 In contrast to Plato’s well-known disparagement of theatrical practices (in Republic, Books III and X, for example), Aristotle held in the Poetics that tragedy in theatrical performance, perhaps tragedy in particular, could have therapeutic value. Whether what he meant was a kind of cognitive therapy or a form of psychological therapy is a question that has vexed scholars to this day; and it turns on how one understands two terms: katharsis and mimesis (Schaper 1968; Golden 1973; Diamond 1989; Lear 1992; Woodruff 1992).  This dispute is interesting first because it reflects the fact that theater has been a topic of philosophical dispute, investigation, use, or illustration since near the beginning of Western philosophy in the ancient Greek world. Second, its terms continue to have influence over current disputes within theater studies and performance theories (Puchner 2013). Finally, and primarily, it links descriptive metaphysical issues, such as what theater is by its nature, with normative issues, such as the value of theatrical performances within a culture. Several recent philosophical works emphasizing descriptive issues have attempted to understand just what is going on in theatrical performances and other performance arts (Saltz 1991a; Thom 1992; Osipovich 2006; Hamilton 2007; D. Davies 2011). This entry will focus largely on topics that are similar to or are themselves the issues examined in these works.