In this article, physiological and pathological forms of excitability are studied in a two-dimensional electrical model of excitable cell endowed with a generic inward persistent conductance. Bifurcation analysis of the model is performed as a function of the maximal inward persistent conductance, the input current, or the voltage dependency of the activation function. Several discharge modes are exhibited, including: (1) a basic mode that corresponds to a resting potential and production of action potential; (2) bistability between resting potential and self-sustained (...) spiking; (3) a pacemaker mode of discharge; and (4) bistability between resting potential and plateau potential. These behaviours can be compared to experimentally described physiological and pathological forms of excitability that depend upon inward persistent conductances. In the results obtained, attractors allow for a qualitative description of physiological and pathological states. However, it is not possible to obtain an unambiguous identification of particular ''physiological attractors'' or ''pathological attractors''. In the perspective of the theory of dynamical systems, we suggest that pathological states can be modelled in two different ways, i.e. by bifurcation (as in the present model) or by perturbation. We also highlight some other theoretical concepts that may be relevant to a theoretical description of pathology. (shrink)

The phenomenon of species extinction raises more and more concern among ecologists facing the actual crisis of biodiversity. Scientific investigations of the causes and effects of extinction must be completed by a philosophical analysis of the concept of extinction that aims to clarify the meanings of the term ‘extinction’ and to analyse modalities, criteria and degrees of extinction. We will focus our attention on the apparent paradox of the possible ‘resurrection’ of species in the near future with the help of (...) genetic biotechnology and cloning techniques. The ontological background of the extinction concept is analysed in relation to the idea of species as classes. We will also show that there is no simple analogy between death and species extinction, and develop a conceptualist and dualistic system of supra-individual entities , supported by an instrumentalist approach to genetic manipulations which transform species into interactive kinds, which can go extinct and be recreated. (shrink)

L’anthropologue Agnès Martial réunit dans cet ouvrage des contributions sur les rapports de genre et les usages sociaux de l’argent au sein de la famille. Modalités de circulation et significations relationnelles des transactions matérielles sontabordées dans les trajectoires conjugales et les relations intergénérationnelles, à travers l’espace et le temps. En se penchant sur les échanges lors de cérémonies de mariage, Anne Attané montre comment dons d’argent et de biens constituent des façon...

As the debate about holism and reductionism in ecology has ebbed in the last twenty years, this article aims to reassess the traditional opposition between holistic and reductionist epistemologies during the development of population biology. The history of the notion of carrying capacity, the upper demographic limit of a viable population, will be analyzed as a paradigmatic case of the progressive imposition of reductionist strategies, from both an epistemological and a semantic point of view, since the middle of the twentieth (...) century. Then, Richard Looijen’s reduction of the carrying capacity concept to the niche partitioning theory will be assessed and rebuked for both empirical and logical reasons. Eventually, some recent “weak” and “hard” emergent conceptualizations of the notion of carrying capacity, in logistic map models or in coupled niche-population systems, will be presented in order to show how they call into question the nature and the use of the notion of carrying capacity as a predefined ecological limit. (shrink)

La philosophie de l’environnement a bouleversé la conception moderne de de l’homme en reconnaissant la part des relations écologiques et des limites environnementales qui le façonnent. Le paysage, à la fois produit des interactions écologiques et espace soumis au jugement esthétique, ne pouvait rester indifférent aux innovations conceptuelles de la pensée environnementale. En ce sens, l’idée de « tiers-paysage » défendue par le paysagiste Gilles Clément a introduit une rupture avec le dogme idéaliste de la philosophie classique du paysage, dont (...) les jugements esthétiques étaient informés par les canons de l’art pictural. Nous nous proposons de prolonger le geste de Clément et de mener à son terme la déconstruction du paysage classique en proposant une appréhension naturaliste du paysage dont le paradigme central serait le tiers-paysage et son fondement sauvage. De ce choix découle une argumentation en faveur d’une esthétique objectiviste du paysage inspirée des théories d’Allen Carlson à laquelle nous adjoignons une dimension évolutionniste qui traduit l’unité originelle et l’interdépendance des relations esthétiques qui englobent toutes les formes de vie dans leur dynamique « paysageante ». (shrink)

The New Evil Demon problem has been hotly debated since the case was introduced in the early 1980’s (e.g. Lehrer and Cohen 1983; Cohen 1984), and there seems to be recent increased interest in the topic. In a forthcoming collection of papers on the New Evil Demon problem (Dutant and Dorsch, forthcoming), at least two of the papers, both by prominent epistemologists, attempt to resist the problem by appealing to the distinction between justification and excuses. My primary aim here is (...) to critically evaluate this new excuse maneuver as a response to the New Evil Demon problem. -/- Their response attempts to give us reason to reject the idea that victims of the New Evil Demon have justification for believing as they do. I shall argue that this approach is ultimately unsuccessful, however much of value can be learned from these attempts. In particular, progress in the debate can be made by following those who advance the excuse maneuver and make explicit the connection between epistemic justification and epistemic norms. By doing so, the questions being debated are clarified, as is the methodology being used to attempt to answer them. (shrink)

There are various equivalent formulations of the Church-Turing thesis. A common one is that every effective computation can be carried out by a Turing machine. The Church-Turing thesis is often misunderstood, particularly in recent writing in the philosophy of mind.

Hypnosis is considered a unique tool capable of modulating cognitive processes. The extent to which hypnotic suggestions intervenes is still under debate. This study was designed to provide a new insight into this issue, by focusing on an unintentional emotional process: attentional bias. In Experiment 1, highly suggestible participants performed three sessions of an emotional Stroop task where hypnotic suggestions aiming to increase and decrease emotional reactivity towards emotional stimuli were administered within an intra-individual design. Compared to a baseline condition (...) (without hypnotic suggestion), a significant increase in attentional bias was found when a hypnotic suggestion to increase emotional reactivity was administered. In contrast, the bias was eliminated when a suggestion to decrease emotional reactivity was administered. Experiment 2 investigated the effect of session repetition on attentional bias across three successive experimental sessions without hypnosis, and showed that the emotional Stroop effect did not vary across sessions. Hence, session repetition could not account for part of the modulation of attentional bias in Experiment 1. Taken together, the results suggest that specific hypnotic suggestions can influence elicitation of unintentional emotional processing. The implications are discussed regarding the locus of intervention of hypnotic suggestion in cognitive and emotional processes. (shrink)

Philosophy of history is analyzed here from the point of its epistemological and ontological meaning. The author considers that the ontological point of view makes it possible to conceptualize the history as the unity of its all times - Past, Present and Future. The connection between these three times based on their relation to the concept of Eternity which has been symbolically formed within the mythological, religious and utopian Weltanschauung. The necessity of these relations transforms philosophy of history into a (...) special kind of ontological historical knowledge. The study of history from the prospect of unity is only possible within the historical interpretation of Future as an epoch of bridging the gap between Time and Eternity. Author calls this philosophical concept the Time of Freedom. (shrink)