They differ from other ascriptions of good (say, at baseball) and bad (say, me playing baseball) in that there is an imperative to be good in this sense whereas it is acceptable to be bad at baseball (I hope).
What do you mean by imperative? Humans have certain imperatives, whether evolved or "purely" cultural, but they are all human-specific: other creatures and minds will potentially have different ones. They can't be called "objective and unbiased between all rational thinking minds".
Do you believe that this inability to define means there is no real concept that underpins the folk conception of ethics or does it just mean we are unable to define it well enough to discuss it?
How can we talk about something if we can't define or at least describe it, or point to examples of it existing? Inability to define by definition means there's no concept. A concept isn't right or wrong, it just is, and it's equivalent to a definition that lets us know what we're talking about.
As for "folk concepts" of ethics, no offence intended, but aren't they roughly in the same category as religion and "sexual morals"?
Humans have certain imperatives, whether evolved or "purely" cultural, but they are all human-specific: other creatures and minds will potentially have different ones.
Aren't you just asserting with this statement, without argument, that there is no objective ethics? Isn't it the question at hand whether or not human imperatives are specific or universal?
(Though I wouldn't exclude the higher order possibility that there could be an objective ethical system defined around imperatives in general; for any arbitrary imperatives that a subsystem defines for itself, there is an objective imperative to have them satisfied.)
And happy new year to everyone.