We study the Knights and Knaves problem, and find that for a proper treatment via theorem-proving, an interaction with natural language processing research is helpful. In particular, wediscuss Ohlbach’s claim that first-order logic is not well suited to handling this problem. Then we provide an interpretation of the problem using indexicals, axiomatize it, and prove the desired result. We conclude by suggesting a broader context for dealing with ‘‘self-utterances’ ’ inautomatic theorem-proving. descriptors: indexicals, knowledge representation, first-order logic, situated logic, utterances I