Immanuel Kant (born Emanuel Kant; 22 April 1724 – 12 February 1804) was a German philosopher. Born in Königsberg, he is considered one of the central thinkers of the Enlightenment. His comprehensive and systematic works in epistemology, metaphysics, ethics, and aesthetics have made him one of the most influential and highly discussed figures in modern Western philosophy.

In his doctrine of transcendental idealism, Kant argued that space and time are mere "forms of intuition [German: Anschauung]" that structure all experience and that the objects of experience are mere "appearances". The nature of things as they are in themselves is unknowable to us. Nonetheless, in an attempt to counter the philosophical doctrine of skepticism, he wrote the Critique of Pure Reason (1781/1787), his best-known work. Kant drew a parallel to the Copernican Revolution in his proposal to think of the objects of experience as conforming to people's spatial and temporal forms of intuition and the categories of their understanding so that they have a priori cognition of those objects.

Kant believed that reason is the source of morality and that aesthetics arises from a faculty of disinterested judgment. Kant's religious views were deeply connected to his moral theory. Their exact nature remains in dispute. He hoped that perpetual peace could be secured through an international federation of republican states and international cooperation. His cosmopolitan reputation is called into question by his promulgation of scientific racism for much of his career, although he altered his views on the subject in the last decade of his life.

Immanuel Kant was born on 22 April 1724 into a Prussian German family of Lutheran faith in Königsberg in East Prussia. His mother, Anna Regina Reuter, was born in Königsberg to a father from Nuremberg. Her surname is sometimes erroneously given as Porter. Kant's father, Johann Georg Kant, was a German harness-maker from Memel, at the time Prussia's most northeastern city (now Klaipėda, Lithuania). It is possible that the Kants got their name from the village of Kantvainiai (German: Kantwaggen – today part of Priekulė) and were of Kursenieki origin.

Kant was baptized as Emanuel and later changed the spelling of his name to Immanuel after learning Hebrew. He was the fourth of nine children (six of whom reached adulthood). The Kant household stressed the pietist values of religious devotion, humility, and a literal interpretation of the Bible. Immanuel Kant's early education was strict, punitive, and highly disciplinary, with an emphasis on Latin and religious instruction rather than mathematics and science. In his later years, Kant lived a strictly ordered life. It was said that neighbors would set their clocks by his daily walks. Kant considered marriage two times, first a widow and then a Westphalian girl, but both times waited too long. Though he never married, he seems to have had a rewarding social life; he was a popular teacher as well as a modestly successful author, even before starting on his major philosophical works.

Kant showed a great aptitude for study at an early age. He first attended the Collegium Fridericianum, from which he graduated at the end of the summer of 1740. In 1740, aged 16, he enrolled at the University of Königsberg, where he would later remain for the rest of his professional life. He studied the philosophy of Gottfried Leibniz and Christian Wolff under Martin Knutzen (Associate Professor of Logic and Metaphysics from 1734 until he died in 1751), a rationalist who was also familiar with developments in British philosophy and science and introduced Kant to the new mathematical physics of Isaac Newton. Knutzen dissuaded Kant from the theory of pre-established harmony, which he regarded as "the pillow for the lazy mind". He also dissuaded Kant from idealism, the idea that reality is purely mental, which most philosophers in the 18th century regarded negatively. The theory of transcendental idealism that Kant later included in the Critique of Pure Reason was developed partially in opposition to traditional idealism. Kant had contacts with students, colleagues, friends and diners who frequented the local Masonic lodge.

His father's stroke and subsequent death in 1746 interrupted his studies. Kant left Königsberg shortly after August 1748; he would return there in August 1754. He became a private tutor in the towns surrounding Königsberg, but continued his scholarly research. In 1749, he published his first philosophical work, Thoughts on the True Estimation of Living Forces (written in 1745–1747).

Kant is best known for his work in the philosophy of ethics and metaphysics, but he made significant contributions to other disciplines. In 1754, while contemplating on a prize question by the Berlin Academy about the problem of Earth's rotation, he argued that the Moon's gravity would slow down Earth's spin and he also put forth the argument that gravity would eventually cause the Moon's tidal locking to coincide with the Earth's rotation. The next year, he expanded this reasoning to the formation and evolution of the Solar System in his Universal Natural History and Theory of the Heavens. In 1755, Kant received a license to lecture in the University of Königsberg and began lecturing on a variety of topics including mathematics, physics, logic, and metaphysics. In his 1756 essay on the theory of winds, Kant laid out an original insight into the Coriolis force.^{[citation needed]}