Historical contingency and counterfactual history: Revisiting the Cushing thesis

James Cushing's Quantum Mechanics: Historical Contingency and the Copenhagen Hegemony published in 1994 is one of the most widely cited, but least studied, counterfactual histories of science in recent times. In this paper, I subject the scenario proposed in that book to careful examination and show that neither Cushing's simple reordering of events in the crucial years around 1926-7, nor his claims about what would have followed are convincing. While I agree that contingency played a critical role in the "the spread of Copenhagen hegemony and the exclusion of a causal theory", it is, ironically, only by neglecting those contingencies that Cushing's counterfactual scenario acquires its apparent plausibility. By stripping away all vestiges of the personal, social, and intellectual context in which an alternative scenario might have unfolded, Cushing fails to present a compelling case. A deeper appreciation of the importance of the wider social and intellectual context and the commitments and predilections of the historical actors involved, has the potential to broaden and enrich both the historiographical debate over counterfactual history and the philosophical debate over contingency and inevitability.