The so-called OBI project (‘Organization of Business Interests’), which Philippe C. Schmitter and Wolfgang Streeck carried out in the early 1980s, provided subsequent scholars with a framework for the analysis of interest groups. One major contribution in this respect was the development of two different sets of opposite associational logics: on the one hand, interest groups can emphasize the ‘logic of influence’ or the ‘logic of membership’; on the other hand, interest groups are also challenged by finding a position between the ‘logic of effective implementation’ and the ‘logic of goal formation’. While this conceptual framework is still being used in today’s analyses of interest groups, there are two main shortcomings in the literature. First, there have never been systematic attempts to operationalize and/or conceptualize the two abovementioned dichotomies. Second, the discussion of these logics has largely ignored the dynamics which can emerge between the individual level of the associations and the level of the interest group system. The article deals exactly with these conceptual and methodological issues. We will develop criteria for all four logics and refer to various modes of creating typologies from the case study tradition. Special emphasis will be placed on the use of set theory, in particular fuzzy set logic, and we will explain the linkage between the relative predominance of a particular ideal type in a given interest group system and the characteristics of that interest group system as a whole.
