Max, thank you for working through all of this so carefully.
On the question Would a tranquil person with no friends, no joys, no positive pleasures — just an undisturbed, empty mind — count as having achieved the blessed life in full?, you wrote:
4) As I understand Epicurus: Yes in theory, but this could never actually happen.
I don't think that the "in theory" gives us a clear answer as to what your position really is. You've just told us that your definition of blessedness, taken on its own terms, is fully satisfied by a life with no friends, no joy, no positive pleasure of any kind — nothing but an undisturbed absence of pain. The only thing keeping that from being your actual recommendation is a claim that it can't happen in practice, not a principled reason why it shouldn't count as the best possible life if it did. That's a strange place for a consistent theory of the good life to land. If your account of blessedness doesn't care whether the life it's describing contains anything anyone would actually want, in what sense is it still a theory of human flourishing rather than an edge case your chosen framework happens to generate?
On the textual basis for "some goods don't contribute to blessedness" — you cited PD20, Men. 128, and PD03. But don't those passages actually establish that once pain is removed, there is no further need to seek anything more. That's a claim about cessation of motivation. What your position would need to show is the stronger claim that additional pleasures, once had, don't count toward the blessedness already achieved. Those are two different claims. "I don't need to look for more" is not the same as "if more comes anyway, it doesn't add to my good."
On friendship, you said its contribution to blessedness runs through security against future fear. But doesn't that just relocate the problem rather than solve it? More security, and a richer stock of memories to draw on, would seem to be exactly as "additive" as more ice cream. Is there a natural limit to how much friendship or security is "enough," past which more of it stops contributing to blessedness, the way Epicurus treats natural and necessary desire as self-limiting? If there is such a limit for friendship, I'd like to hear what it is and where it comes from. If there isn't, then I don't see how friendship escapes the very rule you're using to exclude other additive pleasures from counting.
On what you would actually tell someone to do differently, I am looking for a concrete case where "refer your actions to the goal of nature as tranquility" and "weigh total pleasure against total pain" would recommend different choices. You answered by questioning whether katastematic and kinetic pleasure share a common scale at all. That doesn't answer the question I asked. Can you give me one actual choice where your priority rule and the ordinary whole-life pleasure-pain calculus come apart? If you can't produce one, I think that's itself telling us something: that this may be a dispute over which word gets to be called "the goal," and not a dispute that changes a single thing about how a person should actually live.
Last thing: you've now told me twice, in almost the same words, that you don't know why an additive pleasure can't be the foundation of a blessed life. That's not a side issue - it seems like the foundation of your priority for tranquility. Everything else in your position rests on it. It seems to me that since Epicurus says that he would not know what good is without a list of what is essentially additive pleasures, additive pleasures - normal sensory pleasures including joy and delight - are a very clear foundation for a "blessed life" or "eudaemonia" or "happiness" or whatever other word we want to use to describe the real goal that normal people are looking to hear about.
