Ancient Philosophers or Thinkers You Should Know

Empedocles of Acragas (c. 495-435 B.C.) was known as a poet, statesman, and physician, as well as philosopher. Empedocles encouraged people to look upon him as a miracle worker. Philosophically he believed there were elements that were the building blocks of everything else: earth, air, fire, and water. These are the four elements that are paired with the four humors in Hippocratic medicine and even modern typologies. The next philosophical step would be to realize a different type of universal element -- atoms, as the Pre-socratic philosophers known as Atomists, Leucippus and Democritus, reasoned.

Empedocles believed in transmigration of the soul and thought that he would be come back as a god, so he jumped into the Mt. Aetna volcano.

Parmenides (b 510 B.C.) was a Greek philosophy from Elea in Italy. He argued against the existence of a void, a theory used by later philosophers in the expression "nature abhors a vacuum," which stimulated experiments to disprove it. Parmenides argued that change and motion are only delusions.

Anaximenes (d. c. 528 B.C.) accounted for natural phenomena like lightning and earthquakes though his philosophical theory. A student of Anaximander, Anaximenes did not share his belief that there was an underlying boundless indeterminateness or apeiron. Instead, Anaximenes thought the underlying principle behind everything was air/mist, which had the advantage of being empirically observable. Different densities of air (rarified and condensed) accounted for different forms. Since everything is made of air, Anaximenes' theory of the soul is that it is made of air and holds us together. He believed the earth was a flat disk with fiery evaporations becoming heavenly bodies.

Anaximander of Miletus (c. 611 - c. 547 B.C.) was a pupil of Thales and teacher of Anaximenes. He is credited with inventing the gnomon on the sundial and with drawing the first map of the world in which people live. He may have drawn a map of the universe. Anaximander may also have been the first to write a philosophical treatise. He believed in an eternal motion and a boundless nature.

Heraclitus (fl. 69th Olympiad, 504-501 B.C.) is the first philosopher known to use the word kosmos for world order, which he says ever was and ever will be, not created by god or man. Heraclitus is thought to have abdicated the throne of Ephesus in favor of his brother. He was known as Weeping Philosopher and Heraclitus the Obscure.

Heraclitus uniquely put his philosophy into aphorisms, like "On those stepping into rivers staying the same other and other waters flow." (DK22B12), which is part of his confusing theories of Universal Flux and the Identity of Opposites. In addition to nature, Heraclitus made human nature a concern of philosophy.

Archimedes of Syracuse (c.287 - c.212 B.C.), a Greek mathematician, physicist, engineer, inventor, and astronomer, determined the exact value of pi and is also known for his strategic role in ancient war and the development of military techniques. Archimedes put up a good, almost single-handed defense of his homeland. First he invented an engine that threw stones at the enemy, then he used glass to set the Roman ships on fire -- maybe. After he was killed, the Romans had him buried with honor.

Eratosthenes of Cyrene (276 - 194 B.C.) was the second chief librarian at Alexandria. He calculated the circumference of the earth, created latitude and longitude measurements, and made a map of the earth. He was acquainted with Archimedes of Syracuse.

Euclid of Alexandria (fl. 300 B.C.) is the father of geometry (hence, Euclidean geometry) and his "Elements" is still in use.

Thales was a Greek Pre-Socratic philosopher from the Ionian city of Miletus (c. 620 - c. 546 B.C.). He predicted a solar eclipse and was considered one of the 7 ancient Sages. Aristotle considered Thales the founder of natural philosophy. He developed the scientific method, theories to explain why things change, and proposed a basic underlying substance of the world. He started the field of Greek astronomy and may have introduced geometry into Greece from Egypt.

Aristotle (384 - 322 B.C.) was one of the most important western philosophers, a student of Plato and teacher of Alexander the Great. Aristotle's philosophy, logic, science, metaphysics, ethics, politics and system of deductive reasoning have been of inestimable importance ever since. In the Middle Ages, the Church used Aristotle to explain its doctrines.