This paper discusses the possibility of an absolute vacuum - a space without any substance. The motivation of this study is the contrast between most philosophers, up to Descartes, who stated that a vacuum was impossible, and the 17th century change of outlook, when the possibility and effective existence of the vacuum was accepted after the experiments of Torricelli and Pascal. This article attempts to show that, contrary to the received opinion, the acceptance of an ether is preferable to the (...) acceptance of a vacuum for several reasons. First: it is impossible to provide an empirical proof of the non-existence of the ether; second, an absolute vacuum is unthinkable; third, the ether concept is useful for the understanding of physical phaenomena; and fourth, the hypothesis of an ether in apparently void spaces is useful for the future development of science. The paper also endeavours to show that no recent advance of science changed those conclusions and that no future development can change them. (shrink)

This paper studies Lamarck's scientific method both from the point of view of his methodological discourse and according to his scientific praxis. Lamarck's methodology is compared to Condillac's as well as to that of the idéologues - a group in which Lamarck is usually included. The analysis of this paper shows that Lamarck's methodological discourse is very similar to Condillac's, but his scientific praxis does not follow this view. Instead of following an empiricist approach, Lamarck's work is grounded upon general (...) metaphysical principles concerning nature. Thus, from the ideologues's point of view, Lamarck's work should have been rejected -and that is what really happened - as being a mere metaphysical system grupo no qual se costuma incluir o próprio Lamarck. Mostra-se que o discurso metodológico de Lamarck assemelha-se ao dos ideólogos; no entanto, sua prática científica não se coaduna com esse enfoque. Em vez de seguir uma abordagem empirista, a obra de Lamarck se fundamenta em princípios metafísicos gerais sobre a natureza. Sob o ponto de vista dos ideólogos, seu trabalho deveria ser rejeitado - o que de fato ocorreu - como um mero sistema metafísico - no sentido pejorativo utilizado pelos seguidores de Condillac. No entanto, o presente artigo argumenta que esse é justamente um importante e inovador aspecto da obra de Lamarck, que permitiu a eclosão do evolucionismo moderno. (shrink)