Euthyphro dilemma asked for evolution.

[The Grand Nudger]

If you have any reason to doubt that rationality is a part of human nature, then that'd be a different conversation.

Oh I have reason to doubt that it's consistent or successful application is a part of our nature, lol. I would probably tip my hat to the successful bits of irrationality that we seem to keep around as well if I was going to really dive into whatever the hell our nature is. To elaborate upon this and why i think it's important to consider in deciding what morality (or a moral agent) is or should be, with an example that I don't think will be very controversial. Might makes right. As an argument, it's not compelling. As a justification for any given thing it's severely lacking. However, as a moral principle (or the justification for a moral principle or set of mandates) it does work. It doesn't work by strength of the argument itself, but by the strength of our nature as a social species with social heiarchies. If we're going to systematically decide what morality is, or what a moral agent is (with relation to ourselves, our nature, by demonstration) these things, to my mind, cannot or should not be ignored in favor of some ideal which we prefer (in your case that seems to be a completely logical sense of morality, in mine it would be a mostly logical sense of morality with room for just a little bit of teh crazy).

Exactly what argument are you trying to make here and how does it address the argument I presented (that we've moved past heuristics).

That communication or intent does not move anything past heuristics. Applying a heuristic solution does not change what it is. Communicating the speciics of a heuristic solution does not change what it is.

Morality is a guide to how person should act - what he should and should not do - that much is established. Given that we have countless philosophies trying to answer not only what we should do, but why should we do it (based on different starting premises), I'd say we no longer determine morality by trial and error.

On the other side of the coin, the countless philosophies we have with no definitive answer in sight would seem to suggest to me that we do determine morality by trial and error. Consider for a moment, as well, that the dominant morality (if such a thing could be said to exist) almost always happens to coincide with the dominant forces of history. Perhaps morality is yet another thing written by the victor.

The process of how we apply morality would not be relevant to what morality is and whether we are moral agents. It'd would be relevant to us, but not in context of those questions. That's because the identification of morality and us being a moral agent would always come before the question of its application.

Unless application was precisely what morality is, in a way that we can communicate it, ergo the nod to heuristics. I do like to think, btw, that we can reason our way into any given conclusion, that a reasonable morality could be established, but I have my doubts (obviously).

Do you have a justification for that - as to why everyone should work towards perpetuation of human life? Rather why human life should be perpetuated at all?

Meh, we're "built" for it, it's a pretty effective motivator, it doesn't take a rocket scientist to leverage it (or much in the way of academics to elaborate upon it), and a hefty dollup of self interest. The hook, of course, would be to expand peoples spheres of consideration beyond their immediate circumstances or surroundings. We already do this, it's worked well thusfar though it could obviously stand for some tweaks (if the goal could be said to be the perpetuation of life- which does seem to be the default). What those tweaks may be, meh, thats where any and all justification on my end comes to a full stop, and that's probably why I'm not in the business of morality. Obviously this idea of what the goal of morality should be is heavily influenced by my opinions of what morality is to begin with, and how we fit into that scheme. To me, it's just n elaborate set of tools for a simple purpose. I don't really look to morality for happiness (emotions aren't exactly well known for being grounded in reason btw, and lets be honest, the very word morality invokes a sort of emotional staunchness, more don'ts than do's, more suffering and toil than happiness),