Abstract
This chapter discusses the Fregean hierarchy of senses. A resolution of issues about the hierarchy of senses turns on the resolution of a series of issues of much wider significance in the theory of thought, in epistemology, in metaphysics, and in the philosophy of mind. The acceptability and nature of a Fregean hierarchy of senses involves the correct way of conceiving of the relation between sense and reference. It involves some conception of how thinkers are capable of thinking of abstract objects like senses and Thoughts. Since the hierarchy in turn bears upon issues about thinking about Thoughts, resolutions of these issues also have ramifications in the philosophy of mind for what is involved in the ascription of attitudes to oneself and to others. Correspondingly, evidence drawn from these various areas is pertinent to the assessment of treatments of the Fregean hierarchy.