We evolved with instincts of co-operation. Genes are our masters and they demand social behavior. Okay. But we might equally well say that all humans treat common good is superior. A “selfishness that looks to the needs of others” is a muddle or a contradiction,* but to see my own highest good in something that is so superabundant that it cannot be exhausted by me is just what one expects a highest good to look like. Consider the limit case: an infinite good could never be spent up by me, and yet I could never prefer it to a finite one. We all tend to infinite goods, but the only proof we’ve found one is that we could be the universal, sufficient benefactor to everyone, including ourselves.
Even goods that can’t be shared, as goods, desire to be shared. Look within: The phenomenology of hoarding is not like keeping a museum piece but like jailing something. We are not preserving some resource in a fitting state but holding it at gunpoint. The lock on a hoard is as much to keep others from breaking in as to keep the good itself from breaking out. This is why private property is only a temporary dispensation to best preserve what will belong to all in the eschaton, and why even the exclusivity of eros – which also will not remain in the eschaton – must transcend itself.
Selfishness is for goods, but goods will not be hoarded. They have an energy and structure of their own that is an imitation of the highest good which is a set of persons that, cannot exist at all except as relative to each other. For the Father to hoard the Son would make the Son impossible, and therefore make the Father impossible.
*Or, better yet, it is a sort of working hypothesis to get deeper insight into how the common good is entirely personal and so fully present in our biological dimension.