> That textbook definition of “valid” only applies to purely deductive arguments. Outside of mathematics, most arguments humans make have a significant non-deductive component (inductive and/or abductive). So, unless we assume that moral reasoning is closer to mathematical reasoning than to the kinds of reasoning we normally use in the sciences and humanities-a very dubious assumption-the formal concept of “validity” you are invoking has rather limited relevance to morality.
I don’t have any sense for the various properties of inductive arguments. So to the extent that moral arguments are inductive, I have nothing to say. Thanks for pointing out that I’m assuming moral arguments must be deductive. Any recommendations for an introductory text on inductive arguments?
> That’s why I read your statement as intending “valid” informally rather than formally, since in its informal sense the term is not restricted to purely deductive arguments; and informally it is very much a normative concept (formally, I think it has multiple formal senses, some of which contain more normativity than others)
Understood.
> I think your overall point is, you are expressing scepticism about claims to know the truth of some particular moral proposition, grounded in a more general scepticism of the possibility of any moral knowledge at all.
Yes, that is my point.
> I think that kind of general moral scepticism is (usually) a form of normative scepticism. The big problem I see with normative scepticism, is that attempts to argue for it logically and rationally turn out to be self-refuting, because logic and rationality are themselves normative concepts.
This is the first time that I’ve heard of normative epistemology, which I gather is what you are talking about. One thing I will say though, thinking about this seems smoother than thinking about normative morality because (I think) I don’t have as many childhood memories of people telling me what I ought to think compared to those of people telling me what I ought to do.