More thoughts
A number of authors in this month's Tikkun talk about radical hope, and Messianism. The repeated idea I came across is that a radical Messianism must be a belief in a Messiah that is to come -- but to believe that the Messiah can never come. This means that even were the Messiah to come, then we would still strive for what was better. This is like the idea that whatever God is, God must be beyond whatever we can conceive. Not just what we can conceive right now -- we don't just not know God at this moment -- but what we can ever possibly conceive. The same is true of the Messianic Age. It must be beyond what we can possibly conceive, and so if at any moment we think we have reached the Messianic Age, we must be wrong, because we would not be able to conceive it. It is a belief in the good being that which can always be strived for -- we can never stop striving for it, because whatever limited good we know right now, the good itself is beyond our conception, so we can always know more about it without exhausting it.
This all relies on some epistemological concepts. It relies on the belief in human knowledge being finite about some matters -- that there are some things we just cannot know. I think that perhaps some defense for this can be found in irreducible complexity, quantum theory, chaos theory. If one believed that humans could know everything, then it would be possible to conceive of God, of the limits of goodness. But so long as there is anything we cannot know, then there is something that must remain beyond our conception.
It also all relies on some moral concepts. One, that there is such a thing as good, and that there is such a thing as God. Perhaps the reason why it's impossible to find a perfect good is that good, in general, is an imperfect concept. Maybe it's all based on biological drives and evolutionary enhancements. We have moral feelings because our brain is set up to do so. Does that invalidate the possibility of morality? We can, as Kant says, comprehend the possibility of incomprehensibility. So if we feel a pull towards goodness, and we can conceive of a better goodness, reaching to incomprehensibility, then does that capacity of reason (which is a decision-influencing faculty) give us the possibility to strive for an incomprehensible good, and therefore morality? So if our biological drives did stop pulling us, but they had pulled us so far, then reason could determine that the actions should continue, beyond the pulling of biology, it can theorize, as Kant did, and determine our duty.