Mechanistic explanations in biology have continually confronted the challenge that they are insufficient to account for biological phenomena. This challenge is often justified as accounts of biological mechanisms frequently fail to consider the modes of organization required to explain the phenomena of life. This, however, can be remedied by developing analyses of the modes of organization found in biological systems. In this paper I examine Tibor Gánti’s account of a chemoton, which he offers as the simplest chemical system that exhibits characteristics of life, and build from it an account of autonomous systems, characterized following Moreno as active systems that develop and maintain themselves by recruiting energy and raw materials from their environment and deploying it in building and repairing themselves. Although some theorists would construe such self-organizing and self-repairing systems as beyond the mechanistic perspective, I maintain that they can be accommodated within the framework of mechanistic explanation properly construed.

In this article I will outline the basic theoretical assumptions of two examples of the confederative and the integrative views of the living – respectively Ganti’s Chemoton theory and Maturana and Varela’s autopoietic theory – by showing that they are both consistent perspectives, but they differ in the accounts they make of the role of organization in biological systems. In doing so I will also put into evidence how the choice between these two theoretical frameworks is strictly connected to the problem of structure and function in living organisms and entails different strategies of investigation.

Key words: biological autonomy, organization, autopoiesis, Chemoton theory

The major insight in Robert Rosen’s view of a living organism as an (M, R)-system was the realization that an organism must be “closed to efficient causation”, which means that the catalysts needed for its operation must be generated internally. This aspect is not controversial, but there has been confusion and misunderstanding about the logic Rosen used to achieve this closure. In addition, his corollary that an organism is not a mechanism and cannot have simulable models has led to much argument, most of it mathematical in nature and difficult to appreciate. Here we examine some of the mathematical arguments and clarify the conditions for closure.

Key words: (M, R) systems, Metabolic circularity, Robert Rosen, Definitions of life, Autopoiesis, Autocatalytic sets, Chemoton, Impredicativity

The nature of life has been a topic of interest from the earliest of times, and efforts to explain it in mechanistic terms date at least from the 18th century. However, the impressive development of molecular biology since the 1950s has tended to have the question put on one side while biologists explore mechanisms in greater and greater detail, with the result that studies of life as such have been confined to a rather small group of researchers who have ignored one another’s work almost completely, often using quite different terminology to present very similar ideas. Central among these ideas is that of closure, which implies that all of the catalysts needed for an organism to stay alive must be produced by the organism itself, relying on nothing apart from food (and hence chemical energy) from outside. The theories that embody this idea to a greater or less degree are known by a variety of names, including (M, R) systems, autopoiesis, the chemoton, the hypercycle, symbiosis, autocatalytic sets, sysers and RAF sets. These are not all the same, but they are not completely different either, and in this review we examine their similarities and differences, with the aim of working towards the formulation of a unified theory of life. – Highlights: There have been many isolated attempts to define the essentials of life, A major unifying feature is metabolic closure, Metabolic closure requires some molecules to fulfill more than one function, There can be no hierarchy in the overall organization of a living system.

Key words: Origin of life, (M, R) systems, Autopoiesis, Chemoton, Self-organization

Excerpt: The aim of this chapter is to review the notion of autopoiesis and to present it in the context of present-day research in the life sciences. This will imply some addition to, and modification of, the original theory and also of a recent review of mine on which the first part of this outline is based. This work is also prompted by the observation that cellular theories, such as autopoiesis, are once again attracting attention due to developments in the field of experimental cellular models. In this chapter, the notion of the chemoton developed by Tibor Ganti at about the same time as Maturana and Varela’s autopoiesis will also briefly be considered, in order to see the analogies and differences between these two conceptually related viewpoints. Autopoiesis deals with the question “What is life?” and attempts to isolate and define, above and beyond the diversity of all living organisms, a common denominator that allows for discrimination between the living and the non-living. Autopoiesis is not concerned with the origin of life per se, or with the transition from the non-living to the living; rather, it is an analysis of the living as it is – here and now, as the authors say. Autopoiesis also deals with the various processes connected with life, such as interaction with the environment, evolution, and cognition, and attempts to interpret these aspects in a coherent conceptual scheme. As a consequence, a series of epistemological concepts emerges from the analysis, part of which will be encountered in this chapter.

Excerpt: The theory of autopoiesis is based on taking a picture of the actual behavior of a living cell. As such, it is not an abstract theoretical model for life – there are many of these – but a phenomenological analysis of life as it is on Earth. It is, in a way, a picture of the blueprint of cellular life, and it is fascinating to see how many concepts related to the process of life – emergence, homeostasis, biological autonomy, operational closure, open systems, interaction with the environment, cognition, evolutionary drift, etc. – pour forth from this analysis in a coherent way. We will see some of these concepts in the next chapter. In addition, autopoiesis permits the construction of chemical models, as seen in chemical autopoiesis; and it pertains also to the social sciences, with the notion of social autopoiesis. A bridge between biology to the cognitive domain is also made possible. This richness is not present in the chemoton or any other autocatalytic networking. The main ingredient of this unity is the fact that all is seen “from within,” that is, from the logic of the internal organization of the living system. As soon as the autopoietic unit reaches the complexity of biological autonomy, everything that happens within the boundary, as well as the perturbing events from the outside, are interpreted and elaborated in order to maintain the identity of the living. We have also touched on some of the philosophical implications of these views, and added that the developments of autopoietic thinking have in some cases diverged from the original statements of Maturana and Varela. We will see that particularly in the case of the important notion of cognition, discussed in the next chapter. And we will see then that the notion of cognition permits a bridge between the biology of cellular life and the cognitive sciences. I mention this here just to make the point that autopoiesis is the only available simple theory that is capable of providing a unified view of life from the molecular level up to the level of human perception.