Our histories of culture have long been articulated by stylistic "revolutions," separated by periods of consolidation and stasis. Narratives like these make implicit claims about the varying pace of cultural change, and it's very tempting to test those claims mathematically. But how should we measure the pace of change? That turns out to be a fascinating question, because mathematical formulations of the problem are deeply bound up with beliefs about the differences or similarities that count as culturally meaningful. I'll look at solutions proposed by several different groups of researchers, studying music and fiction, as well as economic life, and using supervised or unsupervised learning algorithms, as well as simple distance metrics. Although I have opinions to express, the question mark at the end of my title is genuine, and I hope to stop often for discussion.