Autopoiesis with or without cognition: defining life at its edge.

This paper examines two questions related to autopoiesis as a theory for minimal life: (i) therelation between autopoiesis and cognition; and (ii) the question as to whether autopoiesis isthe necessary and sufficient condition for life. First, we consider the concept of cognition inthe spirit of Maturana and Varela: in contradistinction to the representationalistic point ofview, cognition is construed as interaction between and mutual definition of a living unit andits environment. The most direct form of cognition for a cell is thus metabolism itself, whichnecessarily implies exchange with the environment and therefore a simultaneous coming tobeing for the organism and for the environment. A second level of cognition is recognized inthe adaptation of the living unit to new foreign molecules, by way of a change in its metabolicpattern. We draw here an analogy with the ideas developed by Piaget, who recognizes incognition the two distinct steps of assimilation and accommodation. While assimilation isthe equivalent of uptake and exchange of usual metabolites, accommodation corresponds tobiological adaptation, which in turn is the basis for evolution. By comparing a micro-organismwith a vesicle that uptakes a precursor for its own self-reproduction, we arrive at the conclusionthat (a) the very lowest level of cognition is the condition for life, and (b) the lowest level ofcognition does not reduce to the lowest level of autopoiesis. As a consequence, autopoiesisalone is only a necessary, but not sufficient, condition for life. The broader consequences ofthis analysis of cognition for minimal living systems are considered