German idealism ran from roughly 1780 to 1830 and concerned the relationship between mind and reality, the structure of self-consciousness, and the conditions under which freedom is possible.
Kant began it with what he called his Copernican turn. Instead of assuming that knowledge must conform to objects, he argued that objects as we can know them conform to the structure of our understanding, which explains how necessary knowledge is possible while leaving things as they are in themselves beyond reach. That last reservation is what his successors could not accept. Fichte tried to derive everything from the self-positing I. Schelling gave nature an equal standing. Hegel argued that the very idea of a limit to knowledge is incoherent, since to mark a boundary is already to have crossed it, and reconstructed the whole of thought as a developmental process arriving at self-knowledge.
The political stakes are larger than the metaphysics suggests. The tradition's central claim about freedom is that it consists in self-determination according to reason and not in the absence of external constraint. A person driven by unexamined impulse is not free merely because nobody is stopping them. Hegel's Philosophy of Right (1821) built an account of ethical life in which freedom is realized through institutions, through family, civil society and state, instead of against them.
After Hegel died in 1831 his school split, and the split mattered enormously. Right Hegelians read the system as underwriting the existing Prussian order. Left Hegelians, among them Feuerbach, Bauer, Stirner and then Marx, read the method as a solvent for it. The tradition's twentieth-century reputation suffered from Popper's charge that Hegel was an apologist for state power and an ancestor of totalitarianism, a reading most specialists now regard as caricature but which shaped a generation of Anglophone opinion.
