Final answer:
A historical institutionalist theory explains how institutions develop and settle into patterns over time, focusing on historical processes that shape structures and behaviors.
Step-by-step explanation:
The theory that attempts to explain how institutions get set in a particular pattern over time is called a historical institutionalist theory. This theory is an approach within political science and sociology that examines how institutions evolve and determine behavior within a specific context. Moreover, historical institutionalism emphasizes the historical processes that influence the development of structures, organizations, and institutions, whether they are formal with written rules or informal. Examples of institutions include families, religious faiths, gangs, businesses, as well as political systems comprising of legislatures, executive branches, and judiciaries.