Are Institutions Rules in Equilibrium? Comments on Guala’s Understanding Institutions

In this comment on Francesco Guala’s Understanding Institutions, I express my admiration for the book but I also raise some critical criticisms: His general account of institutions as rules-in-equilibrium seems to get their ontology wrong by disregarding their material side - their concrete realizations. It also diregards social institutions whose rules are not (and are not meant to be) in equilibrium. Finally, his suggestion that institutional equilibria necessarily involve correlation devices appers to lack justification