Immanuel Kant, a key figure in the field of philosophy, was born in what is now Germany. He grew up in a Lutheran household, part of a family that particularly emphasized piety and vigorous religious devotion. At the age of 16, he enrolled at the University of Konigsberg, and went on to spend his entire career as a member of the faculty there. His best-known and most important published work is The Critique of Pure Reason, first published in 1781.

Kant was a theist, and his religious beliefs provided an underpinning for his understanding of the world. As scientists of his time discovered and described natural laws, Kant came to believe that similar moral laws existed and would become clearer over time. Underlying his theory was a belief in a divine hand that provided order to what we otherwise might term chaos or randomness. He believed that our evolving understanding of scientific and moral laws moved us gradually closer to God.

In 1755, at the age of 31, he published Theory of the Heavens, a book that built on Isaac Newton's description of the basic physical laws that govern our solar system and our lives. Kant hypothesized that stars were created out of the material of nebulae, that stars spiraled around the center of galaxies, and that the galaxies spiraled around the center of the universe. Although we now know that much of what Kant hypothesized was correct, his observations about the universe went largely unnoticed during his time, in part because the publisher of his book went bankrupt.

Kant's observation and description of the cosmological order that determined the formation and movements of stars was, to him, proof that the universe was governed by laws. Following this train of logic, Kant concluded there must also be moral laws that govern human behavior. Following a process similar to what had led to the discovery of physical laws, human understanding of moral laws would be initially imperfect and would evolve over time, moving humanity toward clearer and more complete understanding. He argued that—following the pattern set by physical, scientific laws—moral laws must be true in all situations.

As a test for determining whether a particular action is in harmony with the laws of morality, Kant developed his famous concept of the Categorical Imperative, the idea that an action is morally acceptable if it can be universalized, or done by everyone who finds themselves in a similar situation. For example, Kant's theory tests the moral acceptability of stealing, even something as small as a paper clip from your workplace, by asking what would happen if everyone stole from their workplace. When the end result of a universalized action does not seem right to us, then the individual act must be unacceptable.

Kant's work is closely associated with deontological ethics, a rules-based ethics which the emphasizes the end result. In this ethical schema, the final outcome matters more than the countervailing circumstances or the means by which we arrive at a result. Proponents of deontological ethics hold that the moral laws or moral principles one develops are always and in every circumstance correct, and one must adhere to them, even when it is difficult to do so.

Kant's work made him an important and influential figure in his lifetime, and his influence continues today.