Third, information is withdrawn from perturbations. In The Democracy of Objects I argue, following the autopoietic theorists, that objects are operationally closed. Within this framework, no object has a direct relationship to other objects in the world. Rather, each object is 1) selectively open to the world, and 2) relates to that field of the world to which it is selectively open in terms of its own organization. Selective openness to the world means that objects aren’t receptive to everything in the world. Neutrinos cannot interact with most matter because they have such a neutral charge. Dogs, unlike humans and other primates, cannot detect color in the red end of the spectrum. The utterance “I think therefore I am” resonates differently for a person trained in the history of philosophy than it does for someone who has never read any philosophy. Every object transforms those perturbations to which it is open in its own specific way according to its own particular organization. These perturbations are transformed into information or events that select system-states within an object, and that transformation, in its turn, produces a cascade of effects within the object.
Here Levi makes very important points about systems, but I wanted to point out the next part for Luhmann. Systems still have to interact, but they do so without being able to fully grasp another system. Luhmann doesn't use the term vulnerability particularly, but does employ the concepts of risk and trust in order to explain many of these interactions between systems. Trust is about the ways that systems interact with each other in ways that open the system up to risk. Risk isn't just calculated danger, but risk involves taking chances that exceed calculation, and therefore trust exceeds a system's calculation as well. Luhmann posits that systems that are more likely to trust tend to be ones that are more likely to thrive. Or, to put it another way, trust is "an attitude that allows for risk-taking decisions". This how links up with another of Luhmann's theories, which is the centrality of immunity to any systems function.
Immune systems function through a negation, not from determining what a system is, but by negating what it is not (through negative communication in the environment). An immune system cannot be brittle for proper functioning. "An immune system must be compatible with self-reproduction under changing conditions. It is not simply a mechanism for correcting deviations and re-establishing the status quo ante; it must manage this function selectively, namely, must be able also to accept useful changes." (Social Systems, p. 369) This is, of course, where biopolitics becomes a primary concern of systems theory and vulnerability. Esposito has already briefly taken up Luhmann in Bios, and a bit more extensively in Terza Persona (a book of which I will come back to in another post). As Esposito has wonderfully argued, immunity is necessary for community (this is basically true for Luhmann as well), a problem emerges with auto-immunity disorders (here is one of the key insights of much work in biopolitics. Not just Esposito; but Haraway, Derrida, and even to some degree in Foucault). When an immunity system over-reacts, cripples a system, starts killing itself in order to protect itself. A certain remainder of vulnerability, a certain attitude of trust, is necessary in order to strive off auto-immune.