ArgumentUsing a striking example from the history of applied psychology, the concept of accident proneness, this paper suggests that historians of science may still find viable the idea of simultaneous discovery or construction of a scientific idea. Accident proneness was discovered independently in Germany and in Britain during the period of World War I. Later on, in 1926, the idea was independently formulated and named in both countries. The evidence shows not only striking simultaneity but true novelty and commensurateness of (...) the two formulations that crystallized at the same time in parallel, but distinctly separate, settings. (shrink)