In the 20th century, important contributions were made by Peter Kivy, Jerrold Levinson, Roger Scruton, and Stephen Davies. However, many musicians, music critics, and other non-philosophers have contributed to the aesthetics of music. In the 19th century, a significant debate arose between Eduard Hanslick, a music critic and musicologist, and composer Richard Wagner. Harry Partch and some other musicologists, such as Kyle Gann, have studied and tried to popularize microtonal music and the usage of alternate musical scales. Also many modern composers like Lamonte Young, Rhys Chatham and Glenn Branca paid much attention to a scale called just intonation.