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.
Philosophy of space and time
In 1781, Immanuel Kant published the "Critique of Pure Reason", one of the most influential works in the history of the philosophy of space and time. He describes time as an "a priori" notion that, together with other "a priori" notions such as space, allows us to comprehend sense experience. Kant denies that neither space or time are substance, entities in themselves, or learned by experience; he holds, rather, that both are elements of a systematic framework we use to structure our experience. Spatial measurements are used to quantify how far apart objects are, and temporal measurements are used to quantitatively compare the interval between (or duration of) events. Although space and time are held to be "transcendentally ideal" in this sense, they are also "empirically real"—that is, not mere illusions.