ABSTRACT
Building on Maturana and Varela (1998), Bourgine and Varela (1992, xi) have defined artificial life (AL) as “a research program concerned with autonomous systems, their characterization and specific modes of viability.” Their working definition differs substantially from mainstream attempts to define AL in terms of the extraction of necessary and sufficient conditions of biological life forms, which are then applied to non-biological entities, hoping to thus synthesize life. Rather than opting for an imitation of biological life, they focus on the autonomy of living systems, whether natural or artificial. They emphasize autonomy as the most salient feature of life, which they further define by the constitutive capacities of viability, abduction and adaptability. Viability regards the capacity to respond to unpredictable changes in the environment in a manner that allows the system to maintain its organizational identity (implying operational closure), for instance by changing its internal structure (often entailing structural coupling with other living systems within the environment). To anticipate changes and to respond to unanticipated change, living systems need to function as abduction machines, producing sets of responses that sustain the unity of the system. Adaptability implies that the internal restructuring adequately fits with the challenges produced by the external environment, without annihilating the organizational identity of the system. Clearly, Bourgine and Varela did not consider Plessner’s notion of centricity, let alone eccentricity, as a necessary condition in this regard. For them, neither natural nor artificial life forms presume eccentricity or centricity to qualify as living systems. They do require a measure of autonomy, even if this may not be a sufficient condition. 1 One could associate the way Bourgine and Varela as well as Maturana and Varela define living systems with Plessner’s notion of the border or boundary and with his concept of positionality. For both Varela and Plessner, the difference between the border between a non-living thing and its environment on the one hand, and the border between a living system and its environment on the other hand, is that in the former the border is neither part of the environment nor of the thing, whereas in the latter, the border is actively created and maintained by the living system of which it is also a part. Interestingly, both Plessner and Varela consider living entities to be systems, meaning that the identity of the entity derives from the productive interrelations between its components. Last but not least, both speak of the capacity for self-regulation (Selbstregulierbarheit, Plessner 1975, 160-165; autopoiesis, Maturana and Varela 1998, 47-48) as crucial for living forms, even if Plessner may understand this as a transcendental category rather than an observable.
