Immanuel Kant

Immanuel Kant (22 April 1724 - 12 February 1804) was a German philosopher born in Konigsberg, East Prussia. Kant studied philosophy at the University of Konigsberg, and later became a professor of philosophy. He called his system "transcendental idealism". Kant's writing about epistemology, metaphysics, ethics, and aesthetics have made him one of the most influential figures in the history of philosophy.
Today the town Konigsberg is part of Russia, and is renamed Kaliningrad. When Kant was alive, it was the second largest city in the kingdom of Prussia.
Life
Immanuel Kant was born on April 22, 1724. In 1740 he entered the University of Konigsberg and studied the philosophy of Gottfried Leibniz and his follower Christian Wolff. He studied there until 1746 when his father died, then left Konigsberg to take up a job as tutor. He became the tutor of Count Kayserling and his family. In 1755 Kant became a lecturer and stayed in this position until 1770. He was made the second librarian of the Royal Library in 1766. Kant was eventually given the Chair of Logic and Metaphysics at the University of Konigsberg. In his entire life Kant never travelled more than seventy miles from the city of Konigsberg. Kant died on February 12, 1804 with the final words "Es ist gut" ("It is good").
University
After finishing his study in the university, Kant hoped to be a teacher of philosophy, but it was very difficult. He could have lived a life of private lecturer as interested in physics, both astronomical objects (such as planets and stars) and the earth. He wrote some papers about this, but he became more interested in metaphysics. He wanted to learn the nature of human experience: how humans could know something, and what their knowledge was based on.
First doubts
Under the strong influence of the philosophical system of Leibniz and Wolff, Kant began to doubt the basic answers of past philosophers. Then, Kant read a Scottish philosopher, David Hume. Hume had tried to make clear what our experience had been, and had reached a very strong opinion called "skepticism", that there was nothing to make our experience sure. Kant was very shocked by Hume, and saw the theory he had learned in a new point of view. He began to try finding a third way other than the two that Kant called "skepticism" and "dogmaticism".
Kant read another thinker, named Jean-Jacques Rousseau, who lived in Geneva, Switzerland, and wrote in French. His thought on human beings, especially on morals, human freedom and perpetual peace, impressed Kant.
Philosophy
Some scholars like to include Kant as one of the German idealists, but Kant himself did not belong to that group.
The most-known work of Kant is the book Critique of Pure Reason (Kritik der reinen Vernunft) that Kant published in 1781. Kant called his way of thought "critique", not philosophy. Kant said that critique was a preparation for establishment of real philosophy. According to Kant, people should know what human reason can do and which limits it has. In the Critique of Pure Reason Kant wrote several limits of human reason, to both feeling and thinking something. For sensation, there are two limits inside of human perception: space and time. There are no physical objects, but the limitations of our mind that work whenever we feel something through our senses. For thinking, he said there are twelve categories or pure rational concepts, divided into four fields: quantity, quality, relation and modality. Kant thought human reason applied those ideas to everything.
Ideology
Is what we think only our fantasy? Kant said "No", although without those sensual and rational limitations, we can think nothing, then Kant was convinced there would be something we could not know directly behind our limitations, and even with limitations we could know something. It can not be a personal fantasy either, since those limitations were common to all human reason before our particular experience. Kant called what we could not know directly Ding an sich -- "thing itself". We can think "thing itself" but cannot have any experience about it, nor know it. God, the eternity of soul, life after death, such things belong to "thing itself", so they were not right objects of philosophy according to Kant, although people had liked to discuss them from ancient times.
Books
Kant wrote two other books named Critique: Critique of the practical reason (1788) and Critique of the Judgement (1790). In Critique of the practical reason Kant wrote about the problem of freedom and God. It was his main work of ethics. In Critique of the Judgement Kant wrote about beauty and teleology, or the problem if there was a purpose in general, if the world, a living creature had a reason to exist, and so on. In both books, Kant said we could not answer those problems, because they were concerned with "thing itself".
Influence
Kant had a great influence on other thinkers. In the 19th century, German philosophers like Fichte, Schelling, Hegel, Schopenhauer and writers like Herder, Schiller, and Goethe were influenced by Kant.
In the early 20th century Kant's ideas were very influential on one group of German philosophers. They became known as the new-Kantians. One of them, Windelband, said, "every philosophy before Kant poured into Kant, and every philosophy after Kant pours from Kant".
Kant has influenced many modern thinkers, including Hannah Arendt, and John Rawls.