Claus Emmeche

When posing the question "is artificial life possible?", our immediate answer is that on the one hand : of course it is - people make it, and indeed very interesting and even breathtaking structures have already been constructed, such as `aminats', self-reproducing patterns and the other things, we have seen already. In this sense we are forced to take artificial life as a fact (at least as a fact about a new branch of research), nearly in the same way that the philosopher Kant took the theoretical physics of his days, Newtonian physics, as a matter of fact, and then asked: What are the conditions of possibility for this kind of theoretical science? On the other hand: The situation differs from Kant's. Artificial Life does not confront us with an analogy of theoretical mechanics within the field of biology. We face a curious situation: It is not obvious to the majority of biologists that Artificial Life is possible at all, at least in the purely computational sense of `software life'. Probably, most biologists would never call these artificial constructs `living'. Why not? Because the intuitive notions of life and living systems within biology implies, among other things, that living beings are a result of a long, ongoing evolutionary process that have created autonomous organisms, single-celled and multi-celled, that are highly organized, open (non-equilibrium), material thermodynamic systems based on metabolism and some kind of genetic information supported by macromolecules, that only metaphorically resemble a computer program. It is not that..

The strong version of Artificial Life claim that emergent computational patterns may not simply simulate life but realize the very phenomenon. This is one of several reasons why a definition of life is of interest. In this paper, it is argued that the received view of definitions of life in biology and philosophy is misleading. Generality cannot in general be dispensed with. Though criteria for adequacy of definitions are highly context-dependent, definitions of life are of a special nature, belonging to what is here called ontodefinitions. Separate definitions of life fulfilling a set of relevant criteria exist and belong to distinct paradigms of theoretical biology. Emergence is implicit in these. The paper investigates if emergence entails 'downward causation' (several kinds are defined), and asks if computational models can represent higher orders of emergence. Finally, a comment is made on the role of Wittgenstein's philosophy in understanding the nature of explanation and definition in science. --- ### --- Bibliographical note: Earlier versions of this paper were presented at the Princeton History of Science Workshop on "Growing Explanations", Princeton University, February 15, 1997; and at the meeting in the International Society for the History, Philosophy and Social Studies of Biology (ISHPSSB) in Seattle, USA, July 16-21, 1997. Different parts were published in a modified form as 1) Emmeche (1997): "Autopoietic systems, replicators, and the search for a meaningful biologic definition of life", Ultimate Reality and Meaning 20 (4): 244-264 [the original title was: "Is the definition of life important?"], and 2) Emmeche (1998): "Defining life as a semiotic phenomenon", Cybernetics & Human Knowing 5 (1): 3-17. The present web version below contains the complete argument of both articles. A further thoroughly rewritten version, accessible also for non-specialists, was made in collaboration with Charbel Niño El-Hani, and translated by him into Portuguese as a contribution to a book (this version can also be found at web (dot)archive(dot)org)

The vitalism/reductionism debate in the life sciences shows that the idea of emergence as something principally unexplainable will often be falsified by the development of science. Nevertheless, the concept of emergence keeps reappearing in various sciences, and cannot easily be dispensed with in an evolutionary world-view. We argue that what is needed is an ontological nonreductionist theory of levels of reality which includes a concept of emergence, and which can support an evolutionary account of the origin of levels. Classical explication of emergence as “the creation of new properties” is discussed critically, and specific distinctions between various kinds of emergence are introduced for the purpose of developing an ontology of levels, framed in a materialistic and evolutionary perspective. A concept of the relation between levels as being inclusive is suggested, permitting the “local” existence of different ontologies. We identify, as a working hypothesis, four primary levels and explicate their nonhomomorphic interlevel relations. Explainability of emergence in relation to determinism and predictability is considered. Recent research in self-organizing non-linear dynamical systems represents a revival of the scientific study of emergence, and we argue that these recent developments can be seen as a step toward a final “devitalisation” of emergence.

It is argued that the notion of Umwelt is relevant for contemporary discussions within theoretical biology, biosemiotics, the study of Artificial Life, Autonomous Systems Research and philosophy of biology. Focus is put on the question of whether an artificial creature can have a phenomenal world in the sense of the Umwelt notion of Jakob von Uexküll, one of the founding figures of biosemiotics. Rather than vitalism, Uexküll's position can be interpreted as a version of qualitative organicism. A historical sketch of Autonomous Systems Research (ASR) is presented to show its theoretical roots and fruitful opposition to traditional AI style robotics. It is argued that these artificial systems are only partly 'situated' because they do not in the full sense of the word experience an Umwelt. A deeper understanding of truly situated autonomous systems as being a kind of complex selforganizing semiotic agents with emergent qualitative properties must be gained, not only from the broad field of theoretical biology, but also from the perspective of biosemiotics in the Uexküll tradition. The paper is thus an investigation of a new notion of autonomy that includes a qualitative aspect of the organism. This indicates that the Umwelt concept is not reducible to purely functional notions.