Immanuel Kant began as a private tutor and then taught at the University of Königsberg as an unsalaried lecturer from 1755. His courses ranged across logic, metaphysics, natural science, and geography. His lectures also addressed anthropology and education. Early publications included an account of the formation of the solar system and investigations of physical and philosophical questions. Appointed professor of logic and metaphysics in 1770, he spent the following decade developing the critical philosophy that defined his mature career.

The Critique of Pure Reason appeared in 1781 and was substantially revised in 1787. It examined how experience depends on forms of sensibility and concepts supplied by the understanding, while asking where speculative reasoning exceeds its legitimate limits. Kant sought to explain the possibility of knowledge without claiming that human beings could know things independently of the conditions under which they appear. His arguments reshaped debates between rationalist and empiricist traditions rather than simply choosing one side.

The Groundwork of the Metaphysics of Morals in 1785 and Critique of Practical Reason in 1788 developed an ethics centered on autonomy, duty, and principles that could be willed universally. The Critique of Judgment in 1790 examined aesthetic and purposive judgment, connecting questions about beauty and living nature with the larger philosophical system. Kant also wrote on religion, enlightenment, law, and political order. Perpetual Peace in 1795 proposed institutional conditions intended to reduce war among states.

His religious writings provoked restrictions under the Prussian government, demonstrating the political limits on public philosophical inquiry. He continued teaching and publishing as his health permitted before his death in 1804. The universal claims of his moral philosophy coexist with writings on race and gender that contain hierarchies and exclusions requiring critical examination. His career transformed the study of knowledge, ethics, and aesthetics, while later thinkers disputed both his foundations and the divisions he drew. His relatively local institutional life supported an intellectual project of international reach. Its significance lies not only in individual conclusions but in a method of asking what makes knowledge, obligation, and judgment possible and where their claims must be limited.