hero working papers

Representing Unawareness on State Spaces

Number: 635
Year: 2018
Author(s): Satoshi Fukuda
I study unawareness by the lack of knowledge on a generalized state space. In order to understand and contrast properties of unawareness in a non-partitional standard state space model and a partitional generalized state space model, I provide a generalized framework that accommodates both models. I ask: when and how a generalized (in particular, standard) state space model has a sensible form of unawareness; and how unawareness relates to ignorance and possibility. First, unawareness can only take two forms: an agent is ignorant of knowing that she does not know an event; and the agent is ignorant of knowing an event. In either case, unawareness is also associated with the ignorance of the possibility of knowing an event. Second, the agent, who is unaware of an event, is ignorant (but not necessarily unaware) of being unaware of it. Third, the agent, facing infinitely many objects of knowledge, may know that there is an event of which she is unaware, while she cannot know that she is unaware of any particular event. Fourth, getting more information can cause the agent to become unaware of some event.

Journal of Economic Literature Classification Numbers: C70, D83

Keywords: Unawareness; Awareness; Knowledge; State Space; Ignorance; Possibility