  This paper gives a systematic account of various metrics on probability
distributions (states) and on predicates. These metrics are described in a
uniform manner using the validity relation between states and predicates. The
standard adjunction between convex sets (of states) and effect modules (of
predicates) is restricted to convex complete metric spaces and directed
complete effect modules. This adjunction is used in two state-and-effect
triangles, for classical (discrete) probability and for quantum probability.
