The concept of autopoiesis in itself cannot explain a system’s persistence over time. Autopoiesis happens in a moment. Events passes away as soon as they occur and must be replaced with subsequent events. In order for systems to persist or reproduce themselves, structures must emerge. Only structures persist in time. Thus structural coupling complements autopoiesis. Structure is associated with redundancy--repetition of the same kind of event. Systems recognize the same kinds of event (e.g., medical diagnosis, publication of research, legal decision) and they develop expectations for what counts as an event. Social structures are actually expectations.
Luhmann borrowed the structurally coupling concept from from Humberto Maturana. As Luhmann writes,
Maturana introduced the concept of structural coupling. The distinction [between this concept and autopoiesis] allows us to say that autopoiesis must function in any case since there would otherwise be no system. At the same time, it also indicates that coupling between system and environment concerns only structures [and not operations] and, as the case may be, everything in the environment that is relevant to these structures. Thus, on earth gravity is coordinated with the musculature of a living being that has to move in order to survive. . . . This is a case of structural coupling. This concept is adjusted to the autopoiesis of the system, which is to say that structural coupling does not interfere with the system’s autopoiesis . . . There [can be] the destruction of the system by the environment, but the environment does not actively contribute to the maintenance of the system. This is precisely the point of the concept of ‘autopoiesis.’ The causalities that occur between system and environment are located exclusively in the domain of structural coupling. (Introduction to Systems Theory, 85)
In other words, nothing in a system’s environment can cause a specific structural change, or change of state, to happen in the system. Systems are structurally self-determined.
Simultaneous Dependence and and Exclusion
Luhmann speaks of a simultaneous dependence and exclusion in structural coupling. For instance, the meaning attributed (by society) to a sentence cannot depend on what the speaker was thinking or intending when she uttered the sentence. This means that communication is not bound by consciousness, as in the intentions or desires of a speaker. And with respect to organic systems, while a person has to be alive–blood must be flowing, etc.–to make an utterance (which could include talking in one’s sleep), the meaning of an utterance, clearly, doesn’t depend on the blood pressure or any other elements of the speaker’s body. The communication system determines the meaning. The point is that communication system simply cannot be concerned with all the intentions or the physiological condition of a speaker. As Luhmann puts it,
After all, it is completely unthinkable that communication would have to consider everything that happens physically, chemically, or biologically within all the participants of communication. (Introduction to Systems Theory, 199).
All of that is excluded from communication. Something like blood pressure or cholesterol levels can only be included in a communication system as a topic; that is, it has to be translated into language. But the physiological events in themselves have no meaning.
In order to engage in language-based communication, one must be awake and attending to language. This is a case of structural coupling between a communication system and a consciousness (or psychic) system. Communication depends fundamentally on consciousness, or conscious awareness; however, the events that constitute consciousness are operationally excluded from the communication (or social) system. The events happening from moment to moment in the psychic system are too complex to be incorporated into communication.
It’s important to understand that when two autonomous systems (e.g., two psychic systems or two different function systems) structurally couple, there is not a third system that emerges through combination. That is to say, contrary to some sociological theory, the two systems are not integrated. Two or more psychic systems cannot share the same thoughts, feelings, or perceptions. And while the political system and the economic system do structurally couple, they cannot form a third function system that combines the functions of politics and economics. That is to say, there is no third system that contains economic and political functions. A third system would cause the two systems to “stick together” and so their autonomy. The “division of labor” between the systems would be lost. In the case of integration, if the economy collapsed, the political system would collapse with it–and vice versa.
When a state (an organization that engages in legal, economic, and political communication), taxes citizens and spends money, it acts economically. it structurally couple the economy and politic, which means that if something “bad” happens in the economy, the economy can destabilize the political system (prompting new political decisions). When the state passes a law regulating an economic practice (e.g., an antitrust law), it structurally couples law and the economy. Nonetheless, these functional systems remain distinct, and the political intent can be subverted by the economy. The intentions of a political decision to spend money or pass a law are not relevant once the money is spent or the law is passed.
Systems can be structurally coupled loosely or tightly, and, given the level of taxing and spending, modern politics and the economy are tightly coupled. Tightly coupled systems tend to perturb one another a great deal. For instance, an economic recession can perturb the political system, prompting new decisions regarding who loses and gains political power. Or unwise fiscal decisions of a government can unexpectedly perturb the economy.
A case of loose structurally coupling in modern society would be the coupling between religion and politics. It is unlikely that a change in religious doctrine could significantly destabilize a modern political system, and it is unlikely that a political decision could significantly destabilize religion. Which is why the framers of modern constitutional republics took such pains to keep these politics and religion apart. They didn’t want religious wars that could destroy the political system or the economy.
As for psychic systems, consciousness attends to/notices its environment, which can be sensory impressions arising from within the body (e.g., a racing heart, a fever, a stomach ache) or external forces which impinge on the nervous system (i.e., anything seen, heard, felt, smelled, or tasted). And with internalized language, the psychic system can think about these perceptions, and, of course, think about thoughts. In this case, the psychic system uses the social medium of language for its own purposes.
The main point here is that the events and structures of consciousness are completely excluded from the events and structures of communication. This is what it means to say that autopoietic systems are operationally closed. Consciousness allows communication to happen, but consciousness is excluded from the events of communication; that is to say, consciousness must remain in the environment of the communication system. This is good for consciousness because if communication becomes impossible consciousness does cease its operations. Consciousness and communication don’t rise and fall together. Helen Keller didn’t lack consciousness before she learned to communicate.
Structural Coupling and Uncoupling
Another way of putting this (if yet another way is needed!) is that structural coupling implies structural decoupling. If communication can structurally couple with consciousness, it must also be able to decouple; otherwise the two systems would be one. For instance, sentences spoken or written can remain in a communication system as long as they are repeated or recur in further communication. The “original” speakers and listeners (or writers and readers) can be long dead, but the communication can remain in circulation. It’s true that some human consciousness has to be around to keep the sentence in communicative circulation; however, human consciousnesses (attentive minds) are plentiful and easily replaced. Thus, Luhmann can say that
communication depends completely on consciousness and at the same time excludes it completely. (Intro 199)
So, after all this work, what is gained by excluding everything except except consciousness from the possibility of structurally coupling with communication? What is the evolutionary compensation?
What is gained is that communication has to depend on one and only one thing in its environment; it only has to depend on consciousness. Consciousness, in turn, only has to depend on organic systems of the body. This simplifies matters quite a bit. Communication doesn’t have to directly depend on a properly functioning brain or heart because consciousness depends on all that. If these organic preconditions aren’t met, then there is no question of communication anyway; so why worry about it or try to control it? As Luhmann puts it,
The compensation for this exclusion is the total dependence of communication on consciousness, which in turn depends completely on one’s brain, and the brain requires that the organism be alive. . . . [This is a] paradox of simultaneous total dependence and total independence. Communication happens only via consciousness and with the help of consciousness but never operationally as consciousness. (Introduction to Systems Theory, 200-201).