The Pre-Socratics, including Thales, Anaximander, and Anaximenes, were 6th and 5th-century BCE Greek philosophers who introduced a new way of thinking about the world. Thales is considered the first Greek philosopher because he was the first to give a purely natural explanation of the origin of the world. The Pre-Socratic philosophy began with the three Milesians, and they all attributed the "arche," or the fundamental principle of the universe, to a single substance. These philosophers broke with the poetic and mythological tradition handed down by their predecessors and sought to understand the world through rational inquiry. Thales believed that water was the fundamental substance, while Anaximenes believed that air was the foundation of all things. The Pre-Socratic philosophers' ideas laid the groundwork for the development of Western philosophy and science.
The Sophists were a group of philosophers who emerged in the 5th century BCE and were known for their skepticism and relativism. The most famous representatives of the Sophistic movement were Protagoras, Gorgias, and Antiphon. They believed that truth was relative to the individual and that there was no objective truth. The Sophists' philosophy contained criticisms of religion, law, and ethics. Although many Sophists were apparently as religious as their contemporaries, some attacked traditional religious beliefs and practices. The Sophists' ideas were influential in shaping the philosophical and political landscape of ancient Greece.
The Big Three of Greek philosophy were Socrates, Plato, and Aristotle. Socrates was a philosopher who lived in Athens in the 5th century BCE and is considered the father of Western philosophy. Plato was Socrates' most famous student and is known for his theory of Forms, which posits that there is a realm of abstract entities that exist independently of the physical world. Aristotle was a student of Plato and is considered the founder of logical theory. He believed that the greatest human endeavor is the use of reason in theoretical activity. These three philosophers' ideas have had a profound impact on Western thought and continue to shape philosophy, science, and politics to this day.