Organicism is a philosophical orientation that asserts that reality is best understood as an organic whole. By definition it is close to holism. Plato, Hobbes or Constantin Brunner are examples of such philosophical thought.
Organicism is also a biological doctrine that stresses the organization, rather than the composition, of organisms. William Emerson Ritter coined the term in 1919. Organicism became well-accepted in the 20th century.
Examples of 20th century biologists who were organicists are Ross Harrison, Paul Weiss, and Joseph Needham. Donna Haraway discusses them in her first book. John Scott Haldane (father of J. B. S. Haldane), R. S. Lillie, W. E. Agar, and Ludwig von Bertalanffy are other early twentieth century organicists.
Organicism as a doctrine rejects mechanism and reductionism (doctrines that claim that the smallest parts by themselves explain the behavior of larger organized systems of which they are a part). However, organicism also rejects vitalism, the doctrine that there is a vital force different from physical forces that accounts for living things. A number of biologists in the early to mid-twentieth century embraced organicism. They wished to reject earlier vitalisms but to stress that whole organism biology was not fully explainable by atomic mechanism. The larger organization of an organic system has features that must be taken into account to explain its behavior.
Gilbert and Sarkar distinguish organicism from holism to avoid what they see as the vitalistic of spritualistic connotations of holism. Dusek notes that holism contains a continuum of degrees of the top-down control of organization, ranging from monism (the doctrine that the only complete object is the whole universe, or that there is only one entity, the universe, to organicism, which allows relatively more independence of the parts from the whole, despite the whole being more than the sum of the parts, and/or the whole exerting some control on the behavior of the parts.
Still more independence is present in relational holism. This doctrine does not assert top-down control of the whole over its parts, but does claim that the relations of the parts are essential to explanation of behavior of the system. Aristotle and early modern philosophers and scientists tended to describe reality as made of substances and their qualities, and to neglect relations. Gottfried Wilhelm Leibniz showed the bizarre conclusions to which a doctrine of the non-existence of relations led. Twentieth century philosophy has been characterized by the introduction of and emphasis on the importance of relations,whether in symbolic logic, in phenomenology, or in metaphysics.
William Wimsatt has suggested that the number of terms in the relations considered distinguishes reductionism from holism. Reductionistic explanations claim that two or at most three term relations are sufficient to account for the system's behavior. At the other extreme the system could be considered as a single ten to the twenty-sixth term relation, for instance.
Organicism has some intellectually and politically controversial or suspect associations. "Holism," the doctrine that the whole is more than the sum of its parts, often used synonymously with organicism, or as a broader category under which organicism falls, has been coopted in recent decades by "holistic medicine" and by New Age Thought. German Nazism appealed to organicist and holistic doctrines, discrediting for many in retrospect, the original organicist doctrines. (See Anne Harrington). Soviet Dialectical Materialism also made appeals to an holistic and organicist approach stemming from Hegel via Karl Marx's co-worker Friedrich Engels, again giving a controversial political association to organicism.
Organicism' has also been used to characterize notions put forth by various late 19th-century social scientists who considered human society to be analogous to an organism, and individual humans to be analogous to the cells of an organism. This sort of organicist sociology was articulated by Alfred Espinas, Paul von Lilienfeld, Jacques Novicow, Albert Schäffle, Herbert Spencer, and René Worms, among others (Barberis 2003: 54).