For me the most puzzling thing about Schopenhauer is his idea that the Platonic Ideas are the highest objectification of the underlying Will which is ultimately irrational. Hard to see Platonic Ideas as irrational or as expressing something irrational. Schopenhauer of course admitted that he did not intend by Platonic Ideas the same as Plato himself. Things get more interesting when it becomes clear that Schopenhauer's "Platonic Ideas" are really a lot like Kant's "aesthetic ideas." Let's back up and think about what Schopenhauer might mean by "Platonic Ideas." Remarkably he says they are perceptual. (Plato would never accept that!). Keep in mind that the Platonic Ideas (I will only mean Schopenhauer's Platonic Ideas here, not Plato's) have the same name as concepts. But concepts are rigid things that can be completely given in their definitions. Platonic Ideas are organic wholes and can be realized or expressed in different ways. Again, this makes them like Kant's "aesthetic ideas." Its helpful to think about how these are supposed to work in architecture. The essence of architecture involves expressing the Platonic Ideas of rigidity, light, and so forth. This seems about right for a lot of architecture and certainly fits great modernist architects like Hahn, Le Corbusier and Ando.
My favorite quote on the Idea is that it "develops in him who has grasped it representations that are new as regards the concepts of the same name; it is like a living organism, developing itself and endowed with generative force, which brings forth that which was not previously put into it." (80 in Continental Aesthetics ed. Kearney and Rasmussen). Schopenhauer, unlike Plato, makes a big distinction between ideas and concepts. He writes "just because the Idea is and remains perceptive, the artist is not conscious in abstracto of the intention and aim of his work" (80) Plato and Kant both believed that the artist could not describe his/her intention and aim, although Kant is closer to Schopenhauer on this point. For Schopenhauer, the artist is not able to do this since he works "from feeling and unconsciously, indeed instinctively" and again, "only the genius...is like the organic body that assimilates, transforms and produces." This seems far from the idea that the genius is someone who accurately perceives the ideal and unchanging Forms. Instead of being a rigid activity this is very much an activity of life.
This leads me to be suggest that Schopenhauer can be an inspiration for everyday aesthetics in a very particular way. The relationship between the genius and his materials is very like that of the everyday aesthete, i.e. someone who pays closest attention to everyday life and its essential nature. This would explain Schopenhauer's approach to the works of the Dutch painters. His rejection of allegory goes hand in hand with his downplaying of Concepts as opposed to the same-named Ideas. Schopenhauer's attack on concepts reminds us of Nietzsche's attack on the columbarium of ideas in his essay on Truth. No surprise since N. was very much under the influence of S at that time. "Only the genuine works that are drawn directly from nature and life remain eternally young and strong, like nature and life itself." (80)
"a great injustice is done to the eminent painters of the Dutch school, when their technical skill alone is esteemed, and in other respects they are looked down on with distain, because they generally depict objects from everyday life....We should ...bear in mind that the inward significance of an action is quite different from the outward... The inward significance is the depth of insight into the idea of mankind which it discloses, in that it brings to light sides of that Idea which rarely appear. This it does by causing individualities, expressing themselves distinctly and decidedly, to unfold their peculiar characteristics, by means of appropriately arranged circumstances." (78) There is something other than what we normally think of as Platonic Ideas as play here. First, we have the notion of "sides of an Idea which rarely appear." Second, we value individualities expressing themselves and their peculiar characteristics, through an "unfolding." Since aesthetic perception of Ideas is perceptual it is a matter of seeing the inward significance (for or in relation to Mankind) of individual things. The Platonic ideas are brought down to earth not in an Aristotelian way but in a way strangely like Nietzsche.
There might be an interesting relation between Schopenhauer and Object-Oriented Ontology. Of course Schopenhauer makes a radical distinction between humans and non-humans: he does not accept a flat ontology as I do and as OOO does. But he does believe in speculative realism (the underlying Will is real). Unlike Kant's thing-in-itself Schopenhauer's underlying reality is pretty much the same as nature itself. So I do not think he is guilty of what OOO theorists call co-relationism.
It is still a puzzle to me why genius artist would somehow escape the irrational Will by focusing on its objectifications.
It would be easy enough to write off Schopenhauer with respect to everyday aesthetics. His glorification of the genius and attack on the common man seems itself to be contrary to any concern for the everyday. He writes of the genius as engaging in "constant search for new objects worthy of contemplation" (55) whereas the "common mortal...entirely filled and satisfied by the common present, is absorbed in it, and, finding everywhere his like, has that special ease and comfort in daily life which is denied to the man of genius." This reminds me of the contrast between the aesthetician of everyday life who stresses the extraordinary and the one who stresses comfort in daily life.
Although it is also hard to take Schopenhauer seriously in his acceptance of the notion that the Ideas are eternal, bear in mind also an important modification of the notion that the Ideas are perceptual. For he adds that the genius needs to supplement perception with imagination: it extends "the horizon far beyond the reality of his personal experience, and enable[s] him to construct all the rest out of the little that has come into his own actual apperception" (55) This allows him to "let almost all the possible scenes of life pass by within himself." Imagination allows the genius to go beyond what he actually sees to what nature tried to form.
Still, the pragmatist too gives credit to imagination. Instead of speaking of the imagination as providing us with access to the perfect form, we speak of imagination of enhancing the object as experienced. There is a perfection here too.
And there are points at which the two positions seem closer. The everyday aesthete does linger on the object of contemplation much like the Schopenhauerian genius. "the ordinary man does not linger longer over the mere perception, does not fix his eye on an object for long, but, in everything that presents itself to him, quickly looks merely for the concept under which it is to be brought, just as the lazy man looks for a chair, which then no longer interests him." (55) It is this sort of quick easy classification that the everyday aesthete avoids. "Whereas to the ordinary man his faculty of knowledge is a lamp that light his path, to the man of genius it is the sun the reveals the world." (56) The genius is considering "life itself."
Another point of connection is in the notion of aesthetics as unified. Whereas many aestheticians of everyday life see aesthetics as disunified I have argued for continuity. Schopenhauer writes that since the Idea remains essentially the same in the work of art as in that which it represents "aesthetic pleasure is essentially one and the same, whether it be called forth by a work of art, or directly by the contemplation of nature and of life." (59)