By turning the proving of scientific “facts” into an object of history, Michel Atten and Dominique Pestre, the authors of Heinrich Hertz. L’administration de la preuve, and Peter Galison, the author of Ainsi s’achèvent les expériences: la place des expériences dans la physique du xx^e siècle, take up the issue of proof in science on new grounds and bring to it answers based on solid empirical surveys. In their attempt to describe how convincing arguments are put together, they set about emphasising the diversity and variability of the factors that enter into these arguments. Through these two important, stimulating contributions to social, cognitive and material history of scientific proof, published in 2002, our attention is drawn to the history of science (to use the terminology applied to sciences) as it is practised. To subject these works to an analysis similar to the one they apply in physics by questioning how they deal with proof is a way of taking their contributions seriously.