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for developing a better understanding of the driving forces producing global environmental change and other environmental problems (Rosa and Dietz 1998). As such, they represent an important supplement to natural-science research programs on these topics.

Impacts of Environmental Problems. As noted earlier, environmental sociology was just emerging at the time of the 1973–1974 energy crisis, and it is not surprising that a good deal of effort was made to identify real as well as potential social impacts of energy and other natural resources in this early period of the field. While diverse impacts, from regional migration to consumer lifestyles, were investigated, heavy emphasis was placed on investigating the ‘‘equity’’ impacts of both energy shortages and the policies designed to ameliorate them (Rosa et al. 1988). A general finding was that both the problems and policies often had regressive impacts, with the lower socioeconomic strata bearing a disproportionate cost due, for example, to rising energy costs (Schnaiberg 1975).

Equity has been a persistent concern in environmental sociology, and researchers gradually shifted their attention to the distribution of exposure to environmental hazards (ranging from air and water pollution to hazardous wastes). Again, a persistent finding has been that exposure to environmental hazards is generally negatively correlated with socioeconomic status. A growing number of studies have also found that minority populations are disproportionately exposed to environmental hazards, in part because of their lower- than-average socioeconomic levels but perhaps also because of conscious decisions to locate hazardous sites in minority communities. Such findings, which a few recent studies have challenged, have led to charges of ‘‘environmental racism’’ and efforts to achieve ‘‘environmental justice.’’ At a broader level, international equity is attracting the attention of environmental sociologists, who are investigating the export of polluting industries from wealthy to poor nations, the disproportionate contribution of wealthy nations to many glob- al-level problems, and the consequent hurdles these phenomena pose for international cooperation to solve environmental problems (Redclift and Sage 1998).

Sociologists have not limited themselves to investigating the equity impacts of environmental

problems, and studies of communities exposed to technological or human-made hazards (such as Love Canal) offer particularly rich portrayals of the diverse impacts caused by discovery of community hazards. Whereas natural hazards—such as floods, hurricanes, and earthquakes—have been found to result in a therapeutic response in which communities unite in efforts to help victims, repair damage, and reestablish life as it was before the disaster struck, technological disasters have been found to have very different impacts (Freudenburg 1997). Although a putative hazard often appears obvious to those who feel affected by it, the ambiguities involved in detecting and assessing such hazards often generate a pattern of intense community conflict. Unlike those affected by natural hazards, the ‘‘victims’’ often find themselves at odds not only with public officials but also with other residents who fail to acknowledge the seriousness of the hazard (for fear of economic loss in terms of property values, jobs, etc.). In many cases, such conflicts have resulted in a longterm erosion of community life as well as exacerbation of the victims’ personal traumas stemming from their exposure to the hazards (Couch and Kroll-Smith 1985).

Solutions to Environmental Problems. As was true for the causes of environmental problems, early work by environmental sociologists interested in solutions to these problems often involved explications and critiques of predominant approaches. Early on Heberlein (1974) noted the predilection of the United States for solving environmental problems via a ‘‘technological fix,’’ or developing and applying new technologies to solve problems such as air and water pollution. Understandably popular in a nation with a history of technological progress, such a solution is appealing because it avoids mandating behavioral and institutional change. Unfortunately, solving problems with new technologies sometimes creates even more problems, as illustrated by attempts to solve energy shortages with nuclear power. Consequently, as the seriousness and pervasiveness of environmental problems became more obvious, attention was given to a variety of ‘‘social fixes,’’ or efforts to change individual and institutional behaviors.

Expanding on Heberlein’s analysis, other sociologists (e.g, Dunlap et al. 1994) have identified three broad types of social fixes, or implicit policy

types: (1) the cognitive (or knowledge) fix, which assumes that information and persuasion will suffice to produce the necessary changes in behavior, illustrated by campaigns encouraging energy conservation and recycling; (2) the structural fix, which relies on laws and regulations that mandate behavioral change, reflected in highway speed limits or enforced water conservation; and (3) the intermediary behavioral fix, which employs incentives and disincentives to encourage changes in behavior, as illustrated by pollution taxes (penalties) and tax credits (rewards) for installing pollution-abatement technology (see Gardner and Stern 1996 for a more refined typology of policy approaches and detailed examples of each).

Environmental sociologists, in conjunction with other behavioral scientists, have conducted a range of studies that bear on the efficacy of these differing strategies for solving environmental problems, ranging from field experiments to test the effectiveness of information campaigns in inducing energy and water conservation to evaluations of alternative strategies for generating participation in recycling programs (see Gardner and Stern 1996 for a good summary). A noteworthy sociological study was Derksen and Gartrell’s (1993) investigation of recycling in Edmonton, Alberta, which found that individuals’ level of environmental concern (and, by implication, knowledge about the importance of recycling) was not as important in predicting recycling behavior as was ready access to a curbside recycling program. While sociologists have conducted numerous field experiments and evaluations of community environmental programs, typically investigating the efficacy of one or more of the above-noted ‘‘fixes,’’ they have generally left examinations of national and international environmental policy making to political scientists and economists. However, sociologists have begun to pay attention to efforts to negotiate international agreements to achieve reduction of greenhouse gases (Redclift and Sage, 1998), and we expect more sociological work along these lines.

CURRENT TRENDS AND DEBATES

As the foregoing illustrates, environmental sociology not only emerged in response to societal attention to environmental problems but has focused much of its energy on understanding these problems, especially their causes, impacts, and

solutions. The field has proved to be more than a passing fad, becoming well institutionalized and also increasingly internationalized. But in the process, fundamental assumptions that once served to unify the field—agreement over the reality of environmental degradation; diagnoses of such degradation as inherent to modern, industrialized societies; and the sense that mainstream sociology was largely blind to the significance of environmental matters—have become matters of debate (Buttel 1996, 1997).

The emergence of environmental problems provided the raison d’ etre for environmental sociology, and the seriousness of such problems was seldom challenged. While environmental sociologists from the outset paid attention to ways in which claims about environmental conditions are socially constructed and become the subject of societal conflict (e.g., Albrecht 1975), such efforts seldom questioned the objective existence of environmental problems. In recent years, however, environmental sociology has felt the effects of the larger discipline’s turn toward more cultural and interpretative orientations. A growing number of scholars, particularly in Europe, have not only highlighted the contested nature of claims about environmental problems but—in the postmodern tradition—concluded that there is no reason for privileging the claims of any parties to these debates, including those of environmental scientists as well as activists (Macnaghten and Urry 1998).

Such work has led to the emergence of a strong constructivist/interpretative orientation in environmental sociology that challenges the objectivist/realist perspective that has traditionally been dominant. Whereas the realist orientation assumes that the environment is a biophysical entity existing independent of humans, thereby providing the setting for study of human–envi- ronment interactions as the core of environmental sociology, the constructivist orientation leads its adherents to adopt an agnostic view of such interactions, preferring instead to examine knowledge claims—and the social forces they reflect— about these interactions (Macnaghten and Urry 1998). These competing perspectives can be readily seen in sociological work on global environmental change (GEC), where those in the realist camp have sought to complement naturalscience research by examining, for example, societal processes leading to tropical deforestation

and greenhouse gas emissions (noted previously), while constructivists have highlighted the uncertainties in scientific evidence for GEC and the social, political, and historical forces that have made GEC a central topic of scientific and policymaking interest (see Rosa and Dietz 1998). These differing orientations have led to debate among environmental sociologists, with realists pointing to shortcomings of the constructivist approach (Dickens 1996; Murphy 1997) and constructivists demonstrating the utility of their perspective (Hannigan 1995). Fortunately promising syntheses of constructivist and realist perspectives are beginning to emerge (Rosa 1998).

Another source of debate is the inevitability of continued environmental degradation, particularly on the part of advanced, industrialized nations. Whereas environmental sociologists have traditionally seen the drive toward capital accumulation inherent in such societies as making environmental degradation inevitable (as epitomized by Schnaiberg’s ‘‘treadmill of production’’ argument), European scholars have increasingly suggested that this may not be the case. Obvious successes in environmental amelioration within advanced European nations have led them to build upon economic models of ‘‘industrial ecology,’’ which suggest that modernization of industrial processes can permit production with ever-decreasing levels of material input and pollution output, heralding a new era of ‘‘ecological modernization’’ (Spaargaren and Mol 1992).

This perspective not only adopts a more sanguine image of the future of industrialized societies but, as Buttel (1996, 1997) notes, involves a shift in focus for environmental sociology: from a preoccupation with the origins of environmental degradation to efforts to explain the institutionalization of environmental amelioration (via technological innovation, policy incentives, pressures from citizens’ groups, etc.). While representing an important complement to traditional perspectives in the field and building on larger sociological debates about the future of ‘‘modernity,’’ ecological modernization is vulnerable to criticism. First, its development in northern Europe leads to concerns that ecological modernization is not applicable to less wealthy and technologically disadvantaged nations. Second, although nations such as the Netherlands have made considerable advances

in protecting their own environments, their import of natural resources and export of pollution creates a large ‘‘ecological footprint’’ well beyond their borders (Wackernagel and Rees 1996). Finally, even if continual progress is made in creating cleaner, more efficient production processes, these gains may be offset by continued economic growth and consumption and consequent increased demand for materials and energy (Bunker 1996).

The trends toward adoption of more constructivist/interpretative frameworks and models of ecological modernization are related to a third trend in environmental sociology—the ongoing reassessment of its relationship to the larger discipline. As noted earlier, the emergence of environmental sociology was marked by criticism of mainstream sociology’s neglect of the ecosys- tem-dependence of modern, industrialized societies and consequent inattention to the challenge posed by environmental problems. This critical orientation led many environmental sociologists to look to other disciplines (such as ecology and environmental science) for guidance and probably contributed to a somewhat insular perspective vis- à-vis mainstream sociology.

But in the 1990s environmental problems, particularly global-level threats like climate change, have caught the attention of growing numbers of eminent sociologists, such as Giddens (1990), who have recognized that such problems cannot be ignored in analyses of the future course of industrial societies. Greater interaction between environmental and mainstream sociology has resulted, and the penetration of currently fashionable perspectives, such as cultural/interpretative frameworks and theories of the nature of late modernity into environmental sociology has followed—as exemplified by the popularity of the constructivist and ecological modernization perspectives. This is resulting in considerable debate and self-reflec- tion among environmental sociologists, something that a maturing field can afford. Hopefully, environmental sociology will emerge with renewed relevance to the larger discipline of sociology as well as continued relevance to societal efforts to ensure an ecologically sustainable future for humankind.

(SEE ALSO: Environmental Equity)

REFERENCES

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RILEY E. DUNLAP

EUGENE A. ROSA

EPIDEMIOLOGY

Epidemiology is the study of the distribution of disease and its determinants in human populations. Epidemiology usually takes place in an applied public health context. It focuses on the occurrence of disease by time, place, and person and seeks to identify and control outbreaks of disease through identification of etiological factors. Its approach is to identify associated risk factors and then work back to causes.

Historically, the focus of epidemiology was on large outbreaks, usually of infectious disease. The substance and methods of epidemiology have been applied to most forms of acute and chronic disease and many other physical and mental health conditions. Along with the broadening of the subject matter of epidemiology has come more focus on its methods. Along with the specialization of

epidemiological methods has come the professional identification of persons as epidemiologists. In this entry, we address the origins, methodology, current topics, and professional issues related to epidemiology.

PROFESSIONAL ROLE

Epidemiology is the professional identification of an increasing number of persons who have received specialized training in departments of epidemiology in schools of public health. Many complete approved courses of study at the master’s or doctoral level leading to an M.P.H., Dr. P.H., or Ph.D. with epidemiology as an area of concentration. Some schools offer the M.P.H. to physicians after an abbreviated course of study. Like most other developing professions, graduate epidemiologists are protective of their professional identification and would seek to differentiate their professional credentials from those who have found their ways to epidemiological roles from other educational backgrounds. The problem in this developing professionalism is how to define a unique intellectual content or theory of epidemiology, when the applied nature of the discipline demands that the latest theories and methods of investigating disease be incorporated into any ongoing investigation.

ORIGINS

Langmuir (Roeché 1967, p. xiii) traces the origins of epidemiology as far back as Hypocrites’ report of an outbreak of mumps among Greek athletes, but the written history of mankind is full of major outbreaks of disease, which the practitioners of the time attempted to control with methods ranging from folk remedies and the available medicine, to religion and witchcraft, and even to civil and sanitary engineering. It was the careful and scientific observation of these outbreaks that led to the development of modern epidemiology.

Perhaps the most famous early epidemiological inquiry was John Snow’s careful observation of the house-by-house locations of incident cases of cholera during epidemics in London in the 1840s and 1850s. Snow’s correlation of new cases with some water supply systems, but not others, changed the conventional medical wisdom about how cholera was spread and did so before the microbial nature

of the disease was discovered. Roeché’s Annals of Epidemiology provides a number of examples of the application of epidemiological methods in relation to local outbreaks in the earlier part of the twentieth century. More recent well-known investigations have included those relating to Legionnaires’ disease and AIDS.

Epidemiology as a discipline has grown along with the many associated disciplines of public health and medicine. Microbiology has identified the organisms and modes of transmission for many infectious diseases. Biochemistry, physiology, virology, and related basic medical sciences have provided the scientific background to support the development of the epidemiology of infectious disease. Other sciences ranging from genetics to sociology have contributed to the various specializations within epidemiology, which are broadly classified as infectious disease, chronic disease, cancer, cardiovascular disease, genetic, perinatal, reproductive, oral, occupational, environmental, air pollution, respiratory, nutritional, injury, substance abuse, psychiatric, social, and health care epidemiology as well as pharmaco-epidemiology.

A CONCEPTUAL PARADIGM

A typical paradigm in epidemiology focuses on the interaction of: host, agent, and environment. The host is typically a person but is sometimes another species or organism which provides a reservoir of infection that is subsequently transmitted to humans. In the presence of an epidemic, one tries to understand the characteristics of the host that provide susceptibility to the epidemic condition. Characteristics that are frequently considered are:

(1) genetic characteristics; (2) biological characteristics, such as immunology, physiology, and anatomy; (3) demographic characteristics, such as age, sex, race, ethnicity, place of birth, and place of residence; (4) social and economic factors, such as socioeconomic status, education, and occupation; and (5) personal behaviors, such as diet, exercise, substance use, and use of health services.

The agents in this paradigm have classically been rats, lice, and insects. They may be biological, such as viruses or bacteria, as is the case in most infectious disease epidemiology. Typhus, cholera, smallpox, the Ebola virus, Legionnaires’ disease, and AIDS follow this model. Chemical agents have also contributed to significant epidemics. Some

have been physiological poisons such as the mercury once used in hatmaking, lead in old paint, water pipes, or moonshine liquor; others have been carcinogens such as tobacco or PCBs found as a contaminant in oil spread on roads. Recent focus has been on alcohol and other drugs of abuse. Other physical agents have included asbestos, coal dust, and radioactive fallout. Guns, automobiles, and industrial equipment are also agents of injury and mortality. Sometimes the ‘‘agent’’ has been a nutritive excess or deficiency, demonstrated in Goldberger’s 1915 discovery that a deficiency of niacin, part of the vitamin B complex, causes pellagra. Similarly, stress and other elements of lifestyle have been investigated as contributors to cardiovascular disease. An element in the consideration of agents is the degree of exposure and whether the agent alone is a necessary or sufficient cause of the disorder.

The third element of this paradigm is the environment, which may promote the presence of an agent or increase host susceptibility to the agent. Many elements of the environment may be relevant to the disease process, including (1) the physical environment, such as climate, housing, and degree of crowding; (2) the biological environment, including plant and animal populations, especially humans; and (3) the demographic and socioeconomic environments of the host.

At the core of this simple paradigm is the potential for multiple paths of causation for an epidemic. Rarely is a single cause sufficient to ensure the onset of a disease or condition. Thus the approach considers alternative modes of transmission, such as the influence of a common agent versus transmission from host to host. For many agents there is an incubation period, with delayed onset after ‘‘infection’’ or contact with the agent. Further, exposure may lead to a spectrum of disease with variation in the type and severity of the response to the agent. An important element to observe in any outbreak is who is not affected and whether that is due to immunity or some other protective factor.

METHODOLOGY

Field Methods. The historical method of epidemiology began with the observation that an epidemic was present, with the initial response

beginning with ‘‘shoe leather’’ investigation of who was affected and how. The initial approach focused on identified cases and their distribution over time and place, leading to a methodology that was often able to discern the risk factors for a disease even before a particular pathogen could be identified. The description of cases in terms of geography and environment as well as various demographic characteristics and exposures remains at the core of epidemiology.

Essential complements to epidemiologic field methods are careful clinical observation, measurement, and classification of the disorder, as well as laboratory identification of any pathogens and identification of potential risk factors for the observed disorder. This methodology is drawn from the methods of associated fields such as pathology, bacteriology, virology, immunology, and molecular genetics. Efforts at classification of pathogens have been augmented by the collection of libraries of reference specimens from past outbreaks.

A problem with the investigation of known outbreaks is that many types of epidemic may develop unobserved until a significant proportion of the population is affected. This has led to the development of surveillance strategies. Among these have been the reporting of multiple causes on death certificates and the mandatory reporting to the health department of many communicable diseases, such as tuberculosis and sexually transmitted diseases. The early detection and reporting of outbreaks make various public health interventions possible. Statistical analysis of mortality and morbidity has become a major component of the public health systems of most countries.

Case Registers. An extension to this approach involves case registers, in which identified mortality or morbidity is investigated and compiled in a statistical database, with subsequent investigation of the detailed context for each case. Case registers for particular types of diseases typically identify a case and then collect additional information through review of medical charts and direct field investigations and interviews. Although not as detailed as most case registers, large databases of treated disorders are gathered by various funders or providers of health services. These include the Health Care Finance Administration (Medicare and Medicaid) and various private insurance companies.

The systematic analysis of large databases, whether case registers or those of administrative agencies, makes it possible to monitor the prevalence of various conditions and to detect increases in prevalence or outbreaks long before they would be detected by individual clinicians. Analyses of mortality and morbidity are presented by most public health agencies. Typical methods include the presentation of rates of disorder, such as the number of cases per 100,000 population for geographic and demographic subpopulations. Analyses might ask whether rates are higher in one place compared to another, for a particular birth cohort, or for persons of a particular socioeconomic status. Such comparisons may be crude or adjusted for factors such as age and sex, which may bias such comparisons. Sometimes the analyses provide detailed ageand sex-specific comparisons or breakouts by other risk factors. Yet this approach is dependent on people with diseases being identified through the health system.

Prevalence Surveys. In order to discover the true prevalence of various conditions and risk factors, it is possible to conduct sample surveys of the population of a country or other geographic unit. This approach avoids potential reporting bias from the health care system and can identify conditions that might not otherwise be recognized or reported. Typically a representative sample of persons would be interviewed about their health, and sometimes various examinations or tests would be administered. Large comprehensive surveys of health and nutrition are conducted regularly by the National Center for Health Statistics. More specialized surveys of particular conditions such as blood pressure, substance use, and mental health have been conducted by federal, state, and private agencies. Because participation in most such surveys is voluntary, investigative procedures are usually limited to interviews and test procedures with little discomfort or risk. The limitation of prevalence surveys is that they are expensive and may have respondent selection biases. On the other hand, they have great potential for collecting detailed information about disorders and potential risk factors.

Case-Control Studies. The case-control method is used extensively in epidemiology. This approach typically starts with a sample of cases of a particular disorder and identifies one or more samples of persons who appear similar but who do

not have the disorder. Careful comparison of the groups has potential for identifying risk factors associated with having the disorder or, alternatively, factors that are protective. The most important issue in designing case-control studies is the designation of an appropriate control group in such a way that the process selecting controls neither hides the real risk factors nor pinpoints apparent but false ones. Control groups are frequently designated by geographic or ecological variables and are often matched on individual characteristics such as age and sex. These methods are somewhat similar to those used in natural experiments, in which two groups differ on one or more risk factors and the rates of disorder are compared, but the case-control method starts with identified cases.

Cohort Studies. Unlike the prevalence survey and most case-control studies, which are crosssectional or retrospective in nature, a cohort study endeavors to identify groups of persons who do not have the disorder or disorders in question and then follows them prospectively through the occurrence of the disease, with ascertainment of factors likely to contribute to the etiology of the disease. Such studies may start with a general sample of the population or may select groups based on the presence or absence of hypothesized risk factors prior to onset of the disorder. They then follow the samples for incident disorder. Unlike cross-sectional studies, cohort studies provide the possibility of determining causal order for risk factors and thus avoid the possibility that apparent risk factors are simply consequences of the disease. The main problem with true cohort studies is that they must last as long as it takes for the disease to develop, which may even take longer than the working life of the investigator. Sometimes, however, cohorts can be found that have been identified and assessed historically and thus can be compared in the present. Examples may be insurance groups, occupational groups, or even residents of certain areas. Then the task is to gather the information on exposure and relate it to health outcomes.

Experimental and Quasi-Experimental Methods. A true experiment is dependent on random assignment of persons or groups to conditions, but one would hardly assign a person to a condition known to produce a serious disease. Nonetheless, there are research designs that approximate

true experiments. The most direct is an intervention study in which an intervention that cannot be provided to everyone is provided to one group but not another—or provided to the alternative group at a later time. A quasi-experimental design would identify a group that has been exposed to a risk factor and compare it to another that has not. If the factors that govern the initial exposure appear to be truly accidental, then the quasi-experiment may be nearly as random as a true experiment. In such circumstances or in true randomization, one can determine the effect of the risk factor on outcomes with little risk of the outcome determining the status of the risk factor.

Alternative Methods. There are a number of research designs found in epidemiology. Those presented above are typical but certainly not exhaustive of the alternatives. At the core of nearly all of these methods, however, is the identification of factors associated with the incidence or prevalence of particular types of disorder.

CURRENT ISSUES

In recent epidemiological literature there has been some concern about the future development of epidemiology. A part of this discussion focuses on the basic paradigm being used and whether it has shifted from an ecological approach consistent with the spread of infectious disease and related pathogens to individual risk factors that are more closely related to the current emphasis on chronic diseases. The growing influence of molecular and genetic methods increases this tendency. It has been suggested that this focus on individual and proximate causes blames the individual rather than fixing the prior cause. Some authors have suggested that epidemiology should regain its public health orientation by focusing more on ecological issues affecting the risk status of groups rather than on individual-level factors, and one suggested that the primary focus should be on fighting poverty. A more integrative approach has been suggested by Susser and Susser (1996a, 1996b), who criticize the field for continuing to rely on a multiple risk factor ‘‘black box’’ approach, which is of declining utility, in favor of an approach that encompasses multiple levels of organization and causes from the molecular to the societal.

A second area of concern, identified by Bracken (1998), is the relationship of epidemiology to corporate litigation when various rare disorders are related to sources of risk such as cellular telephones, breast implants, and the like. The issue is the extent to which epidemiologists can provide risk information to journalists and the public without undue burden from unbridled discovery and from the inconsistencies of findings of rare exposures related to rare diseases.

A third issue appears to be the search for professional identity in a discipline that has applicability across the full range of health professions, human and otherwise. The professional positions identified in a 1999 Internet search indicated that there is a continuing market for persons with epidemiological training but that these positions are distributed widely in departments supporting specific disciplines or located in various public health settings. Thus the job titles are often designated in a hyphenated form, such as psychiatricepidemiologist, cancer-epidemiologist, and genet- ic-epidemiologist. For a more complete introduction to the principles and methods of epidemiology see Kleinbaum, Kupper, and Morgenstern (1982), Littlefeld and Stolley (1994), or MacMahon and Trichopolous (1996).

REFERENCES

Ahlbom, Anders, and Staffan Norell 1990 Introduction to Modern Epidemiology. Newton Lower Falls, Mass.: Epidemiology Resources, Inc.

Bracken, M. B. 1998 ‘‘Alarums False, Alarums Real: Challenges and Threats to the Future of Epidemiology.’’

Annals of Epidemiology 8(2):79–82.

Friedman, Gary D. 1980 Primer of Epidemiology, 2nd ed. New York: McGraw-Hill.

Lilienfeld, David E., and Paul D. Stolley 1994 Foundations of Epidemiology. New York: Oxford University Press.

MacMahon, Brian, and Dimitrios Trichopoulos

Epidemiology: Principles and Methods 2nd ed. Boston:

Little, Brown.

Roueché, Berton 1967 Annals of Epidemiology. Boston:

Little, Brown.

Susser M., and E. Susser 1996a ‘‘Choosing a Future for Epidemiology: I. Eras and Paradigms.’’ American Journal of Public Health 86(5):630–632.

86(5):674–677.

CHARLES E. HOLZER, III

EPISTEMOLOGY

The term epistemology is used with two separate meanings according to different cultural traditions. In English-speaking countries, epistemology denotes the philosphical theory of knowledge in general: in this sense, it includes themes and problems such as the question of the possibility of valid knowledge, the analysis of the nature of such validity, the foundation of knowledge on reason or on experience and the senses, the analysis of different types of knowledge, and the limits of knowledge. In continental Europe, the above issues are considered part of the field of the more general discipline of gnoseology (gnoséologie in French, gnoseologia in Italian and Spanish) or theory of knowledge (Erkenntnistheorie in German), whereas the aim of epistemological inquiry is restricted to scientific knowledge.

In this second sense, with particular respect to social sciences (and sociology, in particular) the fundamental epistemological question becomes: ‘‘Is it possible to acquire any valid knowledge of human social reality? And, if so, by what means?’’ As these questions show, epistemological issues are inescapably interconnected with methodological problems; however, they cannot be reduced to simple technical procedures and their validity, as a long empiricist tradition among sociologists has tried to do. A full epistemological awareness, from a sociological point of view, should cope with at least four main issues:

1.Is the nature of the object of social sciences (i.e., social reality) fundamentally different from that of the object of natural sciences (i.e., natural reality)?

2.Consequently, what is the most appropriate gnoseological procedure with which to study and understand social reality?

3.Are we sure that the particular knowledge we get by studying a particular social reality can be generalized?

Historically, the various sociological traditions or schools have answered these four questions differently. We shall trace them by following the three main epistemological debates that took place between three pairs of opposing schools of sociological and epistemological thinking: positivism versus historicism, logical empiricism versus dialectical theory, and realism versus constructivism.

POSITIVISM VERSUS HISTORICISM

At the beginning of the nineteenth century, the discipline of sociology originated as the positivistic science of human society and aligned itself against metaphysical and philosophical speculation about social life. This, according to Auguste Comte, the founder of sociology, implied the straight application of the scientific method used in physics and the other natural sciences to the analysis of human society. His social physics (Comte 1830–42) is the expression of the new culture of the Industrial Revolution and of its practical ambition of a totally planned social life. Comte’s positivistic doctrine is organic and progressive and holds a naive faith in the possibility of automatically translating scientific knowledge of the laws of society into a new harmonious social order.

The uncritical assumptions of Comte as to the reliability and universal applicability of scientific method were at least partially tempered by John Stuart Mill, who considered illiberal and doctrinaire Comte’s idea that, once sociological laws are established by the same scientific method of natural science, they can no longer be questioned. Mill objected that scientific knowledge never provides absolute certainties, and he organically settled the British empiricist tradition in his A System of Logic, Ratiocinative and Inductive (1834). Starting from the epistemological positions of David Hume, Mill considered knowledge as fundamentally grounded on human experience, and the induction as its proper method. The possibility of inductive generalization is based on the idea of regularity and uniformity of human nature, ordinated by laws; and even social events are correlated in the form of empirical laws, which we can understand using the scientific method, considered as a formal logical structure independent from human subjectivity.