Our Churchland episode was exceptional in that we suspended some of our regular rules, including, I think, the one on name dropping, so I want to fill in some of the gaps through this blog by giving you readers an idea who some of these people are.
I brought up W.D. Ross in the context of trying to fill out Churchland's actual ethical views. Churchland concentrates in her book on the back-end story: what's going on in the brain, and what went on in evolution, to produce our moral sense? She was much more forthcoming in our conversation with her about how to resolve actual issues (e.g. re. the drug war), and even that discussion was more of a sketch re. how ethical deliberation might run (i.e. consider all the complicated factors involved, including the history and "facts on the ground") rather than a fully fleshed out example.
I posited that Ross might provide a model for actual ethical decision-making under her general, Humean framework. At the same time, Ross has key elements in common with some of Hume's opponents among his contemporaries who said that relations between ethical terms such as "beneficence" and "gratitude" are given by reason itself (I believe that example is from John Balguy).
Ross was an ethical intuitionist, where intuitions do give us basic rules of thumb like "be grateful if as a response to beneficence" and "don't hurt people" and "help people" and "keep promises." Ross, though, recognizes that these duties can and do compete, and doesn't think there's any meta-rule over and above the intuition to decide between all cases of conflict. These "prima facie duties" provide starting points for ethical reasoning, which itself is irreducibly complex in the way Churchland (following Hume) describes.
For more information on Ross, check out the Stanford Encyclopedia of Philosophy article on him.
Here's a brief lecture by JVukovlectures on Ross. (I'm not sure who this is, exactly, but it's all I could the audio I could find on Ross.) Start at minute 1:45.
Incidentally, I see researching this that Ross's ideas bear a strong resemblance to those of one of Hume's contemporaries, Thomas Reid. Read more about Reid here.