Commitments are soft in the sense that they can be revoked at a cost.
Two commitment devices are particularly studied. Under the first one, each player can commit himself to compensate the other player for damages caused by his deviation from his pre-specified strategy. Explicit characterizations of credible commitments inducing mutual cooperation in prisoner's dilemma, symmetric or asymmetric, are established for these two commitment devices. These characterization results provide a prospective assessment for the selection of liquidated remedies. In particular, it is shown that when viewed ex ante , large liquidated remedies are not incentive compatible.