Synthesized answer
The provided passages do not contain information that answers the question "What questions remain unanswered?" [Passage 1]. The passages only state the title of the book, "The Principles of Linguistic Philosophy" by Friedrich Waismann, its categories, and the number of pages [Passage 1].
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: The Principles of Linguistic Philosophy by Friedrich Waismann Categories: Analysis (Philosophy). Pages: 444