. Only spirit (geist), art, religion, and philosophy can reconcile. Peoples with different understandings of freedom develop different sociopolitical arrangements and customs. Philosophy is first of equals because of spirit, the interpretation of which is philosophy’s job.

For Kant, freedom is transcending natural causes and acting purely from rationality and moral law it imposes. Since all of his conclusions depend on an account of cognition, his successors pursued refinement of criticality – unassailable foundations. Fichte pursued self-consciousness and relations to the object. Schelling replaced dualism with a single indeterminacy. Hegel thought the defeat of skepticism turned on systematic examination of necessary structure of thought, the dialectic. He was the last idealist to attempt Kant’s project based on a priori grounds. The Romantics succeeded this idealism, asserting philosophy’s limitations were fulfilled by art. Romantics deemed such rationality could justify moral and ethical commitments, prompting Hegel’s violently disagreement.