On Monday, I will be lecturing on Plato, as I do near the beginning of each semester. There's something a little like the liturgical year about teaching: the same material comes up again and again, in the same order. And, that can be immensely boring or it can bear me along in a reassuring rhythm, especially when I see something new—with my own eyes or, usually, through the eyes of my undergraduates.
My standard way to introduce students to the theory of Forms is to have them think about beautiful things and what such things have in common that could make them beautiful. This raises a few issues, since most of my students claim to believe that beauty is subjective—they have to be pushed to see that they don't actually judge it this way—and I always have a student or two who wishes to reduce beauty to symmetry or an evolutionary compulsion.
But, I was also thinking about beauty with regard to one of my other courses this semester. In some ways, no matter how all analogies may limp, beauty seems a near perfect example of a supervenient property, thus an apt case for explaining that notion, as well as multiple realizability, to my philosophy of mind students.
There's little question (to me) that the beauty of a piece of music or a face or a painting is determined by its physical properties. I know that this is not accepted by all in aesthetics, but it's near enough to true for me. And, any change in the beauty qua beauty of an object would have to mean a change in that object's physical properties. But, a full catalog of the physical properties of Mozart's Requiem or Michelangelo's David would not capture its beauty. There's just no reducing beauty to the physical, for all the determination by the physical. And, it should be obvious that there are many different ways to achieve beauty. So, this looks to me like an easier entree into the concepts of supervenience and multiple realizability than just hitting them with the mental supervening on the physical.
I'm sure introducing these notions through this example will lead to undreamt of nightmares of explication, but in this I have hope.