conventional

knowledge or information that people generally believe is true, although in fact it is often false The conventional wisdom is that marriage makes a relationship more secure, but as the divorce rates show, this is not necessarily true.

A widely held belief on which most people act. For example, According to conventional wisdom, an incumbent nearly always wins more votes than a new candidate . This term was invented by John Kenneth Galbraith, who used it in The Affluent Society (1958) to describe economic ideas that are familiar, predictable, and therefore accepted by the general public. Today it is used in any context where public opinion has considerable influence on the course of events.