Immanuel Kant (1724-1804) was an influential philosopher and best known for his analysis of reason. Philosopher Friedrich Paulsen (1846-1908) says,
Kant's view of the nature of what is 'actually real' remained unaltered throughout his life. Reality is in itself a system of existing thought-essences brought into a unity by teleological relations that are intuitively thought by the Divine intellect, and by this very act of thought posited as real. (Immanuel Kant: His Life and Doctrine, 1902)This post is a collection of quotes describing Kant's philosophy of reason.
What is reason?
"Reason in a creature is a faculty of widening the rules and purposes of the use of all its powers far beyond natural instinct; it acknowledges no limits to its projects. Reason itself does not work instinctively, but requires trial, practice, and instruction in order gradually to progress from one level of insight to another." (Idea for a Universal History from a Cosmopolitan Point of View, 1784)
"Mathematics, from the earliest times to which the history of human reason can reach, has followed, among that wonderful people of the Greeks, the safe way of science. But it must not be supposed that it was as easy for mathematics as for logic, in which reason is concerned with itself alone, to find, or rather to make for itself that royal road." (Critique of Pure Reason, 1781)
"Human reason is by nature architectonic." (Critique of Pure Reason, 1781)
"Human reason has this peculiar fate that in one species of its knowledge it is burdened by questions which, as prescribed by the very nature of reason itself, it is not able to ignore, but which, as transcending all its powers, it is also not able to answer." (Critique of Pure Reason, 1781)
"It is precisely in knowing its limits that philosophy consists." (Critique of Pure Reason, 1781)