Glycemia Regulation: From Feedback Loops to Organizational Closure.

Endocrinologists apply the idea of feedback loops to explain how hormones regulate certain bodily functions such as glucose metabolism. In particular, feedback loops focus on the maintenance of the plasma concentrations of glucose within a narrow range. Here, we put forward a different, organicist perspective on the endocrine regulation of glycaemia, by relying on the pivotal concept of closure of constraints. From this perspective, biological systems are understood as organized ones, which means that they are constituted of a set of mutually dependent functional structures acting as constraints, whose maintenance depends on their reciprocal interactions. Closure refers specifically to the mutual dependence among functional constraints in an organism. We show that, when compared to feedback loops, organizational closure can generate much richer descriptions of the processes and constraints at play in the metabolism and regulation of glycaemia, by making explicit the different hierarchical orders involved. We expect that the proposed theoretical framework will open the way to the construction of original mathematical models, which would provide a better understanding of endocrine regulation from an organicist perspective

La circularité biologique : concepts et modèles

National audienceThis chapter offers an overview of the theoretical and philosophical tradition that, during the last two centuries, has emphasised the central role of circularities in biological phenomena. In this tradition, organisms realise a circular causal regime insofar as their existence depends on the effects of their own activity: they determine themselves. In turn, self-determination is the grounding of several biological properties and dimensions, as individuation, teleology, normativity and functionality. We show how this general idea has been theorised sometimes through concepts, sometimes through models, and sometimes through both. We analyse the main differences between the various contributions, by emphasising their strengths and weaknesses. Lastly, we conclude by mentioning some contemporary developments, as well ass some future research directions.Ce chapitre propose un aperçu de la tradition théorique et philosophique qui, au cours des deux derniers siècles, a mis la circularité au centre de l'analyse des phénomènes biologiques. Selon cette tradition, les organismes réalisent un régime causal circulaire dans la mesure où leur existence dépend des effets de leur propre activité : les organismes biologiques s'autodéterminent. A son tour, l'autodétermination est le fondement d'un certain nombre de propriétés et dimensions biologiques, telles que l'individuation, la téléologie, la normativité ou encore la fonctionnalité. Nous montrons comment cette idée générale a fait l'objet d'une théorisation qui a pris, selon les cas, la forme d'une conceptualisation, d'une modélisation ou les deux à fois. Nous analysons les différences principales entre les différentes contributions, en soulignant leurs qualités et faiblesses. Enfin, nous concluons en évoquant certains développements contemporains de cette tradition, ainsi que quelques pistes de recherche futures

Réductionnisme, holisme et émergentisme

National audienceL’objectif principal de ce chapitre est de distinguer entre deux formes de réductionnisme possibles en Biologie, de sorte à mieux comprendre les enjeux du débat contemporain à ce sujet. En effet, une attitude réductionniste au sein de la biologie moléculaire peut, en effet, prendre deux formes distinctes, que l’on nommera respectivement « réductionnismemoléculaire » à proprement parler et « réductionnisme génétique». Alors que la première forme soutient une thèse sur la réduction entre les niveaux de description d’un système, et s’oppose à une posture émergentiste, la deuxième forme soutient une thèse sur la réduction entre les systèmes considérés pour expliquer un phénomène, et s’oppose plutôt à une posture holiste. Nous suggérerons que l’évolution de la biologie vers des approches « moins réductionnistes » au cours des dernières décennies se comprend plutôt comme une critique du réductionnisme génétique que comme une critique du réductionnisme moléculaire. Par conséquent, il existe une tendance allant davantage vers des postures holistes sans qu’elles ne soient pour autant plus émergentistes

Action-Dependent Perceptual Invariants: From Ecological to Sensorimotor Approaches

International audienceEcological and sensorimotor theories of perception build on the notion of action-dependent invariants as the basic structures underlying perceptual capacities. In this paper we contrast the assumptions these theories make on the nature of perceptual information modulated by action. By focusing on the question, how movement specifies perceptual information, we show that ecological and sensorimotor theories endorse substantially different views about the role of action in perception. In particular we argue that ecological invariants are characterized with reference to transformations produced in the sensory array by movement: such invariants are transformation-specific but do not imply motor-specificity. In contrast, sensorimotor theories assume that perceptual invariants are intrinsically tied to specific movements. We show that this difference leads to different empirical predictions and we submit that the distinction between motor equivalence and motor-specificity needs further clarification in order to provide a more constrained account of action/perception relations

Biological organisation as closure of constraints.

International audienceWe propose a conceptual and formal characterisation of biological organisation as a closure of constraints. We first establish a distinction between two causal regimes at work in biological systems: processes, which refer to the whole set of changes occurring in non-equilibrium open thermodynamic conditions; and constraints, those entities which, while acting upon the processes, exhibit some form of conservation (symmetry) at the relevant time scales. We then argue that, in biological systems, constraints realise closure, i.e. mutual dependence such that they both depend on and contribute to maintaining each other. With this characterisation in hand, we discuss how organisational closure can provide an operational tool for marking the boundaries between interacting biological systems. We conclude by focusing on the original conception of the relationship between stability and variation which emerges from this framework

Organisational closure in biological organisms

International audienceThe central aim of this paper consists in arguing that biological organisms realize a specific kind of causal regime that we call "organisational closure"; i.e., a distinct level of causation, operating in addition to physical laws, generated by the action of material structures acting as constraints. We argue that organisational closure constitutes a fundamental property of biological systems since even its minimal instances are likely to possess at least some of the typical features of biological organisation as exhibited by more complex organisms. Yet, while being a necessary condition for biological organization, organisational closure underdetermines, as such, the whole set of requirements that a system has to satisfy in order to be taken as a paradigmatic example of organism. As we suggest, additional properties, as modular templates and control mechanisms via dynamical decoupling between constraints, are required to get the complexity typical of full-fledged biological organisms

Biological organization and cross-generation functions

International audienceThe organizational account of biological functions interprets functions as contributions of a trait to the maintenance of the organization that, in turn, maintains the trait. As has been recently argued, however, the account seems unable to provide a unified grounding for both intra- and cross-generation functions, since the latter do not contribute to the maintenance of the same organization which produces them. To face this 'ontological problem', a splitting account has been proposed, according to which the two kinds of functions require distinct organizational definitions. In this article, we propose a solution for the ontological problem, by arguing that intra- and cross-generation functions can be said to contribute in the same way to the maintenance of the biological organization, characterized in terms of organizational self-maintenance. As a consequence, we suggest maintaining a unified organizational account of biological functions

A computable expression of closure to efficient causation

International audienceIn this paper, we propose a mathematical expression of closure to efficient causation in terms of lambda-calculus; we argue that this opens up the perspective of developing principled computer simulations of systems closed to efficient causation in an appropriate programming language. An important implication of our formulation is that, by exhibiting an expression in lambda-calculus, which is a paradigmatic formalism for computability and programming, we show that there are no conceptual or principled problems in realizing a computer simulation or model of closure to efficient causation. We conclude with a brief discussion of the question whether closure to efficient causation captures all relevant properties of living systems. We suggest that it might not be the case, and that more complex definitions could indeed create crucial some obstacles to computability

An Organizational Account of Biological Functions

International audienceIn this paper, we develop an organizational account that defines biological functions as causal relations subject to closure in living systems, interpreted as the most typical example of organizationally closed and differentiated self-maintaining systems. We argue that this account adequately grounds the teleological and normative dimensions of functions in the current organization of a system, insofar as it provides an explanation for the existence of the function bearer and, at the same time, identifies in a non-arbitrary way the norms that functions are supposed to obey. Accordingly, we suggest that the organizational account combines the etiological and dispositional perspectives in an integrated theoretical framework

In search of conceptual bridges: a review of Krohs, U. & Kroes, P. "Functions in Biological and Artificial Worlds"

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