Where our first estate, in its authority over doxa and pragmatics, relates back to the lords of once religious authority, and likewise our second estate, representing a categorically delimitable class by wealth if not by title, relates back to the lords of once aristocratic privilege, our third estate does not map nearly as cleanly.
French third estate was comprised of both peasants and bourgeoisie. So too the wealthy and not-so-wealthy commoners of England.
Our third estate bucks this custom.