Why not compare? It's a janus-faced question, a double entendre, its dual meanings depending on emphasis. On the one hand, what are all the reasons why we should not compare? But, on the other hand, why shouldn't we compare, and what are the costs if we do not? Embedded in these questions are more fundamental ones ranging from the epistemological to the methodological. What do we mean by comparison, what effects do our comparisons have, and how do we actually do comparison? By “we” here, I address those involved in intellectual work who face choices on whether or not to engage in comparison; I do not, in this essay, address those who study how and why individuals or human societies compare and with what consequences.