Circumscriptive Ignorance

In formal systems that reason about knowledge, inferring that an agent actually does not know a particular fact can be problematic. Collins [1] has shown that there are many different modes of reasoning that a subject can use to show that he is ignorant of something; some of these, for example, involve the subject reasoning about the limitations of his own information-gathering and memory abilities. This paper will consider a single type of inference about ignorance, which we call circumscriptive ignorance. We present a partial formalization of circumscriptive ignorance and apply it to the Wise Man Puzzle.