In praise of reductionism

Suppose I have a business making clothing. I want to know how many items of what size to manufacture. If I can know the distribution of men's and women's adult heights in the U.S., I can plan how many shirts or pants to make of each size. Assume that the height data are not readily available. So I draw a sample of people, measure their heights, and calculate means, standard deviations, quartiles, and probably other measures of the distribution. I think that an anthropologist down at the U might be interested in my height data, so I head downtown.

The first anthropologist I run into is a cultural anthropologist. When I show him my data, he chides me for being simplistic. How can I possibly think I have described my population of people when I have only looked at their height? We want to know so much more about people, she says. My little study is ridiculously limited and it can't help him understand people at all. It is reductionist, It is useless. Why did I bother.

Then I run into an evolutionary anthropologist. She likes the data I gathered. She can compare these results with her own measurements of height in Lower Slobovia, and learn something about human height variation. To her, these are interesting and important data.

For my own purposes, and for the evolutionary anthropologist, my little study of height provides important data. It helps each of us answer a question of importance about height. Is this study rigorous and useful? Yes.It is reductionist? Yes, again. Is that bad? Only for the cultural anthropologists who wants more information and more nuance.

You can probably see where I am going here. Over the past couple of years, I have encountered considerable opposition to our work in settlement scaling from archaeologists, historians, and others.

(On the scaling work, see this post from 2014,  or a bunch of posts in Wide Urban World; this is the latest post there.)

These people  complain that this research is reductionist. How can we possibly understand ancient settlements by just comparing the population to one other variable using a graph and an equation? Cities and settlements are far too complex to be explained by two variables. But we have never claimed to explain ancient cities or settlements on the basis of a scaling regression. Instead, we claim to produce a better understanding of a particular limited domain of ancient settlements. If you want a comprehensive analysis of individual ancient cities, then be my guest. I have done that kind of thing (Smith 2008), and it is a useful approach. But now, when I am addressing a limited domain using a few variables, please don't accuse me of reductionism, as if that charge invalidates the research.

This is not just me feeling oppressed by clueless reviewers, colleagues, audience members, and such. The roster of the reductionism naysayers I have encountered includes some good, smart scholars. In fact, even very well-known and respected scholars fall victim to this malady of poo-pooing single indices or variables for not explaining everything one might want to know about a phenomenon. For example, here is what Thomas Piketty, in Capital in the Twenty-First Century, says about the Gini index:  "Indeed, it is impossible to summarize a multidimensional reality with a unidimensional index without unduly simplifying matters and mixing up things that should not be treated together" (Piketty 2014:266). As pointed out by Branko Milanovic (2014), Piketty dismisses the Gini index as an "aseptic" measure of inequality. But who has claimed that the Gini index will tell us everything we want to know about inequality? It tells us one kind of thing, and it allows us to compare separate contexts.

The Gini index, and my hypothetical measure of height, are intentionally reductionist. Their goal is NOT to document or explain everything about some domain. Rather, their goal is to abstract a key dimension from a complex reality, to reduce the messy details to a single measure so that comparisons can be made among domains. Comparative analysis is impossible without simplification, without ignoring a lot of details. If  you want to say, "I'd rather do a detailed comprehensive analysis of one case," that is fine. If you want to say "I don't like statistical studies or regression analysis," that is fine (well, maybe its not really fine, but it is not too uncommon). But please do not say "Because I happen to like details, then your reductionist measure is worthless."

I gave a talk in Europe recently promoting comparative approaches to past urbanism. I made the point that in order to compare cities, one had to abstract some key aspects and ignore many details. This allows one to generate useful and interesting conclusions. When I was done, the first question (from an urban historian) was,"Isn't all this quite reductionistic?" My answer was "Yes! And that is precisely why I do it!"

Take a look at my post from last year , "Against nuance," for some related ideas.

Milanovic, Branko
2014    The Return of 'Patrimonial Capitalism': A Review of Thomas Piketty's Capital in the Twenty-First Century. Journal of Economic Literature 52 (2): 519-534.

Piketty, Thomas
2014    Capital in the Twenti-first Century. Belknap Press, Cambridge, MA.

Smith, Michael E.
2008    Aztec City-State Capitals. University Press of Florida, Gainesville.

Against nuance

I can't find enough good epistemological work on comparative scientific archaeology, so I have to get my kicks elsewhere. I just read a fantastic paper by a sociologist, titled "F*ck Nuance." (thank you to Colin Wren for sending me a link). The author is Kieran Healy, a sociologist at Duke University. His basic point is that when someone calls for more nuance, the result is typically the complexification of ideas and theory to the point where theorizing and comparative analysis suffers. Comparison requires simplification ("abstraction" to Healy), and this is prevented by nuance.

      “Nuance is not a virtue of good sociological theory. Sociologists typically use it as a term of praise, and almost without exception when nuance i mentioned it is because someone is asking for more of it. I shall argue that, for the problems facing sociology at present, demanding more nuance typically obstructs the development of theory that in intellectually interesting, empirical generative, or practically useful.” (p.1)

This paper has been discussed in the Chronicle of Higher Education, and heavily downloaded from Healy's website.

Healy identifies three "nuance traps":

1. Nuance of the fine grain: “the ever more detailed, merely empirical description of the world ... It is a rejection of theory masquerading as increased applicability or range.”
2. Nuance of the conceptual framework: “the ever more extensive expansion of some theoretical system in a way that effectively closes it off from rebuttal or disconfirmation by anything in the world ... It is an evasion of the demand that a theory be refutable.”
3. Nuance of the connoisseur: “the insinuation that your sensitivity to nuance is a manifestation of one’s distinctive ability to grasp and express the richness, texture, and flow of social reality itself ... It is mostly a species of self-congratulatory symbolic violence.”

The paper is discussed briefly (and posted) on the Crooked Timber blog. Comment # 24 uses the nuance concept to contrast development theories of Jeffrey Sachs with those of Acemoglu and Robinson. Very interesting.

The paper closes with:

·         “Given the current state of theory in some field, the question is—should we be trying to increase the supply [of nuance], or reduce it? My context is theorizing in American sociology at the time I am writing. We are glutted with nuance. I say, f*ck it.” (p.11)

Check out the paper. I especially like the abstract: "Seriously, f*ck it."

My sentiment, exactly.  See my paper on arguments later this month in the SAA Archaeological Record for a discussion of parallel ideas in archaeology.

Healy, Keran    2015    Fuck Nuance. Paper presented at the American Sociological Association Meetings.  .

Natural experiments in archaeology

I've been wondering recently why more archaeologists don't use the method and concept of "natural experiment." In one sense, natural experiments are not uncommon in archaeology; we sometimes call them "controlled comparisons," probably borrowing that term from cultural anthropology (Eggan 1954). But we rarely use the phrase "natural experiment," which has been gaining ground in the comparative branches of the social sciences, history, and ecology. This isn't just a terminological issue; natural experiments are all about how to determine causality. Most archaeologists, however, avoid discussing causality, and this may account for the rarity of the natural experiment concept in our field.

(Postmodern, postprocessualist, and other "post" archaeologists can probably stop reading here, unless you are looking for more fodder to critique simplistic scientistic Smith).


A natural experiment is "an observational study that nonetheless has the properties of an experimental research design.” (Gerring 2007: 216). The recent collection edited by Jared Diamond and James Robinson (2010) presents a series of historical natural experiments, including one archaeological case study. In an insightful review of the book in the journal Science, James Mahoney notes:

·         “Historical analysts cannot, of course, test their ideas by running controlled experiments. They cannot randomly assign cases to treatment and control groups. But they can sometimes make a credible claim that the assignment of cases to different groups is “as if” random. The label “natural experiment” (or “quasi-experiment”) is often reserved for those studies in which this assumption seems especially plausible.”(Science vol. 357, p. 1578)

It is probably no surprise that the archaeological example in this book is by Patrick Kirch (2010), who has been doing "natural experiments" or "controlled comparisons" for years. Island societies are productive candidates for natural experiments because of their boundedness and relative isolation. In this chapter he compares Hawaii, the Marquesas and Mangaia as contrasting environments in which initially similar ancestral Polynesian societies evolved in very different directions.

Gerring 2007: 153

I won't go into details here, beyond recommending Diamond and Robinson and other works on natural experiments (Gerring 2007; Dunning 2008; Labizna 2011). But just to show how this line of methodological thinking lines up with archaeology, consider John Gerring's depiction of types of experimental design in case study research (recall that most research in archaeology follows the approach called case study research in other disciplines).

Quadrant #1 is the classic experimental design. Two populations, the treatment group and control group (spatial variation) are observed through time, before and after the "treatment" or the "perturbation" (the term used in Diamond and Robinson 2010). Quadrants 2 and 3, with only temporal or spatial variation, are relatively common in archaeology. The fourth quadrant is for studies where there is no spatial or temporal variation. This is perhaps the most common archaeological situation. You do a study, come up with some results, and then put forward an argument about what they mean: what were the dynamics, how and why did something happen, etc. But since you have made no formal comparison of either a before-and-after nature, or a spatial nature, it is very difficult to demonstrate causality. The typical course of action is make as strong an argument as one can. "That's my story and I'm stickin' to it!" But a methodologically superior method would be to find a way to make an explicit temporal and/or spatial comparison.

When there just happens to be no good comparison one can make, then you need to use counterfactual logic to make a causal claim. There is a rather large literature on formal counterfactual causality in sociology and political science (e.g., Gerring 2005, Heckman 2005, Morgan & Winship 2007). In its simplest form, making a causal claim without an experiment or comparison requires one to consider the counterfactual situation of what would have happened had the hypothesized causal agent not been present, or acted differently. One then shows that such a situation does not match reality, which gives support to the causal hypothesis.

Here is an example. I think that the ability of people (whose houses I have excavated) to cultivate cotton in Aztec-period Morelos was the main source of their economic prosperity. That is, cotton cultivation was a major cause of their prosperity. I don't have a "before and after" comparison (first no cotton, then cotton cultivation), and there are not enough comparative cases of sites where we know about cotton cultivation (presence or absence) and prosperity in enough detail. (Once some current project are complete, this situation will improve). So I explore the counterfactual situation: what would the local economy be like if they were not able to grow cotton? They would have had fewer resources to trade with other areas. Cotton textiles served as money, and thus cotton was far more valuable than other local resources such as maize, bark paper, or basalt. Also, it would have been far more difficult to come up with their taxes, assessed in cotton textiles. (And there would probably be far fewer spindle whorls in domestic middens).

Now I can come up with all sorts of plausible factors to support my causal claim about cotton and prosperity, but the argument will be much more effective once I can add some formal comparisons. For example, were people at Calixtlahuaca, where cotton was not cultivated, less prosperous? This will be a start, but more cases are needed to make a strong argument. Or perhaps I could show that prosperity declined after the Spanish conquest (it almost certainly it did, but demonstrating that is quite difficult), when historical sources tell us that irrigated cotton fields were converted to sugar cane.

In any case, these various comparative scenarios are natural experiments. We mostly do observational (case study) research in archaeology. To the extent that we can design and describe our research in quasi-experimental terms and use this approach to explore causality, our explanations will be more convincing, and scholars and others outside of archaeology will be more likely to view our discipline as an empirical scientific field with something to say about the world. Now, many archaeologists don't want our field to be scientific. They want to use fashionable high-level theory to interpret the past, without the constraints of scientific methods. That is fine for some purposes, but if we want anyone outside of the humanities to pay attention to us and find something of value in our research, then we need to do all we can to beef up our methods in a scientific direction. We need to pursue science #1 (epistemological science) and just just science #2 (jazzy technical methods). And natural experiments are one way to do this.

Diamond, Jared and James A. Robinson (editors)
2010    Natural Experiments of History. Harvard University Press, Cambridge.

Dunning, Thad
2008    Improving Causal Inference: Strengths and Limitations of Natural Experiments. Political Research Quarterly 61: 282-293

Eggan, Fred
1954    Social Anthropology and the Method of Controlled Comparison. American Anthropologist 56:743-763.

Gerring, John
2005    Causation: A Unified Framework for the Social Sciences. Journal of Theoretical Politics 17: 163-198.

Gerring, John
2007    Case Study Research: Principles and Practices. Cambridge University Press, New York.

Heckman, James J.
2005    The Scientific Model of Causality. Sociological Methodology 35: 1-97.

Kirch, Patrick V.
2010    Controlled Comparison and Polynesian Cultural Evolution. In Natural Experiments of History, edited by Jared Diamond and James A. Robinson, pp. 15-52. Harvard University Press, Cambridge.

Labzina, Elena
2011    No Free Lunch: Costs and Benefits of Using the Concept of Natural Experiments in Political Science. M.A. thesis, Department of Political Sciences, Central European University.

Morgan, Stephen L. and Christopher Winship
2007    Counterfacturals and Causal Inference: Methods and Principles for Social Research. Cambridge University Press, New York.

More drive-by history: world history as television

I watched the second and final installment of Niall Ferguson's TV show, "Civilization" last night. (See my post on the first installment here). He covered three of his "killer applications" that explain why western civilization is so much better than the rest of the world.

1. Medicine.  A main point in this section was that imperialism (French imperialism in west Africa) isn't so bad, because some medical advances were made by imperialist physicians in Senegal. At the end of the show, Ferguson decries the fact that "empire" has become a "dirty word." He is frustrated by the fact that people just ignore the great benefits of empires and imperialism. This is so blatant that I can't even think of a clever response!

2. Consumerism.  Blue jeans caused the Prague spring in 1968, and they also caused the Soviet invasion of Czechoslovakia. Blue jeans later caused the fall of the Berlin wall. And the Chinese are the worst-dressed people in the world.

3. Work. There was actually a nice piece on Max Weber and his theory of how Protestantism furthers capitalism. But any insights were offset by explanations like this: Why is church attendance higher in the U.S. than in Europe? Because state monopolies are inefficient.

The field of "world history" has been gaining influence in the past decade. There are now textbooks, journals, and lots of publications. It is good to see historians expanding their horizons in two ways: (1) seeking connections and contacts among widely separated regions; and (2) making comparisons among regions (sometimes even including such bizarre places for historians as Pre-Columbian America). From the perspectives of anthropology and archaeology, these two approaches are pretty pedestrian, but when historians--who command large amounts of very important regional data--take them up, this is a very positive development for scientific scholarship on the past. But books and TV shows like Ferguson's Civilization set back progress in this area. The superficial nature of the ideas, the many very wrong-headed notions, and the glitzy production, all make world history look like prime-time television - in both style and substance.

I hope serious proponents of world history fight back.

Niall Ferguson: Drive-By History

I watched the first installment of Niall Ferguson's TV series, "Civilization: The West and the Rest,"tonight. Much of it was entertaining, and there were many insights. But overall I found it a superficial and simplistic triumphal history. How did the West come to dominate the East? Ferguson attributes the West's victory to six factors (he calls them "killer applications;" it's not clear why he uses a software metaphor): competition, science, property rights, medicine, the consumer society, and the work ethic. Well, this certainly is not a rigorous comparative study. Where did these factors come from? What theoretical model generated this set of six?

David Bronwich published an eloquent, understated, and highly critical review of Ferguson's book of the same name in the New York Review of Books (December 8, 2011) On the six factors, he states, "These make an absurd catalog. It is like saying that the ingedients of a statesman are an Oxford degree, principles, a beard, sociability, and ownership of a sports car."

I have to admit that my attention started to wane after an hour. I was getting tired of hearing how backward the Ottomans were in compared with the Europeans. I picked up my phone and started playing a game, but then my ears pricked up when Ferguson started comparing Spanish and British colonization of the New World. He claims at the outset that "Britain won" this competition. Well, Spain got far richer off its colonies than Britain ever did, and Spain held onto its colonies longer than Britain. So just how did Britain win? What Ferguson meant was that the United States would later develop into a much better society than modern Latin America. I don't think he used the word "better," but that is the clear message of this segment.

Ferguson focused on an important comparison--that colonial development in North America involved many small property owners, whereas Latin America had far fewer, larger, landowners. OK, that is certainly a major difference between the two areas. But how and why did these to different property systems get started? We are told the systems originated because the two sets of European colonists simply made different decisions in the two areas. The British decided to have a small property system, and the Spaniards decided to have big estates. What is completely lacking is the context of this distinction. Key factors that are ignored include demography (the very different size and density of native societies in the two areas; the numbers of natives who survived vs. the.numbers of colonists), the indigenous political structure at time of conquest (states and empires in Latin America, vs. tribal societies in North America), and the nature of the resources in the two areas (mining vs. agriculture, and their labor and organizational requirements).

Thus Ferguson did identify a crucial distinction between two areas, but by completely ignoring the context, he fails to show how and why that distinction originated and developed. His explanation is superficial and misleading.

Ferguson is a respected historian with a number of solid empirical studies to his name. Why did he step down from scholarship to produce a popular book and TV show based on some rather silly ideas? Could publicity and royalties have anything to do with this? Is the image of a nineteenth century capitalist on the cover significant? People may gripe about Jared Diamond's works, but they are based on solid scholarship that relies on work by experts, interpreted in a new fashion. If the TV show is indicative of the book (and the reviews suggest that it is), then Ferguson is not anywhere near Diamond's level of scholarship.

This is drive-by history, a quick and superficial look at the issues. If you want to find about about how and why China and Europe diverged, try reading Ian Morris's far superior book, Why the West Rules (for Now).