[skissane]

There are many philosophers who disagree with Kant's categorical imperative though – even among those who agree that ethics is objective (in some sense). The categorical imperative gives morality a deontological flavour, to which many will object–such as consequentialists. And there are others who don't object to the deontological flavour per se, but who think there are better foundations for such a morality (e.g. natural law theorists).

I agree with your position that ethics is objective, but I don't think Kant's categorical imperative is a very good argument for its objectivity – a person can coherently accept ethics/morality as being objective, yet doubt or deny the categorical imperative. I think "ethics is objective" is one of those things where very many people can agree on a conclusion, yet disagree massively on what is the correct reasoning to reach that conclusion.

[sosull]

It was a somewhat rushed point, admittedly. I was reaching for enlightenment-era imagery to challenge the seeming disavowal of morality itself. I note that OP extended those remarks elsewhere to claim that the law is the preferred source of moral constraint. I'm not even sure of what to say to that.

But I very much appreciate the depth of your point. I've always found validation (?) in the deontological aspect of Kant's idealism because I think it neatly describes why people feel obligations to those they interact with most closely (i.e. I feed my child because I should, rather than to avoid his hunger). I certainly take your point that the categorical imperative isn't the best or only tool for interpreting moral dilemmas. Honestly, I was bringing it up in part because it's a recognisable phrase that might infer that there's more to the question of ethics than unexamined instinct.

[skissane]

> I've always found validation (?) in the deontological aspect of Kant's idealism because I think it neatly describes why people feel obligations to those they interact with most closely (i.e. I feed my child because I should, rather than to avoid his hunger).

It is interesting you bring up that example, because it connects with the moral universalism vs moral particularism debate: moral universalists argue that an essential component of a valid ethical principle is it must be universal in scope (equally applicable to everyone at all times), even though it may still produce quite different outcomes when applied to differing situations. Particularists claim by contrast that one can have moral obligations which are non-universal in character - I owe special obligations to my children because they are mine, beyond those which I owe to children-in-general. Moral universalists have to either deny the existence of such particular obligations, or else insist that they are ultimately universal rather than particular in character. Anyway, the categorical imperative is a classic statement of moral universalism, yet you are invoking one of the favourite examples of moral particularists to support it.

Personally, I think the best way to defend the objectivity of morality is the “companions in the guilt” argument - for every argument that is put forward against the objectivity of morality, there is a closely parallel argument against the objectivity of (theoretical) rationality. If that’s true, then how is it not special pleading to grant objectivity to one yet deny it to the other?