View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Philsci-Archive Like Thermodynamics before Boltzmann. On the Emergence of Einstein’s Distinction between Constructive and Principle Theories Marco Giovanelli Forum Scientiarum — Universität Tübingen, Doblerstrasse 33 72074 Tübingen, Germany
[email protected] How must the laws of nature be constructed in order to rule out the possibility of bringing about perpetual motion? Einstein to Solovine, undated In a 1919 article for the Times of London, Einstein declared the relativity theory to be a ‘principle theory,’ like thermodynamics, rather than a ‘constructive theory,’ like the kinetic theory of gases. The present paper attempts to trace back the prehistory of this famous distinction through a systematic overview of Einstein’s repeated use of the relativity theory/thermodynamics analysis after 1905. Einstein initially used the comparison to address a specic objection. In his 1905 relativity paper he had determined the velocity-dependence of the electron’s mass by adapting Newton’s particle dynamics to the relativity principle. However, according to many, this result was not admissible without making some assumption about the structure of the electron. Einstein replied that the relativity theory is similar to thermodynamics. Unlike the usual physical theories, it does not directly try to construct models of specic physical systems; it provides empirically motivated and mathematically formulated criteria for the acceptability of such theories. New theories can be obtained by modifying existing theories valid in limiting case so that they comply with such criteria. Einstein progressively transformed this line of the defense into a positive heuristics.