The end of the nineteenth century was the period when revolutionary scientific discoveries challenged well-established theories, forcing both philosophers and scientists to ask questions about the nature and certainty of scientific knowledge. A group of French scientists not only performed a thorough critique of contemporary science and its history but proposed a new model that adequately described the development of scientific knowledge. Gaston Milhaud made a significant contribution to this new description of knowledge creation. He is however rarely mentioned in the context of the theory of knowledge and remains overshadowed by his famous colleagues. Despite the fact that more than a hundred years have passed since the conventionalist philosophy of science was formulated, H. Poincaré’s, P. Duhem’s and G. Milhaud’s positions have not gained much popularity beyond the circle of philosophers of science. This article briefly outlines personal relationships within French conventionalist circle, presents important results of Milhaud’s analysis, and the reasons why philosophers do not recognize the role he played in creating a new model for the development of scientific knowledge.