Logistics as a historical force

The constraint of what people can do often plays a large role in what they actually do. The study of logistics is the study of constraints. Logistics has to do with the intersection of resource, activity, space, and time. A plan is an orchestrated sequence of activities over space and time, provisioned by appropriate resources as needed. Historical actors orchestrate their actions in terms of extended plans -- which means that they pay extensive and detailed attention to logistics. And historians need to do so as well.

One common species of historical question is, "Why did the agent do such-and-so?" Why did Napoleon's invasion of Russia fail so formidably? Why did Charles Martel infeudate his central power? Why did Napoleon III fail to respond with effective military action to the Prussian invasion of France in 1870? Why did Alexander the Great avoid the direct route through the Thar Desert? Analysis of constraints is often critical to being able to answer these questions.

In each case logistics comes into the explanation at a more or less evident level. The historian's first impulse is to ask the question of purpose and plan: what was the agent intending to accomplish? How was the observed course of action an intelligent solution? When there is no apparent rational explanation, the historian may then retreat to "miscalculation" or error. But choice always involves an assessment of constraints, and this is where logistics come in. What looks like error may actually be a rational adjustment to constraint. The point here is that logistical obstacles or difficulties are often a hidden factor on the agent's choice -- and these factors may ultimately dictate a strategy or plan that looks otherwise irrational. And historians sometimes give these constraints too little attention.

Logistics is relevant to a wide range of complex social action. Take, for example, the difficult chess match involving two NBA coaches during a forty-eight minute basketball game. Each coach makes a series of substitutions throughout the game. Some are dictated by "match-up" -- getting the right defensive players on the floor given the current offensive set of the opponent. But some of the choices may appear dumb in the eyes of the duffer fan -- "why did he take Iverson out now exactly when he's on a run?" And often, I think, the answer is logistics. Each player has a finite amount of energy and spring in his legs. And each has a finite allotment of personal fouls to give. So the coach's task, in part, is to manage substitutions in such a way as to make maximum use of his star players over the full forty-eight minutes. It doesn't help much to have built up a 10 point lead with four minutes to go if the top scorer and rebounder are out of gas. And this is a logistics problem.

A more serious example -- what about Alexander the Great in his celebrated and brilliant conquest of the world? Why did Alexander make the sometimes puzzling strategic and tactical decisions he made through his campaigns? The answer, according to Donald Engels, is logistics (Alexander the Great and the Logistics of the Macedonian Army). As Engels puts the point, "When the climate, human geography, physical geography, available methods of transport, and agricultural calendar of a given region are known, one can often determine what Alexander’s next move will be." Engels provides careful calculations of fodder, the number of horses needed to provision and feed the Macedonian army, and the rate of speed attainable by such an army -- and finds that Alexander's choices were generally well suited to the logistical constraints and his larger strategic goals.

The study of transportation technology as a historical factor certainly falls within the general topic of "logistics as a historical cause." (See Transportation for more extensive treatment of this topic.) Transport systems like rail networks provide specific opportunities and constraints on choice, and intelligent strategists make every effort to understand these well. So, correspondingly, the historian needs to do so as well if he/she is to explain the choices taken. (If you want to invade Burgundy from Frankfurt in 1860, don't plan to move your army by train. And if you plan to invade Russia by rail in 1910, be prepared for the change of gauge at the frontier.)

Military historians generally pay careful attention to logistical factors as they attempt to understand military choices and strategies. But analysis of resource-time-space-activity factors probably receive less attention in other parts of historical and social research than they should.

Where does the concept of logistics fit into the concepts we use to analyze historical processes and actions? Some historians might say that it is a minor and peripheral analytical tool. But seen properly, I would say that the notion of logistics is actually a key concept that ties together the complex and extended historical actions that we want to be able to explain. It is thus a central concept within an adequate historical ontology.

This point is relevant to historical research at two levels. First, it emphasizes the importance of incorporating a careful analysis of the agent's beliefs about the constraints he/she faces into the analysis of the eventual plans and choices. And second, at a more systemic level, it suggests that study of major logistical systems --transport, water management, urban infrastructure, the food system -- may have substantial value as a source of hypotheses about large historical causes. These systems structure the opportunities and constraints that face rulers and ordinary people alike, and they have the capacity of pushing development in one direction or another in a particular historical conjuncture. They therefore function as historical causes.

M I Finley on the dynamics of the Roman Empire

One of the books I found influential in graduate school in philosophy was M. I. Finley's The Ancient Economy, which appeared in 1973. Finley's book sought to explain important parts of the Roman world by piecing together the best knowledge available about the economic relations that defined its socioeconomic foundation. And the book proposes to consider economic history in a new way:

There is a fundamental question of method. The economic language and concepts we are all familiar with, even the laymen among us, the "principles", whether they are Alfred Marshall's or Paul Samuelson's, the models we employ, tend to draw us into a false account. For example, wage rates and interest rates in the Greek and Roman worlds were both fairly stable locally over long periods ... , so that to speak of a "labour market" or a "money market" is immediately to falsify the situation. (23)

Finley's point here is that we need to conceptualize the ancient economy in terms that are not drawn from current understandings of capitalist market economies; these economic concepts do not adequately capture the socioeconomic realities of the ancient world. Finley argues that the concepts and categories of modern market society fit the socioeconomic realities of the ancient world very poorly. (In this his approach resembles that of Karl Polanyi, who was indeed an important influence on Finley.) One thing that is interesting in this approach is that it is neither neo-classical nor Marxist.

Finley addresses a question that is particularly important in the human sciences, the problem of how to handle heterogeneity within a social whole.

Is it legitimate, then, to speak of the "ancient economy"? Must it not be broken down by further eliminations...? Walbank, following in the steps of Rostovtzeff, has recently called the Empire of the first century "a single economic unit", one that was "knit together by the intensive exchange of all types of primary commodities and manufactured articles, including the four fundamental articles of trade -- grain, wine, oil, and slaves". (33)

This is to take a regionalist perspective on defining an economic region: we emphasize not homogeneity and self-similarity, but rather systemic interconnections among the parts. But to conclude a set of places fall in a single "economic region", Finley argues something else is needed:

To be meaningful, "world market", "a single economic unit" must embrace something considerably more than the exchange of some goods over long distances.... One must show the existence of interlocking behaviour and responses over wide areas. (34)

So what distinguishes the "interlocking behaviour and responses" of the ancient world? Finley's view is that the dominant ethos of the ancient world is not one of producing for accumulation, but rather maintaining status and the social order. And these imply a society sharply divided between haves and have-nots -- nobility and the poor. Finley takes issue with the "individualist" view (43) as applied to the ancient world, according to which each person is equally able to strive for success based on his/her own merits. What he calls the prevailing ideology is one of the moral legitimacy of inequalities, social and economic. Hierarchy is normal in the order of things, in the world view of the ancients. Even the heterodox insistence in the modern world on the concepts of class and exploitation, according to Finley, have little grip on the ideologies and values of the ancients. The idea of the working class fails to illuminate social realities of the ancient world because it necessarily conflates free and bonded labor (49). (Finley quotes Lukács on this point: "status-consciousness ... masks class consciousness" (50).)

There are only a few "structural" factors in Finley's account of the ancient economy. The structure and social reality of property is one -- the ownership of land and labor in the form of estates, small farms, and slaves conditions much of productive activity. Another is the availability of roads and water transport. Production largely took place within one day's transport from the consumers of that production. "Towns could not safely outgrow the food production of their own immediate hinterlands unless they had direct access to waterways" (126). Finley summarizes the "balance of payments" through which towns and cities supported themselves under four categories: local agricultural production, the availability of special resources like silver; the availability of trade and tourism; and income from land ownership and empire (139).

It is interesting to compare Finley's intellectual style in The Ancient Economy with his writing in an earlier book, Aspects of Antiquity: Discoveries and Controversies, published in 1968. Here Finley takes up many topics in a broadly chronological order. And he is more declaratory in his analysis of the broad dynamics of social development. One chapter in particular is an interesting counterpoint to The Ancient Economy, "Manpower and the Fall of Rome". The time is the late fourth century, and the circumstances are the impending military collapse of Rome. Finley estimates the population of the empire at about 60 million, noting that it is impossible to provide anything like a precise estimate. This population supported an army of about 300,000 in the time of Marcus Aurelius (d. 180), and rising to perhaps 600,000 in in the coming century. But increasingly this army was incapable of protecting the Empire from the encroaching Germanic tribes.

Roman armies still fought well most of the time. In any straight fight they could, and they usually did, defeat superior numbers of Germans, because they were better trained, better equipped, better led. What they could not do was cope indefinitely with this kind of enemy [migratory tribes]. (150)

Finley offers what is essentially a demographic and technological explanation for Rome's failure to defend itself: it simply could not sustain the substantially greater manpower needs that the Germanic warfare required, given the nature of the agrarian economy.

With the stabilization of the empire and the establishment of the pax Romana under Augustus, a sort of social equilibrium was created. Most of the population, free or unfree, produced just enough for themselves to exist on, at a minimum standard of living, and enough to maintain a very rich and high-living aristocracy and urban upper class, the courts with its palace and administrative staffs, and the modest army of some 300,000. Any change in any of the elements making up the equilibrium -- for example, an increase in the army or other non-producing sectors of the population, or an increase in the bite taken out of the producers through increased rents and taxes -- had to be balanced elsewhere if the equilibrium were to be maintained. Otherwise something was bound to break. (151)

And this leads to a general causal conclusion:

In the later Roman Empire manpower was part of an interrelated complex of social conditions, which, together with the barbarian invasions, brought an end to the empire in the west.... It was the inflexible institutional underpinning, in the end, which failed: it could not support the perpetual strains of an empire of such magnitude within a hostile world. (152,153)

This is perhaps a sober reminder of the limits of imperial power for the contemporary world.

(For readers interested in the ancient world, here is a related post on agrarian history in Weber's scholarship. And here is a video interview of M. I. Finley that touches on the key influences in his development as an historian.)

Technological inevitability?

Some historians imagine that new technologies force other kinds of social changes, or even that a given technology creates a more or less inevitable process of development in society. Marx is sometimes thought to offer such a theory: "the forces of production create changes in the relations of production." This view is referred to as technological determinism.

The logic underlying this interpretation of history goes something like this: a new technology creates a set of reasonably accessible new possibilities for achieving new forms of value: new products, more productive farming techniques, or new ways of satisfying common human needs. Once the technology exists, agents or organizations in society will recognize those new opportunities and will attempt to take advantage of them by investing in the technology and developing it more fully. Some of these attempts will fail, but others will succeed. So over time, the inherent potential of the technology will be realized; the technology will be fully exploited and utilized. And, often enough, the technology will both require and force a new set of social institutions to permit its full utilization; here again, agents will recognize opportunities for gain in the creation of social innovations, and will work towards implementing these social changes.

This view of history doesn't stand up to scrutiny, however. There are many examples of technologies that failed to come to full development (the water mill in the ancient world and the Betamax in the contemporary world). There is nothing inevitable about the way in which a technology will develop -- imposed, perhaps, by the underlying scientific realities of the technology; and there are numerous illustrations of a more complex back-and-forth between social conditions and the development of a technology. So technological determinism is not a credible historical theory.

For more credible interpretations of the relationships that exist between technology and historical change, we can consider the work of some very gifted historians.

An example of such a study of social-technological development is offered in William Cronon's fascinating history of Chicago, Nature's Metropolis: Chicago and the Great West. Cronon tracks the effects that the extension of the rail network had on the city of Chicago and the region surrounding it into Illinois, Wisconsin, Iowa, and Michigan. Cheap, reliable rail transport between Chicago and New York created large markets for grain and beef. This gave incentives to farmers and traders to organize their activities in such a way as to take advantage of the profits newly available in these markets. But Cronon points out that transportation by railroad of large volumes of grain required a reorganization of the market institutions that were used: the establishment of grain elevators along the rail lines, the establishment of a gradiing system for qualities of grain being sold by farmers to elevator operators, and the establishment of a futures market for grain and beef. And he observes that entrepreneurs recognized the gains that could be achieved by developing these institutions and carried them forward. So the technology "needed" a reorganization of the market for grain; entrepreneurs recognized an opportunity for profits in achieving this reorganization; and the necessary social innovations occurred.

This makes the business and ecological transformation of Chicago's region sound inevitable, given the extension of the rail system into Chicago. However, contingency comes into this story from numerous angles. The build-out of the American rail network was itself a highly contingent matter; the major east-west lines could have been placed in numerous alternative routes, including a network that would have made St. Louis the major rail nexus in the center of the country. Second, the policy environment within which the American rail network developed represented another major form of contingency. As Frank Dobbin demonstrates, England, France, and the United States possessed very different "policy cultures", and these differences created substantial differences in the way in which the basic technology of the railroad was exploited in the three national settings (Forging Industrial Policy: The United States, Britain, and France in the Railway Age). And third, there are multiple social solutions that would work roughly as well as the institutions of the grain elevator and the futures market for solving the business challenges of mass transport and marketing of grain. The solutions that emerged in Chicago were therefore contingent as well.

Cronon and Dobbin illustrate several different aspects of technological causes and technological contingency in their accounts of the railroad. But for an author who takes the contingency of technology change even more seriously, see Thomas Hughes' history of electric power in Networks of Power: Electrification in Western Society, 1880-1930. Hughes demonstrates that the basic scientific discoveries associated with the technology of electric power had multiple possible realizations in machines and devices, and that the social constraints that existed in different national scientific-technical-political cultures led to substantial and fundamental differences in the development of the technology. The celebrated contest between alternating and direct current as the foundation of power transmission is one such example, but there are hundreds of other examples of choice that can be uncovered in the history of this fundamental modern technology. And, most pointedly, Hughes illustrates the way in which different municipal political requirements in England, France, and the United States led to substantially different implementations of the power stations and transmission networks in the three national contexts.

These examples illustrate several fundamental points about the role of technology in historical change. A new technology creates new opportunities for power, wealth, efficiency, or productivity; so a new technology can be a powerful force for social and economic change. Governments, farmers, entrepreneurs, and corporations have a complicated set of incentives that lead them to consider developing the new technology. So new technologies certainly function as effective historical causes. The development of a technology, however, introduces deeply significant elements of contingency. The term "path-dependency" is an accurate description of the process of the development of a major technology. Third, a technology is both influenced by social factors in the society in which it is developed, and also influences the future direction of social factors in the society. Thus technology is both cause and effect of social change. And, finally, it is evident that the study of the history of technology is inevitably a study of social processes and institutions as much as it is a study of machines and inventions. Technology is a social product, shaped by the needs and powers that exist in society as much as it is shaped by scientific imagination and discovery.

Is industrial agriculture sustainable?

The world's food system depends largely on a farming system with post-green-revolution techniques: new seed varieties, substantial use of chemical fertilizers and pesticides, large-scale irrigation, machine-based cultivation, production for large markets, and separation of production from consumption by long distances. This system shows the highest productivity the world has ever seen, whether measured in terms of labor, land, or cost. And the system does a fairly good job of producing enough food for the world's 6 billion people.

But is this system sustainable?

Several large issues arise. First, the system is energy-intensive, so it poses significant demands on the petroleum economy. The use of petroleum and energy pervades the process: fuel for cultivation and transport, energy and inputs into the production of chemical fertilizers and pesticides, energy consumed in irrigation. So a part of the sustainability question has to do with the energy challenge the globe faces.

Second, industrial agriculture has massive environmental effects. Fertilizer and animal waste runoffs lead to groundwater and river pollution (extending into the Gulf of Mexico). Degradation and loss of topsoil is another large and longterm environmental effect with serious consequences for future agricultural productivity. And methane produced by large-scale cattle- and swine-rearing represents a measurable component of global warming. So the environmental effects of industrial agriculture are very large--once again raising the question of global sustainability.

Finally, industrial agriculture, and the integrated global commodity markets from which this system is inseparable, have large and destructive consequences for traditional agriculture and the communities built around traditional farming. The effect of NAFTA and the export of US corn to Mexico has been massive in its disruption of maize-based culture and communities in Mexico.

Three questions are central. First, is this system sustainable in the narrow sense, or will it collapse of its own burden of soil, water, and air pollution in the next 50 years? Second, is it a potential part of a larger sustainable global system of production and consumption from an environmental point of view? Or does global sustainability require radical change in agriculture? And finally, are there feasible alternative systems that would be less environmentally harmful, more sustainable, and less disruptive of agrarian communities? Are these alternatives scaleable to the needs of mass societies, large cities, and a global population of 6-8 billion? Can alternative systems achieve the productivity needed to feed the world's population?

Environmentalists, global justice activists, and food activists have argued that there are alternatives. The Fair Trade movement is trying to get first-world consumers to favor fair-trade-certified products in their consumption--giving greater security and income to third-world farmers. Organic farming advocates argue that a system of smaller farms, organic fertilizers, innovative pest control, and farming techniques more suited to the local environment would have a smaller environmental footprint. "Local food" activists support the idea of shifting consumption towards products that can be grown locally--thus reducing transport and refrigeration and giving more of a market for small farmers.

So there are alternatives in technique and policy that could result in different farm characteristics that are more favorable from the points of view of justice, sustainability, and community. The hard question is whether these alternatives could be scaled to the volume needed to feed a mass population. And this is a question that demands careful scientific analysis.

(An excellent current critique of industrial agriculture is Michael Pollan's The Omnivore's Dilemma: A Natural History of Four Meals.)

The Morandi Bridge collapse and regulatory capture

Lower image: Eugenio Ceroni and Luca Cozzi, Ponte Morandi - Autopsia di una strage

A recurring topic in Understanding Society is the question of the organizational causes that lie in the background of major accidents and technological disasters. One such disaster is the catastrophic collapse of the Morandi Bridge in Genoa in August, 2018, which resulted in the deaths of 43 people. Was this a technological failure, a design failure -- or importantly a failure in which private and public organizational features led to the disaster?

A major story in the New York Times on March 5, 2019 (link) makes it clear that social and organizational causes were central to this horrendous failure. (What could be more terrifying than having the highway bridge under your vehicle collapse to the earth 150 feet beneath you?) In this case it is evident from the Times coverage that a major cause of the disaster was the relationship between Autostrade per l'Italia, the private company that manages the bridge and derives enormous profit from it, and the regulatory ministries responsible for regulating and supervising safe operations of highways and bridges.

In a sign of the arrogance of wealth and power involved in the relationship, the Benetton family threatened a multimillion dollar lawsuit against the economist Marco Ponti who had served on an expert panel advising the government and had made strong statements about the one-sided relationship that existed. The threat was not acted upon, but the abuse of power is clear.

This appears to be a textbook case of "regulatory capture", a situation in which the private owners of a risky enterprise or activity use their economic power to influence or intimidate the government regulatory agencies that nominally oversee their activities. "Autostrade reaped huge profits and acquired so much power that the state became a largely passive regulatory" (NYT March 5, 2019). Moreover, independent governmental oversight was crippled by the fact that "the company effectively regulated itself-- because Autostrade's parent company owned the inspection company responsible for safety checks on the Morandi Bridge" (NYT). The Times quotes Carlo Scarpa, and economics professor at the University of Brescia:

Any investor would have been worried about bidding. The Benettons, though, knew the system and they understood that the Ministry of Infrastructure and Transport, which was supposed to supervise the whole thing, was weak. They were able to calculate the weight the company would have in the political arena. (NYT March 5, 2019)

And this seems to have worked out as the family expected:

Autostrade became a political powerhouse, acquiring clout that the Ministry of Infrastructure and Transport, perpetually underfunded and employing a small fraction of the staff, could not match. (NYT March 5, 2019)

The story notes that the private company made a great deal of money from this contract, but that the state also benefited financially. "Autostrade has poured billions of euros into state coffers, paying nearly 600 million euros a year in corporate taxes, V.A.T. and license fees."

The story also surfaces other social factors that played a role in the disaster, including opposition by Genoa residents to the construction involved in creating a potential bypass to the bridge.

Here is what the Times story has to say about the inspections that occurred:

Beyond fixing blame for the bridge collapse, a central question of the Morandi tragedy is what happened to safety inspections. The answer is that the inspectors worked for Autostrade more than for the state. For decades, Spea Engineering, a Milan-based company, has performed inspections on the bridge. If nominally independent, Spea is owned by Autostrade's parent company, Atlantia, and Autostrade is also Spea's largest customer. Spea's offices in Rome and elsewhere are housed inside Autostrade. One former bridge design engineer for Spea, Giulio Rambelli, described Autostrade's control over Spea as "absolute," (NYT March 5, 2019)

The story notes that this relationship raises the possibility of conflicts of interest that are prohibited in other countries. The story quotes Professor Giuliano Fonderico: "All this suggests a system failure."

The failure appears to be first and foremost a failure of the state to fulfill its obligations of regulation and oversight of dangerous activities. By ceding any real and effective system of safety inspection to the business firms who are benefitting from the operations of the bridge, the state has essentially given up its responsibility of ensuring the safety of the public.

It is also worth underlining the point made in the article about the huge mismatch that exists between the capacities of the business firms in question and the agencies nominally charged to regulate and oversee them. This is a system-level failure at a higher level, since it highlights the fact of the power imbalance that almost always exists between large corporate wealth and the government agencies charged to oversee their activities.

Here is an editorial from the Guardian that makes some similar points; link. There don't appear to be book-length treatments of the Morandi Bridge disaster available in English. Here is an Italian book on the subject by Eugenio Ceroni and Luca Cozzi, Ponte Morandi - Autopsia di una strage: I motivi tecnici, le colpe, gli errori. Quel che si poteva fare e non si è fatto (Italian Edition), which appears to be a technical civil-engineering analysis of the collapse. The Kindle translate option using Bing is helpful for non-Italian readers to get the thrust of this short book. In the engineering analysis inadequate inspection and incomplete maintenance remediation are key factors in the collapse.

G. William Skinner

G. William Skinner was one of the most innovative social scientists to have turned his attention to China in the past thirty years. Bill passed away on October 25, 2008, but his influence on how we think about China will survive him for a long, long time. (See this list of Skinner's publications to get an impression of the depth and scope of his contributions.) Bill was a generous and open scholar, and many scholars working in the field today owe him a permanent debt of gratitude for his advice and support in the past several decades. (See this Chinese obituary documenting Skinner's significance for Chinese scholars.)

Bill was a particularly fertile thinker when it came to using analytical and spatial models to explicate social reality in China (and occasionally Japan or France). (His work on Japanese demographic behavior is a great example; he devised an analytical framework for permitting inferences about family planning choices within Japanese peasant families demonstrating very specific preferences about birth order depending on the age and wealth of the parents. See "Conjugal Power in Tokugawa Japanese Families" in Sex and Gender Hierarchies, edited by B. D. Miller (Cambridge University Press, 1989).) Skinner was insistent that social data need to be analyzed in spatial terms; he believed that many social patterns will be best understood when they are placed in their geographical context. And the reason for this is straightforward: human social activity itself is structured in space, through transport systems, habitation patterns, the circuits of merchants and necromancers, and the waterways that integrate social and economic systems in pre-modern societies. He also believed that identifying the right level of geographical aggregation is an important and substantive task; for example, he argued against the idea of making economic comparisons across provinces in China, on the basis that provincial boundaries emerged as a result of a series of administrative accidents rather than defining "natural" boundaries of human activity.

Several ideas that Skinner developed in detail have had particular impact. His analysis of the marketing systems of Sichuan using the conceptual tools of central place theory was very influential when it appeared in three parts in theJournal of Asian Studies (1964-65) (part I, part II, part III). This analysis was illustrative in several key ways. It gave an important empirical instance for the abstract geometry of cental place theory -- the nested hexagons that represent the optimal spatial distribution of towns, villages, and cities. But more important, the analysis creates an important shift of focus from the village to the larger social systems of interchange within which villages are located -- the patterns of social intercourse that are associated with periodic markets, the flow of ideas associated with the circuits of martial arts specialists, and the likelihood of intersections between economic, cultural, and political processes rooted in the geometry of social exchange.



SOURCE: Skinner, G. William. 1964-65. Marketing and Social Structure in Rural China. Journal of Asian Studies 24 (1-3), pp. 22-23

A second highly influential idea also falls within the intellectual precincts of economic geography. Skinner offered an analysis of the economic geography of late imperial China in terms of a set of eight (or nine) macroregions: physiographically bounded regions consisting of core and periphery, regarding which the bulk of trade occurs internally rather than externally. Skinner argues in this body of research that it is analytically faulty to treat China as a single national market system in this period of time; rather, economic activity was largely confined within the separate macroregions. He used empirical measures to establish the distinctions between core and periphery, as well as to draw boundaries between adjacent macroregions. As he points out, the economic geography of traditional Chinese economy was largely governed by transport cost, and this meant that China's river systems largely defined the shape and scope of intra- and inter-regional markets. And he demonstrated how human activity was structured by the patterns of social interaction defined by these macroregions -- for example, the transfer of soil fertility from periphery to core through the gathering of fuel wood in the periphery, which then is transferred to core soils after burning.

SOURCE: Skinner, G. William. 1977. Regional Urbanization in Nineteenth-Century China. In The City in Late Imperial China, edited by G. W. Skinner. Stanford: Stanford University Press, p. 215.

Another critical contribution that Skinner provided, through his own contribution to the highly important City in Late Imperial China volume (link), is the idea of a hierarchy of urban systems. Skinner argued that there was an orderly hierarchy of places, ranging from higher-level cities through lower-level cities, market towns, and villages. He distinguishes between two types of hierarchy: administrative-bureaucratic hierarchy of places and the economic-commercial hierarchy of places. These two systems create different characteristics and functions for the cities that fall within them. This body of formal analytical ideas is borrowed from urban geographers such as Walter Crystaller and Johann Heinrich von Thünen. Skinner's genius was to recognize that these analytical approaches provided a lens through which to make sense of Chinese social activity across space and time that other approaches do not. In particular, Bill demonstrated the utility of a spatial and regional approach in contrast to both purely statistical analyses of China's economy and village-level ethnographic studies that ignored the urban and town relationships within which village society was situated.

SOURCE: Skinner, G. William, ed. 1977. The City in Late Imperial China, Studies in Chinese society. Stanford, Calif.: Stanford University Press, p. 289

SOURCE: Skinner, G. William, ed. 1977. The City in Late Imperial China, Studies in Chinese society. Stanford, Calif.: Stanford University Press, p. 294

A central and crucial aspect of Skinner's thinking is spatial; he was vastly ahead of the GIS revolution in the social sciences, in that he consistently tried to analyze China's social, economic, and cultural data in terms of the spatial patterns that it displayed decades before the corresponding desktop computation capability was available. I visited his research laboratory at UC-Davis sometime early in the 1990s, and was struck by a couple of vignettes. When I arrived he was poring over a Chinese census atlas in eight gradations with a magnifying glass; he was laboriously coding counties by the color representing a range of social estimates. And when he brought me to examine a wall-sized map he had produced mapping sex ratios across part of southeastern China, he was interested in pointing out how the values of sex ratios corresponded to the core-periphery framework mentioned above. I pointed out a small, bounded region in southwest China that appeared to be anomalous, in that it represented an island of normal sex ratios in a sea of high male-female ratios. He instantly replied: that's an ethnic minority population that doesn't discriminate against girls. Culture and space!

Another of Skinner's crucial contributions to the China field -- and to historical social science more generally -- was his devotion to the project of creating a public database of historical Chinese social, economic, and cultural data at the county level. This effort contributed to the eventual formation of the China Historical Geographical Information System (CHGIS). What is striking about this work is that it was begun at a period in which the desktop computing tools that would permit easy and flexible use of the data -- in producing historical statistical maps, for example -- did not yet exist.

G. William Skinner provided a genuinely unique contribution to our understanding of the social realities of China. His contributions were innovative in the deepest sense possible: he brought an appropriate set of tools to each topic of investigation he addressed, without presuming that existing analytical techniques would do the job.

Cities

Cities are fascinating -- individually and in the aggregate. Are there distinct types of cities? Are there specific social processes that are associated with the development of cities in different countries or civilizations? Are there regularities across cities in different settings?

Two authors I've particularly admired in their analysis of cities -- at very different historical and spatial scales -- are G. William Skinner and Saskia Sassen. Skinner's historical treatment of Chinese cities is innovative and original (The City in Late Imperial China and The Chinese City Between Two Worlds; both edited books, the first including two major essays by Skinner). And Sassen's treatment of the global city in the twenty-first century sets the standard for bold new thinking about the social processes that are transforming the contemporary world (The Global City: New York, London, Tokyo and Global Networks, Linked Cities).

Skinner is fascinated with the spatial arrangement of cities across historical China, and the hierarchies of economic, political, and social relationships that exist among them. And he is interested in the extended historical processes through which great and small cities took their shape. A crucial discovery -- regions rather than nations are the appropriate unit of analysis. "Fairly early in my research on Chinese cities it became clear that in late imperial times they formed not a single integrated urban system but several regional systems, each only tenuously connected with its neighbors" (CLIC 211). Transport systems were the primary integrative mechanism that Skinner identifies, and in China, transport was largely defined by navigable river systems.

In "Regional Urbanization in Nineteenth-Century China" Skinner is interested in explaining regional differences in urbanization rates across macroregions, and he isolates a handful of causal factors: population density of the region, division of labor, application of technology, commercialization/interregional trade, extraregional trade, administration. He finds that these variables do a pretty good job of explaining the urbanization rates for the eight macroregions he identifies (CLIC 235). A second interesting finding has to do with rank-size relationships of cities by region for late imperial China. Referring to a statistical regularity postulated by G. K. Zipf, according to which the rank-size distribution for a country or region is expected to be approximately linear when plotted with double-log scales, Skinner examines the rank-size distribution for the eight macroregions. And in a panel of graphs for the eight regions (CLIC 238-39) he demonstrates that the distributions conform remarkably well to this prediction, with a few interesting outliers (Canton, Kweiyang, Middle and Upper Yangtze regions).

Skinner's other essay in the volume is just as interesting, "Cities and the Hierarchy of Local Systems." In this paper Skinner focuses on the hierarchies within which Chinese cities fall -- one having to do with imperial administration and the other having to do with economic interaction. These hierarchies are both determined by the nature of the social interactions (and social functions) that are focused on various cities. And they are distinct. For the economic hierarchy of cities and towns Skinner's starting point is central place theory; according to this approach, cities and towns are ranked according to the volume of products and services that they provide and the nature of trade that exists between the city and other places in the hinterlands. The central analytical ideas here are "the demand threshold of the supplier and the range of a good" (277). These concepts work out, with appropriate simplifying assumptions, into a hexagonal array of places, containing nested hexagons of lesser places in a descending sequence. Skinner analyzes the location (spatial and hierarchy) of cities and towns in the Upper Yangzi region and finds that the analytical assumptions are born out.

The administrative hierarchy of cities is defined by different criteria -- location within the imperial system and a characteristic set of administrative functions. Skinner lays out this hierarchical system and then classifies cities and towns accordingly; and he finds, once again, a set of highly interesting regularities. In this case he finds that the distribution of administrative functions across cities and towns reflects intelligent administrative design. "These findings effectively dispose of the notion that cities in imperial China were but microcosms of empire, more or less uniform creations of an omnipotent state. Rather, they give evidence of skilled husbanding and deployment of the limited bureaucratic power that a premodern court could effectively control" (345).

Now let's swing forward a century and look quickly at Saskia Sassen's analysis of global cities New York, London, and Tokyo). Sassen takes a different cut on the dynamics and structure of modern cities. She places the great cities of the late twentieth century into networks that are global rather than national or regional. She looks at networks of exchange that include financial transactions, information flows, and movements of expertise and knowledge-based services. And global cities are those cities that serve as dense hubs of these kinds of exchanges on a global basis. (The map at right doesn't come from Sassen, but it appeals to me in the context because it uses the connectedness of cities to rewrite the geography of the globe. See a ContinentalDrift posting for some discussion.)

Sassen singles out seven hypotheses (quoting from the preface to Global Cities):

1. the geographic dispersal of economic activities that marks globalization ... is a key factor feeding the growth and importance of central corporate functions
   
2. these central functions become so complex that increasingly the headquarters of large global firms outsource them
   
3. those specialized service firms engaged in the most complex and globalized markets are subject to agglomeration economies
   
4. the more headquarters outsource their most complex, unstandardized functions ... the freer they are to opt for any location
   
5. these specialized service firms need to provide a global service which has meant a global network of affiliates
   
6. the growing numbers of high level professionals and high-profit making specialized firms have the effect of raising the degree of spatial and socioeeconomic inequality evident in these cities
   
7. the dynamics described in hypothesis six lead to the growing informalization of a range of economic activities which find their effective demand in these cities yet have profit rates that do not allow them to compete
   

And, in a single sentence, her conclusion is:

Economic globalization and telecommunications have contributed to produce a spatiality for the urban which pivots both on cross-border networks and on territorial locations with massive concentrations of resources (xxii).

The book attempts to document and explore these points through a huge range of evidence about flows: flows of investment, flows of telephone calls, flows of scientists and specialists. And global cities are the places where these flows concentrate and originate; they are nodes in the global system of exchange that constitutes the modern knowledge-intensive economy. Like Skinner, she is very interested in networks and hierarchies; unlike Skinner, she doesn't seem particularly interested in spatial patterns (and their graphical expression, maps).

These points just scratch the surface of the insights that these two social scientists have provided as we try to understand cities in relation to larger social networks. But perhaps it's enough to illustrate the crucial point: there is ample room in social science and history for innovative perspectives on old questions.

France 1848

The revolutions of 1848 have gotten renewed attention in light of this year's "Arab Spring" uprisings. (The amazing photo above depicts the barricades in Paris, 1848.) The parallels are obvious -- uprisings in a number of countries, similar grievances across countries, and a degree of cross-communication among the movements and leaders. And, of course, widespread optimism among progressives and activists about the prospects for fundamental social and political reform. The outcomes of 1848 were discouraging to progressives -- repression and authoritarian governments were usually successful in turning back the progressive tide. So one hopes that the prospects for democracy and equality are better in the MENA uprisings.

Particularly interesting, of course, is the example of France. So it is intriguing to look back at the causes and processes of demonstrations and resistance in May and June, 1848, in Paris and in other parts of the country. Roger Price's Documents on the French Revolution of 1848 (Documents in History Series) is worth reading for a number of reasons. First, it provides an astute analysis of the economic, social, and political situation of France in the first half of the nineteenth century, and the events that unfolded into the revolution of 1848. But second, it is a genuinely interesting book from an historiographical point of view. The analytical text takes up roughly 50 pages of an introductory essay. The remainder of the book consists of short extracts from primary documents of the period. The extracts are selected and ordered according to the author's conception of the factors and turning points that were historically central to the moment; so they constitute a narrative of an unusual kind. Price presents his analysis and framing of the events entirely through the extracts he provides; the participants tell the story.

Price's framing essay begins with the point that France was a backward country in the first part of the nineteenth century, compared to Britain. The population was overwhelmingly rural, the economy was primarily agricultural, and the infrastructure of roads and railroads was underdeveloped. Industry was in the most embryonic state of development, and markets were primarily local because of the weakness of the transport system.

The great weakness of the system, however, lay in its transport infrastructure. Communications by water and, particularly, road were slow and costly. Only the first unconnected lines of the future railway network had been constructed before the 1850s. (12)

And, unlike Britain, there were few signs of an emerging proletariat in large factories and industrial cities, along the lines of the Manchester documented decades earlier by Engels:

The typical French worker would be the artisan working in a small workshop rather than the factory worker. This was true in Paris, for example, where the majority found work in industries catering for the material needs of the population -- food, clothing, furniture and housing -- or in the typically Parisian luxury industries, all traditionally operating on a small scale. (18)

These factors had social consequences. Hunger in the countryside was a recurring possibility. Landlords and gentry had great power over the rural population. Social inequalities in both town and countryside were visible and extreme. And neither peasant nor urban worker had a strong social basis for resistance.

The contrast in the living standards of rich and poor that daily greeted the eyes of the urban populations, especially in the larger towns, was often extreme. For as long as such a contrast was felt to be inevitable, it could be accepted only with resignation, or with a resentment that might burst out in violence. But new ideas and the diffusion of a more critical outlook were bound to erode this attitude. (20)

At the same time as economic inequalities were increasing the power of a small sector of elites was increasing as well.

The grand notables -- landowners, financiers, major industrialists, but also politicians and administrators -- collaborated in extending their economic power and safeguarding their social and political authority. This was a group given unity not simply by shared material interests, but by an entire style of life. (23)

Of course it is clear that this is one particular framing of the historical episode, and another historian would have highlighted other issues and other turning points. So the book doesn't serve as a broad repository of documents, potentially relevant to many different interpretations; instead, the documents have been specifically selected to serve as waypoints on a particular path through Price's interpretation. That said, the documents are fascinating to read, from observations by elite participants, to government announcements, to confessions by activist leaders and followers.

Was this a social revolution? Some of the goals of the activists involved radical social transformation; but these goals were entirely unsuccessful. The balance between the propertied and the property-less did not change in any meaningful way. Was it more successful as a political revolution? Again, not really. Universal suffrage was established before the June repression; but what followed was autocratic rule and eventually the election of yet another dictator, Napoleon III. So it is hard to see that the revolution of 1848 in France had much effect on the conditions of freedom and well-being of the majority of the poor in France.

It would be very interesting to have a similar compilation of documents and framing social descriptions for Egypt, 2011. I'm sure that researchers and observers in Cairo have been collecting interviews, posters, and other kinds of documents that will shed more light on the social and political grievances offered by ordinary Egyptians as they participated in the demonstrations and collective resistance that led to the fall of Mubarak. And, likewise, it will be valuable to document the timeline of reaction by the state during these crucial several weeks, including repression, accommodation, and eventually capitulation by the ruling circles in favor of -- the army.

Equilibrium reasoning

A system is in equilibrium with respect to a given characteristic when there is a system of forces in play that push the system back to the equilibrium state when it is subjected to small disturbances or changes. This is referred to as a homeostatic system.

The temperature in a goldfish bowl is in equilibrium if the bowl is provided with a thermostatically controlled heater and cooler; when the external temperature falls and the water temperature begins to fall as well, the thermostat registers the change of temperature and turns on the heater, and when the external temperature rises, the thermostat turns on the cooler. A population of squirrels in a bounded forest may reach an equilibrium size that is balanced by excess reproductive capacity (pushing the population upwards when it falls below the feeding capacity of the environment) and by excess mortality from poor nutrition (pushing the population downwards when it rises above the feeding capacity of the environment).

These examples embody very different causal mechanisms; but each represents a case in which the variable in question (temperature or population size) oscillates around the equilibrium value determined by the features of the environment and the features of the adjustment mechanisms.

There are other physical systems where the concept of equilibrium has no role. The trajectory of a fly ball is not an equilibrium outcome, but rather the direct causal consequence of the collision between bat and ball. And if the course of the baseball is disturbed -- by impact with a passing bird or an updraft of wind -- then the terminus of the ball's flight will be different. The number of telephone calls between Phoenix and Albany is not an equilibrium outcome, even if it is fairly stable over time, but simply the aggregate consequence of the contingent telephone behavior of large numbers of people in the two cities. So systems that reach and maintain equilibrium are somewhat special.

It is also interesting to observe that there are other circumstances that produce a stable steady state in a system besides equilibrium processes. We may observe that elevators in a busy office building most frequently have 10 passengers. And the explanation for this may go along these lines: 10 is the maximum number of adults who can be squeezed into the elevator car; there are always many people waiting for an elevator; so virtually every car is at full capacity of 10 persons. This is an example of a pattern that derives from a population of events that demands full utilization, and a limit condition in the location where activity takes place. In this example, 10 passengers is not an equilibrium outcome but rather a forced outcome deriving from excess demand and a logistical constraint on the volume of activity. A large city may show a population history that indicates a trend of population increase from 4 million to 6 million to 10 million -- and then it stops growing. And the explanation of the eventual stable population size of 10 million may depend on the fact that the water supplies available to the city cannot support a population significantly larger than 10 million.

To what extent are social ensembles and processes involved in equilibrium conditions? The paradigm example of equilibrium reasoning in the social sciences arises in microeconomic theory. Supply and demand curves are postulated as being fixed, and the price of a good is the equilibrium position where the quantity produced at this price is equal to the quantity consumed at this price. If the price rises, demand for the good falls and the price falls; if the price falls below the equilibrium position, producers manufacture less of the good and consumers demand more of it, which induces a price rise.

Another important example of equilibrium analysis in social behavior is the application of central place theory to economic geography. The theory is that places (cities, towns, villages) will be positioned across the countryside in a way that embodies a set of urban hierarchies and a set of commercial pathways. The topology of the system and the size of the nodes are postulated to be controlled by social variables such as transport cost and demand density. And individuals' habitation decisions are influenced in a way that reinforces the topology and size hierarchy of the central place system.

However, even in these simple examples there are circumstances that can make the equilibrium condition difficult to attain. If the supply and demand curves shift periodically, then the equilibrium price itself moves around. If the price and production response characteristics are too large in their effects, then the system may keep bouncing around the equilibrium price, from "too high" to "too low" without the capacity of finetuning production and consumption. The resulting behavior would look like a graph of the stock market rather than a stable, regular system returning to its "equilibrium" value. And, in the case of habitation patterns, some places may gain a reputation for fun that offsets their disadvantages from the point of view of transport and demand density -- thereby disrupting the expected equilibrium outcomes.

So if the conditions defining the terms of an equilibrium change too quickly, or if the feedback mechanisms that work to adjust the system value to current equilibrium conditions are too coarse, then we should not expect the system to arrive at an equilibrium state. (The marble rolling on a rotating dinner plate will continue to roll across all parts of the plate rather than arriving at the lowest point on the plate and staying there.)

I'm inclined to think that equilibria are relatively rare in the social world. The reasons for this are several: it is uncommon to be able to discover homeostatic mechanisms that adjust social variables; when quasi-homeostatic mechanisms exist, they are often too coarse to lead to equilibrium; and, most fundamentally, the constraints that constitute the boundary conditions for idealized equilibria among social variables are often themselves changing too rapidly to permit an equilibrium to emerge. Instead, social outcomes more often look like constrained random walks, in which social actions occur in a fairly uncoordinated way at the individual level and aggregate to singular social outcomes that are highly path-dependent and contingent. Social outcomes are more often stochastic than being guided by homeostatic mechanisms.

What cities have in common

Images: Beijing (1900), Mexico City (2000), London (1600), Chicago (1930)

The "city" is a pretty heterogeneous category, encompassing human places that differ greatly with each other and possess a great deal of internal social heterogeneity as well. Size, population structure, economic or industrial specialization, forms of governance, and habitation and transportation structure all vary enormously across the population of cities. And so New York (2000), Chicago (1930), Rome (200), Mumbai (2008), Beijing (1800), Lagos (1970), London (1600), and Mexico City (1990) are all vastly different human agglomerations; and yet all are "cities". Ancient, modern, medieval, developed, and underdeveloped -- each of these places represents an urban concentration of population and habitation. (Here is an earlier posting that is relevant to the current topic.)

Given these many dimensions of difference, we can reasonably ask whether there are any shared urban characteristics or processes. Is there anything that a scientific or historical study of cities can discover? Is there a body of observation and discovery that might constitute the foundation for a sociology of cities?

Several points emerge quickly when we pose the question in these terms. First, a city is by definition a dense concentration of human inhabitants in a limited space. Human beings have material needs that must be satisfied daily: fresh water, food, shelter, clothing, and fuel, for example. Rural people can satisfy many of these needs directly through access to land, farms, and other natural resources. Urban populations are too dense to support individual or family self-sufficiency. So cities have this in common: they must have developed logistical systems for supplying residents with food, clean water, sanitation, and other basic necessities. This is the insight that motivated von Thünen in the development of central place theory (Isolated State: an English Edition of Der Isolierte Staat); equally it underlies William Cronon's analysis of Chicago in Nature's Metropolis: Chicago and the Great West and G. William Skinner's analysis of urban hierarchies in China (link).

A second feature of cities is the unavoidable need for value-adding, non-agricultural production within the city. This means activities such as manufacturing, artisanal production, and the provision of services for pay. The residents of the city need to gain income in order to have "purchasing power" to acquire the necessities of life from the countryside. This implies a social organization that supports employment and occupations. So cities share this characteristic as well: they are grounded systems of production and exchange, permitting labor, production, circulation of commodities, and consumption. (Reasoning something like this underlay the analysis of Chicago into "ecological zones" pioneered by Chicago School sociologists Park and Burgess in The City: Suggestions for Investigation of Human Behavior in the Urban Environment.)

Given that cities are inherently spatial, the economic characteristics just mentioned also imply a circulation of persons throughout the city. And this implies that cities must possess some organized system of transportation. This may be walking pathways, roads for carriages, streetcars, buses, or subways and railroads. But economic activity and production requires circulation of people, and this implies urban transportation. But, as Sam Bass Warner showed in Streetcar Suburbs: The Process of Growth in Boston, 1870-1900, transport systems in turn create new patterns of residence and work in their wake.

A third common urban characteristic has to do with inequalities of power, influence, and property. Human populations seem always to embody significant inequalities along these lines. But advantages of power and wealth can be almost automatically transformed into facts of urban geography by the nomenklatura, the elites. So cities are likely to bear the signature of the social inequalities of wealth and power that are interwoven in their histories. The attractive locations for homes and gardens, preferred access to amenities such as water and roads, even locations favored from the point of view of pest and disease -- these locations are likely to be stratified by wealth and power. (Engels' description of the habitation patterns of bourgeoisie and proletariat in Birmingham and Manchester are illustrative; The Condition of the Working Class in England. Here's a more developed discussion of Engels' sociology of the city.)

Fourth, cities require formal systems of governance and law. Village society may succeed in establishing stable social order based on informal norms and processes. But cities are too large and complex to function as informal arrangements. Instead, there need to be ordinances for public health and safety, maintenance of public facilities, land use processes, and rules of public safety. Absent such governance, it is inconceivable that a city of one hundred thousand or a million would succeed in maintaining the delicate patterns of coordination needed for the continuing wellbeing of the residents.

So cities can be predicted to possess a variety of forms of social, political, economic, and geographical organization. Cities are not formless concentrations of humanity; rather, they are functional systems that can be investigated in depth. And here is the historical reality that permits this analysis to escape the charge of functionalism; the social systems that cities currently possess are the result of designs and adaptations of intelligent, strategic actors in the past. This means that they may be markedly non-optimal; they are likely to be skewed towards the interests and comfort of elites; but they are likely to work at some level of success.

These observations don't exactly answer the original question in a tidy way; they don't establish specific forms or characteristics that all cities share. But they do define a set of existential circumstances that cities must satisfy, and they pose in turn a series of questions about social organization and function that are likely to shed light on every city. We might look at this discussion as suggesting a matrix of analysis for all cities, corresponding to the large social needs mentioned here. How does a given city handle logistics, provisioning, local economic activity, transportation, land use, governance, public order, sanitation and health, and inequalities? What are the organizations and systems through which these central and inevitable tasks are accomplished? And then, perhaps, we may find a basis for classifying cities into large groups, based on the similarities that exist at this level of structure and organization. (For example, reasoning something like this leads G. William Skinner to distinguish between administrative and commercial cities in late Imperial China.)

A catalogue of social mechanisms

In an earlier post I made an effort at providing the beginnings of an inventory of social mechanisms from several areas of social research. Here I’d like to go a little further with that idea in order to see how it plays into good thinking about social-science methodology.

Some Types of Social Mechanisms CONTENTION Escalation Brokerage Diffusion Coordinated action Social appropriation Boundary activation Certification Framing Competition for power COLLECTIVE ACTION Prisoners' dilemma Free rider behavior Convention Norms Selective benefits Selective coercion Conditional altruism Reciprocity ORGANIZATIONAL ENFORCEMENT Audit and accounting Supervision Employee training Morale building Leadership NORMS AND VALUES Altruistic enforcement Person-to-person transmission Imitation Subliminal transmission Erosion Charisma Stereotype threat

ECONOMIC ACTIVITY Market Auction Ministry direction Contract Market for lemons Democratic decision making Producers' control Soft budget constraint GOVERNMENT Agenda setting Cyclical voting Log rolling Regulatory organizations Influence peddling STATE REPRESSION Secret police files Informers Spectacular use of force Propaganda Deception Control of communications systems SOCIAL COMMUNICATIONS Interpersonal network Broadcast Rumor Transport networks SYSTEM EFFECTS Flash trading Interlocking mobilization Overlapping systems of authority (Brenner) Non-linear networks

These mechanisms have been collected from a wide range of social scientists and researchers -- Charles Tilly, Robert Axelrod, Elinor Ostrom, George Akerlof, Robert Bates, Mancur Olson, Mayer Zald, John Ferejohn, Janos Kornai, Claude Steele, and Charles Perrow, to name a few.

There are at least two kinds of questions we need to ask about a collection like this.

First, where do the entries come from? What kinds of scientific inquiry are required in order to establish that things like these are indeed mechanisms found in the social world?

The most general answer to this question concerning discovery is that much research in the various disciplines of the social sciences is specifically directed at working out the contours of mechanisms like these. Political scientists who focus on legislatures and the US Congress have become expert on identifying and validating the institutional and voting mechanisms through which legislative outcomes come to effect. Organizational sociologists study the inner workings of a range of organizations and are able to identify and validate a wide range of mechanisms at work within these organizations. Economic anthropologists and theorists study the ways in which economic transactions are conducted in a range of human settings. Social psychologists identify many of the ways that individuals acquire normative beliefs and transmit them to other individuals. The greatest difficulty in constructing a table like this is not at the level of identifying mechanisms that might be included; it is the problem of limiting the number of mechanisms identified to a more or less manageable number. There is some reason to fear that social scientists have identified thousands of mechanisms in their research, not dozens.

And second, what role does a table like this play in the conduct of research in the social sciences?

In In Search of Mechanisms: Discoveries across the Life Sciences Craver and Darden argue that biologists often approach novel phenomena with something like this table in the backs of their heads -- an inventory of known causal mechanisms in the domain of biology. From there they attempt to solve the puzzle: what combination of known mechanisms might be concatenated in order to reproduce the observed phenomenon?

Strikingly enough, this description of a heuristic for arriving at an explanatory analysis of a situation has a lot in common with the way that McAdam, Tarrow, and Tilly proceed in Dynamics of Contention. (Here is a more developed analysis of their mechanisms-based approach; link.) MT&T argue that there is a relatively manageable list of social mechanisms that can be observed in many cases of social contention. And they approach new instances with the idea that we may be able to understand the dynamics of the case by teasing out the workings of some of those mechanisms. It seems that MT&T are involved in both parts of the inquiry -- discovery and isolation of recurring mechanisms of contention, and application of these discoveries to the explanation of specific episodes of contention.

For example, they introduce their case studies in Part III of the book in these terms:

Part III of the study takes up three distinct literatures regarding contention -- revolution, nationalism, and democratization -- in view of the paths our quest has followed. The goal of that concluding section is to emphasize the commonalities as well as the differences in those forms of contention through an examination of the explanatory mechanisms and political processes we have uncovered in Parts I and II. (kl 511)

And a few paragraphs later:

Let us insist: Our aim is not to construct general models of revolution, democratization, or social movements, much less of all political contention whenever and wherever it occurs. On the contrary, we aim to identify crucial causal mechanisms that recur in a wide variety of contention, but produce different aggregate outcomes depending on the initial conditions, combinations, and sequences in which they occur. (kl 519)

Here is how they summarize their attempt to explain particular episodes of social contention. They focus on a "number of loosely connected mechanisms and processes":

• A mobilization process triggered by environmental changes and that consists of a combination of attribution of opportunities and threats, social appropriation, construction of frames, situations, identities, and innovative collective action.
• A family of mechanisms still to be elucidated around the processes of actor and identity constitution and the actions that constitute them.
• A set of mechanisms often found in trajectories of contention that recurs in protracted episodes of contention, competition, diffusion, repression, and radicalization. (kl 941)

And this body of social mechanisms is taken to provide a basis for historically grounded explanations of the forms of contention observed in specific cases.

This seems to parallel fairly closely the intellectual process that Craver and Darden describe in the case of biology: create an inventory of common causal mechanisms and analyze new cases by trying to see to what extent some of those known mechanisms can be discerned in the new material.

This account of an important type of social science research resonates well with a broad range of social science disciplines. It aligns with Robert Merton's notion of "theories of the middle range" in the social sciences, and the idea of developing a toolbox of patterns of social behavior on the basis of which to explain specific episodes. Rather than looking for general theories on the basis of which to unify wide swaths of the social world under a deductive explanatory system, this mechanisms-based approach suggests coming at social explanation piecemeal: finding the components and sub-processes of observed social ensembles, on the basis of which we can explain some aspects of the behavior of those ensembles.

We might usefully consider two additional questions. First, is there a theoretically useful way of classifying social mechanisms (formation of the individual actor, collective action, communication, repression, collective decision making, ...)? Can our catalogue provide content-relevant "chapters"? We might argue that a good taxonomy of social mechanisms actually provides a way of theorizing the main dimensions of social activity and organization. And second, are there more fundamental things we can say about how some or many of these mechanisms work? Does a good theory of the actor and a good theory of social organizations suffice to account for the workings of a great many of these mechanisms? If we respond affirmatively to this question, then once again we may have made a small degree of progress towards offering a somewhat more general theory of the social world.