Friedrich Karl Christian Ludwig Büchner (1824-1899), German philosopher and physician, was born at Darmstadt. He studied at Giessen, Strassburg, Würzburg and Vienna. In 1852 he became lecturer in medicine at the university of Tübingen, where he published his great work Kraft und Stoff (1855). In this work, the product, according to Lange, of a fanatical enthusiasm for humanity, he sought to demonstrate the indestructibility of matter and force, and the finality of physical force. The extreme materialism of this work excited so much opposition that he was compelled to give up his post at Tübingen. He retired to Darmstadt, where he practised as a physician and contributed regularly to pathological and physiological magazines. He continued his philosophical work in defence of materialism, and published Natur und Geist (1857), Aus Natur und Wissenschaft (vol. i., 1862; vol. ii., 1884), Fremdes und Eigenes aus dem geistigen Leben der Gegenwart (1890), Darwinismus und Socialismus (1894), Im Dienste der Wahrheit (1899). He died at Darmstadt on the 1st of May 1899. In estimating Büchner's philosophy it must be remembered that he was primarily a physiologist, not a metaphysician.

Matter and force (or energy) are infinite; the conservation of force follows from the imperishability of matter, the ultimate basis of all science. Büchner is not always clear in his theory of the relation between matter and force. At one time he refuses to explain it, but generally he assumes that all natural and spiritual forces are indwelling in matter. "Just as a steam-engine," he says in Kraft und Stoff (7th ed., p. 130), "produces motion, so the intricate organic complex of force-bearing substance in an animal organism produces a total sum of certain effects, which, when bound together in a unity, are called by us mind, soul, thought." Here he postulates force and mind as emanating from original matter - a materialistic monism. But in other parts of his works he suggests that mind and matter are two different aspects of that which is the basis of all things - a monism which is not necessarily materialistic, and which, in the absence of further explanation, constitutes a confession of failure. Büchner was much less concerned to establish a scientific metaphysic than to protest against the romantic idealism of his predecessors and the theological interpretations of the universe.

Nature according to him is purely physical; it has no purpose, no will, no laws imposed by extraneous authority, no supernatural ethical sanction.

See Frauenstädt, Der Materialismus (Leipzig, 1856); Janet, The Materialism of the Present Day: A Criticism of Dr Büchner's System, trans. Masson (London, 1867).