SCI-PHIL provides an in-depth historical and theoretical account of the rise and fall of the ideal of ‘scientific philosophy’ (SP) in Europe from the mid 19th century, when the notion emerged, to the 1930s, with the first international congresses on SP, and WW II, which put an end to the project. It focuses primarily on five geographical areas: France, Germany, Austria-Hungary, England and Italy, with a foray into the Russian context.It is original in two senses: (1) It accounts for a neglected chapter in the history of European philosophy in all its transnational and transcultural scope, as part of a multi-faceted process of articulation of a European intellectual space at times characterized by the conflicting pulls of political nationalism and scientific internationalization and tragically punctuated by two world wars; (2) It focuses on a decisive historical moment wherein the problem of relations between philosophy and the sciences emerged in its current configuration and constituted a burning issue that concerned the very scope and vocation of philosophy itself. Indeed, from the 1930s onwards, with Nazi-fascism and WWII, a sharp fracture between philosophy and science occurred, worsened by the Cold War years. Today, in our age of specialist fragmentation, the stakes in bridging this rift have never been higher. Can philosophy contribute to mending the fragmentation of knowledge or is it destined to merely be one discipline amongst others? More than a century ago, scientific philosophers were asking exactly this kind of question. In fact, SP is not merely an antiquated locution to indicate what we now mean by ‘epistemology’ or ‘philosophy of science’, which are specialized fields in the current academic division of labour. On the contrary, it denoted the high hopes of thinkers who, overcoming the two cultures divide, intended to take seriously the revolutionary scientific breakthroughs and set up a new beginning for philosophy, reshaping its scope and methods.