Leucippus (fl. c. 440) was from Miletus in Ionia, home of Thales and Anaximander. He studied with Zeno at Elea, then started teaching in Abdera, an Ionian Greek colony on the southern shore of Thrace (northeastern Greece).

Although only one sentence of his actual teachings remains, Leucippus will always be remembered as the man who invented the ideas of the atom, empty space, and cause-and-effect. Even the soul, he said, is made up of atoms!

It was Leucippus’ student, Democritus (460-370) of Abdera, who would take these ideas and develop them into a full-bodied philosophy. He travelled extensively, wrote books on every subject, and was considered the equal of the great Plato and Aristotle. But he never founded a school, and so his ideas never had quite the same impact as Plato’s and Aristotle’s on later civilization.

Democritus was quite skeptical of sense data, and introduced the idea of secondary qualities: Things like color and sound and taste are more in your mind than in the thing itself. Further, he said that sensations are a matter of atoms falling on the sense organs, and that all the senses are essentially forms of touch.

He also introduced the idea that we identify qualities by convention -- i.e. we call sweet things “sweet,” and that is what leads us to group them together, not some quality of the things themselves. This is called nominalism, from the Latin word for name. This way of thinking doesn't show up again till the late Middle Ages.

The soul or mind, he said, is composed of small, smooth, round atoms, a lot like fire or energy atoms, and can be found throughout the bodies of both humans and animals, and even the rest of the world.

Happiness comes from acquiring knowledge and ultimately wisdom. Sensual pleasure is way too short-lived and fickle to depend on. Instead, the wise man or woman should seek peace of mind (ataraxia) through cheerfulness, moderation, and orderly living. His moral theory is based on the sense of integrity: “A man should feel more shame in doing evil before himself than before all the world.”

Democritus did not believe in gods nor an afterlife. In fact, he formed an atheist organization called the Kakodaimonistai -- “the devils club.” He is sometimes called the laughing philosopher, because he found life much more cheerful without what he considered to be the depressing superstitions of religion.

He took Leucippus’ materialism very seriously, noting that matter can never be created nor destroyed, that there were an infinity of worlds like our own, and that there was no such thing as chance -- only causation. It would be many centuries before these ideas would again become popular.

A little older than Democrates was Protagoras (480-411), also of Abdera. He is the most famous of the group of philosophers known as the sophists. The word comes from the Greek sophistai, which means teachers of wisdom -- i.e. professors. Because some of these professors taught little more than how to win arguments in court, and did so for exorbitant fees, the name has become somewhat derogatory. Sophistry now means argument for argument’s sake, or for the sake of personal gain. But then, it is also the root of the word sophisticated!

Protagoras, although his teaching fees were in fact high, was a serious philosopher. He can be credited with founding the science of grammar, being the first to distinguish the various conjugations of verbs and declensions of nouns. He was also a major contributor to logic and was using the Socratic method (teaching by question and answer) before Socrates.

He was a skeptic, and believed that there were no ultimate truths, that truth is a relative, subjective thing. “Man is the measure of all things,” is his most famous quote, meaning that things are what we say they are.

Applying this skepticism to the gods, he scared the Athenian powers-that-be, and he was ordered to leave Athens. Apparently, he drowned on his way to Sicily.

Into this idea-rich environment would come the three Athenians that would come to dominate philosophy for the next 2000 years: Socrates, Plato, and Aristotle.

© Copyright C. George Boeree 2000