Sociology, a social science that studies human societies, their interactions, and the processes that preserve and change them. It does this by examining the dynamics of constituent parts of societies such as institutions, communities, populations, and gender, racial, or age groups. Sociology also studies social status or stratification, social movements, and social change, as well as societal disorder in the form of crime, deviance, and revolution.

Social life overwhelmingly regulates the behaviour of humans, largely because humans lack the instincts that guide most animal behaviour. Humans therefore depend on social institutions and organizations to inform their decisions and actions. Given the important role organizations play in influencing human action, it is sociology’s task to discover how organizations affect the behaviour of persons, how they are established, how organizations interact with one another, how they decay, and, ultimately, how they disappear. Among the most basic organizational structures are economic, religious, educational, and political institutions, as well as more specialized institutions such as the family, the community, the military, peer groups, clubs, and volunteer associations.

Sociology, as a generalizing social science, is surpassed in its breadth only by anthropology—a discipline that encompasses archaeology, physical anthropology, and linguistics. The broad nature of sociological inquiry causes it to overlap with other social sciences such as economics, political science, psychology, geography, education, and law. Sociology’s distinguishing feature is its practice of drawing on a larger societal context to explain social phenomena.

Sociologists also utilize some aspects of these other fields. Psychology and sociology, for instance, share an interest in the subfield of social psychology, although psychologists traditionally focus on individuals and their mental mechanisms. Sociology devotes most of its attention to the collective aspects of human behaviour, because sociologists place greater emphasis on the ways external groups influence the behaviour of individuals.

The field of social anthropology has been historically quite close to sociology. Until about the first quarter of the 20th century, the two subjects were usually combined in one department (especially in Britain), differentiated mainly by anthropology’s emphasis on the sociology of preliterate peoples. Recently, however, this distinction has faded, as social anthropologists have turned their interests toward the study of modern culture.

Two other social sciences, political science and economics, developed largely from the practical interests of nations. Increasingly, both fields have recognized the utility of sociological concepts and methods. A comparable synergy has also developed with respect to law, education, and religion and even in such contrasting fields as engineering and architecture. All of these fields can benefit from the study of institutions and social interaction.

Though sociology draws on the Western tradition of rational inquiry established by the ancient Greeks, it is specifically the offspring of 18th- and 19th-century philosophy and has been viewed, along with economics and political science, as a reaction against speculative philosophy and folklore. Consequently, sociology separated from moral philosophy to become a specialized discipline. While he is not credited with the founding of the discipline of sociology, French philosopher Auguste Comte is recognized for having coined the term sociology.

The founders of sociology spent decades searching for the proper direction of the new discipline. They tried several highly divergent pathways, some driven by methods and contents borrowed from other sciences, others invented by the scholars themselves. To better view the various turns the discipline has taken, the development of sociology may be divided into four periods: the establishment of the discipline from the late 19th century until World War I, interwar consolidation, explosive growth from 1945 to 1975, and the subsequent period of segmentation.

Some of the earliest sociologists developed an approach based on Darwinian evolutionary theory. In their attempts to establish a scientifically based academic discipline, a line of creative thinkers, including Herbert Spencer, Benjamin Kidd, Lewis H. Morgan, E.B. Tylor, and L.T. Hobhouse, developed analogies between human society and the biological organism. They introduced into sociological theory such biological concepts as variance, natural selection, and inheritance—asserting that these evolutionary factors resulted in the progress of societies from stages of savagery and barbarism to civilization by virtue of the survival of the fittest. Some writers believed that these stages of society could be seen in the developmental stages of each individual. Strange customs were explained by assuming that they were throwbacks to useful practices of an earlier period, such as the make-believe struggle sometimes enacted between the bridegroom and the bride’s relatives reflecting the earlier custom of bride capture.

In its popular period of the late 19th and early 20th centuries, social Darwinism, along with the doctrines of Adam Smith and Thomas Malthus, touted unrestricted competition and laissez-faire so that the “fittest” would survive and civilization would continue to advance. Although the popularity of social Darwinism waned in the 20th century, the ideas on competition and analogies from biological ecology were appropriated by the Chicago School of sociology (a University of Chicago program focusing on urban studies, founded by Albion Small in 1892) to form the theory of human ecology that endures as a viable study approach.

Since the initial interest in evolutionary theory, sociologists have considered four deterministic theories to replace social Darwinism. This search for new approaches began prior to World War I as emphasis shifted from economic theory to geographic, psychological, and cultural theory—roughly in that order.

The first theory, economic determinism, reflects the interest many sociologists had in the thought of Karl Marx, such as the idea that social differentiation and class conflict resulted from economic factors. This approach had its greatest popularity in Europe, where it remained a strong influence on some sociologists until the 1980s. It did not gain a significant foothold in the United States, because American society was thought to be socially mobile, classless, and oriented to the individual. This neglect of Marxism by American sociologists, however, was not due to scholarly ignorance. Sociologists of all periods had read Marx as well as Charles A. Beard’s economic interpretation of American history and the work of Werner Sombart (who had been a Marxist in his early career). Instead, in the 1960s, neo-Marxism—an amalgam of theories of stratification by Marx and Max Weber—gained strong support among a minority of sociologists. Their enthusiasm lasted about 30 years, ebbing with the breakup of the Soviet system and the introduction of postindustrial doctrines that linked class systems to a bygone industrial era. The persistence of social and economic inequality is now explained as a complex outcome of factors, including gender, race, and region, as well as global trade and national politics.

Representing the second theoretical area, human geographers—Ellsworth Huntington, Ellen Semple, Friedrich Ratzel, Paul Vidal de La Blache, Jean Brunhes, and others—emphasized the impact of climate and geography on the evolution of those societies that flourished in temperate zones. Their theories found no place in mainstream sociological thought, however, except for a brief period in the 1930s when human ecology sought to explain social change by linking environmental conditions with demographic, organizational, and technological factors. Human ecology remains a small but vital part of sociology today.

Psychological theories emphasized instincts, drives, motives, temperament, intelligence, and human sociability in social behaviour and societal evolution. Social psychology modifies these concepts to explain the broader phenomena of social interaction or small group behaviour. Although American sociology even today retains an individualistic (and therefore psychological) bias, by the 1930s sociologists had concluded that psychological factors alone could not explain the behaviour of larger groups and societies.

Finally, cultural theories of the 1930s emphasized human ability to innovate, accumulate, and diffuse culture. Heavily influenced by social and cultural anthropology, many sociologists concluded that culture was the most important factor in accounting for its own evolution and that of society. By 1940 cultural and social explanations of societal growth and change were accepted, with economic, geographic, and biopsychological factors playing subsidiary roles.

Scholars who established sociology as a legitimate social science were careful to distinguish it from biology and psychology, fields that had also begun to generalize about human behaviour. They did this by developing specific methods for the study of society. French sociologist Émile Durkheim (1858–1917), prominent in this regard, argued that various kinds of interactions between individuals bring about certain new properties (sui generis) not found in separate individuals. Durkheim insisted that these “social facts,” as he called them—collective sentiments, customs, institutions, nations—should be studied and explained on a distinctly societal level (rather than on an individual level). To Durkheim the interrelations between the parts of society contributed to social unity—an integrated system with life characteristics of its own, exterior to individuals yet driving their behaviour. By positing a causal direction of social influence (from group to individual rather than the reverse, the model accepted by most biologists and psychologists of the time), Durkheim gave a much-needed framework to the new science of sociology. Some writers called this view “functionalism,” although the term later acquired broader meanings.

Durkheim pointed out that groups can be held together on two contrasting bases: mechanical solidarity, a sentimental attraction of social units or groups that perform the same or similar functions, such as preindustrial self-sufficient farmers; or organic solidarity, an interdependence based on differentiated functions and specialization as seen in a factory, the military, government, or other complex organizations. Other theorists of Durkheim’s period, notably Henry Maine and Ferdinand Tönnies, made similar distinctions—status and contract (Maine) and Gemeinschaft und Gesellschaft (Tönnies)—and predicted that civilization would progress along the lines of specialization, contractual relations, and Gesellschaft.

Later anthropologists, especially Bronisław Malinowski and A.R. Radcliffe-Brown, developed a doctrine of functionalism that emphasized the interrelatedness of all parts of society. They theorized that a change in any single element would produce a general disturbance in the whole society. This doctrine eventually gained such a following among social anthropologists that some advocated a policy of complete noninterference, even with objectionable practices in preliterate societies (such as cannibalism or head-hunting), for fear that eliminating the practice might produce far-reaching social disorganization.

American sociology began undergoing significant development in the 1940s. The monumental growth of university enrollment and research after World War II was fueled by generous federal and private funding of research. Sociologists sought to enhance their status as scientists by pursuing empirical research and by conducting qualitative analysis of significant social problems. Many universities developed large research organizations that spurred important advances in survey research application, measurement, and social statistics. At the forefront were Columbia University (focusing on cultural surveys) and the University of Chicago (specializing in quantitative analysis of social conditions and detailed studies of urban problems). The struggle over the meaningful use of statistics and theory in research began at this time and remained a continuing debate in the discipline.

The early schools of thought each presented a systematic formulation of sociology that implied possession of exclusive truth and that involved a conviction of the need to destroy rival systems. By 1975 the era of growth, optimism, and surface consensus in sociology had come to an end. The functionalist-conflict debate signaled further and permanent divisions in the discipline, and virtually all textbooks presented it as the main theoretical divide, despite Lewis A. Coser’s widely known proposition that social conflict, while divisive, also has an integrating and stabilizing effect on society. Conflict is not necessarily negative, argued Coser in The Functions of Social Conflict (1936), because it can ultimately foster social cohesiveness by identifying social problems to be overcome. In the late 1970s, however, attention to other, everyday social processes such as those elaborated by the Chicago School (competition, accommodation, and assimilation) ceased appearing in textbooks. In its extreme form, conflict theory helped revive the critical theory of the Frankfurt School that wholly rejected all sociological theories of the time as proponents of the status quo. These theoretical divisions themselves became institutionalized in the study and practice of sociology, which suggested that debates on approach would likely remain unresolved.

One of the consequences of the functionalist-conflict divide, recognized by the 1970s as unbridgeable, was a decline in general theory building. Others were growing specialization and controversy over methodology and approach. Communication between the specialties also diminished, even as ideological disputes and other disagreements persisted within the specialty areas. New academic journals were introduced to meet the needs of the emerging specializations, but this further obscured the core of the discipline by causing scholars to focus on microsociological issues. Interestingly, theory building grew within the specialties—fractured as they were—especially as international comparative research increased contact with other social sciences.

Since social stratification is the most binding and central concern of sociology, changes in the study of social stratification reflect trends in the entire discipline. The founders of sociology—including Weber—thought that the United States, unlike Europe, was a classless society with a high degree of upward mobility. During the Great Depression, however, Robert and Helen Lynd, in their famous Middletown (1937) studies, documented the deep divide between the working and the business classes in all areas of community life. W. Lloyd Warner and colleagues at Harvard University applied anthropological methods to study the Social Life of a Modern Community (1941) and found six social classes with distinct subcultures: upper upper and lower upper, upper middle and lower middle, and upper lower and lower lower classes. In 1953 Floyd Hunter’s study of Atlanta, Georgia, shifted the emphasis in stratification from status to power; he documented a community power structure that controlled the agenda of urban politics. Likewise, C. Wright Mills in 1956 proposed that a “power elite” dominated the national agenda in Washington, a cabal comprising business, government, and the military.

The significant growth of sociological inquiry after World War II prompted interest in historical and political sociology. Charles Tilly in From Mobilization to Revolution (1978), Jack Goldstone in Revolutions: Theoretical, Comparative and Historical Studies (1993), and Arthur Stinchcombe in Constructing Social Theories (1987) made comparative studies of revolutions and proposed structural theories to explain the origins and spread of revolution. Sociologists who brought international and historical perspectives to their study of institutions such as education, welfare, religion, the family, and the military were forced to reconsider long-held theories and methodologies. As was the case in almost all areas of specialization, new journals were founded.