> if you use that data as general background knowledge to synthesize aggregative works such a history of the vietnam war, or trends in musical theatre in the 1980s relative the 1970s, or shifts in the language usage of formal honorifics, then that seems to me to be clearly fair-use categories
I don't think this is clear. If someone were to train a model on several books about the Vietnam War and then publish my own model-created book on history of the Vietnam War, I would be inclined to say that that is infringement. And if they changed the dataset to include a plurality of additional books which happen to not be about Vietnam, I don't think that changes the analysis substantially.
I think it is hard to earnestly claim that in that instance the output (setting aside the model itself, which is also a consideration) is transformative, and so I would think, absent more specific facts, that all four fair use factors are against it.
I think the question is if it changes analysis if the dataset DOES include a bunch of books and articles related to Vietnam beyond your specific book.
In the first cast where it just rewriting a single books content, the unfairness is clear.
But in case where it is producing a new synthesis and analysis of the data, derived in part, but not regurgitating the source material, is that unfair?
The latter isn't clear to me.
These technical distinctions like these probably will matter in whatever form regulation eventually ends up becoming.