Simplify the following text for a Grade 13 native English-speaking person.
Original: Often doctrine specifically connotes a corpus of religious dogma 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 .
Simplified: Examples include the Monroe Doctrine , the Stimson Doctrine , the Truman Doctrine , the Eisenhower Doctrine , the Nixon Doctrine , the Brezhnev Doctrine , the Kirkpatrick doctrine , and the Bush Doctrine .