|Born||Gustav Theodor Fechner
April 19, 1801
Groß Särchen (near Muskau), Saxony, Holy Roman Empire
|Died||November 18, 1887
Alfred North Whitehead
Gustav Theodor Fechner (April 19, 1801 – November 18, 1887), was a German philosopher and experimental psychologist. An early pioneer in experimental psychology and founder of psychophysics, he inspired many 20th century scientists and philosophers. He is also credited with demonstrating the non-linear relationship between psychological sensation and the physical intensity of a stimulus via the formula: "S = K Log I", which became known as the Weber–Fechner law.
Early life and scientific career 
Fechner was born at Groß Särchen, near Muskau, in Lower Lusatia, where his father was a pastor. Despite being raised by his religious father, Fechner became an atheist in later life. He was educated first at Sorau. In 1817 he studied of medicine at the Medizinisch-Chirurgische Akademie in Dresden and from 1818 at the University of Leipzig, the city in which he spent the rest of his life. In 1834 he was appointed professor of physics. But in 1839, he contracted an eye disorder while studying the phenomena of color and vision, and, after much suffering, resigned. Subsequently recovering, he turned to the study of the mind and its relations with the body, giving public lectures on the subjects dealt with in his books.
Gustav Fechner published chemical and physical papers, and translated chemical works by J. B. Biot and Louis Jacques Thénard from the French language. A different but essential side of his character is seen in his poems and humorous pieces, such as the Vergleichende Anatomie der Engel (1825), written under the pseudonym of "Dr. Mises."
Fechner's epoch-making work was his Elemente der Psychophysik (1860). He starts from the monistic thought that bodily facts and conscious facts, though not reducible one to the other, are different sides of one reality. His originality lies in trying to discover an exact mathematical relation between them. The most famous outcome of his inquiries is the law known as the Weber–Fechner law which may be expressed as follows:
- "In order that the intensity of a sensation may increase in arithmetical progression, the stimulus must increase in geometrical progression."
Though holding good within certain limits only, the law has been found to be immensely useful. Fechner's law implies that sensation is a logarithmic function of physical intensity, which is impossible due to the logarithm's singularity at zero; therefore, S. S. Stevens proposed the more mathematically plausible power-law relation of sensation to intensity in his famous 1961 paper entitled "To Honor Fechner and Repeal His Law."
Fechner's general formula for getting at the number of units in any sensation is S = c log R, where S stands for the sensation, R for the stimulus numerically estimated, and c for a constant that must be separately determined by experiment in each particular order of sensibility. Fechner's reasoning has been criticized on the grounds that although stimuli are composite, sensations are not. "Every sensation," says William James, "presents itself as an indivisible unit; and it is quite impossible to read any clear meaning into the notion that they are masses of units combined."
The Fechner color effect 
In 1838, he also studied the still-mysterious perceptual illusion of what is still called the Fechner color effect, whereby colors are seen in a moving pattern of black and white. The English journalist and amateur scientist Charles Benham, in 1894, enabled English-speakers to learn of the effect through the invention of the spinning top that bears his name. Whether Fechner and Benham ever actually met face to face for any reason is not known.
The median 
Fechner, along with Wilhelm Wundt and Hermann von Helmholtz, is recognized as one of the founders of modern experimental psychology. His clearest contribution was the demonstration that because the mind was susceptible to measurement and mathematical treatment, psychology had the potential to become a quantified science. Theorists such as Immanuel Kant had long stated that this was impossible, and that therefore, a science of psychology was also impossible.
Though he had a vast influence on psychophysics, the actual disciples of his general philosophy were few. Ernst Mach was inspired by his work on psychophysics. William James also admired his work: in 1904, he wrote an admiring introduction to the English translation of Fechner's Büchlein vom Leben nach dem Tode (Little Book of Life After Death).
Fechner's world concept was highly animistic. He felt the thrill of life everywhere, in plants, earth, stars, the total universe. Man stands midway between the souls of plants and the souls of stars, who are angels. God, the soul of the universe, must be conceived as having an existence analogous to men. Natural laws are just the modes of the unfolding of God's perfection. In his last work Fechner, aged but full of hope, contrasts this joyous "daylight view" of the world with the dead, dreary "night view" of materialism. Fechner's work in aesthetics is also important. He conducted experiments to show that certain abstract forms and proportions are naturally pleasing to our senses, and gave some new illustrations of the working of aesthetic association. Charles Hartshorne saw him as a predecessor on his and Alfred North Whitehead's philosophy and regretted that Fechner's philosophical work had been neglected for so long.
Fechner's position in reference to predecessors and contemporaries is not very sharply defined. He was remotely a disciple of Schelling, learnt much from Benedict de Spinoza, Gottfried Wilhelm Leibniz, Johann Friedrich Herbart, Arthur Schopenhauer, and Christian Hermann Weisse, and decidedly rejected Georg Hegel and the monadism of Rudolf Hermann Lotze.
- Praemissae ad theoriam organismi generalem (1823).
- (Dr. Mises) Stapelia mixta (1824). Google (Harvard)
- Resultate der bis jetzt unternommenen Pflanzenanalysen (1829). Google (Stanford)
- Maassbestimmungen über die galvanische Kette (1831).
- (Dr. Mises) Schutzmittel für die Cholera (1832). Google (Harvard) — Google (UWisc)
- Repertorium der Experimentalphysik (1832). 3 volumes.
- (ed.) Das Hauslexicon. Vollständiges Handbuch praktischer Lebenskenntnisse für alle Stände (1834–38). 8 volumes.
- Das Büchlein vom Leben nach dem Tode (1836). 6th ed., 1906. Google (Harvard) — Google (NYPL)
- (Dr. Mises) Gedichte (1841). Google (Oxford)
- Ueber das höchste Gut (1846). Google (Stanford)
- (Dr. Mises) Nanna oder über das Seelenleben der Pflanzen (1848). 2nd ed., 1899. 3rd ed., 1903. Google (UMich) 4th ed., 1908. Google (Harvard)
- Zend-Avesta oder über die Dinge des Himmels und des Jenseits (1851). 3 volumes. 3rd ed., 1906. Google (Harvard)
- Ueber die physikalische und philosophische Atomenlehre (1855). 2nd ed., 1864. Google (Stanford)
- Professor Schleiden und der Mond (1856). Google (UMich)
- Elemente der Psychophysik (1860). 2 volumes. Volume 1. Google (ULausanne) Volume 2. Google (NYPL)
- Ueber die Seelenfrage (1861). Google (NYPL) — Google (UCal) — Google (UMich) 2nd ed., 1907. Google (Harvard)
- Die drei Motive und Gründe des Glaubens (1863). Google (Harvard) — Google (NYPL)
- Einige Ideen zur Schöpfungs- und Entwickelungsgeschichte der Organismen (1873). Google (UMich)
- (Dr. Mises) Kleine Schriften (1875). Google (UMich)
- Erinnerungen an die letzen Tage der Odlehre und ihres Urhebers (1876). Google (Harvard)
- Vorschule der Aesthetik (1876). 2 Volumes. Google (Harvard)
- In Sachen der Psychophysik (1877). Google (Stanford)
- Die Tagesansicht gegenüber der Nachtansicht (1879). Google (Oxford) 2nd ed., 1904. Google (Stanford)
- Revision der Hauptpuncte der Psychophysik (1882). Google (Harvard)
- Kollektivmasslehre (1897). Google (NYPL)
- Fancher, R. E. (1996). Pioneers of psychology (3rd Ed.). New York: W. W. Norton & Company.
- Sheynin, Oscar (2004), "Fechner as a statistician.", The British journal of mathematical and statistical psychology (2004 May) 57 (Pt 1): 53–72, doi:10.1348/000711004849196, PMID 15171801
- Michael Heidelberger (2004). "1: Life and Work". Nature from within: Gustav Theodor Fechner and his Psychophysical Worldview. University of Pittsburgh Press. p. 21. ISBN 9780822970774. "The study of medicine also contributed to a loss of religious faith and to becoming atheist."
- Fechner, Gustav Theodor at vlp.mpiwg-berlin.mpg.de
- Keynes, John Maynard; A Treatise on Probability (1921), Pt II Ch XVII §5 (p 201).
- Pojman, Paul, "Ernst Mach", The Stanford Encyclopedia of Philosophy (Winter 2011 Edition), Edward N. Zalta (ed.), URL = <http://plato.stanford.edu/archives/win2011/entries/ernst-mach/>
- Marshall, M E (1969), "Gustav Fechner, Dr. Mises, and the comparative anatomy of angels.", Journal of the history of the behavioral sciences (1969 Jan) 5 (1): 39–58, doi:10.1002/1520-6696(196901)5:1<39::AID-JHBS2300050105>3.0.CO;2-C, PMID 11610088
- For Hartshorne's appreciation of Fechner see his Aquinas to Whitehead – Seven Centuries of Metafysics of Religion. Hartshorne also comments that William James failed to do justice to the theological aspects of Fechner's work. Hartshorne saw also resemblances with the work of Fechner's contemporary Jules Lequier. See also: Hartshorne – Reese (ed.) Philosophers speak of God.
Further reading 
- Heidelberger, M. (2001) Gustav Theodor Fechner, Statisticians of the Centuries (ed. C. C. Heyde and E. Seneta) pp. 142–147. New York: Springer.
- Michael Heidelberger. Nature From Within: Gustav Theodor Fechner and his Psychophysical Worldview Trans. Cynthia Klohr. Pittsburgh, PA: University of Pittsburgh Press, 2004.
- Stephen M Stigler. The History of Statistics: The Measurement of Uncertainty before 1900, Cambridge, MA: Harvard University Press 1986. pp. 242–254.
- Works of Gustav Theodor Fechner at Projekt Gutenberg-DE. (German)
- Excerpt from Elements of Psychophysics from the Classics in the History of Psychology website.
- Robert H. Wozniak’s Introduction to Elemente der Psychophysik.
- Biography, bibliography and digitized sources in the Virtual Laboratory of the Max Planck Institute for the History of Science