Social explanation and causal mechanisms

To explain a social outcome or regularity, we need to provide an account of why and how it came about; and this means providing a causal analysis in terms of which the explanandum appears as a result.

Having a causal theory of a realm requires having an ontology: what kinds of things exist in this realm, and how do they work? Along with others, I offer a social ontology grounded in the actions and relations of socially constituted actors, which I refer to as methodological localism (link). (This is also the ontology asserted by the programme of "analytical sociology";  link.)

This entails, basically, that we need to understand all higher-level social entities and processes as being composed of the activities and thoughts of individual agents at a local level of social interaction; we need to be attentive to the pathways of aggregation through which these local-level activities aggregate to higher-level structures; and we need to pay attention to the iterative ways in which higher-level structures shape and influence individual agents.  Social outcomes are invariably constituted by and brought into being by socially constituted, socially situated individual actors (methodological localism). Both aspects of the view are important. By referring to "social constitution" we are invoking the fact that past social arrangements have created the social actor. By referring to "social situatedness" we invoke the idea that existing social practices and rules constrain and motivate the individual actor. So this view is not reductionist, in the sense of aiming to reduce social outcomes to pre-social individual activity.

We also want to refer to supra-individual actors -- firms, agencies, organizations, social movements, states. The social sciences are radically incomplete without such constructs. But all such references are bound by a requirement of microfoundations: if we attribute intentionality to a firm, we need to be able to sketch out an account of how the individuals of the firm are led to act in ways that lead to the postulated decision-making and action (link).

So, then: what is involved in asserting that social circumstance A causally produces social circumstance B? There are, of course, numerous well developed answers to this question: statistical inference based on correlations of occurrences, conditional probabilities, and necessary-sufficient condition analysis. My view, however, is that there is a more basic meaning of causation: A caused B iff there is a sequence of causal mechanisms leading from A to B. This approach is especially suitable for the social realm because, on the one hand, there are few strong statistical regularities among social outcomes, and on the other, it is feasible to identify social mechanisms through a variety of social research methods -- comparative analysis, process tracing, case studies, and the like.

The social mechanisms approach (and the scientific realism that lies behind it) goes back at least as early as the late 1980s. An early statement of the view was presented in my Varieties Of Social Explanation: An Introduction To The Philosophy Of Social Science in 1991.  Mario Bunge and Jon Elster took similar positions. The view took a large step forward, on the theory side, with the publication of Hedstrom and Swedberg's Social Mechanisms: An Analytical Approach to Social Theory (1998), and on the empirical research side with the publication of McAdam, Tarrow, and Tilly's Dynamics of Contention (2001). There are important differences; theorists within analytical sociology largely favor methodological individualism and mechanisms grounded in rational individuals, whereas Tilly and his colleagues favor "relational" mechanisms. But in each case the model of agent-centered explanations that either require microfoundations or are plainly compatible with such a requirement.  (Here is a recent post on causal mechanisms.)

Several social scientists have anticipated this approach through their own concrete analysis of aggregation phenomena.  A good illustration is Thomas Schelling.  His work presents a large number of examples of mundane social outcomes that he explains on the basis of simple individual-level choices and an aggregation mechanism (Micromotives and Macrobehavior, Choice and Consequence). Features of organized crime, traffic patterns, segregation, and dying seminars all come in for treatment.  Schelling demonstrates in concrete terms what sorts of things we can identify as "social mechanisms" and traces them back to the circumstances of action of individuals in social situations.

The framework of social mechanisms as a basis for social explanation raises an important question about the role and scope of generalizability that we expect from a social explanation. Briefly, the mechanisms identified here show a degree of generalizability; as McAdam, Tarrow and Tilly assert, social mechanisms can be expected to recur in other circumstances and times. But the event itself is one-of-a-kind. This is a familiar feature of Tilly's way of thinking about contentious events as well: the American Civil War was a singular historical event. But a good explanation will invoke mechanisms that recur elsewhere. We shouldn't expect to find general theories of civil wars; but our explanations of particular civil wars can invoke quasi-general theories of mid-level mechanisms of conflict and escalation. (Here is a recent posting on general and specific causal claims.)

Another important methodological question for this approach to social explanation is the issue of explaining general statistical patterns in social life.  What if we want to explain something more quantitative -- say a gradually rising divorce rate or the finding that co-habitants before marriage have higher divorce rates than non-co-habitants? On the social mechanisms approach, we would want two things. First, we would like an agent-level mechanism that explains the statistic; and second, we would like to find a common cause if the phenomenon is similar in several countries.

Finally, the actor-based mechanisms approach invites an area of study which is now being referred to as "aggregation dynamics" (link, link).  We need to have theories and tools that permit us to aggregate different micro-level processes over time into meso- and macro-outcomes, taking into account the complexity of causal interactions in a dynamic process.  The tools of agent-based modeling are relevant here (link).

Social explanation and causal mechanisms

To explain a social outcome or regularity, we need to provide an account of why and how it came about; and this means providing a causal analysis in terms of which the explanandum appears as a result.

Having a causal theory of a realm requires having an ontology: what kinds of things exist in this realm, and how do they work? Along with others, I offer a social ontology grounded in the actions and relations of socially constituted actors, which I refer to as methodological localism (link). (This is also the ontology asserted by the programme of "analytical sociology";  link.)

This entails, basically, that we need to understand all higher-level social entities and processes as being composed of the activities and thoughts of individual agents at a local level of social interaction; we need to be attentive to the pathways of aggregation through which these local-level activities aggregate to higher-level structures; and we need to pay attention to the iterative ways in which higher-level structures shape and influence individual agents.  Social outcomes are invariably constituted by and brought into being by socially constituted, socially situated individual actors (methodological localism). Both aspects of the view are important. By referring to "social constitution" we are invoking the fact that past social arrangements have created the social actor. By referring to "social situatedness" we invoke the idea that existing social practices and rules constrain and motivate the individual actor. So this view is not reductionist, in the sense of aiming to reduce social outcomes to pre-social individual activity.

We also want to refer to supra-individual actors -- firms, agencies, organizations, social movements, states. The social sciences are radically incomplete without such constructs. But all such references are bound by a requirement of microfoundations: if we attribute intentionality to a firm, we need to be able to sketch out an account of how the individuals of the firm are led to act in ways that lead to the postulated decision-making and action (link).

So, then: what is involved in asserting that social circumstance A causally produces social circumstance B? There are, of course, numerous well developed answers to this question: statistical inference based on correlations of occurrences, conditional probabilities, and necessary-sufficient condition analysis. My view, however, is that there is a more basic meaning of causation: A caused B iff there is a sequence of causal mechanisms leading from A to B. This approach is especially suitable for the social realm because, on the one hand, there are few strong statistical regularities among social outcomes, and on the other, it is feasible to identify social mechanisms through a variety of social research methods -- comparative analysis, process tracing, case studies, and the like.

The social mechanisms approach (and the scientific realism that lies behind it) goes back at least as early as the late 1980s. An early statement of the view was presented in my Varieties Of Social Explanation: An Introduction To The Philosophy Of Social Science in 1991.  Mario Bunge and Jon Elster took similar positions. The view took a large step forward, on the theory side, with the publication of Hedstrom and Swedberg's Social Mechanisms: An Analytical Approach to Social Theory (1998), and on the empirical research side with the publication of McAdam, Tarrow, and Tilly's Dynamics of Contention (2001). There are important differences; theorists within analytical sociology largely favor methodological individualism and mechanisms grounded in rational individuals, whereas Tilly and his colleagues favor "relational" mechanisms. But in each case the model of agent-centered explanations that either require microfoundations or are plainly compatible with such a requirement.  (Here is a recent post on causal mechanisms.)

Several social scientists have anticipated this approach through their own concrete analysis of aggregation phenomena.  A good illustration is Thomas Schelling.  His work presents a large number of examples of mundane social outcomes that he explains on the basis of simple individual-level choices and an aggregation mechanism (Micromotives and Macrobehavior, Choice and Consequence). Features of organized crime, traffic patterns, segregation, and dying seminars all come in for treatment.  Schelling demonstrates in concrete terms what sorts of things we can identify as "social mechanisms" and traces them back to the circumstances of action of individuals in social situations.

The framework of social mechanisms as a basis for social explanation raises an important question about the role and scope of generalizability that we expect from a social explanation. Briefly, the mechanisms identified here show a degree of generalizability; as McAdam, Tarrow and Tilly assert, social mechanisms can be expected to recur in other circumstances and times. But the event itself is one-of-a-kind. This is a familiar feature of Tilly's way of thinking about contentious events as well: the American Civil War was a singular historical event. But a good explanation will invoke mechanisms that recur elsewhere. We shouldn't expect to find general theories of civil wars; but our explanations of particular civil wars can invoke quasi-general theories of mid-level mechanisms of conflict and escalation. (Here is a recent posting on general and specific causal claims.)

Another important methodological question for this approach to social explanation is the issue of explaining general statistical patterns in social life.  What if we want to explain something more quantitative -- say a gradually rising divorce rate or the finding that co-habitants before marriage have higher divorce rates than non-co-habitants? On the social mechanisms approach, we would want two things. First, we would like an agent-level mechanism that explains the statistic; and second, we would like to find a common cause if the phenomenon is similar in several countries.

Finally, the actor-based mechanisms approach invites an area of study which is now being referred to as "aggregation dynamics" (link, link).  We need to have theories and tools that permit us to aggregate different micro-level processes over time into meso- and macro-outcomes, taking into account the complexity of causal interactions in a dynamic process.  The tools of agent-based modeling are relevant here (link).

Social explanation and causal mechanisms

To explain a social outcome or regularity, we need to provide an account of why and how it came about; and this means providing a causal analysis in terms of which the explanandum appears as a result.

Having a causal theory of a realm requires having an ontology: what kinds of things exist in this realm, and how do they work? Along with others, I offer a social ontology grounded in the actions and relations of socially constituted actors, which I refer to as methodological localism (link). (This is also the ontology asserted by the programme of "analytical sociology";  link.)

This entails, basically, that we need to understand all higher-level social entities and processes as being composed of the activities and thoughts of individual agents at a local level of social interaction; we need to be attentive to the pathways of aggregation through which these local-level activities aggregate to higher-level structures; and we need to pay attention to the iterative ways in which higher-level structures shape and influence individual agents.  Social outcomes are invariably constituted by and brought into being by socially constituted, socially situated individual actors (methodological localism). Both aspects of the view are important. By referring to "social constitution" we are invoking the fact that past social arrangements have created the social actor. By referring to "social situatedness" we invoke the idea that existing social practices and rules constrain and motivate the individual actor. So this view is not reductionist, in the sense of aiming to reduce social outcomes to pre-social individual activity.

We also want to refer to supra-individual actors -- firms, agencies, organizations, social movements, states. The social sciences are radically incomplete without such constructs. But all such references are bound by a requirement of microfoundations: if we attribute intentionality to a firm, we need to be able to sketch out an account of how the individuals of the firm are led to act in ways that lead to the postulated decision-making and action (link).

So, then: what is involved in asserting that social circumstance A causally produces social circumstance B? There are, of course, numerous well developed answers to this question: statistical inference based on correlations of occurrences, conditional probabilities, and necessary-sufficient condition analysis. My view, however, is that there is a more basic meaning of causation: A caused B iff there is a sequence of causal mechanisms leading from A to B. This approach is especially suitable for the social realm because, on the one hand, there are few strong statistical regularities among social outcomes, and on the other, it is feasible to identify social mechanisms through a variety of social research methods -- comparative analysis, process tracing, case studies, and the like.

The social mechanisms approach (and the scientific realism that lies behind it) goes back at least as early as the late 1980s. An early statement of the view was presented in my Varieties Of Social Explanation: An Introduction To The Philosophy Of Social Science in 1991.  Mario Bunge and Jon Elster took similar positions. The view took a large step forward, on the theory side, with the publication of Hedstrom and Swedberg's Social Mechanisms: An Analytical Approach to Social Theory (1998), and on the empirical research side with the publication of McAdam, Tarrow, and Tilly's Dynamics of Contention (2001). There are important differences; theorists within analytical sociology largely favor methodological individualism and mechanisms grounded in rational individuals, whereas Tilly and his colleagues favor "relational" mechanisms. But in each case the model of agent-centered explanations that either require microfoundations or are plainly compatible with such a requirement.  (Here is a recent post on causal mechanisms.)

Several social scientists have anticipated this approach through their own concrete analysis of aggregation phenomena.  A good illustration is Thomas Schelling.  His work presents a large number of examples of mundane social outcomes that he explains on the basis of simple individual-level choices and an aggregation mechanism (Micromotives and Macrobehavior, Choice and Consequence). Features of organized crime, traffic patterns, segregation, and dying seminars all come in for treatment.  Schelling demonstrates in concrete terms what sorts of things we can identify as "social mechanisms" and traces them back to the circumstances of action of individuals in social situations.

The framework of social mechanisms as a basis for social explanation raises an important question about the role and scope of generalizability that we expect from a social explanation. Briefly, the mechanisms identified here show a degree of generalizability; as McAdam, Tarrow and Tilly assert, social mechanisms can be expected to recur in other circumstances and times. But the event itself is one-of-a-kind. This is a familiar feature of Tilly's way of thinking about contentious events as well: the American Civil War was a singular historical event. But a good explanation will invoke mechanisms that recur elsewhere. We shouldn't expect to find general theories of civil wars; but our explanations of particular civil wars can invoke quasi-general theories of mid-level mechanisms of conflict and escalation. (Here is a recent posting on general and specific causal claims.)

Another important methodological question for this approach to social explanation is the issue of explaining general statistical patterns in social life.  What if we want to explain something more quantitative -- say a gradually rising divorce rate or the finding that co-habitants before marriage have higher divorce rates than non-co-habitants? On the social mechanisms approach, we would want two things. First, we would like an agent-level mechanism that explains the statistic; and second, we would like to find a common cause if the phenomenon is similar in several countries.

Finally, the actor-based mechanisms approach invites an area of study which is now being referred to as "aggregation dynamics" (link, link).  We need to have theories and tools that permit us to aggregate different micro-level processes over time into meso- and macro-outcomes, taking into account the complexity of causal interactions in a dynamic process.  The tools of agent-based modeling are relevant here (link).

Microfoundationalism

detail: Lynn Cazabon photo

The philosophy of social science encompasses several important tasks, and key among them is to provide theories of social ontology and social explanation. What is the nature of social entities? What is needed in order to substantiate a claim of social causation? What constitutes an acceptable social explanation?

The concept of microfoundations is relevant to each of these domains. A microfoundation is:

a specification of the ways in which the properties and structure of a higher-level entity are produced by the activities and properties of lower-level entities.

In the case of the social sciences, this amounts to:

a specification of the ways that properties, structural features, and causal powers of a social entity are produced and reproduced by the actions and dispositions of socially situated individuals.

This concept is relevant to social ontology in this way. Social entities are understood to be compositional; they are assemblages constituted and maintained by the mentality and actions of individuals. So providing an account of the microfoundations of a structure or causal connection -- say a paramilitary organization or of the causal connection between high interest rates and the incidence of alcohol abuse -- is a specification of the composition of the social-level fact. It is a description of the agent-level relationships and patterns of behavior that cohere in such a way as to bring about the higher-level structure or causal relationship.

The concept of microfoundations is directly relevant to explanation. If we assert a causal or explanatory relation between one social entity or condition and another, we must be prepared to offer a credible sketch of the ways in which this influence is conveyed through the mentalities and actions of individuals.

Much turns, however, on what precisely we mean to require of a satisfactory explanation: a full specification of the microfoundations in every case, or a sketch of the way that a given social-level process might readily be embodied in individual-level activities. If we go with the second version, we are licensing a fair amount of autonomy for the social-level explanation; whereas if we go with the first version, we are tending towards a requirement of reductionism from higher to lower levels in every case. I am inclined to interpret the requirement in the second way; it doesn't seem necessary to disaggregate every claim like "organizational deficiencies at the Bhopal chemical plant caused the devastating chemical spill" onto specific individual-level activities. We understand pretty well, in a generic way, what the microfoundations of organizations are, and it isn't necessary to provide a detailed account in order to have a satisfactory explanation.

The ontological position associated with microfoundationalism falls in the general area of methodological individualism and reductionism, in that it insists on the compositional nature of the social. However, there is a recursive aspect of the theory that distinguishes it from strict reductionism. The individuals to which microfoundations are traced are not a-social; rather, their psychology, beliefs and motives are constituted and shaped by the social forces they and others constitute. So the microfoundational account of the workings of a paramilitary organization may well refer to the locally embodied effects of that organization on the current psychology of the members of the organization; and their behavior in turn reproduces the organization in the next iteration. This is why I prefer the idea of methodological localism over that of methodological individualism (link).

The theory of microfoundations is also very consistent with the idea of social mechanisms. When we ask about the microfoundations of a social process, we are asking about the mechanisms that exist at a lower level that create and maintain the social process.

One way of motivating the theory of microfoundations is to observe that it is a prescription against "magical thinking" in the social realm. There is no "social stuff" that has its own persistent causal and structural characteristics; rather, all social phenomena are constituted by patterns of behavior and thought of populations of individual human beings. And likewise, social events and structures do not have inherently social causal properties; rather, the causal properties of a social structure or event are constituted by the patterns of behavior and thought of the individuals who constitute them and nothing else.

The theory of supervenience is often invoked to express the idea that social entities and properties are constituted by individuals. (Jaegwon Kim is the primary creator of the theory of supervenience in the philosophy of mind; Supervenience and Mind: Selected Philosophical Essays.) This basic idea is expressed as:

No difference at level N without some difference at lower level K.

The advantage of the theory of supervenience is that it provides a way of recognizing the compositional nature of higher-level entities without presupposing explanatory reductionism from one level to the lower level.

The explicit idea of microfoundations appears to have been first developed in the domain of microeconomics; there it referred to the necessity of deriving macroeconomic phenomena from the premises of rational economic behavior (Weintraub, Microfoundations: The Compatibility of Microeconomics and Macroeconomics). (Here is an interesting article by van den Bergh and Gowdy on recent analysis of the microfoundations debate in economics.) Maarten Jansen describes the theory of microfoundations in economics in his entry in The New Palgrave Dictionary of Economics and the Law:

The quest to understand microfoundations is an effort to understand aggregate economic phenomena in terms of the behavior of individual economic entities and their interactions. These interactions can involve both market and non-market interactions. The quest for microfoundations grew out of the widely felt, but rarely explicitly stated, desire to stick to the position of methodological individualism ..., and also out of the growing uneasiness among economists in the late 1950s and 1960s with the co-existence of two subdisciplines, namely microeconomics and macroeconomics, both aiming at explaining features of the economy as a whole. Methodological individualism, as explained in the entry on the topic, is the view according to which proper explanations in the social sciences are those that are grounded in individual motivations and their behavior.

The idea of microfoundations is now important in many areas of the social sciences, including especially sociology and political science. Particularly important were ideas formulated by James Coleman in Foundations of Social Theory. Coleman doesn't use the term "microfoundations" explicitly in this work, but his analysis of the relationship between the macro and the micro seems to imply a requirement of providing microfoundations as a condition on good explanations in the social sciences. The Coleman boat (link) seems to be a graphical way of representing the microfoundations of a macro-level fact.

A second mode of explanation of the behavior of social systems entails examining processes internal to the system, involving its component parts, or units at a level below that of the system. The prototypical case is that in which the component parts are individuals who are members of the social system. In other cases the component parts may be institutions within the system or subgroups that are part of the system. In all cases the analysis can be seen as moving to a lower level than that of the system, explaining the behavior of the system by recourse to the behavior of its parts. This mode of explanation is not uniquely quantitative or uniquely qualitative, but may be either. ... I call [this] the internal analysis of system behavior. (2)

Coleman's view here is complex, though, and isn't entirely unambiguous. Consider this qualification a few pages later, which refers unexpectedly to "emergent phenomena" and intermediate levels of explanatory mechanisms between the macro and the micro:

Those readers familiar with debates and discussions on methodological holism and methodological individualism will recognize that the position taken above on explanation is a variant of methodological individualism. But it is a special variant. No assumption is made that the explanation of systemic behavior consists of nothing more than individual actions and orientations, taken in aggregate. The interaction among individuals is seen to result in emergent phenomena at the system level, that is, phenomena that were neither intended nor predicted by the individuals. Furthermore, there is no implication that for a given purpose an explanation must be taken all the way to the individual level to be satisfactory. The criterion is instead pragmatic. (5)

Other more explicit advocates of the microfoundations principle are Jon Elster, John Roemer, Adam Przeworski, and other contributors to the theories of analytical Marxism (Analytical Marxism). Here is how I attempted to synthesize some of this thinking in 1994:

Marxist thinkers have argued that macro-explanations stand in need of microfoundations: detailed accounts of the pathways by which macro-level social patterns come about. These theorists have held that it is necessary to provide an account of the circumstsances of individual choice and action that give rise to aggregate patterns if macro-explanations are to be adequate. Thus in order to explain the policies of the capitalist state it is not sufficient to observe that this state tends to serve capitalist interests; we need to have an account of the processes through which state policies are shaped or controlled so as to produce this outcome. ("Microfoundations of Marxism," reprinted in D. Little, Microfoundations, Methods, and Causation, 4)

As noted in a prior post, the idea of microfoundations is also a core constituent of the methodology of analytical sociology (Peter Hedström, Dissecting the Social: On the Principles of Analytical Sociology).

In short, a fairly wide range of social science research today embraces the general idea of providing microfoundations for macro-level assertions. And this seems to be a very reasonable requirement, given what we know about how social entities, processes, and forces are composed.

Microfoundationalism

detail: Lynn Cazabon photo

The philosophy of social science encompasses several important tasks, and key among them is to provide theories of social ontology and social explanation. What is the nature of social entities? What is needed in order to substantiate a claim of social causation? What constitutes an acceptable social explanation?

The concept of microfoundations is relevant to each of these domains. A microfoundation is:

a specification of the ways in which the properties and structure of a higher-level entity are produced by the activities and properties of lower-level entities.

In the case of the social sciences, this amounts to:

a specification of the ways that properties, structural features, and causal powers of a social entity are produced and reproduced by the actions and dispositions of socially situated individuals.

This concept is relevant to social ontology in this way. Social entities are understood to be compositional; they are assemblages constituted and maintained by the mentality and actions of individuals. So providing an account of the microfoundations of a structure or causal connection -- say a paramilitary organization or of the causal connection between high interest rates and the incidence of alcohol abuse -- is a specification of the composition of the social-level fact. It is a description of the agent-level relationships and patterns of behavior that cohere in such a way as to bring about the higher-level structure or causal relationship.

The concept of microfoundations is directly relevant to explanation. If we assert a causal or explanatory relation between one social entity or condition and another, we must be prepared to offer a credible sketch of the ways in which this influence is conveyed through the mentalities and actions of individuals.

Much turns, however, on what precisely we mean to require of a satisfactory explanation: a full specification of the microfoundations in every case, or a sketch of the way that a given social-level process might readily be embodied in individual-level activities. If we go with the second version, we are licensing a fair amount of autonomy for the social-level explanation; whereas if we go with the first version, we are tending towards a requirement of reductionism from higher to lower levels in every case. I am inclined to interpret the requirement in the second way; it doesn't seem necessary to disaggregate every claim like "organizational deficiencies at the Bhopal chemical plant caused the devastating chemical spill" onto specific individual-level activities. We understand pretty well, in a generic way, what the microfoundations of organizations are, and it isn't necessary to provide a detailed account in order to have a satisfactory explanation.

The ontological position associated with microfoundationalism falls in the general area of methodological individualism and reductionism, in that it insists on the compositional nature of the social. However, there is a recursive aspect of the theory that distinguishes it from strict reductionism. The individuals to which microfoundations are traced are not a-social; rather, their psychology, beliefs and motives are constituted and shaped by the social forces they and others constitute. So the microfoundational account of the workings of a paramilitary organization may well refer to the locally embodied effects of that organization on the current psychology of the members of the organization; and their behavior in turn reproduces the organization in the next iteration. This is why I prefer the idea of methodological localism over that of methodological individualism (link).

The theory of microfoundations is also very consistent with the idea of social mechanisms. When we ask about the microfoundations of a social process, we are asking about the mechanisms that exist at a lower level that create and maintain the social process.

One way of motivating the theory of microfoundations is to observe that it is a prescription against "magical thinking" in the social realm. There is no "social stuff" that has its own persistent causal and structural characteristics; rather, all social phenomena are constituted by patterns of behavior and thought of populations of individual human beings. And likewise, social events and structures do not have inherently social causal properties; rather, the causal properties of a social structure or event are constituted by the patterns of behavior and thought of the individuals who constitute them and nothing else.

The theory of supervenience is often invoked to express the idea that social entities and properties are constituted by individuals. (Jaegwon Kim is the primary creator of the theory of supervenience in the philosophy of mind; Supervenience and Mind: Selected Philosophical Essays.) This basic idea is expressed as:

No difference at level N without some difference at lower level K.

The advantage of the theory of supervenience is that it provides a way of recognizing the compositional nature of higher-level entities without presupposing explanatory reductionism from one level to the lower level.

The explicit idea of microfoundations appears to have been first developed in the domain of microeconomics; there it referred to the necessity of deriving macroeconomic phenomena from the premises of rational economic behavior (Weintraub, Microfoundations: The Compatibility of Microeconomics and Macroeconomics). (Here is an interesting article by van den Bergh and Gowdy on recent analysis of the microfoundations debate in economics.) Maarten Jansen describes the theory of microfoundations in economics in his entry in The New Palgrave Dictionary of Economics and the Law:

The quest to understand microfoundations is an effort to understand aggregate economic phenomena in terms of the behavior of individual economic entities and their interactions. These interactions can involve both market and non-market interactions. The quest for microfoundations grew out of the widely felt, but rarely explicitly stated, desire to stick to the position of methodological individualism ..., and also out of the growing uneasiness among economists in the late 1950s and 1960s with the co-existence of two subdisciplines, namely microeconomics and macroeconomics, both aiming at explaining features of the economy as a whole. Methodological individualism, as explained in the entry on the topic, is the view according to which proper explanations in the social sciences are those that are grounded in individual motivations and their behavior.

The idea of microfoundations is now important in many areas of the social sciences, including especially sociology and political science. Particularly important were ideas formulated by James Coleman in Foundations of Social Theory. Coleman doesn't use the term "microfoundations" explicitly in this work, but his analysis of the relationship between the macro and the micro seems to imply a requirement of providing microfoundations as a condition on good explanations in the social sciences. The Coleman boat (link) seems to be a graphical way of representing the microfoundations of a macro-level fact.

A second mode of explanation of the behavior of social systems entails examining processes internal to the system, involving its component parts, or units at a level below that of the system. The prototypical case is that in which the component parts are individuals who are members of the social system. In other cases the component parts may be institutions within the system or subgroups that are part of the system. In all cases the analysis can be seen as moving to a lower level than that of the system, explaining the behavior of the system by recourse to the behavior of its parts. This mode of explanation is not uniquely quantitative or uniquely qualitative, but may be either. ... I call [this] the internal analysis of system behavior. (2)

Coleman's view here is complex, though, and isn't entirely unambiguous. Consider this qualification a few pages later, which refers unexpectedly to "emergent phenomena" and intermediate levels of explanatory mechanisms between the macro and the micro:

Those readers familiar with debates and discussions on methodological holism and methodological individualism will recognize that the position taken above on explanation is a variant of methodological individualism. But it is a special variant. No assumption is made that the explanation of systemic behavior consists of nothing more than individual actions and orientations, taken in aggregate. The interaction among individuals is seen to result in emergent phenomena at the system level, that is, phenomena that were neither intended nor predicted by the individuals. Furthermore, there is no implication that for a given purpose an explanation must be taken all the way to the individual level to be satisfactory. The criterion is instead pragmatic. (5)

Other more explicit advocates of the microfoundations principle are Jon Elster, John Roemer, Adam Przeworski, and other contributors to the theories of analytical Marxism (Analytical Marxism). Here is how I attempted to synthesize some of this thinking in 1994:

Marxist thinkers have argued that macro-explanations stand in need of microfoundations: detailed accounts of the pathways by which macro-level social patterns come about. These theorists have held that it is necessary to provide an account of the circumstsances of individual choice and action that give rise to aggregate patterns if macro-explanations are to be adequate. Thus in order to explain the policies of the capitalist state it is not sufficient to observe that this state tends to serve capitalist interests; we need to have an account of the processes through which state policies are shaped or controlled so as to produce this outcome. ("Microfoundations of Marxism," reprinted in D. Little, Microfoundations, Methods, and Causation, 4)

As noted in a prior post, the idea of microfoundations is also a core constituent of the methodology of analytical sociology (Peter Hedström, Dissecting the Social: On the Principles of Analytical Sociology).

In short, a fairly wide range of social science research today embraces the general idea of providing microfoundations for macro-level assertions. And this seems to be a very reasonable requirement, given what we know about how social entities, processes, and forces are composed.

Microfoundationalism

detail: Lynn Cazabon photo

The philosophy of social science encompasses several important tasks, and key among them is to provide theories of social ontology and social explanation. What is the nature of social entities? What is needed in order to substantiate a claim of social causation? What constitutes an acceptable social explanation?

The concept of microfoundations is relevant to each of these domains. A microfoundation is:

a specification of the ways in which the properties and structure of a higher-level entity are produced by the activities and properties of lower-level entities.

In the case of the social sciences, this amounts to:

a specification of the ways that properties, structural features, and causal powers of a social entity are produced and reproduced by the actions and dispositions of socially situated individuals.

This concept is relevant to social ontology in this way. Social entities are understood to be compositional; they are assemblages constituted and maintained by the mentality and actions of individuals. So providing an account of the microfoundations of a structure or causal connection -- say a paramilitary organization or of the causal connection between high interest rates and the incidence of alcohol abuse -- is a specification of the composition of the social-level fact. It is a description of the agent-level relationships and patterns of behavior that cohere in such a way as to bring about the higher-level structure or causal relationship.

The concept of microfoundations is directly relevant to explanation. If we assert a causal or explanatory relation between one social entity or condition and another, we must be prepared to offer a credible sketch of the ways in which this influence is conveyed through the mentalities and actions of individuals.

Much turns, however, on what precisely we mean to require of a satisfactory explanation: a full specification of the microfoundations in every case, or a sketch of the way that a given social-level process might readily be embodied in individual-level activities. If we go with the second version, we are licensing a fair amount of autonomy for the social-level explanation; whereas if we go with the first version, we are tending towards a requirement of reductionism from higher to lower levels in every case. I am inclined to interpret the requirement in the second way; it doesn't seem necessary to disaggregate every claim like "organizational deficiencies at the Bhopal chemical plant caused the devastating chemical spill" onto specific individual-level activities. We understand pretty well, in a generic way, what the microfoundations of organizations are, and it isn't necessary to provide a detailed account in order to have a satisfactory explanation.

The ontological position associated with microfoundationalism falls in the general area of methodological individualism and reductionism, in that it insists on the compositional nature of the social. However, there is a recursive aspect of the theory that distinguishes it from strict reductionism. The individuals to which microfoundations are traced are not a-social; rather, their psychology, beliefs and motives are constituted and shaped by the social forces they and others constitute. So the microfoundational account of the workings of a paramilitary organization may well refer to the locally embodied effects of that organization on the current psychology of the members of the organization; and their behavior in turn reproduces the organization in the next iteration. This is why I prefer the idea of methodological localism over that of methodological individualism (link).

The theory of microfoundations is also very consistent with the idea of social mechanisms. When we ask about the microfoundations of a social process, we are asking about the mechanisms that exist at a lower level that create and maintain the social process.

One way of motivating the theory of microfoundations is to observe that it is a prescription against "magical thinking" in the social realm. There is no "social stuff" that has its own persistent causal and structural characteristics; rather, all social phenomena are constituted by patterns of behavior and thought of populations of individual human beings. And likewise, social events and structures do not have inherently social causal properties; rather, the causal properties of a social structure or event are constituted by the patterns of behavior and thought of the individuals who constitute them and nothing else.

The theory of supervenience is often invoked to express the idea that social entities and properties are constituted by individuals. (Jaegwon Kim is the primary creator of the theory of supervenience in the philosophy of mind; Supervenience and Mind: Selected Philosophical Essays.) This basic idea is expressed as:

No difference at level N without some difference at lower level K.

The advantage of the theory of supervenience is that it provides a way of recognizing the compositional nature of higher-level entities without presupposing explanatory reductionism from one level to the lower level.

The explicit idea of microfoundations appears to have been first developed in the domain of microeconomics; there it referred to the necessity of deriving macroeconomic phenomena from the premises of rational economic behavior (Weintraub, Microfoundations: The Compatibility of Microeconomics and Macroeconomics). (Here is an interesting article by van den Bergh and Gowdy on recent analysis of the microfoundations debate in economics.) Maarten Jansen describes the theory of microfoundations in economics in his entry in The New Palgrave Dictionary of Economics and the Law:

The quest to understand microfoundations is an effort to understand aggregate economic phenomena in terms of the behavior of individual economic entities and their interactions. These interactions can involve both market and non-market interactions. The quest for microfoundations grew out of the widely felt, but rarely explicitly stated, desire to stick to the position of methodological individualism ..., and also out of the growing uneasiness among economists in the late 1950s and 1960s with the co-existence of two subdisciplines, namely microeconomics and macroeconomics, both aiming at explaining features of the economy as a whole. Methodological individualism, as explained in the entry on the topic, is the view according to which proper explanations in the social sciences are those that are grounded in individual motivations and their behavior.

The idea of microfoundations is now important in many areas of the social sciences, including especially sociology and political science. Particularly important were ideas formulated by James Coleman in Foundations of Social Theory. Coleman doesn't use the term "microfoundations" explicitly in this work, but his analysis of the relationship between the macro and the micro seems to imply a requirement of providing microfoundations as a condition on good explanations in the social sciences. The Coleman boat (link) seems to be a graphical way of representing the microfoundations of a macro-level fact.

A second mode of explanation of the behavior of social systems entails examining processes internal to the system, involving its component parts, or units at a level below that of the system. The prototypical case is that in which the component parts are individuals who are members of the social system. In other cases the component parts may be institutions within the system or subgroups that are part of the system. In all cases the analysis can be seen as moving to a lower level than that of the system, explaining the behavior of the system by recourse to the behavior of its parts. This mode of explanation is not uniquely quantitative or uniquely qualitative, but may be either. ... I call [this] the internal analysis of system behavior. (2)

Coleman's view here is complex, though, and isn't entirely unambiguous. Consider this qualification a few pages later, which refers unexpectedly to "emergent phenomena" and intermediate levels of explanatory mechanisms between the macro and the micro:

Those readers familiar with debates and discussions on methodological holism and methodological individualism will recognize that the position taken above on explanation is a variant of methodological individualism. But it is a special variant. No assumption is made that the explanation of systemic behavior consists of nothing more than individual actions and orientations, taken in aggregate. The interaction among individuals is seen to result in emergent phenomena at the system level, that is, phenomena that were neither intended nor predicted by the individuals. Furthermore, there is no implication that for a given purpose an explanation must be taken all the way to the individual level to be satisfactory. The criterion is instead pragmatic. (5)

Other more explicit advocates of the microfoundations principle are Jon Elster, John Roemer, Adam Przeworski, and other contributors to the theories of analytical Marxism (Analytical Marxism). Here is how I attempted to synthesize some of this thinking in 1994:

Marxist thinkers have argued that macro-explanations stand in need of microfoundations: detailed accounts of the pathways by which macro-level social patterns come about. These theorists have held that it is necessary to provide an account of the circumstsances of individual choice and action that give rise to aggregate patterns if macro-explanations are to be adequate. Thus in order to explain the policies of the capitalist state it is not sufficient to observe that this state tends to serve capitalist interests; we need to have an account of the processes through which state policies are shaped or controlled so as to produce this outcome. ("Microfoundations of Marxism," reprinted in D. Little, Microfoundations, Methods, and Causation, 4)

As noted in a prior post, the idea of microfoundations is also a core constituent of the methodology of analytical sociology (Peter Hedström, Dissecting the Social: On the Principles of Analytical Sociology).

In short, a fairly wide range of social science research today embraces the general idea of providing microfoundations for macro-level assertions. And this seems to be a very reasonable requirement, given what we know about how social entities, processes, and forces are composed.

Dissecting the social

The past dozen years or so have witnessed the emergence of a distinctive approach to the social sciences that its practitioners refer to as "analytical sociology." Peter Hedström's Dissecting the Social: On the Principles of Analytical Sociology (2005) serves as a manifesto for the approach, and Pierre Demeulenaere, ed., Analytical Sociology and Social Mechanisms, and Peter Hedström and Peter Bearman, eds., The Oxford Handbook of Analytical Sociology provide substantive foundations for several areas of research within this approach.  And the European Network of Analytical Sociologists provides an institutional framework within which research approaches and findings can be shared (link).

Hedström describes the analytical sociology approach in these terms:

Although the term analytical sociology is not commonly used, the type of sociology designated by the term has an important history that can be traced back to the works of late nineteenth- and early twentieth-century sociologists such as Max Weber and Alexis de Tocqueville, and to prominent mid-twentieth-century sociologists such as the early Talcott Parsons and Robert K. Merton. Among contemporary social scientists, four in particular have profoundly influenced the analytical approach.  They are Jon Elster, Raymond Boudon, Thomas Schelling and James Coleman. (kl 113)

One important characteristic of the analytical approach is that it aims to gain understanding by dissecting the social phenomena to be explained.  To dissect, as the term is used here, is to decompose a complex totality into its constituent entities and activities and then to bring into focus what is believed to be its most essential elements. (kl 65)

And here is how Hedström and Bearman describe the approach in the Handbook:

Analytical sociology is concerned first and foremost with explaining important social facts such as network structures, patterns of residential segregation, typical beliefs, cultural tastes, common ways of acting, and so forth. It explains such facts not merely by relating them to other social facts -- an exercise that does not provide an explanation -- but by detailing in clear and precise ways the mechanisms through which the social facts under consideration are brought about.  In short, analytical sociology is a strategy for understanding the social world. (3-4)

Two interrelated aspects are of particular importance: the explanatory principles guiding the approach and the type of explanatory factors being evoked. Analytical sociology explains by detailing mechanisms through which social facts are brought about, and these mechanisms invariably refer to individuals' actions and the relations that link actors to one another. (4)

In my assessment, AS rests on three central ideas.

First, there is the idea that social outcomes need to be explained on the basis of the actions of individuals.  This position is referred to variously as methodological individualism, methodological localism, or microfoundationalism.  It is often illustrated by reference to "Coleman's Boat" in James Coleman, Foundations of Social Theory (1994:8) describing the relationship that ought to exist between macro and micro social phenomena:

The diagram indicates the relationship between macro-factors (Protestant religious doctrine, capitalism) and the micro factors that underlie their causal relation (values, economic behavior).  Here are a few of Hedström's formulations of this ontological position:

In sociological inquiries, however, the core entity always tends to be the actors in the social system being analyzed, and the core activity tends to be the actions of these actors. (kl 106)

To be explanatory a theory must specify the set of causal mechanisms that are likely to have brought about the change, and this requires one to demonstrate how macro states at one point in time influence individuals' actions, and how these actions bring about new macro states at a later point in time. (kl 143)

Further, Hedström is drawn to a broad version of rational-choice theory -- what he calls the "Desire-Belief-Opportunity theory".

Desires (D), beliefs (B) and opportunities (O) are the primary theoretical terms upon which the analysis of action and interaction will be based.  ... The desires, beliefs and opportunities of an actor are here seen as the proximate causes of the actor's action. (kl 507)

This is a variant of rational choice theory, because the actor's choice is interpreted along these lines: given the desires the actor possesses, given the beliefs he/she has about the environment of choice, and given the opportunities he/she confronts, action A is a sensible way of satisfying the desires. It is worth pointing out that it is possible to be microfoundationalist about macro outcomes while not assuming that individual actions are driven by rational calculations. Microfoundationalism is distinct from the assumption of individual rationality.

Second is the idea that social actors are socially situated and socially constructed; the values, perceptions, emotions, and modes of reasoning of the actor are influenced by social institutions, and their current behavior is constrained and incented by existing institutions. (This position has a lot in common with the methodological localism that I've defended.) Practitioners of analytical sociology are not reductionist about social behavior, at least in the way that economists tend to be; they want to leave room conceptually for the observation that social structures and norms influence individual behavior and that individuals are not unadorned utility maximizers. (Gary Becker's effort to explain much of social life on the basis of the premise of maximizing utility is an example of the reductionist tendency of purist rational choice theory; Uncommon Sense: Economic Insights, from Marriage to Terrorism.) In the Hedström-Bearman introduction to the Handbook they put the point this way:

Structural individualism is a methodological doctrine according to which social facts should be explained as the intended or unintended outcomes of individuals' actions. Structural individualism differs from traditional methodological individualism in attributing substantial explanatory importance to the social structures in which individuals are embedded. (4)

This is a direction of thought that is not well advanced within analytical sociology, but would repay further research.  There is no reason why a microfoundational approach should not take seriously the causal dynamics of identity formation and the formation of the individual's cognitive, practical, and emotional frameworks.  These are relevant to behavior, and they are plainly driven by concrete social processes and institutions.

Third, and most distinctive, is the idea that social explanations need to be grounded in a hypothesis about the concrete social causal mechanisms that constitute the causal connection between one event and another. Mechanisms rather than regularities or necessary/sufficient conditions provide the fundamental grounding of causal relations and need to be at the center of causal research.  (This is a position developed and discussed many times in this blog; thread.) This approach has several intellectual foundations, but one is the tradition of critical realism and some of the ideas developed by Roy Bhaskar (A Realist Theory of Science). Hedström advocates for a theory of causal explanation that is grounded in the idea of a causal mechanism:

The position taken here, rather, is that mechanism-based explanations are the most appropriate type of explanations for the social sciences.  The core idea behind the mechanism approach is that we explain a social phenomenon by referring to a constellation of entities and activities, typically actors and their actions, that are linked to one another in such a way that they regularly bring about the type of phenomenon we seek to explain. (kl 65)

A social mechanism, as defined here, is a constellation of entities and activities that are linked to one another in such a way that they regularly bring about a particular type of outcome. (kl 181)

In addition to these three orienting frameworks for analytical sociology, there is a fourth characteristic that should be mentioned.  This is the idea that the tools of computer-based simulation of the aggregate consequences of individual behavior can be a very powerful tool for sociological research and explanation.  So the tools of agent-based modeling and other simulations of complex systems have a very natural place within the armoire of analytical sociology.

In short, analytical sociology is a compact, clear approach to the problem of understanding social outcomes.  It lays the ground for the productive body of research questions associated with the "aggregation dynamics" research program (link).  There is active, innovative research being done within this framework of ideas, especially in Germany, Sweden, and Great Britain.  And its clarity permits, in turn, the formulation of rather specific critiques from researchers in other sociological traditions who reject one or another of the key components.  (This is the thrust of Andrew Abbott's article on mechanisms, discussed previously.)

(An earlier post described John Levi Martin's effort to show how social structures come to be as the result of the accretion of patterns of individual social interaction.  Where Levi Martin proceeds from micro to macro through aggregation, Hedström proceeds from macro to micro through disaggregation (or dissection, in his words). But both are fundamentally interested in analyzing the micro-macro link.)

Dissecting the social

The past dozen years or so have witnessed the emergence of a distinctive approach to the social sciences that its practitioners refer to as "analytical sociology." Peter Hedström's Dissecting the Social: On the Principles of Analytical Sociology (2005) serves as a manifesto for the approach, and Pierre Demeulenaere, ed., Analytical Sociology and Social Mechanisms, and Peter Hedström and Peter Bearman, eds., The Oxford Handbook of Analytical Sociology provide substantive foundations for several areas of research within this approach.  And the European Network of Analytical Sociologists provides an institutional framework within which research approaches and findings can be shared (link).

Hedström describes the analytical sociology approach in these terms:

Although the term analytical sociology is not commonly used, the type of sociology designated by the term has an important history that can be traced back to the works of late nineteenth- and early twentieth-century sociologists such as Max Weber and Alexis de Tocqueville, and to prominent mid-twentieth-century sociologists such as the early Talcott Parsons and Robert K. Merton. Among contemporary social scientists, four in particular have profoundly influenced the analytical approach.  They are Jon Elster, Raymond Boudon, Thomas Schelling and James Coleman. (kl 113)

One important characteristic of the analytical approach is that it aims to gain understanding by dissecting the social phenomena to be explained.  To dissect, as the term is used here, is to decompose a complex totality into its constituent entities and activities and then to bring into focus what is believed to be its most essential elements. (kl 65)

And here is how Hedström and Bearman describe the approach in the Handbook:

Analytical sociology is concerned first and foremost with explaining important social facts such as network structures, patterns of residential segregation, typical beliefs, cultural tastes, common ways of acting, and so forth. It explains such facts not merely by relating them to other social facts -- an exercise that does not provide an explanation -- but by detailing in clear and precise ways the mechanisms through which the social facts under consideration are brought about.  In short, analytical sociology is a strategy for understanding the social world. (3-4)

Two interrelated aspects are of particular importance: the explanatory principles guiding the approach and the type of explanatory factors being evoked. Analytical sociology explains by detailing mechanisms through which social facts are brought about, and these mechanisms invariably refer to individuals' actions and the relations that link actors to one another. (4)

In my assessment, AS rests on three central ideas.

First, there is the idea that social outcomes need to be explained on the basis of the actions of individuals.  This position is referred to variously as methodological individualism, methodological localism, or microfoundationalism.  It is often illustrated by reference to "Coleman's Boat" in James Coleman, Foundations of Social Theory (1994:8) describing the relationship that ought to exist between macro and micro social phenomena:

The diagram indicates the relationship between macro-factors (Protestant religious doctrine, capitalism) and the micro factors that underlie their causal relation (values, economic behavior).  Here are a few of Hedström's formulations of this ontological position:

In sociological inquiries, however, the core entity always tends to be the actors in the social system being analyzed, and the core activity tends to be the actions of these actors. (kl 106)

To be explanatory a theory must specify the set of causal mechanisms that are likely to have brought about the change, and this requires one to demonstrate how macro states at one point in time influence individuals' actions, and how these actions bring about new macro states at a later point in time. (kl 143)

Further, Hedström is drawn to a broad version of rational-choice theory -- what he calls the "Desire-Belief-Opportunity theory".

Desires (D), beliefs (B) and opportunities (O) are the primary theoretical terms upon which the analysis of action and interaction will be based.  ... The desires, beliefs and opportunities of an actor are here seen as the proximate causes of the actor's action. (kl 507)

This is a variant of rational choice theory, because the actor's choice is interpreted along these lines: given the desires the actor possesses, given the beliefs he/she has about the environment of choice, and given the opportunities he/she confronts, action A is a sensible way of satisfying the desires. It is worth pointing out that it is possible to be microfoundationalist about macro outcomes while not assuming that individual actions are driven by rational calculations. Microfoundationalism is distinct from the assumption of individual rationality.

Second is the idea that social actors are socially situated and socially constructed; the values, perceptions, emotions, and modes of reasoning of the actor are influenced by social institutions, and their current behavior is constrained and incented by existing institutions. (This position has a lot in common with the methodological localism that I've defended.) Practitioners of analytical sociology are not reductionist about social behavior, at least in the way that economists tend to be; they want to leave room conceptually for the observation that social structures and norms influence individual behavior and that individuals are not unadorned utility maximizers. (Gary Becker's effort to explain much of social life on the basis of the premise of maximizing utility is an example of the reductionist tendency of purist rational choice theory; Uncommon Sense: Economic Insights, from Marriage to Terrorism.) In the Hedström-Bearman introduction to the Handbook they put the point this way:

Structural individualism is a methodological doctrine according to which social facts should be explained as the intended or unintended outcomes of individuals' actions. Structural individualism differs from traditional methodological individualism in attributing substantial explanatory importance to the social structures in which individuals are embedded. (4)

This is a direction of thought that is not well advanced within analytical sociology, but would repay further research.  There is no reason why a microfoundational approach should not take seriously the causal dynamics of identity formation and the formation of the individual's cognitive, practical, and emotional frameworks.  These are relevant to behavior, and they are plainly driven by concrete social processes and institutions.

Third, and most distinctive, is the idea that social explanations need to be grounded in a hypothesis about the concrete social causal mechanisms that constitute the causal connection between one event and another. Mechanisms rather than regularities or necessary/sufficient conditions provide the fundamental grounding of causal relations and need to be at the center of causal research.  (This is a position developed and discussed many times in this blog; thread.) This approach has several intellectual foundations, but one is the tradition of critical realism and some of the ideas developed by Roy Bhaskar (A Realist Theory of Science). Hedström advocates for a theory of causal explanation that is grounded in the idea of a causal mechanism:

The position taken here, rather, is that mechanism-based explanations are the most appropriate type of explanations for the social sciences.  The core idea behind the mechanism approach is that we explain a social phenomenon by referring to a constellation of entities and activities, typically actors and their actions, that are linked to one another in such a way that they regularly bring about the type of phenomenon we seek to explain. (kl 65)

A social mechanism, as defined here, is a constellation of entities and activities that are linked to one another in such a way that they regularly bring about a particular type of outcome. (kl 181)

In addition to these three orienting frameworks for analytical sociology, there is a fourth characteristic that should be mentioned.  This is the idea that the tools of computer-based simulation of the aggregate consequences of individual behavior can be a very powerful tool for sociological research and explanation.  So the tools of agent-based modeling and other simulations of complex systems have a very natural place within the armoire of analytical sociology.

In short, analytical sociology is a compact, clear approach to the problem of understanding social outcomes.  It lays the ground for the productive body of research questions associated with the "aggregation dynamics" research program (link).  There is active, innovative research being done within this framework of ideas, especially in Germany, Sweden, and Great Britain.  And its clarity permits, in turn, the formulation of rather specific critiques from researchers in other sociological traditions who reject one or another of the key components.  (This is the thrust of Andrew Abbott's article on mechanisms, discussed previously.)

(An earlier post described John Levi Martin's effort to show how social structures come to be as the result of the accretion of patterns of individual social interaction.  Where Levi Martin proceeds from micro to macro through aggregation, Hedström proceeds from macro to micro through disaggregation (or dissection, in his words). But both are fundamentally interested in analyzing the micro-macro link.)