>I can't see how it's not perfectly fine to rationally discuss subjective claims

You're correct, I was thinking that in defending reproduction being our purpose that you were claiming that this is true and that people who deny this are wrong to do so---but certainly, we can make objective claims about subjective beliefs.

>You mentioned detachment from life, and I think curiosity is what makes us humans stand out. I think what we need for fulfilment is so simple that it's so hard for people full of curiosity to accept it. That's why I agree with the idea that a rigorous approach to truth (including truth you don't like) will bring you back to what matters.

So my point about the rigorous approach to truth is that (insofar as this is something that the existentialists don't do) it's not feasible to bootstrap yourself Cartesian-style from "I think, therefore I am" all the way to normal, everyday truths---but I think this is OK; we should instead embrace a level of uncertainty in our beliefs, and this shouldn't prevent us from acting---there comes a time when we have to step out of the shade of analyzing things rigorously and out into the sunlight of actually doing things in the real world. I suspect you'd largely agree with this.

>You have an intuition that reproduction is far too simple a story.

So, construed as just a psychological fact about what people find meaningful, I think either it's simply not the correct story with a strict interpretation or it's just not a very meaningful story with a loose interpretation. People find meanings in things that aren't reproduction, which is why I say the strict interpretation can't be correct, but if we interpret actions being motivated by reproductive drives so loosely that all kinds of things get categorized as being motivated by a reproductive drive, then I don't see that this story is really telling us anything. Like, there's the famous strawman caricature of Adlerian psychoanalysis, that the psychoanalyst looks at a person who jumps into a lake to save a drowning child and says, "Clearly, this person was motivated by feelings of inferiority to save that child---his behavior was compensation!", and then looks at a person who doesn't jump into a lake to save a drowning child and says, "Clearly, this person was motivated by feelings of inferiority to not save that child---he felt too inferior to do so!" Like, this person hasn't really told us anything meaningful, no matter what happens, he's quick to explain it away through feelings of inferiority. Maybe it's true, maybe it's not (this analogy isn't for me to dispute evolution or evolutionary drives, don't misunderstand me)---it hasn't really told us anything about what actually happens. And I see this as the situation with characterizing all activities people find meaningful as being motivated by a reproductive drive, if that makes sense.

>I can't see how 'objective purpose' is not an oxymoron. A hacker is someone who dismisses the notion of an objective purpose in a tool and repurposes it as they will.

I would normally say that there is a kind of objective purpose in a tool. For example, a hammer. When I talk about the objective purpose of a hammer, I'm talking about the hammer's utility qua hammer---so whether it's hard enough for nails to get driven in when hit, whether the handle is long enough for someone to grasp it, etc. A bad hammer might be one that's made out of sponge or something, so it doesn't actually move any nails. It can be repurposed to be, for example, a paperweight, and maybe do an ok job at doing that. But it's failed to fulfill its purpose as a hammer. And I think there's an analogical sense in which humans can be good qua human. I would talk about a summum bonom, a highest good, under which various virtuous activities fall under.

It's interesting that you bring up hackers. I think repurposing tools to do what they're not meant to do is generally seen as a hack. And in an engineering context, this is generally seen as a bad thing in the long-term, or at least an indicator something's not right---tools should get used for the purpose for which they were designed, at least, in the long-term. (That's not to say anything bad about hackers; I love the idea of a hacker.)

>Purpose is always subject to a being's existence. You have an intuition behind the word 'purpose' that I do not seem to have, as if purposes can exist without any beings. Do you really believe that morals can exist without any beings?

I suppose not, but I also think there can't be any physical facts if there aren't any physical things. But I don't think this means physical facts aren't objectively true; likewise, I still think moral facts are objectively true.

>Do you agree with every single word of the bill of human rights? Or do you see that it is also subject to interpretation?

I see that it's subject to interpretation, yes, because I don't think that any moral truths are grounded in the bill of rights anymore than truths about Newtonian physics are grounded in Newton's Principia. What we think and say about truths is distinct from the existence of truths themselves.

>You think morality is progressive like science/knowledge.

Well, to be sure, there's a distinction between moral epistemology and moral ontology. What I was saying there is that I can be mistaken about moral truths---perhaps even humanity as a whole can be mistaken about moral truths, and they might even regress morally at times, and yet, the fact of the matter about morality doesn't change. This is because our beliefs about morals do not themselves determine what morals are, just like our beliefs about science do not themselves determine what scientific facts are---if humanity were to suddenly regress and start thinking the Earth was flat again, that wouldn't change the roundness of the Earth.

>I don't think you can prove slavery is wrong a priori, because the premises will always require experience to accept them.

Well, I think that we have a strong intuition that it is morally impermissible to deprive one of certain rights, and from that, it logically follows that slavery (in the relevant sense---I think you know what I'm talking about) is immoral.

>You'll only be preaching to the choir, so to speak.

I mean, maybe so - in the same sense that I might be preaching to the choir when I talk about the existence of physical things. Like, maybe I tell you about the chair I'm sitting on, and you say, "Well, I see the chair you're sitting on, and I can touch it, but I don't share the intuition that that means that the chair exists physically." And if you say that, there's nothing more I can really say to you---that's just an intuition you don't share. But of course, I still believe that the chair really is there.

>Anyway, I still can't grasp what you mean by the word 'purpose'. It seems logocentric to me. I genuinely don't have the same intuition. I think the difference lies there, and so I don't think we're going to make sense of the differences with words. I understand how people could have a sense for moral realism, and I think some dogma is necessary for culture, so although we don't agree, I don't think it matters all that much.

I suspect we won't come to an agreement here either---though I do kind of suspect that you do share the same intuition. I certainly don't think you act as if morals are subjective. Like, I suspect that if you came across a culture in which people randomly chose a child every day to kill for no particular reason, you wouldn't think, "Well, that's just their culture---I find it distasteful, but if they believe it's morally right to do this, then I guess it is morally right for them." What I'm basically saying is that we have strong intuitions that morals are true independently of what people think, and that objections like "people disagree about morals" or "people have changed their stances on morals" aren't objections to my intuitions any more than "people disagree about scientific facts" or "people have changed their stances on scientific facts" are objections to science. It is true that the manner in which moral truths exist are strange---it's not like you can go out and touch them. But I also think the same is true for, for example, numbers---I would say that numbers exist, even though we can't go out and touch them. Not that numbers and moral truths exist in the same sense---just providing some intuition.