Primer: Comparative History

Kenneth Pomeranz
Map of the world with colors indicating the level of judicial independence in each state's constitution.


Comparison is used in many different ways in world history, both implicitly and explicitly. Explicit types of comparison used by historians today include “entangled comparisons,” which compare pairs in which the similarities might come from interaction with each other; “encompassing comparison,” in which the pair may not interact with each other directly, but are both parts of some larger system that influences them both; and “reciprocal” comparison, in which each term of the comparison is viewed as “deviant” from the perspective of the other. In this essay, historian Kenneth Pomeranz examines comparative history as an approach to world history, and assesses its strengths and weaknesses.


You can’t compare apples and oranges, according to a well-worn cliché. But while apples and oranges are more different than two apples, they are similar enough that you can usefully compare them along any number of axes: nutritional content, ease of cultivation in different places, price at specific times in specific markets, and (more subjectively) taste, or symbolic significance in particular cultural settings. However, apples and airports are truly non-comparable.

Few entities in world history are as closely comparable as two McIntosh apples, but many are at least as close as apples and oranges, or even McIntoshes and Fujis. Moreover, comparison is essential to historical analysis, even when it is only implicit. After all, any claim that “the cold climate of the seventeenth century led to poor harvests and anti-tax revolts” implies a comparison with a real or hypothetical place where the climate was better; non-causal claims, such as “Chinese elites viewed marriage differently from their Mongol conquerors” or “the Khoisan did not have a [modern Western] concept of landed property,” also depend on comparative standards, whether acknowledged or not.

Yet the kinds of comparison that were central to the emerging social sciences of post-Enlightenment Europe are often impossible or misleading for world historians. For one thing, classic comparative strategies, as outlined by John Stuart Mill in the nineteenth century, require that the two things being compared do not influence each other, like the control and subject in a laboratory experiment. While we can sometimes find such examples in world history, especially if they are remote in space and/or time -- for instance, maritime expansion and colonization efforts by fifth-century B.C.E. Athens and seventh-twelfth century C.E. Srivijaya -- such pairs often differ from each other in so many ways that it is hard for the comparison to reveal much about the significance of any one difference. On the other hand, a pair of comparators that allow the historian to start from intriguing similarities – e.g. medieval Christian and Muslim ideas of holy war, or Hindu and Muslim mathematics – often have those similarities precisely because they interacted with each other; this can make it very hard to distinguish between developments in either case that emerged from intrinsic differences and those that are attributable to the effect of one “case” upon the other. Many historians have taken to calling these “entangled comparisons.” Comparisons in this vein among various early modern states and empires are particularly well-developed, but there are many other examples as well. Certain modern phenomena that appeared in many countries at roughly the same time – such as new kinds of family law, mass public education, and tighter drug regulation (including criminalization of some previously legal substances) are also promising subjects for this kind of analysis, with a world history approach revealing influential patterns of competition and imitation that can be overlooked by purely national histories of (for instance) “changes in Japanese divorce law, 1868-1990.” Indeed, such comparisons often change the questions historians ask – comparisons with Europe, for instance, might shift a historian’s focus from “How did the welfare state expand in the mid-20th century U.S.?” to “Why did the U.S. welfare state remain so limited?”

Another kind of non-independent comparison important for world history is what Charles Tilly called the “encompassing comparison.” This involves social formations that may not interact with each other directly, but are both parts of some larger system that influences them both. Nineteenth-century Puerto Rico and the Philippines, for instance, may have had little direct contact, but both were sugar-producing colonies within the Spanish empire, and so influenced by decisions made in Madrid. It is worth noting that the larger system may be designed to influence its different parts in the same way (e.g., a corporation trying to maximize profit at two different plants, or a hierarchical religion seeking converts in two areas) or it may create a division of labor that drives increasing differentiation (e.g., an empire that sees one region as a good source of soldiers and another as a site for commercial development).

Crucially, deciding whether a particular comparison fits one or another of these comparisons is often not a simple, categorical decision. For instance, somebody studying regimes for racial segregation in the twentieth-century U.S. south and South Africa can assume that the architects of these systems knew something about each other; but she or he is likely to be far into the research before being able to decide whether that reciprocal awareness influenced either case enough to make this an “entangled” comparison. In other cases, there will be room for argument about whether two places were indeed part of a common system, or whether that system was strong enough to matter: was there, for instance, enough of a “world economy” in 1550 to really shape the lives of silk weavers in both China and India?

Moreover, comparative questions in world history have often been shaped by an unwarranted assumption, inherited from nineteenth-century social science, that certain historical trajectories abstracted from European history represent the “normal” path of development, so that comparisons with non-European cases become inquiries into why those other places “failed” to parallel European paths. Once stated, this assumption may seem obviously wrong; yet it lies behind any number of frequently asked questions, from “Why didn’t Muslims create modern science?’ to “Why didn’t Russia have a democratic revolution?” to “Why didn’t China have an industrial revolution?”

While exploring such questions has led to some very valuable research, it simultaneously short-circuits other inquiries, which might be even more fruitful. By assuming that people in non-European places were looking for something that was probably not on their minds, such questions tend to warp our understanding of what actual historical actors were trying to achieve when they investigated the natural world, reformed political institutions, or sought greater material benefit for themselves or those they served. That science and industry, in particular, eventually helped Europeans project power across the globe, convincing many people elsewhere that they had to seek what Europeans had in order to survive, has made it even harder to see that non-Europeans were quite likely pursuing different goals before they felt this pressure – and perhaps doing so successfully. At the same time, such an approach distorts European histories, too, making one particular outcome seem all-but inevitable (and consciously sought) when it probably was, like most big historical developments, quite contingent.

Such problems were so entrenched that they led may scholars, particularly in the heyday of postmodernism in the 1980s and 1990s, to argue that comparison was simply impossible and/or dangerous, and would always wind up reinforcing Eurocentric narratives of world history. Others, however, have sought a way out in what they call “balanced” or “reciprocal” comparisons. The idea is simple, at least in theory: to view each term of the comparison as “deviant” from the perspective of the other. Thus, for instance, one needs to ask not only why China’s richest region, the Yangzi Delta, did not industrialize, but also why England did not follow the path of the Yangzi Delta, as it seemed for a while to be doing: becoming a relatively rich, heavily commercialized area with lots of handicraft industries, but no transition to energy-intensive, mechanized production, and increasing difficulty supplying its growing population with certain important products of the land. Or one could compare the fiscal apparatus of the eighteenth-century British Empire with any of its European competitors and note that it was the most successful at raising the funds need for warfare; but from the perspective of those rivals what is striking is how Britain suffered an unparalleled “failure” by losing thirteen colonies to a secessionist tax revolt. One can also try to get away from old narratives of what “should” happen by emphasizing comparisons in which neither comparator has been seen as representing the normative path nor an obvious failure: a comparison of, say, Ottoman and Qing imperial administration, or of female property rights in Safavid Persia and Mughal India.

As these and other examples should make clear, there is no single, perfect, way to use comparison in world history. Each comparison provides a lens that is good for illuminating certain issues, and less good for others. Moreover, historians must be very careful about generalizing beyond the cases they have compared, even if those cases are numerous: even a study of how every army involved in World War II fought is still only a study of that historical moment, not of “warfare” – much less “violence” in general. What is important is to use as many of these lenses as one needs, and to be fully aware of what each one can and cannot do.

Primary Sources

Map of the world with colors indicating the level of judicial independence in each state's constitution.

Comparisons across world history, as historian Kenneth Pomeranz explains, can be productive if done with care. For example, the Constitute Project from the University of Texas-Austin has created a database of world constitutions that includes a feature for comparing various nations' constitutions to look for similarities and differences. The Constitute website lets users pin and export relevant passages for comparison. For example, students can search how constitutions across the world address “freedom of religion.” Students can view side-by-side text comparisons of two constitutions after clicking the “Compare” button for two results, like France and Liberia. The Constitute Project has also created maps like this one that allows for comparisons of how much political independence the judiciary in various nations' constitutions. A slider bar allows users to view change over time. To read more about the Constitute Project and how to use it in a world history classroom, take a look at Sara Collini's review.


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Kenneth Pomeranz, University Professor of History, University of Chicago

How to Cite This Source
Kenneth Pomeranz Primer: Comparative History in World History Commons,