Wednesday, September 30, 2015

Marx on peasant consciousness

One of Marx's more important pieces of political writing is the The Eighteenth Brumaire of Louis Bonaparte (1851) (pdf). Here is his analysis of the causes of the specific nature of peasant political consciousness leading to the election of Napoleon III:
The small-holding peasants form an enormous mass whose members live in similar conditions but without entering into manifold relations with each other. Their mode of production isolates them from one another instead of bringing them into mutual intercourse. The isolation is furthered by France‘s poor means of communication and the poverty of the peasants. Their field of production, the small holding, permits no division of labor in its cultivation, no application of science, and therefore no multifariousness of development, no diversity of talent, no wealth of social relationships. Each individual peasant family is almost self-sufficient, directly produces most of its consumer needs, and thus acquires its means of life more through an exchange with nature than in intercourse with society. A small holding, the peasant and his family; beside it another small holding, another peasant and another family. A few score of these constitute a village, and a few score villages constitute a department. Thus the great mass of the French nation is formed by the simple addition of homologous magnitudes, much as potatoes in a sack form a sack of potatoes. Insofar as millions of families live under conditions of existence that separate their mode of life, their interests, and their culture from those of the other classes, and put them in hostile opposition to the latter, they form a class. Insofar as there is merely a local interconnection among these small-holding peasants, and the identity of their interests forms no community, no national bond, and no political organization among them, they do not constitute a class. They are therefore incapable of asserting their class interest in their own name, whether through a parliament or a convention. They cannot represent themselves, they must be represented. Their representative must at the same time appear as their master, as an authority over them, an unlimited governmental power which protects them from the other classes and sends them rain and sunshine from above. The political influence of the small-holding peasants, therefore, finds its final expression in the executive power which subordinates society to itself.
This a particularly interesting analysis of the social psychology of group solidarity, and one that has contemporary significance as well. It sheds a lot of light on how Marx thinks about the formation of class consciousness -- even as it significantly misunderstands the agency of rural people.

What are the limitations of the French peasantry, according to Marx here? They are isolated, burdened, unsophisticated, primitive, apolitical, and ignorant of the larger forces around them. Therefore, Marx says, they cannot constitute a unified and purposive political force. (The photo of a battalion of Vietnam Minh troops in Indochina just a century later refutes this conception.)

From this description we can draw several positive ideas about the foundations of collective solidarity. Here are the elements that Marx takes to be crucial in the formation of collective consciousness in this passage:
  1. The group needs to possess "manifold relations" to each other.
  2. There needs to be effective communication and transportation across space, not just local interaction.
  3. There needs to be a degree of economic interdependence.
  4. There need to be shared material conditions in the system of production.
  5. There needs to be an astute appreciation of the social and economic environment.
  6. There needs to be organization and leadership to help articulate a shared political consciousness and agenda. 
And Marx seems to have something like a necessary and sufficient relation in mind between these conditions and the emergence of collective consciousness: these conditions are jointly sufficient and individually necessary for collective consciousness in an extended group.

There are several crucial ideas here that survive into current thinking about solidarity and mobilization. So Marx's thinking about collective consciousness was prescient. It is interesting to consider where his thoughts about collective solidarity came from. How did he come to have insightful ideas about the social psychology of mobilization and solidarity in the first place? This isn't a topic that had a history of advanced theory and thinking in 1851.

Two sources seem likely. First is the tradition of French socialist thought in which Marx was immersed in the 1840s. French socialist thinkers were in fact interested in the question of how a revolutionary spirit came to be among a group of people. And second is Marx's own experience of working people in Paris in 1843-45. He writes of his own observations of working people in the Economic and Philosophic Manuscripts in 1844:
When communist artisans associate with one another, theory, propaganda, etc., is their first end. But at the same time, as a result of this association, they acquire a new need – the need for society – and what appears as a means becomes an end. In this practical process the most splendid results are to be observed whenever French socialist workers are seen together. Such things as smoking, drinking, eating, etc., are no longer means of contact or means that bring them together. Association, society and conversation, which again has association as its end, are enough for them; the brotherhood of man is no mere phrase with them, but a fact of life, and the nobility of man shines upon us from their work-hardened bodies.
Here Marx gives as much importance to the substantive relations of friendship and everyday association as he does to shared material interests in the formation of the class consciousness of French workers.

Marx's misunderstanding of the political capacity and consciousness of peasant communities has been noted by many scholars of rural revolutions. James Scott once opened a public lecture on the revolutions of the twentieth century by saying that his lecture would only treat the peasant revolutions of the century. But he then paused and laughed, and said, this isn't much of a limitation, because they were all peasant revolutions! Marx's assumption that only urban workers were capable of revolutionary consciousness was a serious misreading of the coming century of anti-capitalist and anti-colonial struggles. (Here is an earlier post on Scott's studies of peasant politics. Scott's accounts can be found in Weapons of the Weak: Everyday Forms of Peasant Resistance and The Moral Economy of the Peasant: Rebellion and Subsistence in Southeast Asia. Eric Wolf's Peasant Wars of the Twentieth Century picks up similar themes.)

Also interesting in the Eighteenth Brumaire is Engels' statement on the law of history as class struggle in his preface to the third edition of the book:
In addition, however, there was still another circumstance. It was precisely Marx who had first discovered the great law of motion of history, the law according to which all historical struggles, whether they proceed in the political, religious, philosophical or some other ideological domain, are in fact only the more or less clear expression of struggles of social classes, and that the existence and thereby the collisions, too, between these classes are in turn conditioned by the degree of development of their economic position, by the mode of their production and of their exchange determined by it. This law, which has the same significance for history as the law of the transformation of energy has for natural science -- this law gave him here, too, the key to an understanding of the history of the Second French Republic. He put his law to the test on these historical events, and even after thirty-three years we must still say that it has stood the test brilliantly.
Engels plainly endorses the idea of laws of motion of society and the idea of class conflict as the primary motor of historical change. "History is a history of class struggle." There is not much room for contingency or conjunctural causation here! But this is a dimension of Marxist theory that is plainly incorrect. Far better is to understand history in a more multi-factoral way in which contingency, conjunction, and agency all play a role.

Wednesday, September 23, 2015

Durkheim's nightmare

So here is Paris today ... thousands of anonymous strangers on Boulevard Saint-Germain at 5 pm, no sense of common bond or shared identity, a void of powerful values, lives of bleak consumerism. Anomie writ large. No friends, no community, no ceremony, no shared rituals. No eye contact on the street, no presumption of common cause. A Tom Waits world. It is Durkheim's nightmare about modernity.

Or is it? It is a city, to be sure, unlike a village. So the anonymity quotient is very high. But is it really a place of rampant anomie and hermetic individual dissatisfaction? Or is it instead a location for many thousands of micro-communities--religious, civic, ethnic, occupational? Is it a place with dense networks of friends, associates, and family, more intimately connected by cell phones than the village ever was through chance meetings at the market or the church? Is it in fact a powerful environment for human flourishing and social deepening?

In fact, it appears that the latter is the case for a large number of Parisians.

This may seem like a point that Durkheim anticipated through his distinction between mechanical and organic solidarity. But Durkheim's emphasis with the latter concept was on economic interdependency -- the division of labor -- rather than a recognition of the possibility of manifold micro-social relationships constituting a patchwork social world.

We might say that rather than anomie, the key shortcoming of modern cities like Paris -- or New York, Chicago, or London -- is social inequality and dramatically reduced opportunities for the bottom half of the income ladder. The people captured in the photo above have something in common beyond their cell phones -- they are mostly employed and affluent. But that profile of affluence is representative only of a fraction of the city's residents -- as documented by the excellent Observatoire des inégalités ( Just take the RER or Metro to the banlieue that surround the city to see the sharp separation of social worlds that Paris encompasses (

So it seems that the conception of the modern city implicit in Durkheim's thought is seriously wrong. The city is a different kind of locus for social interaction and individual life than the traditional town or village. But it is not inherently toxic for that reason. What is toxic is rather the dimension brought out by Marx -- the tendency of modern capitalist society to sharpen the separation between have's and have-nots.

It is not entirely an accident that I'm brought to think of Durkheim, since he spent much of his career less than a kilometer up Boule St.-Germain from this intersection. Ironically, Marx was here too in 1843.

Thursday, September 17, 2015

Microfoundations and mechanisms

The topics of microfoundations and causal mechanisms have come up frequently in this work. The microfoundations thesis maintains that social attributions and explanations based on macro-level entities and structures depend upon pathways at the level of the individual actors through which the entities and processes are maintained. The causal mechanisms thesis maintains that the best way of understanding causal assertions linking A to B is to identify the concrete causal mechanisms through which the powers of A bring about the properties of B.

Is there a relation between these two bodies of philosophical theory about the social world? There is, in a fairly obvious way. When we ask for the microfoundations of a hypothesized social process, we are really asking about the lower-level social mechanisms that bring the process about.

For example: What is it about an extended population that creates the observed features of the spread of rumor or panic? Or in other words, what are the social mechanisms through which socially interacting actors spread rumors or contribute to a broader occurrence of panic and fear? When we provide an account of the ways in which individuals communicate with each other and then demonstrate how messages diffuse through the given network structure, we have identified one of the social mechanisms of the social process in question.

Asking for the microfoundations of X is asking for an answer to two related questions: What is X (at the micro level)? And how does X work (also at the micro level)? The latter question can be paraphrased as: what are the sub-level mechanisms through which the X-level processes work? The first question is not so clearly a question about mechanisms; it is rather a question about composition. What is it about the substrate that gives rise to (constitutes) the observed macro-level properties of X? But in their book In Search of Mechanisms: Discoveries across the Life Sciences Craver and Darden argue that mechanisms play both roles. Mechanisms can be invoked to account for both process and structure (link). Here is their diagram illustrating the role that mechanisms can play with respect to higher-level structures and processes:

So here is a preliminary answer to the question of whether microfoundations and mechanisms are related. In the most immediate sense, we might say that the search for microfoundations is a search for a group of lower-level social mechanisms, to account for both the constitution and the causal dynamics of the higher-level structure. Searching for microfoundations involves learning more about the substrate of a given level of structure and process, and the causal mechanisms that occur at that lower level. Microfoundations is the question and mechanisms is the answer.

This response is not fully satisfactory, however, for several reasons.

First, there is an implication in this analysis that mechanisms live at the substrate level -- in the case of the social world, at the level of individual social actors. This is clearly assumed in the analytical sociology literature (Hedstrom, Dissecting the Social: On the Principles of Analytical Sociology). But this is an unnecessary and narrow stipulation about causal mechanisms. It is plausible to maintain that there are causal mechanisms at a range of levels (link); for example, at the cognitive level, the motivational level, the organizational level, or the system level (link).

Second, we might also observe that various social mechanisms themselves possess microfoundations. There are processes in the causal substrate that constitute the causal necessity of a specified mechanism. A spark in the presence of methane and oxygen brings about an explosion. This is a mechanism of combustion. The substrate is the chemical composition of methane and oxygen and the chemical processes that occur when an electrical spark is introduced into the environment. So the question of "level" is a relative one. A given set of objects and causal processes has its own substrate at a lower level, and simultaneously may serve as the substrate for objects and processes at higher levels.

We might also consider the idea that the two concepts have a different grammar. They play different roles in the language of science. The microfoundations conceptual scheme immediately invokes the idea of level and substrate. It brings along with it an ontological principle (the higher level is constituted by the properties of the substrate), and a partial methodological principle (the generative strategy of showing how higher-level processes come about as a consequence of the workings of the substrate). The mechanisms conceptual scheme does not inherently presuppose higher-level and lower-level structures; instead, a mechanism is something like a unit of causation, and it may be found at any level from molecular biology to organizational change.

(In an earlier post I considered a similar question, the relation between powers and mechanisms. There I argued that these two concepts are symmetrical: mechanisms lead us to powers, and powers lead us to mechanisms.)

Saturday, September 12, 2015

A survey of agent-based models

Federico Bianchi and Flaminio Squazzoni have published a very useful survey of the development and uses of agent-based models in the social sciences over the past twenty-five years in WIREs Comput Stat 2015 (link). The article is a very useful reference and discussion for anyone interested in the applicability of ABM within sociology.

Here is their general definition of an ABM:
Agent-based models (ABMs) are computer simulations of social interaction between heterogeneous agents (e.g., individuals, firms, or states), embedded in social structures (e.g., social networks, spatial neighborhoods, or institutional scaffolds). These are built to observe and analyze the emergence of aggregate outcomes. By manipulating behavioral or interaction model parameters, whether guided by empirical evidence or theory, micro-generative mechanisms can be explored that can account for macro-scale system behavior, that is, an existing time series of aggregate data or certain stylized facts. (284)
This definition highlights several important features of the ABM approach:
  • unlike traditional rational choice theory and microeconomics, it considers heterogeneous agents
  • it explicitly attempts to represent concrete particulars of the social environment within which agents act
  • it is a micro to macro strategy, deriving macro outcomes from micro activities
  • it permits a substantial degree of "experimentation" in the form of modification of base assumptions
  • it is possible to provide empirical evidence to validate or invalidate the ABM simulation of a given aggregate outcome 
Bianchi and Squazzoni note that the primary areas of application of agent-based models in social-science research include a relatively limited range of topics. The first of these topics included uncoordinated cooperation, reciprocity, and altruism. Robert Axelrod's work on repeated prisoners' dilemmas represents a key example of modeling efforts in this area (link).

A peculiar form of altruism is punishment: imposition of a cost on non-cooperators by other actors. Without punishment the exploitation strategy generally extinguishes the cooperation strategy in a range of situations. A "reciprocator" is an actor who is open to cooperation but who punishes previous non-cooperators on the next interaction. Bianchi and Squazzoni spend time describing an ABM developed by Bowles and Gintis (link) to evaluate the three strategies of Selfish, Reciprocator, and Cooperator, and a derived Shirking rate in a hypothetical and heterogeneous population of hunter-gatherers. Here is Bowles and Gintis' hypothesis:
The hypothesis we explore is that cooperation is maintained because many humans have a predisposition to punish those who violate group-beneficial norms, even when this reduces their fitness relative to other group members. Compelling evidence for the existence and importance of such altruistic punishment comes from controlled laboratory experiments, particularly the study of public goods, common pool resource, ultimatum, and other games.
And here is their central finding, according to Bianchi and Squazzoni:
They found that the robustness of cooperation depended on the coexistence of these behaviors at a group level and that strong reciprocators were functional in keeping the level of cheating under control in each group (see the shirking rate as a measure of resources lost by the group due to cheating in Figure 1). This was due to the fact that the higher the number of cooperators in a group without reciprocators, the higher the chance that the group disbanded due to high payoffs for shirking. (288)
Here is the graph of the incidence of the three strategies over the first 3000 periods of the simulation published in the Bowles and Gintis article:
This graph represents the relative frequency of the three types of hunter-gatherers in the population, along with a calculated shirking rate for each period. The Selfish profile remains the most frequent (between 40% and 50%, but Reciprocators and Cooperators reach relatively stable levels of frequency as well (between 30% and 40%, and between 20% and 30%). As Bowles and Gintis argue, it is the robust presence of Reciprocators that keeps the Selfish group in check; the willingness of Reciprocators to punish Selfish actors keeps the latter group from rising to full domination.

In this simulation the frequencies of Selfish and Shirking begin high (>85%) and quickly decline to a relatively stable rate. After 1000 iterations the three strategies attain relatively stable frequencies, with Selfish at about 38%, Reciprocator at 37%, Cooperator at 25%, and a shirking rate at about 11%.

It is tempting to read the study as representing a population that reaches a rough equilibrium. However, it is possible that the appearance of equilibrium conveyed by the graph above is deceptive. Other areas of complex phenomena raise the possibility that this is not a longterm equilibrium, but rather that some future combination of percentages of the three strategies may set off a chaotic redistribution of success rates. This is the key characteristic of a chaotic system: small fluctuations in parameters can lead to major deviations in outcomes.

Also interesting in Bianchi and Squazzoni's review is their treatment of efforts to use ABMs to model the diffusion of cultural and normative attitudes (293ff.). Attitudes are treated as local "contagion" factors, and the goal of the simulation is to model how different adjacencies influence the pattern of spread of the cultural features.
Agents interacted with neighbors with a probability dependent on the number of identical cultural features they shared. A mechanism of interpersonal influence was added to align one randomly selected dissimilar cultural feature of an agent to that of the partner, after interaction. (294ff.)
Social network characteristics have been incorporated into ABMs in this area.

Bianchi and Squazzoni also consider ABMs in the topic areas of collective behavior and social inequality. They draw a number of useful conclusions about the potential role that ABMs can play in sociology, including especially the importance of considering heterogeneous agents:
At a substantive level, these examples show that exploring the fundamental heterogeneity of individual behavior is of paramount importance to understand the emergence of social patterns. Cross-fertilization between experimental and computational research is a useful process. It shows us that by conflating the concept of rationality with that of self-interest, as in standard game theory and economics, we cannot account for the subtle social nuances that characterize individual behavior in social contexts. (298)
And they believe -- perhaps unexpectedly -- that the experience of building ABMs in a range of sociological contexts underlines the importance of institutions, norms, and social context:
Moreover, these ABM studies can help us to understand the importance of social contexts even when looking at individual behavior in a more micro-oriented perspective. The role of social influence and the fact that we are embedded in complex social networks have implications for the type of information we access and the types of behavior we are exposed to. (301)
This is a useful contribution for sociologists, as a foundation for a third alternative between statistical studies of sociological phenomena and high-level deductive theories of those phenomena. ABMs have the potential of allowing us to derive large social patterns from well chosen and empirically validated behavioral assumptions about actors.

I mentioned the common finding in complexity studies that even fairly simple systems possess the capacity for sudden instability. Here is a simulation of a three-body gravitational system which illustrates periods of relative stability and then abrupt destabilization.

ABMs permit us to model populations of interactive adaptive agents, and often the simulation produces important and representative patterns at the aggregate level. Here is an interesting predator-prey simulation on YouTube using an ABM approach by SSmithy87:

The author makes a key point at 2:15: the pattern of variation of predator and prey presented in the simulation is a well-known characteristic of predator-prey populations. (Red is predator and blue is prey.)

But the equations representing this relationship were not built into the model; instead, this characteristic pattern is generated by the model based on the simple behavioral assumptions made about prey and predators. This is a vivid demonstration of the novelty and importance of ABM simulations.

Friday, September 4, 2015

Range of reactions to realism about the social world

My recent post on realism in the social realm generated quite a bit of commentary, which I'd like to address here.

Brad Delong offered an incredulous response -- he seems to think that any form of scientific realism is ridiculous (link). He refers to the predictive success of Ptolemy's epicycles, and then says, "But just because your theory is good does not mean that the entities in your theory are "really there", whatever that might mean...." I responded on Twitter: "Delong doesn't like scientific realism -- really? Electrons, photons, curvature of space - all convenient fictions?" The position of instrumentalism is intellectually untenable, in my opinion -- the idea that scientific theories are just convenient computational devices for summarizing a range of observations. It is hard to see why we would have confidence in any complex technology depending on electricity, light, gravity, the properties of metals and semiconductors, if we didn't think that our scientific theories of these things were approximately true of real things in the world. So general rejection of scientific realism seems irrational to me. But the whole point of the post was that this reasoning doesn't extend over to the social sciences very easily; if we are to be realists about social entities, it needs to be on a different basis than the overall success of theories like Keynsianism, Marxism, or Parsonian sociology. They just aren't that successful!

There were quite a few comments (71) when Mark Thoma reposted this piece on economistsview. A number of the commentators were particularly interested in the question of the realism of economic knowledge. Daniel Hausman addresses the question of realism in economics in his article on the philosophy of economics in the Stanford Encyclopedia of Philosophy (link):
Economic methodologists have paid little attention to debates within philosophy of science between realists and anti-realists (van Fraassen 1980, Boyd 1984), because economic theories rarely postulate the existence of unobservable entities or properties, apart from variants of “everyday unobservables,” such as beliefs and desires. Methodologists have, on the other hand, vigorously debated the goals of economics, but those who argue that the ultimate goals are predictive (such as Milton Friedman) do so because of their interest in policy, not because they seek to avoid or resolve epistemological and semantic puzzles concerning references to unobservables.
Examples of economic concepts that commentators seemed to think could be interpreted realistically include concepts such as "economic disparity".  But this isn't a particularly arcane or unobservable theoretical concept. There is a lot of back-and-forth on the meaning of investment in Keynes's theory -- is it a well-defined concept? Is it a concept that can be understood realistically? The question of whether economics consists of a body of theory that might be interpreted realistically is a complicated one. Many technical economic concepts seem not to be referential; instead, they seem to be abstract concepts summarizing the results of large numbers of interactions by economic agents.

The most famous discussion of realism in economics is that offered by Milton Friedman in relation to the idea of economic rationality (Essays in Positive Economics); he doubts that economists need to assume that real economic actors do so on the basis of economic rationality. Rather, according to Friedman this is just a simplifying assumption to allow us to summarize a vast range of behavior. This is a hard position to accept, though; if agents are not making calculating choices about costs and benefits, then why should we expect a market to work in the ways our theories say it should? (Here is a good critique by Bruce Caldwell of Friedman's instrumentalism; link.)

And what about the concept of a market itself? Can we understand this concept realistically? Do markets really exist? Maybe the most we can say is something like this: there are many social settings where stuff is produced and exchanged. When exchange is solely or primarily governed by the individual self-interest of the buyers and sellers, we can say that a market exists. But we must also be careful to add that there are many different institutional and social settings where this condition is satisfied, so there is great variation across the particular "market settings" of different societies and communities. As a result, we need to be careful not to reify the concept of a market across all settings.

Michiel van Ingen made a different sort of point about my observations about social realism in his comment offered on Facebook. He thinks I am too easy on the natural sciences.
This piece strikes me as problematic. First, because physics is by no means as successful at prediction as it seems to suggest. A lot of physics is explanatorily quite powerful, but - like any other scientific discipline - can only predict in systemically closed systems. Contrasting physics with sociology and political science because the latter 'do not consist of unified deductive systems whose empirical success depends upon a derivation of distant observational consequences' is therefore unnecessarily dualistic. In addition, I'm not sure why the 'inference to the best explanation' element should be tied to predictive success as closely as it is in this piece. Inference to the best explanation is, by its very definition, perfectly applicable to EXPLANATION. And this applies across the sciences, whether 'natural' or 'social', though of course there is a significant difference between those sciences in which experimentation is plausible and helpful, and those in which it is not. This is not, by the way, the same as saying that natural sciences are experimental and social ones aren't. There are plenty of natural sciences which are largely non-experimental as well. And lest we forget, the hypothetico-deductive form of explanation DOES NOT WORK IN THE NATURAL SCIENCES EITHER!
This critique comes from the general idea that the natural sciences need a bit of debunking, in that various areas of natural science fail to live up to the positivist ideal of a precise predictive system of laws. That is fair enough; there are areas of imprecision and uncertainty in the natural sciences. But, as I responded to Delong above, the fact remains that we have a very good understanding of much of the physical realities and mechanisms that generate the phenomena we live with. Here is the response I offered Michiel:
Thank you, Michiel, for responding so thoughtfully. Your comments and qualifications about the natural sciences are correct, of course, in a number of ways. But really, I think we post-positivists need to recognize that the core areas of fundamental and classical physics, electromagnetic theory, gravitation theory, and chemistry including molecular biology, are remarkably successful in unifying, predicting, and explaining the phenomena within these domains. They are successful because extensive and mathematicized theories have been developed and extended, empirically tested, refined, and deployed to help account for new phenomena. And these theories, as big chunks, make assertions about the way nature works. This is where realism comes in: the chunks of theories about the nature of the atom, electromagnetic forces, gravitation, etc., can be understood to be approximately true of nature because otherwise we would have no way to account for the remarkable ability of these theories to handle new phenomena.
So I haven't been persuaded to change my mind about social realism as a result of these various comments. The grounds for realism about social processes, structures, and powers are different for many social sciences than for many natural sciences. We can probe quite a bit of the social world through mid-level and piecemeal research methods -- which means that we can learn quite a bit about the nature of the social world through these methods. Here is the key finding:
So it seems that we can justify being realists about class, field, habitus, market, coalition, ideology, organization, value system, ethnic identity, institution, and charisma, without relying at all on the hypothetico-deductive model of scientific knowledge upon which the "inference to the best explanation" argument depends. We can look at sociology and political science as loose ensembles of empirically informed theories and models of meso-level social processes and mechanisms, each of which is to a large degree independently verifiable. And this implies that social realism should be focused on mid-level social mechanisms and processes that can be identified in the domains of social phenomena that we have studied rather than sweeping concepts of social structures and entities.
(Sometimes social media debates give the impression of a nineteenth-century parliamentary shouting match -- which is why the Daumier drawing came to mind!)

Tuesday, September 1, 2015

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.)