ABSTRACT
Franz Brentano's most famous work, Psychology from an Empirical Standpoint, published in 1874, was primarily concerned with epistemology. Its central aim was to present new foundations for scientific—that is, empirical—psychology. For Brentano, an "empirical" science is a "purely phenomenal science"—a science whose objects are not substances but phenomena. Empirical natural science should not be viewed as the science of physical substances, namely of bodies, but as the "science of physical phenomena". The idea is that science in general can, and should, dispense with the metaphysical assumption that there are substances that underlie the phenomena we witness. Thus, as indicated in the title of an 1888–9 lecture course, descriptive psychology is best seen as a "descriptive phenomenology". Applied to psychology, Brentano's empiricist claim is that psychological knowledge refers to phenomena and only to phenomena. Brentano's intentionality thesis—"is a mental phenomenon" is necessarily equivalent to "is intentional"—may be construed in terms of such analysis or decomposition.
