I use the language of observational claims and interpretive claims. An expository thesis starts with an arguable truth claim, which is usually an observational claim: something does something. It’s followed by a first-order interpretive claim: in order to do or because of something. That is followed by a second-order interpretive claim, which answers the question: and this is important because?

Tilar J Mazzeo, How to Write a Bestseller, loc. 57