The following excerpt is heavily edited to get at the essence but I can highly recommend the entire chapter.
Just as truth ultimately serves to create a consensus, so in the short run does acceptability. Ideas come to be organized around what the community as a whole or particular audiences find acceptable.
Numerous factors contribute to the acceptability of ideas. To a large extent, of course, we associate truth with convenience—with what most closely accords with self-interest and personal well-being or promises best to avoid awkward effort or unwelcome dislocation of life. ... But perhaps most important of all, people approve most of what they best understand. ... Therefore we adhere, as though to a raft, to those ideas which represent our understanding.
Because familiarity is such an important test of acceptability, the acceptable ideas have great stability. They are highly predictable. It will be convenient to have a name for the ideas which are esteemed at any time for their acceptability, and it should be a term that emphasizes this predictability. I shall refer to these ideas henceforth as the Conventional Wisdom. [...]
The enemy of conventional wisdom is not ideas but the march of events. As I have noted, the conventional wisdom accommodates itself not to the world that it is meant to interpret, but to the audience's view of the world. Since the latter remains with the comfortable and the familiar, while the world moves on, the conventional wisdom is always in danger of obsolescence. [...]
Ideas need to be tested by their ability, in combination with events, to overcome inertia and resistance. This inertia and resistance the conventional wisdom provides.
John Kenneth Galbraith,The Affluent Society