From The Art and Popular Culture Encyclopedia
Doctrine is a codification of beliefs or a body of teachings or instructions, taught principles or positions, as the essence of teachings in a given branch of knowledge or belief system. The Greek analogue is the etymology of catechism.
Often doctrine specifically suggests a body of religious principles as it is promulgated by a church, but not necessarily; doctrine is also used to refer to a principle of law, in the common law traditions, established through a history of past decisions, such as the doctrine of self-defense, or the principle of fair use, or the more narrowly applicable first-sale doctrine. In some organizations, doctrine is simply defined as "that which is taught", in other words the basis for institutional teaching of its personnel internal ways of doing business.