For Aristotle, the plot of a tragedy hinges on action. Aristotle argues that a tragedy is not a reflection of any specific person, but an emulation of the action that comprises life. Aristotle states, "Without action, there cannot be a tragedy." Since action underpins the plot of a tragedy, the plot matters most. The characters play a secondary role. Aristotle views the characters as mere agents or repositories for the action.
In Aristotle's theory, there are two types of tragic action: simple and complex. A simple plot is absent of anagnorisis and peripeteia. Since there is no anagnorisis, there is no dramatic discovery. Minus peripeteia, there is no sudden swing in fortune. On the other hand, a complex plot features a reversal of situation, an important recognition, or both.
For an example of how anagnorisis and peripeteia function in a complex plot, Aristotle discusses the story of Oedipus. Here, anagnorisis and peripeteia coincide—something that Aristotle advocates. Eventually, Oedipus discovers who his real parents are. The recognition results in a drastic change of circumstances. His mother/wife commits suicide, and Oedipus blinds himself before entering exile.
The Oedipus myth highlights Aristotle’s belief that the deepest kind of recognition relates to the recognition of persons. When attached to peripeteia, the discovery of a person’s real role within the action produces emotions like fear and pity, which are, in Aristotle’s estimation, central to tragedy.