Epicureanism is a system of philosophy based upon the teachings of Epicurus (c340-c270 BC), founded around 307 BC. Epicurus was an atomic materialist, following in the steps of Democritus. His materialism led him to a general attack on superstition and divine intervention. Following Aristippus—about whom we know very little—Epicurus believed that the greatest good was to seek modest pleasures such as tranquility and freedom from fear through knowledge. Although some equate Epicureanism with hedonism or a form of it (as "hedonism" is commonly understood), professional philosophers of Epicureanism deny that misconception.
For Epicurus, the highest pleasure (tranquility and freedom from fear) was obtained by knowledge, friendship, and living a virtuous and temperate life. He lauded the enjoyment of simple pleasures, by which he meant abstaining from bodily desires, such as sex and appetites, verging on asceticism. He argued that when eating, one should not eat too richly, for it could lead to dissatisfaction later, such as the grim realization that one could not afford such delicacies in the future. Likewise, sex could lead to increased lust and dissatisfaction with the sexual partner. Epicurus did not articulate a broad system of social ethics that has survived.
Some writings by Epicurus have survived. In addition, many scholars consider the epic poem On the Nature of Things by Lucretius to present in one unified work the core arguments and theories in Epicurus's writings.
Epicurean materialism is presented very simply, but anticipates a great deal of later scientific discovery in important respects. Dalton's atomic theory and Darwin's theory of evolution can both be seen in Epicurean writings.
Epicureanism emphasizes the neutrality of gods on earth and that they do not interfere with the world we live in. It also states that gods, matter and souls are all made from the same thing (atoms). Souls are made from atoms, and gods possess souls, but their souls adhere to the bodies without escaping. In the case of humans we do have the same kind of souls, but the forces between our atoms do not possess the fortitude to hold the soul forever. The Epicureans also used the atomist theories of Democritus and Leucippus to describe that man has free will. They held that all thoughts are merely atoms swerving randomly. This explanation was used to relieve the ever-curious minds of people who wondered anxiously about their role in the universe.
Some would interpret this doctrine of the gods as really a disguised atheism. Fully aware of the fate of Socrates when brought up on a charge of impiety, Epicurus avoided expressing an overt atheism. Instead, he reduced the gods to mere physical beings, shut them up in a distant part of the cosmos, without a thought or care for what happens to mankind. This renders his philosophy atheistic on the practical level, but avoids the charge of atheism on the theoretical level.
Epicureanism is probably the first philosophical school which introduced the social contract, in that the laws established by this school of thought are based on mutual agreement, not divine decree.
Epicurus' school, called "The Garden ," seems to have been a moderately ascetic community which rejected the political limelight of Athenian philosophy. They were fairly cosmopolitan by Athenian standards, including women and slaves, and were probably vegetarians.
Epicureanism was originally a challenge to Platonism, though later it became the main opponent of Stoicism. Epicurus and his followers shunned politics and as such it was never a major philosophy. After the death of Epicurus, its main proponent was the Roman Lucretius. It had all but died out by the end of the Roman Empire, and was again resurrected by the atomist Pierre Gassendi during the Enlightenment.
Thomas Jefferson refered to himself as an Epicurean.