Before revision:   We discuss the importance of actuarial fairness, defined as the expected benefits equalling the contributions for each member, and whether actuarial unfairness can be seen as solidarity between members.
After revision:  We discuss the importance of actuarial fairness, defined as the expected benefits equalling the contributions for each member, in the context of pooling mortality risk and comment on whether actuarial unfairness can be seen as solidarity between members.