Anti-psychologism

Anti-psychologism in Logic is a theory about the nature of logical truth, that it does not depend upon the contents of human ideas but exists independent of human ideas. The term was coined by Gottlob Frege (the most famous anti-psychologist of Logic), and has been the centre of an important debate in analytical philosophy, closely related to the internalism and externalism debate in logic and epistemology.

The rival thesis, psychologism, is not widely held amongst logicians, but it does have some high-profile defenders, for example Dov Gabbay.

Edmund Husserl was an 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. Psychologism was criticized in logic also by Charles Sanders Peirce whose fields included logic, philosophy, and experimental psychology, and generally in philosophy by Maurice Merleau-Ponty who held the chairs of philosophy and child psychology at Sorbonne in France.