Philosophy as Science: 19th century philosophy between logic and psychology

The aim of my project is to analyze the development of the idea of philosophy as science in the 19th century from a novel perspective; in particular my goal is to bring out for the first time the deeper connection of psychology and logic to this idea. Normally these two disciplines are seen in opposition, rather than in agreement with each other. While research has been done on the relation between philosophy and psychology on the one hand, and the development of symbolic logic on the other, I would like to investigate the developments of psychology and logic in the 19th century as consequences of the attempts to establish philosophy as science.

The relation between philosophy and science has always been a highly interesting subject, from the beginnings of philosophical thought to the present day. For centuries philosophy was regarded as universal science and the sum of all knowledge, every philosopher was a homo universalis. There were certainly debates about the subject, method and demarcation of specific disciplines, but these were internal to philosophy as a whole. Before the 19th century, few would have felt the need to articulate the relation between philosophy and science as between two foreign enterprises or to argue that philosophy would need to become scientific. Indeed, prior to the 19th century most empirical and experimental research was considered to be part of natural philosophy. If philosophy had a model outside itself, it was geometry or mathematics rather than physics. This changed dramatically in the course of the 19th century, to such an extent that we are still feeling the aftershocks now. For a significant part this change was due to the extraordinary growth, progress and increasing differentiation among and within the natural sciences, which had become progressively emancipated and estranged from philosophy. Besides progressive specialization within the various fields of (applied) natural science, we also witness increasing growth and a progressive professionalization of universities. Even though most scientists did not consider themselves philosophers anymore and only few philosophers could seriously claim to be able to embrace the depth and breadth of the former “natural philosophy”, the idea of philosophy as science was not abandoned, but became a problem in urgent need of a solution. Philosophy needed to re-establish its proper role and function, beneath, between or beyond the sciences. In the wake of Hegel’s death and the end of German Idealism, various conflicting systems were advanced, increasing rather than decreasing the problem with their claims of being rigorously “scientific”, amidst the spectacular success of the sciences, quite independently from philosophy. If philosophy really were a science, what would determine its scientific character and, correlatively, what would distinguish it from the other sciences? One might argue that philosophy would share the same field as the natural sciences, but with a different method, or that it would have a field of its own and share their method. The former was mainly propounded as the method of speculation of German Idealism, specifically Hegel. The latter, became increasingly widespread after Hegel’s death. However this would seem to simply turn philosophy into a special science itself, alongside the other special sciences. Nevertheless, two disciplines within philosophy claimed a more significant role: psychology and logic. On the one hand, it was argued that philosophy would principally investigate the internal, rather than the external world, becoming a science of thought and the mind. Since any and all science involves cognition, psychology, not as science of the soul but of the mind, could provide an elucidation or even a foundation for the sciences and restore the scientific character of philosophy. On the other hand, truth and knowledge could be considered the proper field of inquiry for philosophy, establishing epistemology and logic as foundational for all sciences. Unsurprisingly, this lead to heated debates concerning the nature, priority and distinction of the two disciplines. What both orientations had in common, though, was the aim to establish themselves as rigorously scientific. Philosophy, however, was apparently left empty handed. The progressive emancipation of psychology from philosophy lead to the foundation of several laboratories for experimental psychology and ultimately to the establishment of psychology as an natural science, independent from philosophy. Parallel to this also logic sought and found the support of an already established branch of science: mathematics. Following the arithmetization of geometry and the development of non-euclidean geometries, mathematics remained as the one and only truly formal science. In the last decades of the 19th century this led to a new form of logic, “mathematized” or  “symbolic” logic.

Around the turn of the century, however, both attempts to establish a scientific philosophical discipline, appear to fail: the crisis in the foundations of mathematics seems to pull out the rug under the idea of logic as a foundational science and psychology completely emancipates and separates from philosophy. Neither avenue seems to lead ultimately to establishing philosophy as science. Nonetheless, or perhaps rather precisely because of this, at the opening of the 20th century, multiple books, journals and essays address and press this very issue: philosophy must be or become a strict science.

An alternative account, not limited by the mainstream accounts of the history of psychology and logic, is possible. Instead of considering these two disciplines as competing and their approaches as mutually exclusive, we should look at the intriguing and promising attempts that try to successfully combine them. To this purpose, the school of Franz Brentano appears as one of the most original and interesting approaches to the problem of establishing philosophy as science, with lasting effects and widespread influence, across traditions and reaching to the present day. Among the shared interests and methods of the representatives of this school we find a good alternative to the negative account sketched above. Brentano was a staunch proponent of the idea that the true method of philosophy was that of the natural sciences and that psychology could be established as an empirical, but not experimental science, i.e. a full-blooded science of the mind that does not require a reduction to the physical in order to be scientific. Notably, Brentano is credited with re-introducing the notion of intentionality in contemporary philosophy, as an irreducible and distinguishing feature of consciousness versus natural phenomena. Furthermore, he was one of the very few proponents of a reform of Aristotelean logic, amidst the revolution of symbolic logic all around him. Brentano was the teacher of several prominent philosophers who founded schools and exerted great influences of their own: Carl Stumpf, Anton Marty, Alexius Meinong, Christian von Ehrenfels, Edmund Husserl, etc. Significantly it was Husserl who at the turn of the century set out with a new ambitious philosophical programme that prominently included the idea of philosophy as a strict science, combining aspects from both the strategies taken in psychology and in logic, but from an entirely new angle. Husserl is also probably the last philosopher who stood before the analytical/continental split, which can likewise be seen as two contrasting responses to the problem of philosophy as science.