Here's an excerpt from a good article on Girard in the Stanford University News:
People are social creatures, and their behavior is based on imitation to a much greater degree than generally supposed. How else to explain why a generation decides at once to pierce their tongues, or why stocks rise and fall? How to explain how a child learns language? Even our desires are not our own; we learn them from others.
"We don't even know what our desire is. We ask other people to tell us our desires," Girard said during a lecture at Stanford's Old Union in February. "We would like our desires to come from our deepest selves, our personal depths—but if it did, it would not be desire. Desire is always for something we feel we lack."
Envy and resentment are the inevitable consequences of this drive toward mimesis. These emotions, in turn, fuel conflict; it occurs whenever two or more "mimetic rivals" want the same thing, which can go to only one. It might be a woman, a presidency or a research grant. Many religious prohibitions are meant to regulate and control such conflict.
"When we describe human relations, we lie," Girard said. "We describe them as normally good, peaceful and so forth, whereas in reality they are competitive, in a war-like fashion."
In literature, such mimetic desire can create comic masterpieces: A Midsummer Night's Dream is a classic he frequently cites. Or it can inspire the novels of Balzac, in which the characters strive to outdo each other in snobbery and imitative social values. Such imitation can even be totally imaginary. Don Quixote wishes to be a knight errant, because he is imitating the heroes in the books he has read.
On a societal level, such conflict seeks a release, and the outlet is a scapegoat. A third party—often an outsider, a foreigner, a woman, someone who is disabled, the king or president—is blamed and demonized for having caused the conflict. Scapegoats are not seen as innocent victims; they are seen as the guilty cause of the disorder. The calls mount for the sacrificial victim, and the mob itself creates a sense of harmony.
See also: René Girard at Microsoft