This paper responds to the 'existence theory' proposed by Baert, Morgan and Ushiyama. It considers their proposals in light of two main thematics: the general account of human existence, and the more empirical sociology of existential milestones. Both elements are appraised in light of existentialist philosophy and earlier attempts at 'existentialist sociology'. It is suggested that the authors engage with generational theory, and also give an account of the commodification of significant life-stages by the milestones culture industry. [ABSTRACT FROM AUTHOR]