I agree with Aristotle that ethics cannot be an exact science. I also hold with Leibniz that all necessity whatsoever is conditional.
Practical judgment or phronesis discerns differences and gradients, not “things as they are”. Questions of the form “What is to be done in circumstance c” do not in general have a single, necessary answer.
Ground-level ethical rules, I want to say, have no value apart from such always somewhat open judgment of situations. If all I were doing were conforming to a rule, I would be showing no sign of reason or intelligence. (Kant at least partially makes a similar point by distinguishing between rules and concepts of rules, though it it is a bit unclear what this means.) Only if I can be said to have reasonably judged that following rule r in circumstance c was situationally appropriate, was my rule-following rational. Judgment could not be reducible to simply applying a pre-existing formula.
Needless to say, I don’t really like deontology. Necessity in first-order ethics smells to me of subrational compulsion.
On the other hand, it would be absurd to say that because there is no hard necessity in first-order ethics, anything goes. An ought that we positively assert about anything in particular is based on differences and gradients, not binary necessity. Binary necessity could at best apply only to prohibitions, not to any positive injunction to do x. I don’t even believe it applies in the negative case. But in any event, what we ought positively to do is the real concern of ethics, and that is a weaker sort of ought.
Still, we “ought” (in some different, stronger sense that applies only to meta-level generalities like the categorical imperative) to be faithful to our best judgment of those differences and gradients. I would also agree that we “ought” in this stronger sense to practice mutual recognition as described by Hegel, and we “ought” to practice wise charity as described by Leibniz. Brandom points out two more things that I agree “ought” in this stronger sense not to be done: affirming contradictory things, and affirming something while denying a consequence of it. I have no issue with speaking of necessity in these meta-level cases.
In line with a practice of interpretive charity, I want to resolve the ambiguity in Kant’s (and Hegel’s) talk about moral “necessity” by saying that any true necessity must refer to meta-level principles in themselves, not their application.
In chapter 1 of Making It Explicit, Brandom talks about the desirability avoiding “regulism”, or the attempt to rely on explicit rules all the way down. Wittgenstein’s infinite regress of rules-to-interpret-rules is said to show that the conception of norms as rules “is not an autonomous one, and so does not describe the fundamental form of norm”. This seems promising. He both invokes Kant’s distinction between rules and concepts of rules, and suggests a move from rules to practices, attitudes, and construals. Mere conformity to a norm is not even a candidate for a construal in accordance with a normative attitude.
I also want to say, as Aristotle would, that the correctness of such construals, though emergently relatively objective in terms of something like multidimensional gradients of “should”, is not in general decidable in Boolean yes/no terms. Brandom seems more worried about avoiding collapse of moral necessity into causal necessity or mere factual regularity. While I thoroughly agree that normative conclusions cannot be derived from non-normative premises, I take overly rigid prescription to be still the more practically important concern. Pufendorf’s doctrine of imposition of norms by a sovereign will is huge step backward from Aristotle.
What is needed is ground-level, broadly rational interpretation of real-world situational particulars, complexities, and ambiguities that is not strict rule application; i.,e., phronesis.
The objectivity of ethics does not consist in strictly univocal determinations, but in shareable reasonableness. The interesting cases are not like “It’s raining and I don’t want to be wet, so I should open my umbrella.” There could be no precise formula for how to balance independent concerns when they are in partial conflict. (See also Binding.)