Every discipline, every business has its own language. Meant to obfuscate and to limit the number of people who are included. In the academy you have Paradigms and precepts that inform your work. This course is about how we know what we know.
All data are contingent and temporal.
A theory is a belief that guides an action or understanding. Also called a model, an intellectual construct. The good historian would also explain the effects of the Depression on society. He was a Marxist, which we may look up in our dictionary. A concept is a general idea that is inferred or derived from specific occurrences.