Kusch, Martin. Psychologism: A Case Study in the Sociology of Philosophical Knowledge. London; New York: Routledge, 1995. See also the online appendices:
Four Appendices to PSYCHOLOGISM (1995)
This book is fascinating. Abstruse as it is, for me it’s like reading a detective novel. I put this among the top half dozen books illuminating aspects of the history of philosophy that relate to my interests.
Kusch analyzes in great detail the point-for-point philosophical issues involved in the war over psychologism and the institutional turf that was fought over, and eventually with the First World War and the Weimar Republic, the overall social and ideological climate that liquidated the debate of earlier decades.
The war against psychologism was waged first by Frege and then by Husserl, who was accused of psychologism by Frege and later purged said elements from his philosophy. Frege as we know was the godfather of analytical philosophy, while Husserl became the progenitor of so-called continental philosophy. Understanding the dynamics of the battles of the time presumably helps to explain this split, but ultimately we learn more about the development of German philosophy from the controversies in which Husserl was engaged.
Kusch seeks to rescue the nature of this historical philosophical dynamic from the oblivion to which the victory of the anti-psychologistic tendency relegated it. This is, as he calls it, the victory of the anti-naturalistic perspective.
Now, this seems a bit odd to me, because the initial debate was over the status of logic. The abstract objects of logic and mathematics and the deductive necessity that renders them independent of the subjective wills of their human creators creates an ontological problem for anyone not committed to objective idealism but who nonetheless rejects subjective idealism. The notion that logic can be explained by human psychology seems to rob it of its objectivity. One strategy is to affirm logic’s normative character. Kusch presents all the various positions presented in these arguments. I must say I have no sympathy of any kind for psychologism, and I am on the side of Frege and Husserl here, but I would not call my world-view anti-naturalistic.
Experimental psychology was on the rise in the late 19th century. Institutionally it was ensconced within philosophy departments, and the psychologists’ purview intruded into what would properly be considered as philosophy, and given the institutional arrangements constituted a threat to traditional philosophy. (One of the main partisans of the psychologistic camp was Wilhelm Wundt.) Hence the war began, and was not in the end limited to logic and mathematics.
An interesting facet of these battles was how the term “psychologism” was deployed. At some point, everyone accused everyone else of “psychologism,” but one is hard-pressed to find a consistent application of the term.
Kusch, having reviewed the literature of the time, provides charts itemizing all the issues and charges on all sides of the debates, and summarizes them in the book.
I do not find the arguments in favor of psychologism convincing. Perhaps this could be a lesson in pitfalls of naturalizing epistemology (discussed at that time as well), though I would add that naturalizing logic and mathematics, despite their real-world correlates and applications, presents a much more daunting issue, given the non-uniqueness of formalized logics and axiomatic systems. The issue, from what I gather here, is not really a naturalistic world view in general, but rather the naiveté and limitations of empiricism, competing with . . . whatever Frege and Husserl ultimately represent. Among better alternatives I would count Popper’s “three worlds” schema. (I do not recall, however, how Popper differentiates (if he does or should) between the character of logic and mathematics and other shared artifacts of the human intellect and imagination.)
Note that, while up to this point the issues described involve the ontological status of logical and mathematical constructs, what we see from here on in is an all-out war over the relationship between the advocates of experimental psychology and “pure” philosophy.
An interesting chapter on the institutional conflicts involves what Kusch refers to as role hybridization. Psychology at the moment the conflict interrupts is to be found within departments of philosophy directed by “pure” philosophers. Added to the intrinsic intellectual issues was the possible threat of the eventual extinction of pure philosophy as (experimental) psychology advances.
If one wants to frame the limitations of all sides of the philosophical war, one might want to take a look at the larger sociocultural conflicts. Advocates of psychology such as Brentano and Heymans that psychology could counteract the cultural decline they perceived. Problems as they saw them included the divorce rate, religious displacement, job instability, and fragmentation in general. Brentano advocated a prominent role for psychology in politics. Marbe thought psychology could be the central axis for a range of endeavors. Advocacy of psychology for the military was not far behind. Furthermore, psychology could combat the plague of materialistic world views. (pp. 151-2)
The totally reactionary conception of society here (my judgment, not Kusch’s) may well be related to the limitations of the philosophies in combat. As to whom the plague of materialism applies, while I do not know what Brentano had in mind, my first thought is the German Social Democrats, i.e. Marxists. We shall see eventually how badly all these people behaved in World War I.
Of interest also is the advocacy of psychology (note: not sociology or political economy) as the foundation of the Geisteswissenschaften, or human sciences. (153) Wundt, Lipps, and Lamprecht were behind this, for example. There were also arguments for psychology as the foundation of philosophy, or the condition of progress in philosophy. Note that, in addition to the dubiousness of these claims, one should beware of premature claims of naturalizing philosophy (epistemology) when both the naturalizing and the philosophy are so ideologically loaded.
The institutional stage following that of role hybridization Kusch names role purification: the “pure” philosophers retaliate. Kusch highlights Dilthey, Rickert, Windelband, and Husserl.
Dilthey objected to the utilization of the hypothetical-deductive method of the natural sciences, the inability (according to Dilthey) to adjudicate competing hypotheses, the premise of determining and interrelating atomic psychological elements, the presumption of psychophysical parallelism, and the presumption that all psychological phenomena could be derived from sensations and feelings, and the paucity of mental phenomena under investigation. Dilthey claimed that mental phenomena could be immediately rather than experimentally known. (163) Dilthey also claimed that psychophysical parallelism was actually a form of materialism, whose narrow determinism constituted a danger to criminology. (164) Dilthey countered experimental psychology with a descriptive and analytical psychology, which would deploy all means of investigation including the works of geniuses and works of art. (164-5) Dilthey’s method involved introspection, and what looks to me like a holist rather than atomistic approach. To me his program looks like a different brand of psychologism, but it appealed to a variety of “pure” philosophers.
At first neo-Kantians were sympathetic to experimental psychology. Windelband, while acknowledging the importance of psychology, insisted that it constitutes a separate discipline and should be institutionalized entirely outside of philosophy departments. (170) His attitude towards psychology grew more negative with time. He blamed psychology, physiology, and historical relativism for what he deemed the decline of philosophy in the 1880s and 1890s. Windelband proposed (1894) his own classification of the sciences, rejecting the traditional distinction between Geisteswissenschaften and Naturwissenschaften (natural sciences), as psychology drew on aspects of both, proposing instead a schema of nomothetic (seeking general laws) and idiographic sciences (based on particular facts or events). Empirical psychology would then be a nomothetic science. (171-2) Windelband also argued that historical sciences proceed with natural knowledge of human nature in mind, not on the basis of scientific psychology. (172)
Rickert distinguished between Geisteswissenschaften and Naturwissenschaften on the basis of their natures of concept formation, i.e. concepts based on generality or particularity of the phenomenon under investigation. He went beyond Windelband, linking culture to values. (173) Thus empirical psychology was not a cultural science. The cultural sciences were concerned with values, not psychology. Scientific psychology was of little use to the historian. (174)
Rickert was also troubled by the prospects of downsizing the great men of history. He railed against a “materialistic historiography” that “depends for the most part on the specific wishes of social democracy”. With its “guiding cultural ideal” being “democratic”, “it creates the tendency […] to regard the great personalities as inessential and to accept only that which comes from the masses.” 
Rickert also saw the objectivity of values as the highest objectivity.
For Stumpf the catastrophe of German philosophy consisted entirely in the materialistic writings of Feuerbach, Vogt, Büchner, Marx, Engels, and Stirner. (175)
Well, well, well!
Schlick repudiated Windelband’s and Rickert’s distinctions between the Geisteswissenschaften and Naturwissenschaften, finding both generality and particularity in both. (177) Schlick disintguished between two kinds of concept formation on the basis of quantitative vs. qualitative methods.
Coming installment(s): Balance of chapter on role purification: Husserl’s relation to psychology, “pure” philosophy & the new psychology, the petition to exclude experimental philosophers from philosophy departments, ensuing controversies; why Husserl was influential and not Frege in these controversies. Then: World War I & the patriotic drum-beating of the German philosophers, the rise of Lebensphilosophie, the hegemony of irrationalism, and the triumph of phenomenology in the Weimar Republic, the fate of Cassirer and the appearance of the Vienna Circle. Kusch’s summary & conclusions; my conclusions.
Items of related interest:
Hanna, Robert. Review of Psychologism: A Case Study in the Sociology of Philosophical Knowledge by Martin Kusch (London: Routledge, 1995), Philosophy and Phenomenological Research, vol. 57, no. 4, December 1997, pp. 961-964.
Jacquette, Dale, ed. Philosophy, Psychology and Psychologism: Critical and Historical Readings on the Psychological Turn in Philosophy. New York; Boston; Dordrecht; London; Moscow: Kluwer Academic Publishers, 2003. (Philosophical Studies Series; 91)