How does the author use foreshadowing in The Playboy of the Western World?

In Act II, foreshadowing is employed when Pegeen tells Christy of the story she read in the newspaper about the young man who was hanged for killing his father. The concept of good versus evil is still present as the diligently structured Shawn attempts to convince Christy to leave for America. Shawn seems to symbolize the voice of reason or conscience in the atmosphere of the village, which has been awed by Christy's appearance.