Essence and existence

A quick glance at Jon Cogburn's recent APA paper surprised me.  Cogburn contrasts Bertrand Russell's view, according to which "only our words are vague, not the world they describe," with Schopenhauer's.  Cogburn calls Russell's kind of vagueness "R-vagueness" and writes:

R-vagueness should be contrasted with S-vagueness, named for Schopenhauer, who, in a representative passage early in The World as Will and Representation, argues that our ability to interpret facial expressions depends upon concepts that are unable to capture the subtleties of such expressions (1989: 56-7). For Schopenhauer, the minutia of facial expressions is too extensive for our concepts to ever catch up to them, and he compares them to a mosaic having sharply defined colour boundaries that represent gradual changes in hue. Likewise, in the typical neo-Kantian tradition, concepts are thought of as precise and the perceived reality (“intuitions”) to which they apply is thought of as vague.

Later he says that "one can view S-vagueness in a way closer to Schopenhauer’s own perspective, as the reverse of Russell’s view."

When I say I'm surprised I don't mean that Cogburn has got Schopenhauer wrong. It's just that I think of Schopenhauer as denying that reality can be vague (although I suppose noumenal reality is about as vague as it gets). Here's the passage I think of in connection with this, from On the Freedom of the Will:

Here one must be reminded that every existence presupposes an essence, must have a definite nature. It cannot exist and yet be nothing, it cannot be something like the ens metaphysicum, that is, a thing which simply is and no more than is, without any definitions and properties, and consequently, without a definite way of acting which flows from them. As little as an essence yields a reality without an existence (as Kant expounded in the familiar example of the 100 talers), just as little can an existence do this without an essence. For every thing-in-being must have a nature which is essential and peculiar to it, in virtue of which it is what it is, which this being always maintains, and whose manifestations are called forth of necessity by causes; while on the other hand this nature itself is by no means the effect of those causes, nor can it be modified by them. But all this is just as true of man and his will as of all other beings in nature. He too has an essence in addition to existence, that is, fundamental properties which make up his character and require only an outside inducement in order to reveal themselves. Consequently, to expect that a man should act one time in one way, another time quite differently, in response to the same cause, would be no different than to expect that the same tree which bore cherries this summer should bear pears in the next. Freedom of the will, when carefully analyzed, means an existence without an essence, which means that something is and at the same time is nothing, which in turn means is not, and consequently is a self-contradiction.

This makes an interesting contrast with Sartre's existentialism ("existence precedes essence"), but also seems to deny that (phenomenal) reality could be vague or indeterminate. Perhaps I'm reading too much into it, or perhaps he contradicts himself in The World as Will and Representation. Or, very possibly, I'm misunderstanding what it means for reality to be vague. I'll have to check.