A parti or parti pris comes from the French prendre parti meaning "to make a decision". Often referred to as the big idea, it is the chief organizing thought or decision behind an architect's design presented in the form of a basic diagram and / or a simple statement. The development of the parti frequently, but not always, precedes the development of plan, section, and elevation diagrams.
In a figurative way parti pris is used when a researcher starts with a preconceived opinion to prove that this opinion is true.