From the mid 1980s to the early 2000s the wide-ranging resources of the concept we now call sensitivity. For which Robert Nozick used to give an analysis of the concepts of knowledge and evidence, went largely unappreciated in epistemology. This chapter focuses on the consequences of the move, made of combining sensitivity and adherence with closure via a recursion clause. The author's imposition of closure on a sensitivity-based view of knowledge has seemed to some unexplanatory and to lead to cheap knowledge. Obviously a definition of knowledge of logical implication is needed to complete the recursion clause and the definition of knowledge. One can make knowledge as expensive as one likes with regard to sensitivity, and still maintain a kind of closure. Brueckner's complaint about the bruteness of the imposition of closure occurs within an objection to the consequences of the author's view for brain-in-a-vat skepticism.