Request/Question on Aesthetics
Yes, I'll always be coming back to aesthetics. I've got some discussion of it in *Anthropomorphics*, where I focus mostly on satire, but that by no means exhausts the question. There's an argument to be made for the primacy of aesthetics in GA--i.e., that aesthetics grounds and includes morality and ethics. I'll mention in this context that some of Eric Gans's most valuable work is on aesthetics--his chapter on the history of aesthetics in *Originary Thinking* is especially important. His basic definition of aesthetics is as an oscillation on the originary scene--there is a moment when the participant on the scene is directed to the central object by the gesture of the other, but once he has turned away from the gesture to the object the object loses some of it's attractiveness (which was enhanced by the other's desire), so he turns back to the gesture, and so on--this creates the "beauty" of the object. It then becomes possible to "frame" an object or scene as enhancing and suspending the desires of a community. When we aestheticize, we want to sacralize some object or scene, but more sophisticated art (which can distinguish between the aesthetic and the sacred) knows that this can't be done, so the best art includes within itself a resistance to the sacred and to sacrifice: to borrow from (and revise) Kant, one could say art is suffused with "not quite conclusive intentionality." Anyway, what interests me most now (and this follows up on Gans's history of aesthetics, which focuses on the scene of art containing a representation of itself within itself, which is to say, including and "reading" its own audience) is the boundary between what is art and what is not art, which is the primary focus on post-classical and post-realist art. The end point of minimizing that boundary is to make everyone artists, which is to say, participants in constructing the social order. This comes back to what you say here--we want to construct a world that holds us on the ostensive-imperative level, while giving us something to talk about (declaratively).
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Having never read Spengler, I can't respond to the way you draw on him, but a way of "fusing" the aesthetic with technics and social practices more generally is by thinking in terms of design. You design a building, but you also design an organization, and it's always possible to think of whatever you do as a kind of design, and whatever you encounter as something that has been designed, and could be redesigned. It's a way of taking an "active" approach to things.
I would assume that the first forms of high art would have been things like temples and palaces, so, yes, architecture would have come first. Learning to think about architecture in the context of urban design is very important, because the design of material structures is really the designing of "interfaces" articulating relations between people.