​PLANCK, KARL CHRISTIAN (1819-1880), German philosopher, was born at Stuttgart on the 17th of January 1819. He studied at Tubingen, where he became doctor of philosophy in 1840 and Privatdozent in 1848. During this period the influence of Reiff led him to oppose the dominant Hegelianism of the time. In 1850-1851 he published his great book, Die Weltalter, in which he developed a complete original system of philosophy, based on the realistic view that thought should proceed from nature to the highest forms of existence in the spiritual life. Not only did Planck oppose the idealism of his confreres, his views were, in another aspect, directly antagonistic to the Darwinian theory of descent, which he specifically attacked in Wahrheit und Flachheit des Darwinisrnus (Nordlingen, 1872). The natural consequence of this individuality of opinion was that his books were practically disregarded, and Planck was deeply incensed. The ill success of Die Weltalter nerved him to new efforts, and he repeated his views in Katechismus des Rechts (1852), Grundlinen einer Wissenschaft der Natnr (1864), Seele und Geist (1871), and numerous other books, which, however, met with no better fate. In the meantime he left Tubingen for Ulm, whence he came finally to the seminary of Maulbronn. He died on the 7th of June 1880 in an asylum after a short period of nervous prostration. After his death a summary of his work came into the hands of K. Kostlin (author of Aesthetics, 1869), who published it in 1881 under the title Testament einesDeutschen, Philosophze der N atur und der M enschheit. Planck's views were elaborately developed, but his method of exposition told heavily against their acceptance. He regarded himself as the Messiah of the German people.

Beside the works above quoted, he wrote System des reinen Idealismus (1851); Anlhropologie und Psychologie auf naturwissenschaftlicher Grundlage (1874); a political treatise, Bismarck: Suddeutschland und der deutsche Nalionalslaal (1872); and L0g'iS6heS Causalgesetz und nalurliche Zweckmassigkeil (1874). See Umfrid, Karl Planck, dessert Werke und Wirken (Tubingen, 1881); and Schmidt, “Das Lebensideal Karl Christian Plancks, " in the Vorlrage der philosophischen Gesellschaft (Berlin, 1896).