Hermann von Helmholtz : « De la formation du système planétaire » ou des mythes et des hypothèses au savoir scientifique

Abstract

At the beginning of 1871, Helmholtz gave a lecture to an audience of non-specialists in Heidelberg on “the genesis of the planetary system”. His subject was what he called the Kant-Laplace theory. He did not begin by explaining what was meant by this theory but instead explained to his listeners how science now viewed the formation of celestial bodies and their probable evolution in the light of progress in knowledge, the discovery of new laws and the use of increasingly sophisticated instruments. The validity of Kant’s and Laplace’s hypothesis was thus confirmed a posteriori and their boldness legitimised. In this way, the approach adopted by Helmholtz implicitly—and perhaps unwittingly—relativises the postulated rigour of the sound scientific method. The cosmogony sketched out by Helmholtz resembles a well-researched spectacle in which the audience is made up of the spectators, scientists are the actors and purified science is the most important issue. The main aim of our analysis of this text is to identify and recall the contextual elements that give the text depth—from the Franco-Prussian war to the ideological, philosophical and scientific tensions underpinning the text.