What do you mean by “thorough and satisfactorily.” How do you determine it is satisfactory. What makes your interpretation of human behavior better than another? Those questions involve reasoning about evidence, explanatory adequacy and competing hypotheses.
A good example is conceptions of fairness, how it evolved, and what it’s for and what it does, in evolutionary ethics. The most well known theory says that people bargain to get what they can get away with without incurring a bad reputation. It evolved because those who took too little would lose out in evolutionary fitness; and those who took too much would get a bad reputation and lose future collaborative opportunities and therefore evolutionary fitness.
This sounds great, possibly to a computer, because it sounds like a plausible explanation for “fairness”. But it fails entirely to account for the well-documented phenomenon of “other-directed equity aversion”: not wanting to see one’s partners get less than they deserve. Never mind trying to rip them off as much as possible and hoping they won’t notice. The explanation given is that of a sociopath, not a normal human being. I don’t believe a computer would know that instinctively – you would have to tell it, and then present it with all your evidence, and then you might as well do it yourself.
I don’t exactly extrapolate from myself to all of humanity. I use myself as a data test centre to see how theories hold up when examined in the light of my experience. But I also use scientific data a lot. It’s well known that people exist on spectrums with dimensions, and I occupy points on those spectrums.
I see metaethics as basically moral theory – talking about how morality is put together like a machine or system, determined from all the nuts and bolts from anthropology, psychology, all those humanities subjects. From this model, it’s very easy to answer and make sense of longstanding metaethical questions.
For example, moral realism depends on having the goal of welfare, which we all have. Once we have that goal, it’s necessary to do certain things – we ought to do them, as a descriptive fact.
