One of the most important contributions Luhmann has made to the study of social systems has been in the sociology of law. His approach represents a substantial break with traditional theories of law and ideology. As he explained it, recent theories of law have tried to separate the subjective goals of the individual from the true basis for formulating laws and replace them with objective nonideological grounds.

In place or ethical theories of society that attempted to attribute to the agent goals and right action, there have arisen new theories that seek to show that the existence of society is independent of the "subjective" goals of individuals. In addition theories have been proposed that seek to explain causally the positing of goals, and thus to unmask them as ideological. The aim of this line of thought is to reduce the orientations of the individual agent to his economic interests or his "objective situation," and to explain law in a given society as a product of ideology."

Though this approach may sound reasonable, as Luhmann so aptly pointed out, "Even if particular causal dependencies can be established, with some degree of plausibility, between ideas and their material situation, the form of these dependencies (i.e, the statement of an invariable relation between particular causes and particular effects) is much too simple to do justice to the very complicated structure of modern societies." His approach, developed from general systems theory and cybernetics with some additional explanation illustrates some very significant examples of the kind of properties that are typical of social systems. To begin with, we need to clarify this statement concerning complexity.

By employing ideas worked out in the general theory of systems and in cybernetics, we can define social configurations in systems that, in an inordinately complex environment, hold constant a less Complex network of expectations and thereby are able to orient action.

As I explained above, through social differentiation, semi-autonomous sub-structures form, each of which serves as one element in a complex society. Through both their own semi-autonomy and that of those elements of the external complexity they are in contact with, each must deal with only a small part of the variety that exists in the environment. This is the equivalent to what Luhmann calls a reduction of complexity. Each such substructure exacts from the realm of all possible expectations a limited arbitrary selection and it is from among this limited selection that the individual will be constrained by the system to choose. The choice of arbitrary selections is not a blind groping. These substructures gain their stability by providing for the members of the society a common feeling of solidarity specifically because they are meaningfully related to each other. Luhmann put it in these terms;

Because of the way actions are meaningfully related to one another and reinforce one anothers selectivity, systems can be maintained as frame-works for orienting action, even though their own complexity is less than that of the environment. In social systems thus defined, positive law and ideology acquire the function of reducing the complexity of the system and its environment.

For Luhmann positive law and ideology are separate though related subsystems. Positive law refers to the legal decisions of the political system and ideology refers to the value structure of the society. It is important that we keep them separate, what is common to both lies not in their content, but in their form. He said, "Positive law and ideology resemble each other in that each naturally implies a characteristic distance toward itself." We can, avoid the functionalist reification by translating that statement into the concept that both positive law and ideology are structures recognized by the individuals in a society as semi-autonomous entities and can be reflected upon by those individuals as products of their own society which can be modified by them to serve the purposes they recognize as pertinent to the society. Luhmann then said, "positive law is made valid by decisions: a law of any content whatsoever can gain legitimate legal validity; and~the same decision that makes the law a valid one can also withdraw its validity." The foundation of law, then, instead of resting on an objective unchanging truth, rests instead on an assumption of contingency In other words positive law, being a subject of reflection by the members of the society must relate to the assumptions, including ideological assumptions, of the society where those assumptions are commonly held. "The stability and validity of the law," Luhmann explained, "no longer rests upon a higher and more stable order, but instead upon a principle of variation. It is the very alterability of law that is the foundation for its stability and its validity. Positive law is part of a complex social system and is thus constrained by the social and cultural norms of the society. But these too are contingent and it is because law is a subject of reflection by those who practice it and those who promulgate it, and because it is free to change, or rather be changed, that the members of the society have faith in its validity. Ideology, on the other hand, has to do with an evaluation of values As Luhmann defined it, "A value can be defined very generally as any point of view specifying which consequences of action are to be preferred to others." In this way an absolute value is a value without a function, thus are immediately discredited. A permanent set of values is not possible since there can be no intrinsic hierarchy of values. What is important is that the ordering of values must be opportunistic. "It must foresee the possibility of varying the order of values according to what actions are possible or urgent and according to how much the various values have been realized." To translate that into the actions of individuals rather than envisaging a system which thinks for itself, we begin with the concept that the people who follow an ideology and those on the outside who study or criticize it, are able to identify the ordering of values that are currently accepted. Just as with positive law ideology is a higher level system which constrains the activities of the people who follow it. At the same time they create it, thus reflection on the ideological system is a form of self reflection for the members of the society. it is through this reflexivity that the followers of an ideology identify with it and contribute to its development and change. Because it is a complex system, it contains a kind of circularity where the system is created by the members, constrains them and in turn is modified by them.

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