The authors of some of the most memorable works of nonfiction establish the problem and solution proposed in their works by classifying people into two opposing groups.
Most of the time these groups are arbitrary. The people in them, including the reader, do not intentionally identify with a certain group. The author, however, points out the dangers and deception of falling into the trap of the group of people experiencing pain.
Here are a few examples off the top of my head:
Zero to One: Monopolists vs. Non-monopolists
Essentialism: Essentialists vs. Non-essentialists
The 4-Hour Work Week: New Rich vs. Old Rich
Real Artists Don’t Starve: Thriving Artists vs. Starving Artists
The War of Art/Turning Pro/Do the Work: Professionals. vs. Amateurs
The advantage of this approach to nonfiction writing is that one class of people is described in an aspirational way. We all want the benefits of being in the class of people described in the books and the process in the books help us get there. While we may not go around calling ourselves “essentialists” or “monopolists,” we do recognize the qualities that we want to aspire to obtain.
These books also show how we are oppressed in some way and enslaved by a culture than puts us in another class in which we get the same poor results day after day. We often are unable to see why we fail and the description of the oppression we experience as a lower class helps us see the changes we need to make to be free.
In this way a nonfiction book becomes a journey from one class of people to another class. We use the tools in the book to break free and become a new kind of person.