TELEOLOGY (Gr. Taos, end)  , in philosophy and theology, strictly that branch of study which considers " final causes " as real principles of explanation, i.e. which explains things as existing solely as pre-requisites of the results which they produce . More commonly the term is applied to the doctrine that the universe as a whole has been planned on a definite design, or at least that it tends towards some end . The term has been used very loosely, and its meaning has changed considerably . The root idea arises from the analogy of the acts of human beings which are observed to have certain purposes: hence it was natural to assume that the whole sum of existence with its amazing complexity and its orderly progress can be explained only on the assumption of a similar plan devised by a conscious agent . Such a view is essential to any theistic view of the universe which postulates God as the Creator, omniscient and all-good . The modern theory of evolution, on the other hand, has reintroduced a scientific teleology of another type . This is discussed, from the biologist's point of view, in the article ZOOLOGY . Teleology, in this narrower sense, as the study of the adaptation of organic structures to the service of the organisms in which they occur, was completely revolutionized by Darwinism and the research founded on it .