Mathematics,experience and laboratories: Herbart’s and Brentano’s role in the rise of scientific psychology

In this article we present and compare two early attempts to establish psychology as an independent scientific discipline that had considerable influence in central Europe: the theories of Johann Friedrich Herbart (1776—1841) and Franz Brentano (1838—1917). While both of them emphasize that psychology ought to be conceived as an empirical science, their conceptions show revealing differences. Herbart starts with metaphysical principles and aims at mathematizing psychology, whereas Brentano rejects all metaphysics and bases his method on a conception of inner perception (as opposed to inner observation) as a secondary consciousness, by means of which one gets to be aware of all of one’s own conscious phenomena. Brentano’s focus on inner perception brings him to deny the claim that there could be unconscious mental phenomena — a view that stands in sharp contrast to Herbart’s emphasis on unconscious, ‘repressed’ presentations as a core element of his mechanics of mind. Herbart, on the other hand, denies any role for psychological experiments, while Brentano encouraged laboratory work, thus paving the road for the more experimental work of his students like Stumpf and Meinong. By briefly tracing the fate of the schools of Herbart and Brentano, respectively, we aim to illustrate their impact on the development of psychological research, mainly in central Europe.