Immanuel Kant (born Emanuel Kant; 22 April 1724 – 12 February 1804) was a German philosopher. Born in Königsberg in the Kingdom of Prussia, he is considered one of the central thinkers of the Enlightenment. His comprehensive and systematic works in epistemology, metaphysics, logic, ethics, aesthetics, political theory, and philosophy of religion have made him one of the most influential and highly discussed figures in modern Western philosophy.
Kant's philosophy is centered on the human subject and motivated by the desire to secure the possibility of both knowledge and morality against the threats of skepticism and determinism. In the Critique of Pure Reason (1781/1787), Kant argues for transcendental idealism, the doctrine that space and time are mere "forms of intuition" (German: Anschauung) that structure all experience and that we have knowledge only of "appearances" and not of the nature of things in themselves. 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 the understanding, instead of the traditional method of showing how the mind might conform to its objects.
Kant believed that reason is the source of morality and that the categorical imperative binds all rational agents. He believed that aesthetics arises from a faculty of disinterested judgment. Kant hoped that perpetual peace could be secured through an international federation of republican states and international cooperation. Kant believed that true religion is grounded on morality. The exact nature of his religious views is a matter of dispute.
Immanuel Kant was born on 22 April 1724 into a Prussian German family of Lutheran faith in Königsberg in East Prussia (now Kaliningrad Oblast, Russia). 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). Kant believed his family to be of Scottish descent and that his paternal grandfather's name was originally "Cant", although this has not been verified by genealogical research.
Kant was baptized as Emanuel, changing 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 watches by his daily walks. Kant considered marriage twice, first to a widow and then to a Westphalian woman, but on both occasions waited too long. Although he never married, he nevertheless had a rewarding social life; he was a popular teacher and a modestly successful author, even before commencing his major philosophical works.
Kant demonstrated an early aptitude for study. He first attended the Collegium Fridericianum (then directed by Franz Albert Schultz), 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 main publisher, Johann Friedrich Hartknoch, was also a Freemason.
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).
During the Russian occupation of Königsberg during the Seven Years' War (1758–1762), Kant's financial circumstances improved, as he obtained a number of well-paid tutoring assignments from Russian military officers and civil administrators stationed in the city. In December 1758, after the death of Johann David Kypke, Kant petitioned Empress Elizabeth for appointment to the vacant chair of logic and metaphysics at the University of Königsberg, but the position was awarded to another candidate.
Kant is best known for his work in the philosophy of ethics and metaphysics, but he also contributed significantly to other disciplines. In 1754, while contemplating a prize question by the Berlin Academy about the problem of Earth's rotation, he argued that the Moon's gravity would slow down the Earth's spin. 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 at 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 ("New Remarks toward an Elucidation of the Theory of Winds"), Kant laid out a qualitative insight into what is now called Coriolis force.
In 1756, Kant also published three papers on the 1755 Lisbon earthquake. Kant's theory, which involved shifts in huge caverns filled with hot gases, though inaccurate, was one of the first systematic attempts to explain earthquakes in natural rather than supernatural terms. In 1757, Kant began lecturing on geography, making him one of the first lecturers to explicitly teach geography as its own subject. Geography was one of Kant's most popular lecturing topics and, in 1802, a compilation by Friedrich Theodor Rink of Kant's lecturing notes, Physical Geography, was released. After Kant became a professor in 1770, he expanded the topics of his lectures to include lectures on natural law, ethics, and anthropology, along with other topics.
In the Universal Natural History, Kant laid out the nebular hypothesis, in which he deduced that the Solar System had formed from a large cloud of gas, a nebula. Kant also correctly deduced that the Milky Way was a large disk of stars, which he theorized had formed from a much larger spinning gas cloud. He further suggested that other distant "nebulae" might be other galaxies. These postulations opened new horizons for astronomy, for the first time extending it beyond the solar system to galactic and intergalactic realms.
From then on, Kant devoted his efforts increasingly towards philosophical issues, even though he continued to write on the sciences throughout his life. In the early 1760s, he produced a series of important works in philosophy. The False Subtlety of the Four Syllogistic Figures, a work in logic, was published in 1762. Two more works appeared the following year: Attempt to Introduce the Concept of Negative Magnitudes into Philosophy and The Only Possible Argument in Support of a Demonstration of the Existence of God. By 1764, Kant had become a notable popular author, and wrote Observations on the Feeling of the Beautiful and Sublime; he was second to Moses Mendelssohn in a Berlin Academy prize competition with his Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morality (often referred to as "The Prize Essay"). In 1766 Kant wrote a critical piece on Emanuel Swedenborg's Dreams of a Spirit-Seer.