This, for example, suggests that lying is absolutely immoral, because if lying were universally accepted as good, we would not be able to trust each other.

It seems odd that an absolute would depend on something subjective, doesn't it?

we would not be able to trust each other.

That sounds like a pretty utilitarian concern to me, rather than a contradiction.

Go deep enough and eventually everything is subjective. Even things like fundamental axioms.

That there exists more than one explanation for a phenomenon, like ethics and moral values, doesn't mean that choosing any of those at random yields a good explanation. It also doesn't mean that there is no valid explanation at all.

That's just lazy not-100%-sure-therefore-I-substituite-my-own-reality-ism.

For example, I would say that crossing the street on a red light when you can see that there are no cars for miles is going to be considered moral by a huge percentage of people. It will also be considered illegal in most places.

What is truly ethically absolute?

Nothing, as far as I know.

Their understanding of the thing was different, and wrong, the thing in of it self wasn't.

Let me ask you this: we can test theories about how light works by making predictions about how light will behave in some circumstance and then by running an experiment and checking if the prediction was correct.

If instead I have a moral theory which suggests something is absolutely moral, what prediction can I make based on that theory?

Hmmm, something tells me that their era was profoundly different in serious ways that aren't captured in recorded evidence that is available to us.

Before you even get to social interaction among peers, simply weather, disease, medicine, wild animals and poverty were all probably profound dangers to everyone across the face of the earth.

Nevermind literacy, and writing, just imagine how many normal human beings were completely feral, or mute, or inacapable of communicating verbally, for a wide range of reasons, including growing up in isolated wilderness and simply never learning organized speech, as part of a formal language.

Anyone who might help another person by sharing food and staying warm was probably of marginal pratical use, until the next period of hard times, either because of the random of marauders or nature taking its course.

I'm pretty sure healthy people who you could hold a conversation with were in short enough supply that once familiar, everyone made quick use of any luxuries available. No books or formal education, meant bootstrapping these things as new ideas which had no generational inertia, which means probably very nearly everything for most societies was very comfortably (or not comfortably at all) based on oral traditions.

Also people fucking died. Early. Lots of people's teeth were probably gone by 25. Blindness in an eye or both was probably kind of a little bit normal by 30 for many.

So, age was probably a different thing back then. In places where misery is coming from all directions, I'll allow for degrees of moral relativism. Especially for any period pre-dating the emergent modernity of ancient Rome. Any nomadic society that can't exactly distinguish diseases from curses and witchcraft, or even weather and plagues from punishing deities, kind of gets a hall pass.

Maybe, depending on other alternatives available.

> Deontology or absolutist moral theories prescribe that killing is always immoral.

Most real deontological systems prescribe situations in which murder is justified, and self-defense and defense of others are common examples, and the broad outline ends up looking a lot like what common utilitarian approaches would yield. (There's a good argument to be made that most moral systems are rationalizations from preferred treatments of common situations and that people don't really tend to reason forward from principles, anyway, so it's not that surprising that the radically different root principles of utilitarian and deontological approaches end up with similar results, because they are mostly alternate rationalizations for those results.)