My aim in this study is to show that the philosophical program elaborated by Brentano in his Psychology is largely indebted to the research conducted by Brentano on British empiricism and Comte's positive philosophy at Würzburg. This research represents the starting point of, and backdrop to, the project for philosophy as science, which is at the heart of his Psychology, and sheds new light on the philosophical stakes of many debates he leads in that work. Furthermore, Brentano's research informs us about his philosophical preoccupations during the Würzburg period, and simultaneously provide us with a new perspective on the evolution of his thought from his habilitation at Würzburg in 1866 to his arrival in Vienna in 1874. In this study, I ...