Self-reference

Volker Halbach (Oxford) gives a talk at the Workshop on Mathematical Philosophy titled "Self-reference". Abstract: What does it mean for a sentence to say about itself that it is P? Here P can stand for any unary sentential function such as 'is provable', 'is not provable', 'is true', or 'is a sentence'. I will study this question in a metamathematical setting. After reviewing some early attempts to tackle the question and their impact on problems in metamathematics such as Henkin's problem, I will put forward a new proposal and test its adequacy with some examples.