The notion of rational solidarity may ap¬pear as a contradiction of terms at first glance to a sociologist, in that actors are either rational or solidary. This dichoto¬my, however, leads to problems, for in¬stance in explaining public allocations in the welfare state. This is because much sociological theory is based on the di¬stinction between homo economicus and homo sociologicus and therefore cannot have a concept of collective rationality. This is a self-imposed limitation created at the level of general theory in the so-called problem of order or collective action. This limitation is illustrated in an analysis of the works of Talcott Parsons, Jon Elster and Jürgen Habermas. In order to develop a concept of collec¬tive rationa¬lity, sociology must change some of its basic assumptions. Following the thoughts of Niklas Luhmann it must re¬place action and individuals with com¬munication as the basic unit of society. By doing so, it will be possible to appreci¬ate the fact that solidarity is not some¬thing typical of archaic societies or small groups, but rather a medium for the allocation of collective goods by the welfare state. The idea of rational solidarity sym¬bolizes the difference between individual and collective rationality as a unity: one should sacrifice individual opportuni¬ties to achieve collective goods and solve social problems. Taken as a medium for the allocation of collective goods, there is more to solidarity than Luhmann will admit: solidarity is the nexus of functio¬nal differentiation.
The article is based on the idea that the problem of unity or integration of modern society has not yet been solved in sociological theory. The paper attempts a new solution based on a creative synthesis of elements from Talcott Parsons' functionalism, rational choice theory, and Niklas Luhmann's new systems theory. The core idea is that the state and the political sphere work together as an integrating centre of modern societies. Present approaches understand the political allocation of resources either as an exchange process or as solidarity caused by internalized social norms. None of them embodies a concept of collective rationality: therefore they cannot give a dynamic account of the public allocation of collective goods. This dichotomy of individual rationality and norm-guided behaviour will be produced and reproduced on the level of general theory in the discussion on the problem of order or collective action as long as sociology is founded on the assumption that society is made up of individual human beings and their actions. However, by replacing action with Luhmann's concept of communication and rethinking collective action within this new framework, it becomes possible to develop a concept of collective rationality. This new conceptualization is used to clear up problems and overcome shortcomings in Luhmann's own theory of modern society as functionally differentiated. Observed as a consequence of action, function is collective action. A solution to the problem of collective action or social order is found with the emergence of rational solidarity as a medium that symbolizes the difference between individual and collective rationality as a unity: one should sacrifice individual opportunities to achieve collective goals and solve problems for the society to which one belongs.