Well, without some sort of working theory for what happens, we're left to gauge morality based on the results of this life.
Without such a theory, there's no reason to adopt the sort of transcendant moral posture that seems to drive the objectivists. Indeed, objectivists' theory ("this life and you're done" ) much demands that morality boils down the old bumpersticker: "He who dies with the most toys, wins."
Note that there are no particular rules mentioned for how one gets those toys -- if you manage to die old, rich, and happy, you've won.
What it reduces to is a pragmatic approach, such as general_re has described in this thread, to the effect that on average, people who behave well will do well. Unfortunately, pragmatism doesn't preclude the mafia don or murderous Pharaoh who, by "getting away with it," can be "winners" in the same sense as an honest man. We can say it's wrong -- but really we can only justify retaliation based on our communal dislike for what they do; we have no objective basis for saying it's wrong.
For transcendant moral values to have any meaning at all, they must have some consequence beyond our lifetime. In the "evolutionary approach," the consequences may be an inability to pass on our genes. From the Christian perspective, we know we will be judged.
Ironically, the objectivist self-interest angle seems to be one of those which logically cannot support the existence of those transcendant values it claims to have derived. It simply cannot answer the question of why the happy Pharaoh is wrong.
Moral systems cheerfully offered, FOC ;)
Unfortunately, pragmatism doesn't preclude the mafia don or murderous Pharaoh who, by "getting away with it," can be "winners" in the same sense as an honest man. We can say it's wrong -- but really we can only justify retaliation based on our communal dislike for what they do; we have no objective basis for saying it's wrong.
Well, we can reason from the consequences of such behavior, and judge whether the sort of society that would tolerate and accept the existence of such behavior is really one that we would want to live in. Such a system would probably not be "objective" in the strong sense, but on the other hand, it wouldn't be completely detached from reality - we would have some rational basis for moral tenets, even if they failed to exist independently of moral actors.
In any case, the common failing of all moral codes is that none of them preclude the actual existence of mobsters and murderers - it's rather difficult to see how one would. At best, what a theistic system offers is another factor for potential violators to weigh as they consider their acts, by proposing further consequences to those acts beyond the merely physical consequences imposed by society. And it's not at all clear from the last few millennia that those additional consequences serve to moderate behavior much at all - murder and mayhem are not twentieth-century inventions of objectivism, secular humanism, or atheism.
Instead, I propose something akin to an innate sense of morality that functions within people, albeit more strongly in some than in others - whether instilled by God or the byproduct of evolution or originating someplace else entirely being neither here nor there. Consider: suppose for a moment that it were rationally proven beyond any shadow of a doubt that God does not exist and never has existed - this is purely hypothetical, so nevermind the inherent impossibility of such a thing. Would you then feel no constraints upon your personal behavior, such that you felt no compunctions about murder or theft or adultery or whatever? Something makes me doubt it, because I suspect that this innate moral sense would continue to operate within you regardless of whether you felt that there were consequences beyond the here and now. I suspect that most people operate morally for reasons beyond mere fear of the consequences, whether societally imposed consequences or divinely imposed consequences.