yes / This paper discusses Leibniz’s view and defence of heliocentrism, which was one of the main achievements of the Scientific Revolution (1543-1687). As Leibniz was a defender of a strictly mechanistic worldview, it seems natural to assume that he accepted Copernican heliocentrism and its completion by figures like Kepler, Descartes and Newton without reservation. However, the fact that Leibniz speaks of the Copernican theory as a hypothesis (or plausible assumption) suggests that he had several reservations regarding heliocentrism. On a first approach Leibniz employed two of his most cherished principles to defend the Copernican hypothesis against the proponents of geocentrism: these were the principle of the relativity of motion and the principle of the equivalence of hypotheses. A closer analysis reveals, however, that Leibniz also appeals to dynamic causes of planetary motions, and these constitute a much stronger support for heliocentrism than his two philosophical principles alone.

Aux XVIIIe et XIXe siècles, les historiens des sciences associaient généralement Francis Bacon et Galilée pour leur rôle dans l’émergence de la science moderne, mais, à la fin du XIXe et au début du XXe siècle, la Révolution scientifique fut identifiée de manière stricte à la construction de la physique mathématique, ce qui eut souvent pour conséquence de rejeter Bacon hors de l’histoire des sciences. Nous reprenons l’étude conjointe de ces deux auteurs pour mesurer quelle est exactement la nature de leur divergence. Dans la première partie de notre travail, nous abordons les questions cosmologiques. Sur quels arguments Galilée fonde-t-il sa défense publique du copernicianisme entre 1610 et 1616, jusqu’à la première condamnation de l’opinion copernicienne par l’Eglise Catholique ? Pour quelles raisons Bacon, qui suit cette campagne copernicienne, rejette-t-il la plupart des découvertes astronomiques de Galilée ? Pourquoi Bacon, tout en réussissant à percevoir le caractère (trop peu) systématique du géocentrisme, refuse-t-il l’héliocentrisme ? Dans la deuxième partie de notre travail, nous abordons les questions relatives à la méthode, ainsi que les théories de la matière et du mouvement. Quel est le rôle de la perception sensible et la fonction des mathématiques dans les théories de Bacon ? Quelle est la signification de sa théorie du mouvement, qui multiplie les objets d’étude en proposant une typologie des différents mouvements concrets, alors que la physique mathématique tend à réduire tout déplacement au seul mouvement linéaire inertiel ? Quelle est la fonction de l’atomisme mathématique de Galilée ? Dans quelle mesure sa science du mouvement se distingue-t-elle de l’approche baconienne ? La différence fondamentale entre la science galiléenne et la démarche de Bacon consiste, selon nous, dans la nature des expériences et des observations qui sont convoquées, ainsi que dans le type d’abstraction que ces deux auteurs veulent conférer à la philosophie naturelle. / During the eighteenth and nineteenth centuries, historians of science usually considered that Francis Bacon and Galileo had respectively played their role in the merging of modern science, but, at the end of the nineteenth and the beginning of the twentieth century, Scientific Revolution has been strictly reduced to the elaboration of mathematical physics, which had for consequence to exclude Bacon from the history of science. Our aim is to underline the exact nature of the difference between those two authors. In the first part, we deal with the cosmological problems. What arguments did Galileo produce to sustain his public commitment for the Copernican system, from 1610 to 1616, until the first condemnation of copernicanism by the Roman Church ? For what reasons did Bacon reject most of Galileo’s astronomical discoveries ? Why Bacon, who clearly perceived the fact that the geocentric theory lacked systematic character, refused heliocentrism ? In the second part, we deal with the methodological questions, we analyse matter theories and the science of motion. What is the role of sense perception and what is the fonction of mathematics in Bacon’s theories ? What is the significance of his theory of motion, which multiplies the objects of study, proposing a typology of concrete movements, while mathematical physics aims at reducing any motion to the rectilinear inertial movement ? What is the fonction of the mathematical atomism proposed by Galileo ? In what measure does his science of motion distinguish from the baconian approach ? We think that the fondamental difference between the science of Galileo and the theories of Bacon consists in the nature of the experiments and observations used, and in the type of abstraction they are looking for in natural philosophy.

Made available in DSpace on 2017-07-10T18:26:29Z (GMT). No. of bitstreams: 1 Luiz Antonio Brandt.pdf: 1067816 bytes, checksum: 69a6a677b5382a0454f7bbd9551ddd1f (MD5) Previous issue date: 2011-12-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this thesis, we aim to conduct a study and reconstruction of the criticism that Galileo undertakes to physics and cosmology of Aristotle, and works as an anchor Sidereus Nuncius and First Day of Dialogue Concerning the Two Chief World Systems. The arguments developed by Italian physicist these works, consolidating the Copernican theory and revolutionize the way we study nature. For centuries, the Western conception of the universe was supported by the assumptions of cosmology of Aristotle. Aristotelian cosmology had as fundamental points the idea of the incorruptibility of the heavens, the earth and the immobility of a hierarchy of elements. For the peripatetic, the cosmos was finite and heterogeneous, and was divided into two distinct regions: the sublunary (terrestrial) and above the Moon (heavenly). The telescopic observations made by Galileo in 1609, showing craters and mountains on the moon and Jupiter's satellites, were in evidence against the heaven-earth dichotomy proposed by Aristotle. For it revealed "imperfections" in the heavenly bodies, and showed that not all the stars had their revolutions as the center of the Earth, the idea of asking the same centrality in the cosmos. Moreover, the break with Aristotelian cosmology destabilizing the very physics of Aristotle, whose explanation of the movements of bodies depended on the cosmological structure, since there were three types of moves, straight toward the center, straight away from the center and circular around the center, which required a motionless earth occupying the center of the cosmos. The idea of centrality and immobility of the Earth is therefore fundamental point of Aristotelian physics and cosmology. Most of the work of Galileo Galilei seems to think about a central objective: the defense of the Copernican theory. Since his public adhesion to the Copernicanism in 1610, in Sidereus Nuncius, until Dialogue published in 1632, the Pisan Phisycist sought to break with the assumptions of the Aristotle s natural philosophy which supported the geocentric conception. As a result, it is in First Day of Dialogue that, certainly, we could find a more systematic and focused effort against the Aristotelic conception of world and its main characteristic: the dissociation of the cosmos into two distinct regions, the celestial and sublunary. / Nesta dissertação, temos como objetivo realizar um estudo e reconstrução das críticas que Galileu empreende à física e à cosmologia de Aristóteles, tendo como âncora as obras Sidereus Nuncius e Primeira Jornada do Diálogo sobre os dois máximos sistemas do mundo. Os argumentos desenvolvidos pelo físico pisano nestas obras, consolidam a teoria copernicana e revolucionam a maneira de se estudar a natureza. Durante séculos, a concepção ocidental de universo esteve apoiada nos pressupostos da cosmologia de Aristóteles. A cosmologia aristotélica tinha como pontos fundamentais a ideia de incorruptibilidade do céu, de imobilidade da Terra e de uma hierarquia dos elementos. Para o peripatético, o cosmos era finito e heterogêneo, e se encontrava dividido em duas regiões distintas: a sublunar (terrestre) e a supralunar (celeste). As observações telescópicas realizadas por Galileu em 1609, ao mostrar crateras e montanhas na Lua, e satélites em Júpiter, constituíram-se em evidências contrárias à dicotomia céu-Terra proposta por Aristóteles. Pois revelavam imperfeições nos corpos celestes, e mostravam que nem todos os astros tinham como centro de suas revoluções a Terra, questionando a ideia de centralidade da mesma no cosmos. Além disso, a ruptura com a cosmologia aristotélica desestabilizava a própria física de Aristóteles, cuja explicação dos movimentos dos corpos dependia da estrutura cosmológica, uma vez que existiam três tipos de movimentos: retilíneo em direção ao centro, retilíneo se afastando do centro e circular em torno do centro, o que requeria uma Terra imóvel ocupando o centro do cosmos. A ideia de centralidade e imobilidade da Terra é, portanto, ponto fundamental da física e da cosmologia aristotélicas. Grande parte da obra de Galileu parece girar em torno de um objetivo central: a defesa da teoria copernicana. Desde a sua adesão pública ao copernicanismo em 1610, no Sidereus Nuncius, até o Diálogo publicado em 1632, o físico pisano buscou romper com os pressupostos da filosofia natural de Aristóteles que sustentavam a concepção geocêntrica. Com efeito, é na Primeira Jornada do Diálogo que poderemos encontrar um esforço mais sistemático e concentrado contra a concepção aristotélica de mundo e sua principal característica: a dualidade do cosmos.