I've been thinking about this question and I have read some previous discussions/arguments erupting due to what I believe are disagreements in what a class should be defined as. The discussion on "Monks" and especially Forton has made me continue to think about this, and I wanted to see what Obsidian has to say on the matter:
What defines a class? What makes one character in your world a different class than another character? From the definitions provided, they seem to be descriptions for a career path or a mental state that a character would be. But I can't be sure how exactly you are distinguishing between your classes.
Are they distinguished by the skills they can have?
By their combat styles?
Philosophies or personalities of these characters?
Any information on this would be really beneficial to us, the players. The reason I bring this up is because sometimes the distinction between classes are very vague, and often, different criteria distinguishes between classes (as opposed to a singular criteria effective across all classes). It's easy to distinguish between a fighter and a wizard, but the same criteria cannot be used to distinguish between a fighter, a monk, and a barbarian. The same thing occurs with a rogue and a ranger.
Monks, especially, are the product of a philosophy fit into a combat style within a specific culture. No other class really is described this way.
As I said in another thread, I hope the devs can articulate these distinctions to us and utilize one definition for the word "class" and define their classes by distinguishing between them through that singular lens so that a lot of these arguments between what a paladin or a monk mean can be better understood by us the players.
D&D, because it is a game that has evolved through each new edition has had its definitions diluted, corrupted and sometimes made backward-incompatible, has made convoluted descriptions that are difficult to understand. When starting a completely new IP and gameworld, we do not have to work with these adulterated definitions. We should be clear about what we mean.