  It is unlikely that this argument proves that ethical egoism generates all of the standard duties to others. For the argument depends on the ability of others to cooperate with me or attack me should I fail to cooperate. In dealings with others who lack these abilities, the egoist has no reason to cooperate. The duties to others found in standard moral theories are not conditional in this way. I do not, for example, escape a duty to save a drowning person, when I can easily do so, just because the drowning person (or anyone watching) happens never to be able to offer fruitful cooperation or retaliation.