GUSTAV THEODOR

FECHNER (1801-1887)  , German experimental psychologist, was born on the 19th of April 18or at Gross-Sarchen, near Muskau, in Lower Lusatia, where his father was pastor . He was educated at Sorau and Dresden and at the university of Leipzig, in which city he spent the rest of his life . In 1834 he was appointed professor of physics, but in 1839 contracted an affection of the eyes while studying the phenomena of colour and vision, and, after much suffering, resigned . Subsequently recovering, he turned to the study of mind and the relations between body and mind, giving public lectures on the subjects of which his books treat . He died at Leipzig on the 18th of November 1887 . Among his works may be mentioned: Das Biichlein vont Leben nach dem Tode (1836, 5th ed., 1903), which has been translated into English; Nanna, oder i ber das Seelenleben der Pflanzen (1848, 3rd ed., 1903); Zendavesta, oder ' The liqueur is said to have been manufactured by the Benedictine monks of the abbey as far back as 151o; since the Revolution it has been produced commercially by a secular company . The familiar legend D . O . M . (Deo Optimo Maximo) on the bottles preserves the memory of its original makers . caber die Dinge des $immels and des Jenseits (1851, 2nd ed. by Lasswitz, Igor); Ober die physikalische and philosophische Atomenlehre (1853, 2nd ed., 1864); Elemente der Psychophysik (x86o, 2nd ed., 1889); Vorschule der Asthetik (1876, 2nd ed., 1898); Die Tagesansicht gegeniiber der Nachtansicht (1879) . He also published chemical and physical papers, and translated chemical'works by J .

B .

Biot and L . J . Thenard from the French . 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 (186o) . He starts from the Spinozistic 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 Weber's or Fechner's 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 immensely useful . Unfortunately, from the tenable theory that the intensity of a sensation increases by definite additions of stimulus, Fechner was led on to postulate a unit of sensation, so that any sensation s might be regarded as composed of n units . Sensations, he argued, -thus being representable by numbers, psychology may become an " exact " science, susceptible of mathematical treatment . His 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 . This reasoning of Fechner's has given rise to a great mass of controversy, but the fundamental mistake in it is simple .

Though stimuli are composite, sensations are not . " Every sensation," says Professor

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." Still, the idea of the exact measurement of sensation has been a fruitful one, and mainly through his influence on Wundt, Fechner was the father of that " new " psychology of laboratories which investigates human faculties with the aid of exact scientific apparatus . Though he has had a vast influence in this special department, the disciples of his general philosophy are few . His world-conception is highly animistic . He feels 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 . Fechner's position in reference to predecessors and contemporaries is not very sharply defined .

He was remotely a

disciple of Schelling, learnt much from Herbart and Weisse, and decidedly rejected Hegel and the monadism of Lotze . See W . Wundt, G . Th . Fechner (Leipzig, 1901) ; A . Elsas, " Zum Andenken G . Th . Fechners," in Grenzbote, 1888; J . E . Kuntze, G . Th . Fechner (Leipzig, 1892) ; Karl Lasswitz, G .

Th . Fechner (

Stuttgart, 1896 and 19o2); E . B . Titchener, Experimental Psychology (New York, 19o5); G . F . Stout, Manual of Psychology (1898), bk. ii. ch. vii.; R . Falckenberg, Hist. of Mod . Phil . (Eng. trans., 1895), pp . 6or foil.; H . Hoffding, His& of Mod . Phil .

(Eng. trans., r900), vol. ii. pp . 524 foil.; Liebe, Fechners Metaphysik,

im Umr!ss dargestellt (1903) . (H .