The paper develops and argues the following theses: (1) Brentano’s theory of the four phases of philosophy was designed independently of Comte’s law of the three stages of thought. (2) Brentano took considerable care to underline the correspondence between the two theories. (3) The two theories start from different views of history: Comte’s theory encompasses the history of the fundamental positive sciences that developed in a linear, progressive and ascending direction, and is not affected by any lawlike occurring phases of decay, but nevertheless knows stagnations. By contrast, Brentano’s theory refers primarily to the history of philosophy, though indirectly also to the fine arts. According to Brentano’s theory, the historical developments follow a cyclical course and know periods of scientific rise and decline, which repeat themselves. (4) Each theory provides a different strategy aiming at a fundamental reformation of philosophy. For Comte, the new philosophy must work positively and independently of the philosophical tradition. By contrast, Brentano advocates the view that philosophy, by its method, conducts empirical research analogous to research in natural science, and that it remains principally committed to the philosophical tradition. (5) Brentano’s “pure theoretical interest” involves not only positive-scientific components, but also metaphysical ones that are closely related to his general philosophical view. For this reason, he does not consider Comte and Mill as representatives of the new rising philosophical phase of his time, but as exponents of a hypercritical philosophy that sets aside the metaphysical questions and belongs to the second declining phase of philosophy, skepticism. (6) Despite its metaphysical dimension, Brentano’s psychology can be read as a contribution to positive philosophy in the sense of A. Comte and J. S. Mill, for the following reasons: (i) the objectives of Brentanian empirical psychology coincide with the objectives of the general positive view of scientific knowledge; (ii) the role played by Comte’s scale of sciences in grounding his empirical psychology; (iii) the methodological steps from PES that show what an important role Mill’s inductive-deductive model of science was to play in the methodological building of Brentano’s psychology. (7) By contrast, Brentano’s descriptive psychology constitutes the liberation of psychological research from the paradigm of positive science. (8) Chisholm’s interpretation of Brentano’s view of intuitive induction neglects the fact that, in Descriptive Psychology, Brentano uses induction in a narrower sense as well as induction in a broader sense.