:-} I imagine some sociobiologists disagree with me. I sincerely doubt that all biologists disagree with me.
Reciprocal altruism is key to the survival of a social animal.
Reciprocal altuism is just another way of saying that morality is an allusion. What mechanism directs the individual to rationalize an altruistic act by saying to himslef. Ah, this is beneficial to the species so I will lay down my life for my fellow soldier?
And a moral sense is essential to reciprocal altruism.
Hardly, in fact they are mutually exclusive in some sense. That sense being that there is nothing inherently moral in an altrusistic act if one expects reciprocity.
Nothing says that.
The individual says 'I trusted that individual, and he cheated me; I won't trust him next time'. Or 'I trusted that individual once, and he cheated me, but he has by paying a penalty for doing so, attempted to make it up to me; maybe it is worth while trusting him again'.
That sense being that there is nothing inherently moral in an altrusistic act if one expects reciprocity.
Unless the reward comes in the afterlife, eh?
You're assuming what drives us to be moral is a conscious thought process. But why should it be? Isn't it more likely to be an innate sense of 'justice' or 'forgiveness' or 'generosity' or 'loyalty'. After all; you don't have conscious control of your heart rate; why would you need conscious control of your innate moral sense?
This would be much easier: Can you name even one biologist with relevant professional bonafides who DOES agree with you, that natural selection should eliminate (or preclude the development of) a moral sense? And/or, in the meantime, maybe you can provide us some coherent argument as to why it should?
You made this as a flat assertion and simply declared it a conundrum. I don't see the conundrum at. Quite the opposite. The conundrum to me would be if evolution hadn't come up with something like morality.
Once you have fairly intelligent animals living in groups you have complex social relations, and once you have that a moral sense (or something very similar) seems nearly essential for individuals to manage and navigate the social scene.
For example an intelligent social animal needs to be able to avoid triggering acts of retribution by other members of his society, or least by too many other members. How does the animal know what behaviors are likely to trigger retribution unless he has some sense of what is "wrong".
From the other end the payoffs of mutual cooperation are so high (as are the costs of mutual aggression) that retribution systems are sure to develop. There will be a very strong pressure on social animals to figure out which individuals they can cooperate with, and which are uncooperative (don't reciprocate, cheat, etc). The later individuals will be to whatever extent denied the advantages of cooperation, and you have a system of retribution or shunning, and with that you have the basic mechanisms and structures of a moral system.