>> For a meaningful life, action and communication, the reduction of complexity is essential. And this is where social systems come into play, as their core function is to reduce this complexity by including certain aspects in a system and excluding others. Systems set boundaries about what belongs to them and what doesn't. With regard to the functional system of science, this means, for example, that e.g. For example, scientific articles on climate change are part of internal communication, but a newspaper article on the topic is not. Buying a new television in a specialist store is part of the economic system: an exchange of goods becomes more likely when money is used, i.e. H. To put it simply: if you want to buy a consumer good, the probability that you will get it increases if you pay money for it.
However, the law that stipulates that it can be taken back by the specialist retailer is not one of them. Because every system has its own, binary leading distinction: the leading distinction of economics is payment or non-payment, the leading distinction of politics is power or non-power and that of science is true or false. From the perspective of systems theory, to put it simply, the world can always be divided into two concepts; based on this distinction, complexity can be reduced and the environment can be observed. Systems theorists are so-called “second-degree observers” who analyze their environment by focusing on these binary codes of the respective object of observation. System-theoretical thinking always depends on the perspective of the relevant observer: who viewed from which perspective which problems, which key distinctions, concepts or solutions come into play?
Central terms
communication
Communication is the central, constitutive and sustaining operation of social systems. Systems do not consist of people or institutions, but of communications.

Means: Humans are not a unit of analysis in systems theory, but communication and, contrary to common models, this does not consist of a sender, a message and a receiver, but rather of the unit of selection of information, communication and understanding (Luhmann, 1990, p. 4 )
Example: The social system of science is maintained through the autopoietic operation of publishing. A scientist (1) selects a specific result as relevant information, decides (2) to communicate this in the form of a specialist article so that another scientist can (3) understand this information in the form of this communication (understanding in this context does not mean understanding the content , but understanding that the article is a communication). Only when all three steps come together is communication complete.

Autopoiesis
“Autopiesis is the self-reproduction of the system based on its own elements” (Luhmann, 1993, p. 189)

Means: The system can only maintain itself through self-determined operations; events in the environment can only be processed once they have been translated into the system's code.

Example: If a researcher violates good scientific practice, for example by falsifying data, then a publication based on this data can hardly be legally removed from the scientific communication space. However, it can be ignored by the professional community in the future, ie it can no longer be cited. Autopoietic follow-up communications no longer take place, and publication loses its importance as part of the science system.
Operational unity
Operational closure describes the relationship between the system and its environment as well as the process of drawing boundaries between them, which in turn is only possible from within the system itself (Luhmann, 1990, p. 276) and refers to the way in which this occurs System reproduced autopoietically (Mayr, 2012, p. 85).

Means: Things that happen in a system's environment are not initially understood or processed by the system; they only appear as noise. A system can only process events if they are translated into the way the system operates.

Example: If a journalist finds out through research that twenty percent of cancer treatments do not comply with guidelines, then this finding can be incorporated into science, for example by a healthcare scientist quoting the relevant newspaper article. However, the science system, i.e. the collected knowledge on the topic, can only be structurally determined if it is translated into the way science operates, for example if the corresponding health care scientist uses this knowledge, e.g. B. empirically proven and published about it. Influences from the system's environment are only processed according to the system's own rules.

Environmental openness
However, what a system processes may well arise from the system environment. Otherwise the system would eventually become lost in “barren tautology and indefinable arbitrariness” (Hornbostel, 1997, p. 137). An autopoietic system does not operate in “empirical isolation” (Luhmann, 1991, p. 1420), but rather open to the environment.

This means that systems can be influenced by the environment, but only if operational unity is a condition that makes it possible to process these influences. (Luhmann, 1990, p. 276)

Example: see operational closure
Systems theory and health services research
Although systems theory has so far only been used little (Dittmer, 2019), particularly in organizational health services research, with the exception of some considerations of inpatient interventions (Dittmer, Nowak, Karbach, & Pfaff, 2018), it is very suitable in the complex world of health care to provide a theoretical basis for empirical observation of relevant issues. In the area of health care, many different (sub)systems come together, the investigation of which touches on central questions in health care research. On the macro level this is the health system, on the meso level this concerns institutional or organizational structures such as hospitals or the relationship between inpatient and outpatient service providers and on the micro level it concerns the relationship between doctor and patient. Holger Pfaff therefore values systems theory (alongside action theory) as “useful for at least understanding things” (Stegmaier, 2020, p. 33). This particularly includes complex interventions, which, according to Pfaff, have relevant implications not only in social systems, but also in technical (machines) and psychological (patient) systems (ibid.). A systems theory approach is particularly interesting when observing implementation processes, i.e. for the analysis of the “last mile” in which findings from health services research are disseminated into the health system (Borgetto, 2011, p. 296). However, in order for systems theory to be used on a broader basis in health services research, not only a uniform terminology but also a corresponding method inventory must first be developed (Dittmer et al., 2018). <<