Philosophy is, in a nutshell, the study of the human experience – how we understand and react to the world. There have been a number of important thinkers who developed the discipline, but these five philosophers are the ones that you need to know.

Plato
The founder of the first school of higher education in the Western world, Plato’s teachings inspired virtually every future thinker in Western philosophy. His theories of forms, immaterial abstractions that possess the true nature of their material counterparts, is vital for study of philosophy.

Aristotle
Without Aristotle’s development of written systems to analyze and criticize, the development of philosophy would have been very different. His teachings covered an incredibly broad spectrum of subjects.

Rene Descartes
Widely regarded as the father of modern philosophy, Descartes was not only a great thinker who advanced the concept of dualism, he also developed Cartesian geometry, one of the most important mathematical breakthroughs of the 17th century.

Confucius
The central thinker of Eastern philosophy, Master Kong Qiu, who we know as Confucius, was born in 551 BC and helped make the empires of China some of the most robust on Earth. His systems of morals and ethics paralleled and even surpassed the ones being developed in Greece at the same time.

John Locke
Regarded as the “Father of Liberalism,” philosopher John Locke brought concepts of humanism and universal freedom into the arena of thought. He was a huge influence on the framers of the Constitution and the first Presidents of the United States.