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.
A priori and a posteriori
The 18th-century German philosopher Immanuel Kant (1781) advocated a blend of rationalist and empiricist theories. Kant says, "Although all our cognition begins with experience, it does not follow that it arises [is caused by] from experience" According to Kant, "a priori" cognition is transcendental, or based on the "form" of all possible experience, while "a posteriori" cognition is empirical, based on the "content" of experience. Kant states, "[…] it is quite possible that our empirical knowledge is a compound of that which we receive through impressions, and that which the faculty of cognition supplies from itself sensuous impressions [sense data] giving merely the "occasion" [opportunity for a cause to produce its effect]." Contrary to contemporary usages of the term, Kant thinks that "a priori" knowledge is not entirely independent of the content of experience. And unlike the rationalists, Kant thinks that "a priori" cognition, in its pure form, that is without the admixture of any empirical content, is limited to the deduction of the conditions of possible experience. These "a priori", or transcendental conditions, are seated in one's cognitive faculties, and are not provided by experience in general or any experience in particular (although an argument exists that "a priori" intuitions can be "triggered" by experience).