Natural Classes in Brentano's Psychology

This article argues that Brentano’s classification of mental phenomena is best understood against the background of the theories of natural classification held by Auguste Comte and John Stuart Mill. Section 1 offers a reconstruction of Brentano’s two-premise argument for his tripartite classification. Section 2 gives a brief overview of the reception and historical background of the classification project. Section 3 addresses the question as to why a classification of mental phenomena is needed at all and traces the answer back to Mill’s view that psychological laws are class-specific. Section 4 and 5 connect the second premise of Brentano’s argument to Comte’s principle of comparative likeness and Mill’s insistance that class membership is determined by the possession of common characteristics. And section 6 briefly discusses the evidence Brentano provides for the first premise.