This chapter examines the influence that Kuhn's involvement in the history of quantum mechanics project had on his career, and his relationship with historians of science.

This chapter analyses the careers of two distinct narratives about Mach’s philosophical legacy that prevailed among German-speaking physicists and philosophers for more than a generation. Planck’s polemic against Mach sired the idea of a Machian philosophical system that was irreconcilable with modern physics, Boltzmann’s legacy foremost. But Planck also bereaved Mach’s positivism of its naturalist foundation and identified it straight with phenomenalism. In contrast, many Austrians considered the epistemologies of Mach and Boltzmann as even mutually supportive for a defence of empiricist indeterminism. Taking positivism in its original, more general understanding, they underscored Mach’s broader anti-metaphysical and empiricist stance, eventually adopting him as a standard-bearer for the new movement of Logical Empiricism. While these understandings were not necessarily tied to a positive or negative assessment, they often amounted to simplifications, transformations, or even contortions of Mach’s thinking, which made it increasingly difficult to declare oneself in Mach’s footsteps and simultaneously to advocate scientific modernism.

Jean Perrin argued in the early twentieth century that the agreement, or “convergence,” of measured values of Avogadro’s number was compelling evidence for the existence of atoms. Max Planck argued, in a similar way, that the convergence of measured values of Planck’s constant was compelling evidence for the quantization of energy. Philosopher John Losee has argued that convergence of the measured value of a new constant of nature is the strongest possible evidence for the correctness of the theory that contains the constant. Milgrom’s theory contains such a constant (the “acceleration scale,” a0, or “Milgrom’s constant”), and this chapter presents the results of observational determinations of the value of that constant. The values are convergent, suggesting, according to Losee’s argument, that Milgrom was justified in postulating a modified acceleration law in place of dark matter.