Immanuel Kant
Immanuel Kant (; ; 22 April 1724 – 12 February 1804) was a German philosopher who is a central figure in modern philosophy. In his doctrine of transcendental idealism, he argued that space, time and causation are mere sensibilities; "things-in-themselves" exist, but their nature is unknowable. In his view, the mind shapes and structures experience, with all human experience sharing certain structural features. He drew a parallel to the Copernican revolution in his proposition that worldly objects can be intuited "a priori" ("beforehand"), and that intuition is therefore independent from objective reality. Kant believed that reason is the source of morality, and that aesthetics arise from a faculty of disinterested judgment. Kant's views continue to have a major influence on contemporary philosophy, especially the fields of epistemology, ethics, political theory, and post-modern aesthetics.
Otto Liebmann
A forerunner of Neo-Kantianism, in his best-known book, "Kant und die Epigonen", he deals with the philosophy after Kant, discussing Fichte, Schelling, Hegel, Fries, Herbart and Schopenhauer. Having credited Kant's philosophy (though criticizing it on the vital point of accepting a thing-in-itself), he focuses on what he sees as the shortcomings in the approaches of Kants successors. He frequently ends a section with the statement that one should return to Kant.