logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the study of deductively valid inferences or logical truths. It examines how conclusions follow from premises based on the structure o ...

, anti-psychologism (also logical objectivism or logical realism) is the

theory A theory is a systematic and rational form of abstract thinking about a phenomenon, or the conclusions derived from such thinking. It involves contemplative and logical reasoning, often supported by processes such as observation, experimentation, ...

that

logical truth Logical truth is one of the most fundamental concepts in logic. Broadly speaking, a logical truth is a statement which is true regardless of the truth or falsity of its constituent propositions. In other words, a logical truth is a statement whic ...

does not depend upon the contents of human ideas, but exists independent of human ideas.

Overview

The anti-psychologistic treatment of logic originated in the works of

Immanuel Kant Immanuel Kant (born Emanuel Kant; 22 April 1724 – 12 February 1804) was a German Philosophy, philosopher and one of the central Age of Enlightenment, Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works ...

and

Bernard Bolzano Bernard Bolzano (, ; ; ; born Bernardus Placidus Johann Nepomuk Bolzano; 5 October 1781 – 18 December 1848) was a Bohemian mathematician, logician, philosopher, theologian and Catholic priest of Italian extraction, also known for his liberal ...

. The concept of logical objectivism or anti-psychologism was further developed by

Johannes Rehmke Johannes Rehmke (1 February 1848 – 23 December 1930) was a German philosopher and since 1885 professor at Greifswald University, later also provost of this university. He offered sharp criticisms of Immanuel Kant's approach to epistemology. In h ...

(founder of Greifswald objectivism) and

Gottlob Frege Friedrich Ludwig Gottlob Frege (; ; 8 November 1848 – 26 July 1925) was a German philosopher, logician, and mathematician. He was a mathematics professor at the University of Jena, and is understood by many to be the father of analytic philos ...

(founder of

logicism In the philosophy of mathematics, logicism is a programme comprising one or more of the theses that – for some coherent meaning of 'logic' – mathematics is an extension of logic, some or all of mathematics is reducible to logic, or some or al ...

the most famous anti-psychologist in the

philosophy of mathematics Philosophy of mathematics is the branch of philosophy that deals with the nature of mathematics and its relationship to other areas of philosophy, particularly epistemology and metaphysics. Central questions posed include whether or not mathem ...

), and has been the center of an important debate in early

phenomenology Phenomenology may refer to: Art * Phenomenology (architecture), based on the experience of building materials and their sensory properties Philosophy * Phenomenology (Peirce), a branch of philosophy according to Charles Sanders Peirce (1839� ...

and

analytical philosophy Analytic philosophy is a broad movement within Western philosophy, especially English-speaking world, anglophone philosophy, focused on analysis as a philosophical method; clarity of prose; rigor in arguments; and making use of formal logic, mat ...

. Frege's work was influenced by Bolzano. Elements of anti-psychologism in the historiography of philosophy can be found in the work of the members of the 1830s speculative theist movement and the late work of

Hermann Lotze Rudolf Hermann Lotze (; ; 21 May 1817 – 1 July 1881) was a German philosopher and logician. He also had a medical degree and was well versed in biology. He argued that if the physical world is governed by mechanical laws and relations, then de ...

. The psychologism dispute () in 19th-century German-speaking philosophy is closely related to the contemporary

internalism and externalism Internalism and externalism are two opposite ways of integrating and explaining various subjects in several areas of philosophy. These include human motivation, knowledge, justification, meaning, and truth. The distinction arises in many areas of d ...

debate in

epistemology Epistemology is the branch of philosophy that examines the nature, origin, and limits of knowledge. Also called "the theory of knowledge", it explores different types of knowledge, such as propositional knowledge about facts, practical knowle ...

;

psychologism Psychologism is a family of philosophical positions, according to which certain psychological facts, laws, or entities play a central role in grounding or explaining certain non-psychological facts, laws, or entities. The word was coined by Joh ...

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). Psychologism was defended by

Theodor Lipps Theodor Lipps (; 28 July 1851 – 17 October 1914) was a German philosopher, known for his theory regarding aesthetics, creating the framework for the concept of ''Einfühlung'' (empathy)'','' defined as, "projecting oneself onto the object of p ...

, Gerardus Heymans,

Wilhelm Wundt Wilhelm Maximilian Wundt (; ; 16 August 1832 – 31 August 1920) was a German physiologist, philosopher, and professor, one of the fathers of modern psychology. Wundt, who distinguished psychology as a science from philosophy and biology, was t ...

, Wilhelm Jerusalem, Christoph von Sigwart,

Theodor Elsenhans Theodor Elsenhans (; 7 March 1862 – 3 January 1918) was a German psychologist and neo-Kantian philosopher. He was born in Stuttgart and died in Dresden. Life Elsenhans started studying theology at the University of Tübingen, but became interest ...

, and

Benno Erdmann Benno Erdmann (; 30 May 1851 – 7 January 1921) was a German neo-Kantian philosopher, logician, psychologist and scholar of Immanuel Kant. Biography Erdmann received his Ph.D. in 1873 from the University of Berlin with a dissertation on Kan ...

Edmund Husserl Edmund Gustav Albrecht Husserl (; 8 April 1859 – 27 April 1938) was an Austrian-German philosopher and mathematician who established the school of Phenomenology (philosophy), phenomenology. In his early work, he elaborated critiques of histori ...

was another important proponent of anti-psychologism, and this trait passed on to other phenomenologists, such as

Martin Heidegger Martin Heidegger (; 26 September 1889 – 26 May 1976) was a German philosopher known for contributions to Phenomenology (philosophy), phenomenology, hermeneutics, and existentialism. His work covers a range of topics including metaphysics, art ...

, 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 In logic and mathematics, statements p and q are said to be logically equivalent if they have the same truth value in every model. The logical equivalence of p and q is sometimes expressed as p \equiv q, p :: q, \textsfpq, or p \iff q, depending on ...

to "It is thought that 'no-p is a not-p'", psychologism does not logically stand.

Charles Sanders Peirce Charles Sanders Peirce ( ; September 10, 1839 – April 19, 1914) was an American scientist, mathematician, logician, and philosopher who is sometimes known as "the father of pragmatism". According to philosopher Paul Weiss (philosopher), Paul ...

—whose fields included logic, philosophy, and experimental psychology—could also be considered a critic of psychologism in logic.

The return of psychologism

Psychologism is not widely held amongst logicians today, but something like it has some high-profile defenders especially among those who do research at the intersection of logic and

cognitive science Cognitive science is the interdisciplinary, scientific study of the mind and its processes. It examines the nature, the tasks, and the functions of cognition (in a broad sense). Mental faculties of concern to cognitive scientists include percep ...

, for example

Dov Gabbay Dov M. Gabbay (, ; born October 26, 1945) is an Israeli logician. He is Augustus De Morgan Professor Emeritus of Logic at the Group of Logic, Language and Computation, Department of Computer Science, King's College London. Work Gabbay has autho ...

and John Woods, who concluded that "whereas mathematical logic must eschew psychologism, the new logic cannot do without it". See also:

Notes

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Overview

The return of psychologism

Notes

Further reading