De la faillibilité au serf-arbitre : le tournant herméneutique de Paul Ricoeur

Ce mémoire a pour but de montrer que le premier tournant herméneutique de Paul Ricœur en 1960 gravite essentiellement autour de la problématique de la volonté mauvaise. Nous soutenons autrement dit que Ricœur a initialement donné une tournure herméneutique à sa philosophie pour penser le serf-arbitre, c’est-à-dire pour penser la liberté captive d’elle-même. Afin de rendre compte adéquatement de ce tournant, notre attention sera principalement dirigée vers le deuxième tome de la Philosophie de la volonté de Ricœur, Finitude et culpabilité. Notre question se pose ainsi : comment et pourquoi, dans une problématique du mal, Ricœur entame-t-il son tournant herméneutique? Pour y répondre, nous expliciterons le parcours de Ricœur allant de L’homme faillible à La symbolique du mal. Nous verrons dans un premier temps que si le philosophe arrive à thématiser le concept de faillibilité à partir d’une ontologie de la disproportion, si la réflexion a accès à la possibilité du mal, il n’en ira pas de même pour le noème inintelligible que constitue le mal moral. Afin de penser la faute, nous verrons que Ricœur se tournera vers l’herméneutique en se mettant à l’écoute du langage de l’aveu. Ainsi, dans la deuxième partie de notre mémoire, nous expliciterons les trois moments de compréhension (phénoménologique, herméneutique et réflexif) propre à l’herméneutique philosophique de Ricœur de 1960.The purpose of this dissertation is to show that the first hermeneutics turn of Paul Ricœur in 1960 essentially revolves around the problematic of bad will. We argue ie that Ricœur initially gave a hermeneutics twist to his philosophy to think the servile will, that is the freedom captive of itself. To properly account for this turn, our attention was mainly directed to the second volume of the Philosophy of the Will of Ricœur, Faillible man and The symbolism of evil. Our question is this : how and why, in a problematic of evil, Ricœur starts his hermeneutics turn? To answer this question, we will explain the course of Ricœur from Fallible man to The Symbolism of evil. We will see at first that if the philosopher comes to thematize the concept of fallibility from an ontology of disproportion, if the reflection has access to the possibility of evil, it does not go well for the unintelligible noema that is moral evil. To think of the fault, we will see that Ricœur will turn to hermeneutics is by listening to the language of confession. Thus, in the second part of our dissertation, we will explain the three stages of understanding (phenomenological, hermeneutics and reflexive) to own philosophical hermeneutics of Ricœur 1960

Study of the hydrogen escape rate at Mars during Martian years 28 and 29 from comparisons between SPICAM/Mars Express observations and GCM-LMD simulations

EPSC-DPS Joint Meeting 2019, held 15-20 September 2019 in Geneva, Switzerland, id. EPSC-DPS2019-499-2.- © Author(s) 2019. CC Attribution 4.0 license. https://creativecommons.org/licenses/by/4.0/deed.esWe simulate the 3D Martian hydrogen corona during the Martian years 28 and 29 at different solar longitudes using a set of models of atomic hydrogen density from the surface to the exosphere. These simulations are compared to Mars Express / SPICAM observations and show a strong underestimate of the brightness by our models near southern summer that could be due to an underestimate of the amount of water vapor delivered to the upper atmosphere at this season

No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations

The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere, which-given methane's lifetime of several centuries-predicts an even, well mixed distribution of methane. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally

Martian dust storm impact on atmospheric H₂O and D/H observed by ExoMars Trace Gas Orbiter

Global dust storms on Mars are rare but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere, primarily owing to solar heating of the dust. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes, as well as a decrease in the water column at low latitudes. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere

Effect of the lateral exospheric transport on the horizontal hydrogen distribution at the exobase of Mars

International audienceWe describe the horizontal distribution of hydrogen density at the exobase of Mars as simulated by coupling a 3D GCM with an exospheric balistic model, taking into account the flight balistic time of the exopheric hydrogen atoms. Such a description is more realistic than the assumptions used in our past study [4]. We simulate 4 Martian rotations at three different seasons. The horizontal variations of the hydrogen density at the exobase are reduced when the exospheric balistic transport is included compared to our previous simulations

Study of the hydrogen escape rate at Mars during Martian years 28 and 29 from comparisons between SPICAM/Mars Express observations and GCM-LMD simulations

International audienceWe simulate the 3D Martian hydrogen corona during the Martian years 28 and 29 at different solar longitudes using a set of models of atomic hydrogen density from the surface to the exosphere. These simulations are compared to Mars Express / SPICAM observations and show a strong underestimate of the brightness by our models near southern summer that could be due to an underestimate of the amount of water vapor delivered to the upper atmosphere at this season

Study of the hydrogen escape rate at Mars during Martian years 28 and 29 from comparisons between SPICAM/Mars Express observations and GCM-LMD simulations

International audienceWe simulate the 3D Martian hydrogen corona during the Martian years 28 and 29 at different solar longitudes using a set of models of atomic hydrogen density from the surface to the exosphere. These simulations are compared to Mars Express / SPICAM observations and show a strong underestimate of the brightness by our models near southern summer that could be due to an underestimate of the amount of water vapor delivered to the upper atmosphere at this season

Study of the hydrogen escape rate at Mars during Martian years 28 and 29 from comparisons between SPICAM/Mars Express observations and GCM-LMD simulations

International audienceWe simulate the 3D Martian hydrogen corona during the Martian years 28 and 29 at different solar longitudes using a set of models of atomic hydrogen density from the surface to the exosphere. These simulations are compared to Mars Express / SPICAM observations and show a strong underestimate of the brightness by our models near southern summer that could be due to an underestimate of the amount of water vapor delivered to the upper atmosphere at this season

Study of the hydrogen escape rate at Mars during Martian years 28 and 29 from comparisons between SPICAM/Mars express observations and GCM-LMD simulations

International audienceWe have simulated the 3D atomic hydrogen density in the Martian upper atmosphere and associated Jeans escape rate during Martian years 28 and 29. The coronal Lyman-α brightness is computed using a 3D radiative transfer model which accounts for the monthly average hydrogen density for these two years and is compared to a large set of observations by Mars Express/SPICAM. The simulated brightness is generally in good agreement with the observations for Ls 330° for Martian year 28 and Ls  340° for Martian year 29, but the model strongly underestimated the brightness for 230 25 to 6x1026s-1 (equivalent to a global layer of water ~33 to 2000 mm deep every billion years), in agreement with the seasonal variations estimated directly from the fit of the SPICAM observations during the Martian year 28 by Chaffin et al. (2014). Our analysis suggests that episodic dust storms and associated enhancements at high altitude near perihelion are a major factor in the H escape estimates averaged over one martian year or longer periods, but the accumulated water lost at this rate for 4 billion years is much lower than the amount of water needed to form the flow channels observed on Mars

Hydrogen escape at Mars : Comparisons from MGCM-LMD simulations and observations from Mars-Express/SPICAM

International audienc