Overview[edit]

The anti-psychologistic treatment of logic originated in the works of Immanuel Kant and Bernard Bolzano.^[4]


The concept of logical objectivism or anti-psychologism was further developed by Johannes Rehmke (founder of Greifswald objectivism)^[5] and Gottlob Frege (founder of logicism the most famous anti-psychologist in the philosophy of mathematics), and has been the center of an important debate in early phenomenology and analytical philosophy. Frege's work was influenced by Bolzano.^[6]


Elements of anti-psychologism in the historiography of philosophy can be found in the work of the members of the 1830s speculative theist movement^[7] and the late work of Hermann Lotze.^[8]


The psychologism dispute (German: Psychologismusstreit)^[9] in 19th-century German-speaking philosophy is closely related to the contemporary internalism and externalism debate in epistemology; psychologism is often construed as a kind of internalism (the thesis that no fact about the world can provide reasons for action independently of desires and beliefs) and anti-psychologism as a kind of externalism (the thesis that reasons are to be identified with objective features of the world).^[10]


Psychologism was defended by Theodor Lipps, Gerardus Heymans, Wilhelm Wundt, Wilhelm Jerusalem, Christoph von Sigwart, Theodor Elsenhans, and Benno Erdmann.^[11]


Edmund Husserl was another important proponent of anti-psychologism, and this trait passed on to other phenomenologists, such as Martin Heidegger, whose doctoral thesis was meant to be a refutation of psychologism. They shared the argument that, because the proposition "no-p is a not-p" is not logically equivalent to "It is thought that 'no-p is a not-p'", psychologism does not logically stand.


Charles Sanders Peirce—whose fields included logic, philosophy, and experimental psychology^[12]—could also be considered a critic of psychologism in logic.^[13]