The first page of DDG results doesn't have much to say about this search-term. "Intersectionality" is a term that I think originates in some fields of sociology, referring to the idea that the problems of queer people, black people, and other excluded groups shouldn't be treated as distinct sets of problems.
I haven't the first notion what that has to do with "scientific method" (a principle that I don't happen to think has much to do with sociology).