Georg Ivanovas From Autism to Humanism - systems theory in medicine
The function of the sensory nervous system is the classical example for a structure-determined system. Already in the first half of the 19th century, Johannes Müller described that sensory nerves do not ‘perceive’ anything. They just send an undifferentiated signal to the brain. The sensory impression is constructed out of the impulses which only differ in their frequency. Müller stated: “Some have come to the realization that a sensory nerve is not a mere passive conductor, but that inherent in each particular sensory nerve are also certain special energies or qualities that are merely stimulated and brought out by exciting causes. Therefore, sensation is not the conduction of a quality or state of external bodies to consciousness, but the conduction of a quality or a state of nerves to consciousness, excited by an external cause” (cited in Foerster/Bröcker 2002: 36).
The nerve does not provide any qualitative information. The nerve is, out of its structure, the qualitative information.
In their influential article What the frog’s eye tells to the frog’s brain (Lettvin et al 1959) Maturana and McCulloch revived these thoughts. They demonstrated that perception, in a more general sense, depends on the structure of the nervous system and does not depict an outer reality. That is, perception is a structurally determined reaction to environmental perturbations. Such findings influenced the theory of cognition, learning and artificial intelligence. Radical Constructivism developed these ideas further and investigated a lot of their consequences (Glasersfeld 1995). For pedagogics, for example, it became clear that it is impossible to teach. Knowledge can’t be poured into the brain of a pupil as with Nürnberger Trichter (funnel of Nuremberg). It is as impossible as to bring a steak into a person without digesting it. In teaching only the inner structure can be perturbed (Thissen 1997).