Guglielmo Militello, “Functional Integration in the Endosymbiotic Origin of Mitochondria”

Functional integration is broadly defined in life sciences as the causal interdependence among the subsystems forming an organism. Since the concept of ʻfunctional integrationʼ is based on a common sense (physiological) view of organisms, it appears vague and unable to provide a stringent criterion for biological individuality. Although functional integration plays an important role in most of functional explanations, neither systemic, nor etiological, nor dispositional approaches to biological functions have taken it into account. The organizational perspective, by contrast, interprets functional integration as the mutual dependence of the constitutive constraints that collectively maintain the whole biological organization by allowing it to exhibit biological individuality.

It is highly debated whether functional integration is an important requirement for defining the biological individuality of symbiotic organisms (e.g., holobionts), because the mutual dependence among the functions of different organisms in many cases does not lead to an ʻintegratedʼ individual. The purpose of this talk is to investigate how the endosymbiotic relationship between the proto-mitochondrion and a proto-eukaryotic cell has led to a more integrated biological organization and a new biological individual (i.e. the eukaryotic cell) by means of a functional redefinition of both the endosymbiont and the host. Two theoretical questions will be addressed: first, how did the endosymbiont and the host achieve a functionally integrated organization?; second, what were its evolutionary consequences?

These questions will be discussed by adopting an organizational approach, according to which the analysis of both structural and physico-chemical conditions of biological phenomena can shed some light on the organization of living beings. The functional redefinition of the bioenergetic systems of the proto-mitochondrion and proto-eukaryote will be examined, because they seem to have played a pivotal role in the emergence of a more functionally integrated organization of the eukaryotic cell. In particular, three phenomena will be analysed: first, the selective loss of biochemical pathways both in the endosymbiont and in the host; second, the appearance of the translocase of inner membrane (TIM) and outer membrane (TOM) of the mitochondrion; finally, the control of the redox poise of the electron transport chain.

These three phenomena suggest that the functional redefinition of bioenergetic systems contributed to not only the metabolic co-dependency between the host and the endosymbiont, but also a dramatic transformation of both organisms that led to a new biological individual (i.e. the eukaryotic cell). Thus, the functional redefinition of the systems involved in energy production was a key factor for the functional integration between a proto-mitochondrion and a proto-eukaryotic cell.

It will be argued that, in the case of eukaryogenesis, the concept of ʻfunctional integrationʼ is intimately connected with those of ʻbiological noveltyʼ and ʻbiological individualityʼ, insofar as the emergence of a more integrated symbiotic organization has led, by means of functional redefinition of the host and the endosymbiont, to new biological functions and a new biological structure exhibiting a specific kind of individuality.

Olof Söderlind, « Du savoir pratique au savoir continu »

Avec les notions de continu, discret et savoir nous pouvons créer quatre catégories : savoir du continu, savoir du discret, savoir continu et savoir discret. Laissons de côté les deux premières. Définissons savoir discret comme une pièce d'information, ex. « Paris est la capitale de la France ». Y a-t-il du savoir qui n'est pas discret ? Y a-t-il du savoir continu ? Dans ma présentation je propose une ébauche d'une réponse à ses questions à travers une critique de l'intellectualisme de Jason Stanley selon lequel tout savoir est savoir propositionnel – savoir discret ? – ou peut être réduit à du savoir propositionnel. La réduction qu'il propose du savoir pratique, à partir des notions de « know-wh », de savoir propositionnel et de mode de présentation pratique, manque, selon moi, son but car elle ne respecte pas l'aspect fondamentalement temporel – continu ? – du savoir pratique. L'argument tournera autour d'une expérience de pensée mettant en scène deux protagonistes, M. Dupont et M. Dupont 2000, une réplique exacte du premier avec la particularité d'avoir un contrôle absolu de ses états internes. Je soutiendra qu'il existe une différence de savoir pratique entre les deux Dupont, mais que la théorie de Stanley est incapable de rendre compte de cette différence.