[woodruffw]

> To say good isn't subjective is to say there is some part of the universe at some fundamental level that defines good.

Not especially: there is an abundance of immanent ethical theories that define the Good (or Right) in terms of basic things in our grasp: the number of people who go hungry, the number of people who die of preventable diseases, &c. These don't require some spooky or transcendental universal fundamental: they're about seeing people suffer in ways that we can measure, seeing that many patterns of suffering are generalizable, and taking actions to countermand that.

(There are also plenty of ethical systems that are both immanent and non-consequentialist. I follow one of them. But it's maybe beyond the point of the original comment to explain them.)

[skissane]

> there is an abundance of immanent ethical theories that define the Good (or Right) in terms of basic things in our grasp

The problem with all those theories, is they can be attacked as simply efforts to define "good" – with the ensuing problem that other people will define "good" in contrary ways, and if "good" is just a definition, then how can a mere definition be, in an objective sense, superior to a competing proposed definition?

That's basically G. E. Moore's argument against naturalistic objective ethics. If one agrees with it, then the only options available are to reject objective ethics, or to reject naturalism.

[woodruffw]

Fair enough! I wasn't expecting to have Moore's naturalistic fallacy pulled on me :-)

Neither intersubjective nor Kantian ethics have this problem: intersubjective ethics doesn't admit of an objective Good, and Kantian ethics don't admit of an is-ought distinction (all "ought"s are in fact "is"es that are bound in actions).

[skissane]

> intersubjective ethics doesn't admit of an objective Good

I agree, but intersubjective ethics might not actually work in practice in a world in which people are approaching ethics from wildly different starting points. Consider an issue like abortion – people who support the legal availability of abortion, and people who oppose it, have such widely different ethical views that I think there is no intersubjectivity to be had (on that issue at least)

> Kantian ethics don't admit of an is-ought distinction (all "ought"s are in fact "is"es that are bound in actions).

I wonder, if you could expand on that point?

In my mind, Kant's categorical imperative could be viewed as either a proposed definition of the good (in which case Moore's argument is applicable), or a claim about what actually is good (in which case it escape's Moore's argument)

Kant had a lot to say about normative ethics, but the question of what his metaethical views actually were seems more disputed: https://plato.stanford.edu/entries/kant-moral/#Meta

[woodruffw]

> In my mind, Kant's categorical imperative could be viewed as either a proposed definition of the good (in which case Moore's argument is applicable), or a claim about what actually is good (in which case it escape's Moore's argument)

It’s an academic opinion, but I believe it’s the latter: the very first line in the GMS asserts that the metaethical object itself is the good will: “nothing in the world (or indeed beyond it) can possibly be conceived as good without qualification except for the Good Will.”

The CI is the logical consequence (according to Kant) of what the good is. But that distinction is definitely subtle in the context of his normative ethics.

[donatj]

All those still depend on the idea that humans and life itself are more than just a long running, self-replicating electrochemical reaction which again pushes the burden of proof on to you.

[woodruffw]

Going back to the original response: you don't actually need to be a moral realist to observe (as in, witness with the globs of goo in your eyesockets) intersubjective ethics.

You don't have to agree with them, but it's a real phenomenon. It's up to you to decide how you handle it.