Depth

The third condition is the one I find hardest to summarize without giving up too much.

Epistemic depth is not "the system has a self-model." Lots of systems have self-models. The thermostat has a self-model in some impoverished sense; so does GPT.

Epistemic depth is the property that the world model contains the knowledge that it exists. It is the recursive coupling of the model to itself, distributed across the hierarchy, continuously self-evidencing.

Field-evidencing

The authors call this field-evidencing. The world model knows itself non-locally — meaning the knowing is not located in any one node of the inference hierarchy; it is the aggregate dynamic of the hierarchy as a whole.

This is the move that distinguishes consciousness of from meta consciousness about. You can have the latter without the former. The former, on their view, is constitutive.

Reading on

The book proper has a long middle section on what this implies for meditation and psychedelic states — the regimes where epistemic depth weakens or strengthens or fragments. I'll skip ahead to those notes in the next pass.