Measurement theory and subsethood

The connection between logical implication and the subsethood relationship is apparent when bivalent logic and crisp set theory are examined. When fuzzy logic and fuzzy set theory are examined, however the connection is not always clear. Ragin Ragin (1987) introduced fuzzy subsethood into the social sciences as a tool for detecting necessary and sufficient conditions. Unfortunately, Ragin's efforts were dismissed by social scientists becasue of the problem of scale. This paper examines the use of fuzzy subsethood as tools for detecting causality.