  Another problem is that conversion can be costly. I might be required by my non-egoist morality to make a sacrifice for which I cannot be compensated (or pass up a gain so large that passing it up will not be compensated for). Since I have converted from egoism, I can no longer reject making the sacrifice or passing up the gain on the ground that it will not pay. It is safer, and seemingly feasible, to remain an egoist while cooperating in most cases. If so, ethical egoism and standard moralities will diverge in some cases. (For discussion of the cooperation argument, see Frank 1988; Gauthier 1986 ch. 6; Kavka 1984 and 1986 Part II; Sidgwick 1907 II.V.)