Sociologists study social structure and the effects that structures have on individual behavior and life outcomes. But what do they have in mind when they refer to "structure"?
It turns out that there are important ambiguities in the idea of social structure. The word is sometimes used to refer to functioning entities or systems within society. The state is a structure within society; likewise is the system of public education. But the term can also be used to refer to the structure of society. Here we have statements like "the age structure of Egypt is X" and "the occupational structure of Great Britain is Y". In this usage, we are being directed to a descriptive feature of society -- the way that various elements hang together. Income stratification is a structural feature; the state is a structural entity.
There is a third meaning associated with "structure" as well: the idea that society possesses a structure of interconnected parts and sub-systems, and that the parts influence each other in systematic ways. To outline the structure of society is to provide a theory of how it works (in part, anyway).
This usage is illustrated in Marx's extended concept of the capitalist mode of production, in which various large elements -- technology and production, distribution, wage labor, property ownership, political authority, culture and ideology -- hang together in functional ways. Marx describes this system as one consisting of a base (forces and relations of production) and superstructure (state, ideology, culture), with the workings of class interest serving as the engine of stability and change. So Marx looks at capitalism as a system. Consider this statement from the Preface to A Contribution to the Critique of Political Economy:
In the social production of their life, men enter into definite relations that are indispensable and independent of their will, relations of production which correspond to a definite stage of development of their material productive forces. The sum total of these relations of production constitutes the economic structure of society, the real foundation, on which rises a legal and political superstructure and to which correspond definite forms of social consciousness. The mode of production of material life conditions the social, political and intellectual life process in general.
Here and elsewhere Marx picks out the forces of production and relations of production as the basic determinants of social change. The mode of production represents a complex and objective reality to which individuals must adapt in their behaviors.
By mode of production we shall designate not what is generally marked out as the economic (i.e. relations of production in the strict sense), but a specific combination of various structures and practices which, in combination, appear as so many instances or levels, i.e. as so many regional structures of this mode. A mode of production, as Engels stated schematically, is composed of different levels or instances, the economic, political, ideological and theoretical: it is understood that this is merely a schematic picture and that a more exhaustive division can be drawn up. The type of unity which characterizes a mode of production is that of a complex whole dominated, in the last instance, by the economic. (13-14)
These texts serve to illustrate a specific and comprehensive view of the sense in which society has a structure. Each substantive term warrants analysis.
Definite relations of production -- property relations, relations of power and authority, relations defining the terms of economic interaction. The terms of these relations are essentially beyond the control of the individuals who fall within them; they represent a supra-individual reality to which the individual must accommodate. The system of wage labor is a clear example in Marx's theory. In a society in which wage labor is the dominant system of labor control, individuals gain the resources needed to satisfy life needs by selling their labor time which is then directed and managed by the purchaser. This is a structural condition that the worker confronts in the social environment around him or her.Marx and other scholars who work within the framework of historical materialism hold, as a large empirical hypothesis, that there are causal and systemic relations among these items, and the generic mechanism of class interest and class conflict is the transmission belt that conveys causal influence from one sector to another. They believe that the "needs" of the economic structure are secured by the political structure, through the mechanism of class interests; likewise, the ideological and theoretical structure is shaped by the interests of various classes, leading to a high degree of conformance between the content of "social consciousness" and the prerequisites of stability of the economic structure.
Material productive forces -- the level and implementation of productive technology, including locations of production, tools, machines, materials processing, mines, agriculture, and the forms of knowledge associated with each of these. The ensemble of these items constitutes another fixed aspect of the social environment within which human beings live and subsist.
Economic structure of society -- the system of property relations and material institutions and technology through which society produces goods and conducts the distribution of value and surplus value (income and access to goods).
Legal and political superstructure -- the institutions through which law and political power are exercised and maintained.
Forms of social consciousness -- the cognitive and epistemic frameworks through which ordinary members of society understand the forces that surround them and the roles that they play within those forces and institutions.
Levels or instances of social organization -- the clusters of institutions that make up the "economic, political, ideological, and theoretical "'levels'" of existing society. Factories, department stores, and banks fall in the economic level; the legislature, the police and military forces, and the agencies of the state fall in the political level; and the contents and institutions of transmission of beliefs about the world fall in the ideological and theoretical levels.
The template of historical materialism as a "Gray's Anatomy" for modern capitalism has often been criticized as being mechanistic, over-simplified, and even fictional. But in its heart the scheme is a perfectly intelligible hypothesis about how several aspects of contemporary society fit together. Property relations define individual interests, and the system of wage labor defines the opportunities available to working people. Legislative and governmental policies have effects on the property system, and the class that owns the bulk of this property is perfectly capable of recognizing the consequences of this policy or that. Having the means to influence government, the owning class is able to shape government policy and personnel in ways that are compatible with its interests. Likewise, owners of property are able to recognize the advantage of being in a position to influence public consciousness and the terms of public debate. So the components of the "ideological apparatus" -- think tanks, newspapers, publishing houses, television networks -- are intensely contested, and the power of the owning class to influence the content of these outlets is great. Here again we have a fairly simple empirical argument for the conformance of the organs of social consciousness to the needs of the propertied class. And if it seems far fetched to hold that the owners of wealth are very willing to exert their power in these ways, just look at the recent announcement of the 2016 election-year budget of the political network funded by the Koch brothers -- $889,000,000 (link)!
It is no longer common in sociology to find value in Marx's theory of capitalist society. But really, the structuralist view he arrived at in the 1850s and 1860s seems pretty prosaic today in the context of an economic system that systematically creates astronomical wealth for the one percent and stagnant poverty for the majority of society. Median household income in 2012 in the United States was $51,371, and almost all states showed a decline in median household income between 2000 and 2012 (link). And it is almost tautological to say that the property system explains both facts -- the explosion of the wealth and income of the one percent and the stagnant or declining incomes of the majority of the population.
Or as Marx concludes Chapter Six of Volume I of Capital:
On leaving this sphere of simple circulation or of exchange of commodities, which furnishes the “Free-trader Vulgaris” with his views and ideas, and with the standard by which he judges a society based on capital and wages, we think we can perceive a change in the physiognomy of our dramatis personae. He, who before was the money-owner, now strides in front as capitalist; the possessor of labour-power follows as his labourer. The one with an air of importance, smirking, intent on business; the other, timid and holding back, like one who is bringing his own hide to market and has nothing to expect but — a hiding.