Aristotle's Poetics:Chapter 15
As for characters, tragic characters should have four qualities. First, they should be good. Second, they should be appropriate to type, for example, a brave woman Aristotle finds inappropriate to type. Third, tragic characters should align with human nature. And fourth, they should be consistently represented; even an inconsistent character should be consistent in that inconsistency.
As with plot, it should appear that characters’ words and actions are both necessary and probable. Thus, dénouements of plots also should come from character. Because tragedy should be interested in better, serious people than comedy, tragic poets should follow the example set by good portrait painters who take liberties with their subjects to improve them, minimizing their less desirable or less flattering aspects. In this way, Homer presented Achilles as good, but still similar to other people, plausible, but still moral.
Chapter 15, Analysis
After his discussion of plot that has occupied several chapters, Aristotle now moves to a discussion of character. In tragedy, he argues, characters should be morally good, appropriate, in line with human nature, and consistent. Aristotle’s distinctions here surely reflect the prejudices of the time, as when he distinguishes between categories of goodness, suggesting that both women and slaves could be “good,” but only within the limits of categories which are inherently inferior or worthless, respectively. He also emphasizes that tragic characters should be presented plausibly, while concluding that because of the seriousness of the tragic genre, their low or unseemly qualities should be downplayed in order to heighten their morality or goodness.