Timeline of Greek and Roman Philosophers

Greek philosopher and statesman Empedocles (c.490 - c.430 BC), a follower of Pythagoras and Parmenides, circa 1493. Original Artwork: From Hartmann Schedel - Liber Chronicorum Mundi, Nuremberg Chronicle. Hulton Archive / Stringer/ Hulton Archive 

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What was the first cause of our existence? What is real? What is the purpose of our lives? Questions like these have become the basis of the study known as philosophy.

While these questions were addressed in ancient times through religion, the process of logically and methodically thinking through life's big questions did not begin until about the 7th century BCE.

As different groups of philosophers worked together, they developed "schools" or approaches to philosophy. These schools described the origins and purpose of existence in very different ways. Individual philosophers within each school had their own particular ideas.

The Pre-Socratic philosophers are the earliest of the philosophers. Their concern was not so much with the topics of ethics and knowledge that modern people associate with philosophy, but concepts we might associate with physics.  Empedocles and Anaxagoras are counted as Pluralists, who believed there is more than one basic element from which everything is composed. Leucippus and Democritus are Atomists.

More or less following the Pre-Socratics came the trio of Socrates-Plato-Aristotle, the schools of the Cynics, Skeptics, Stoics, and Epicureans.

The Milesian School: 7th-6th Centuries BCE

Miletus was an ancient Greek Ionian city-state on the western coast of Asia Minor in today’s Turkey. The Milesian School consisted of Thales, Anaximander, and Anaximenes (all from Miletus). The three are sometimes described as "materialists," because they believed that all things derived from a single material.

Thales (636-546 BCE) Greek philosopher. Thales was certainly a real historical individual, but very little evidence remains of his work or writing. He believed that the "first cause of all things" was water, and may have written two treatises entitled On the Solstice and On the Equinox, focusing on his astronomical observation. He may also have developed several significant mathematical theorems. It is likely that his work strongly influenced Aristotle and Plato.

Anaximander (c.611-c.547 BCE) Greek philosopher. Unlike Thales, his mentor, Anaximander actually wrote materials can be credited to his name. Like Thales, he believed that just one material was the source of all things--but Anaximander called that one thing "the boundless" or infinite. His ideas may well have strongly influenced Plato.

Anaximenes (d. c. 502 BCE) Greek philosopher. .Anaximenes may well have been a student of Anaximander. Like the other two Milesians, Anaximenes believed that a single substance was the source of all things. His choice for that substance was the air. According to Anaximenes, when the air becomes finer, it becomes fire, when it is condensed, it becomes first wind, then cloud, then water, then earth, then stone.

The Eleatic School: 6th and 5th centuries BCE

Xenophanes, Parmenides, and Zeno of Elea were members of the Eleatic School(named for its location in Elea, a Greek colony in southern Italy). They rejected the idea of many gods and questioned the idea that there is one reality.

Xenophanes of Colophon (c. 570-480 BCE) Greek philosopher. Xenophanes rejected the anthropomorphic deities and considered there to be one incorporeal god. Xenophanes may have asserted that men may have beliefs, but they don't have certain knowledge.

Parmenides of Elea (c. 515-c. 445 BCE) Greek philosopher. Parmenides believed that nothing comes into being because everything must derive from something that already exists.

Zeno of Elea, (c. 490-c. 430 BCE) Greek philosopher. Zeno of Elea (in southern Italy) was known for his intriguing puzzles and paradoxes.

Pre-Socratic and Socratic Philosophers of the 6th and 5th Centuries BCE

• Anaxagoras of Clazomenae
  (c. 499-c. 428)Greek philosopher
• Protagoras
  (480-411)Greek philosopher & Sophist
• Socrates
  (c. 469-399)Greek philosopher
• Plato
  (c. 427-347)Greek philosopher
• Diogenes of Sinope
  (412-323)Greek philosopher

Philosophers of the 4th Century BCE

• Aristotle
  (384-322)Greek philosopher
• Epicurus
  (341-271)Greek philosopher
• Euclid
  (c. 325-265)Greek mathematician
• Aristarchos
  (c. 310-250)Greek astronomer

Philosophers of the 3rd Century BCE

• Chrysippus
  (c. 280-207)Hellenistic philosopher
• Eratosthenes
  (276-194)Hellenistic astronomer

Philosophers of the 2nd Century BCE

• Panaetius
  (c. 185-110)Stoic and Neo-Platonic Philosopher
• Lucretius
  (c. 98-55)Roman poet and Epicurean philosopher

Philosophers of the 1st Century CE

• Epictetus
  (50 - 138)Roman philosopher
• Marcus Aurelius
• (121-180)Roman emperor and philosopher

Philosophers of the 3rd Century CE

• Plotinus
  (c. 204-270)Greco-roman philosopher

Philosophers of the 4th Century CE

• Hypatia of Alexandria
  (c. 370-415)Alexandrian philosopher

Philosophers of the 4th Century CE

• Boethius
  (480-525)Philosopher and Christian martyr who was called the last of the Romans.