Georg Theodor Ziehen was a German neurologist

Neurologist

A neurologist is a physician who specializes in neurology, and is trained to investigate, or diagnose and treat neurological disorders.Neurology is the medical specialty related to the human nervous system. The nervous system encompasses the brain, spinal cord, and peripheral nerves. A specialist...

 and psychiatrist

Psychiatrist

A psychiatrist is a physician who specializes in the diagnosis and treatment of mental disorders. All psychiatrists are trained in diagnostic evaluation and in psychotherapy...

 born in Frankfurt am Main. He was the son of noted author, Eduard Ziehen (1819-1884).

As a gymnasium student he studied the works of Immanuel Kant

Immanuel Kant

Immanuel Kant was a German philosopher from Königsberg , researching, lecturing and writing on philosophy and anthropology at the end of the 18th Century Enlightenment....

 and Arthur Schopenhauer

Arthur Schopenhauer

Arthur Schopenhauer was a German philosopher known for his pessimism and philosophical clarity. At age 25, he published his doctoral dissertation, On the Fourfold Root of the Principle of Sufficient Reason, which examined the four separate manifestations of reason in the phenomenal...

 at Lessing-Gymnasium in Frankfurt. Later he studied medicine in Würzburg

Würzburg

Würzburg is a city in the region of Franconia which lies in the northern tip of Bavaria, Germany. Located at the Main River, it is the capital of the Regierungsbezirk Lower Franconia. The regional dialect is Franconian....

 and Berlin

Berlin

Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

, where he received his doctorate in 1885. While a medical student he studied the writings of David Hume

David Hume

David Hume was a Scottish philosopher, historian, economist, and essayist, known especially for his philosophical empiricism and skepticism. He was one of the most important figures in the history of Western philosophy and the Scottish Enlightenment...

, Spinoza, Plato

Plato

Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...

 and George Berkeley

George Berkeley

George Berkeley , also known as Bishop Berkeley , was an Irish philosopher whose primary achievement was the advancement of a theory he called "immaterialism"...

. Following graduation he worked as an assistant to Karl Ludwig Kahlbaum

Karl Ludwig Kahlbaum

Karl Ludwig Kahlbaum was a German psychiatrist. In 1855 he received his medical doctorate at Berlin, and subsequently worked as a physician at the mental asylum in Wehlau. For a period of time he was also a lecturer at the University of Königsberg , and from 1867 was director of the mental...

 at the mental hospital in Görlitz

Görlitz

Görlitz is a town in Germany. It is the easternmost town in the country, located on the Lusatian Neisse River in the Bundesland of Saxony. It is opposite the Polish town of Zgorzelec, which was a part of Görlitz until 1945. Historically, Görlitz was in the region of Upper Lusatia...

, and in 1887 became an assistant to Otto Binswanger

Otto Binswanger

Otto Ludwig Binswanger was a Swiss psychiatrist and neurologist who came from a famous family of physicians; his father was founder of the Kreuzlingen Sanatorium, and he was uncle to Ludwig Binswanger who was a major figure in the existential psychology movement...

 at the Psychiatric Clinic in Jena

Jena

Jena is a university city in central Germany on the river Saale. It has a population of approx. 103,000 and is the second largest city in the federal state of Thuringia, after Erfurt.-History:Jena was first mentioned in an 1182 document...

. At Jena one of his patients was philosopher Friedrich Nietzsche

Friedrich Nietzsche

Friedrich Wilhelm Nietzsche was a 19th-century German philosopher, poet, composer and classical philologist...

.

Subsequently he was a professor of psychiatry in Utrecht

Utrecht (city)

Utrecht city and municipality is the capital and most populous city of the Dutch province of Utrecht. It is located in the eastern corner of the Randstad conurbation, and is the fourth largest city of the Netherlands with a population of 312,634 on 1 Jan 2011.Utrecht's ancient city centre features...

 (from 1900), Halle

Halle, Saxony-Anhalt

Halle is the largest city in the German state of Saxony-Anhalt. It is also called Halle an der Saale in order to distinguish it from the town of Halle in North Rhine-Westphalia...

 (from 1903) and Berlin

Berlin

Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

 (1904-1912). In 1912 he moved with his family to a small villa in Wiesbaden

Wiesbaden

Wiesbaden is a city in southwest Germany and the capital of the federal state of Hesse. It has about 275,400 inhabitants, plus approximately 10,000 United States citizens...

, where he spent the next few years as a private scholar. From 1917 he worked as a professor of philosophy

Philosophy

Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

 at the University of Halle, and in 1930 he retired to Wiesbaden, where he died on 29 December 1950.

Ziehen published nearly 450 works on psychology

Psychology

Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...

, neurology, anatomy

Anatomy

Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...

, et al. He was author of an important textbook Die Geisteskrankheiten des Kindesalters (Mental Diseases of Childhood), which was one of the first systematic works concerning child psychiatry in Germany. He also penned the textbook Psychiatrie für Ärzte und Studirende which was published in four editions between 1894 and 1911. In his writings, Ziehen is credited with introducing the terms "affective psychosis

Psychosis

Psychosis means abnormal condition of the mind, and is a generic psychiatric term for a mental state often described as involving a "loss of contact with reality"...

" and "psychopathic constitution". Along with neurologist Hermann Oppenheim

Hermann Oppenheim

Hermann Oppenheim was one of the leading neurologists in Germany. He studied medicine at the Universities of Berlin, Göttingen and Bonn. He started his career at the Charité-Hospital in Berlin as an assistant of Karl Westphal...

, the Ziehen-Oppenheim syndrome is named, which is a genetic torsion dystonia

Dystonia

Dystonia is a neurological movement disorder, in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning or reaction to...

 (spasms) due to a lesion of the basal ganglia

Basal ganglia

The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...

.

In 1898 he published Psychophysiologische Erkenntnistheorie (Psychophysiological Theory of Knowledge), with psychology being the basis of his philosophic belief system. He was a practitioner of associative psychology, and from a philosophic standpoint advocated monistic

Monism

Monism is any philosophical view which holds that there is unity in a given field of inquiry. Accordingly, some philosophers may hold that the universe is one rather than dualistic or pluralistic...

 positivism

Positivism

Positivism is a a view of scientific methods and a philosophical approach, theory, or system based on the view that, in the social as well as natural sciences, sensory experiences and their logical and mathematical treatment are together the exclusive source of all worthwhile information....

, or what he called the "principle of immanence

Immanence

Immanence refers to philosophical and metaphysical theories of divine presence, in which the divine is seen to be manifested in or encompassing of the material world. It is often contrasted with theories of transcendence, in which the divine is seen to be outside the material world...

".

Selected works

• Sphygmographische Untersuchungen an Geisteskranken (Sphygmographic Studies on Mental Health), Jena, 1887.
• Leitfaden der physiologischen Psychologie (Guide to Physiological Psychology), Jena, 1891
• Das Centralnervensystem der Cetaceen (The Central Nervous System of Cetaceans), 1892.
• Psychiatrie für Ärzte und Studirende (Psychiatry for Doctors and Students), 1894
• Das Centralnervensystem der Monotremen und Marsupialier (The Central Nervous System of Monotremes and Marsupials), 1897.
• Psychophysiologische Erkenntnistheorie (Psychophysiological Epistemology), Jena, 1898.
• Anatomie des Centralnervensystems (Central Anatomy of the Nervous System), In: Handbuch der Anatomie des Menschen, Jena, 1899
• Über die allgemeinen Beziehungen zwischen Gehirn und Seelenleben (Concerning the Overall Relations between the Brain and Soul), Leipzig, 1902.
• Die Prinzipien und Methoden der Begabungs-, insbesondere der Intelligenzprüfung (Principles and Methods of High-ability, in particular the Assessment of Intelligence), 1908; 5. Aufl., 1923.
• Die Erkennung der psychopathischen Konstitutionen und die öffentliche Fürsorge für psychopatisch veranlagte Kinder (Detection of Psychopathic Constitutions and Public Concern for Psychopathic-assessed Children), Jena, 1912; 3. Aufl., 1916.
• Ärztliche Wünsche zur Fürsorgeerziehung (Requests for Medical Care Education), Langensalza, 1913.
• Erkenntnistheorie auf psychophysiologischer und physikalisher Grundlage, Jena, 1913.
• Zum gegenwärtigen Stand der Erkenntnistheorie : zugleich Versuch einer Einteilung der Erkenntnistheorien (The Present State of Epistemology: with an Attempt to Schedule Realization Theories) Wiesbaden: J. F. Bergmann, 1914.
• Die Grundlagen der Psychologie, (Foundations of psychology), Leipzig and Berlin, 1915.
• Die Geisteskrankheiten des Kindesalters einschließlich des Schwachsinns und der psychopathischen Konstitutionen (Mental Illnesses of Childhood, including Psychopathic Constitutions) 2 parts, Berlin, 1915-1917; 2. Aufl., 1926.
• Das Verhältnis der Logik zur Mengenlehre, Berlin, 1917.
• Über das Wesen der Beanlagung und ihre methodische Erforschung (Regarding the Nature of Beanlagung and their Methodical Exploration); Langensalza, 1918; 4. Aufl., 1929.
• Lehrbuch der Logik auf positivistischer Grundlage mit Berücksichtigung der Geschichte der Logic, Bonn, 1920.
• Die Beziehungen der Lebenserscheinungen zum Bewußtsein (The Relationship of Life to Awareness-Appearances) 1921.
• Grundlage der Naturphilosophie (Basis of Natural Philosophy), 1922.
• Vorlesungen über Ästhetik (Lectures on Aesthetics); (2 volumes), 1923 und 1925).
• Das Seelenleben der Jugendlichen (The "Soul Lives" of Young People); Langensalza, 1923; 4. Aufl., 1931.
• Die Grundlagen der Charakterologie (The Foundations of Character Studies); Langensalza, 1930.