In biology, Epicurus prefigures the modern doctrine of natural selection. He said the natural forces give rise to different types of organisms, and only those who are able to support themselves and spread can survive.
Theory of Knowledge :
To be liberated from fear and achieve happiness, men must learn to know the world. This knowing activity is first done, according to Epicurus, through sensations.
Epicurean psychology is decidedly materialistic. it claims that sensations are caused by a continuous stream of particles (or "simulacra") that bodies emit and which affect our senses. All sensations are reliable; the error arises only when they are wrongly interpreted by the understanding: the errors of the senses are actually wrong judgments.
There are also two other criteria of truth about the world: the affections, that is to say essentially the pleasure and pain, which are the only two possible states of our body; the "prolepses" Epicurus defines as "anticipatory fears" that are kind of general ideas, preconceptions, linked to a name.
The soul is composed of fine particles distributed throughout the body. The dissolution of the body in death leads to the dissolution of the soul that is physical in nature and can not exist outside the body, and its eventual survival is impossible. Since death means total extinction, it has no meaning for the living or the dead because "when we are, death is not and when death is, we're not. "
Ethics
The Epicurean ethics is based on justice, honesty, friendship, caution or finding the balance between pleasure and pain
The pleasure is the goal towards which all should strive existence, and this can be verified empirically. It is therefore a question for the wise to seek ways to achieve it, so as to live "like a god among men. "
Friendship is also a virtue to be cultivated: it is self-serving because it provides pleasure, but it is devoid of any complacency and dullness. Friendship is also preferable to love, which tends to disturb the peace of mind and daily life, as well as the intellectual pleasures will be to focus on sensual pleasures. Epicurean Hedonism teaches that only through self-control, moderation and detachment that one can achieve peace and tranquility.
Despite its materialism, the Epicurean doctrine believes in freedom of the will : even atoms are free and, on occasion, they can move themselves.
