Immanuel Kant
Prussian · 1724–1804
Immanuel Kant was a Prussian philosopher whose Critique of Pure Reason (1781) attempted to resolve the standoff between rationalism and empiricism by arguing that the mind imposes structure — space, time, causality — on raw experience, so that we never know things as they are in themselves but only as they appear under those conditions. His ethical works grounded morality in the categorical imperative: act only on principles you could will to be universal laws. Kant's "problem situation" — how secure knowledge like Newtonian physics was possible at all if experience alone is insufficient — became the puzzle Karl Popper later took himself to have solved.