[Social capital, from sociology to epidemiology: critical analysis of a transfer across disciplines].

In recent years, social capital has emerged in epidemiological studies as a new concept, improving our understanding of the relationships between social inequalities and health inequalities. This concept, borrowed from social sciences, has three distinct sociological sources. However, only the most recent theory, which emphasizes the role of civic trust and is useful for analysis at community level, has been used in epidemiological studies. Social capital poses three kinds of problem: i) theoretical problems, because it is defined by its effects rather than by its causes, and because it is presumed that these effects are positive, although they can in fact be negative; ii) methodological problems, because of the heterogeneity of empirical scales, from micro to macro, and because of the diversity of its semantic content, including contradictions; iii) political problems, because of the emphasis placed on individual responsibility and due to the imposition of a model of civic virtue, to the detriment of structural analysis.