In this article I address some questions concerning the emerging conjunction of musical research on improvisation and work in the ‘posthumanities’, in particular the theoretical results of the ‘ontological turn’ in the humanities. Engaging with the work of the composer John Cage, and George E. Lewis’s framing of Cage’s performative indeterminacy as a ‘Eurological’ practice that excludes ‘Afrological’ jazz improvisation, I examine how critical discourse on Cage and his conception of sound is relevant to the improvisation-posthumanities conjunction. After discussing some (...) criticisms of ontological and materialist approaches to sound, I consider the Actor-Network Theory (ANT) of Bruno Latour, posed as offering an alternative to these approaches. Following an examination of some limitations to ANT based around the themes of critique and abstraction, I draw from the work of Gilles Deleuze and Georgina Born to suggest that work on improvisation and the posthumanities may be fruitful, but must be part of a pluralistic mode of inquiry that does not reject critique and abstraction, as some work in the posthumanities has done. (shrink)