 Another aspect is the rôle of reduction within the global picture of the development of physics. Most physicists, but not all, tend to view their science as an enterprise which accumulates knowledge in a continuous manner. For example, they would not say that classical mechanics has been disproved by relativistic mechanics, but that relativistic mechanics has partly clarified where classical mechanics could be safely applied and where not. This view of the development of physics has been challenged by some philosophers and historians of science, especially by the writings of T. Kuhn and P. Feyerabend. These scholars emphasize the conceptual discontinuity or “incommensurability” between reduced theory \(T\) and reducing theory \(T'\). The structuralistic accounts of reduction now opens the possibility of discussing these matters on a less informal level. The preliminary results of this discussion are different depending on the particular program. 