How do we define improvised music? What is the relationship of highly improvised performances to the work they are performances of? How do we decide what are the important parts of an improvised musical work? In Intents and Purposes, Eric Lewis uses a series of case studies to challenge assumptions about what defines a musical work and musical performance, seeking to go beyond philosophical and aesthetic templates from Western classical music to foreground the distinctive practices and aesthetics of jazz. Pushing aside the assumption that composition and improvisation are different (or even opposed) musical practices, Lewis' philosophically informed approach revisits key topics in musical ontology, such as how to define the triangle of composer-performer-listener, and the status of live performances in relation to scores and recordings. Drawing on critical race theory, feminist theory, new musicology, sociology, cognitive science, and genre theory, Lewis opens up new questions about agency in performance, as well as new ways of considering the historical relationships between improvisational practices with roots in different cultural frameworks. By showing how jazz can be both art, idea, and action all at the same time, Lewis offers a new way of seeing any improvised musical performance in a new culturally and aesthetically rich context.