So, with your vast knowledge of the art world and your degrees in fine art and art history you are able to determine how much of a science it is? If you had even the slightest understanding what is involved in the study of art, you would know that your broad-sweeping statements are beyond ridiculous.
Art is defined by conventions within the art community, which is more global than any other community I know. We cross borders and boundaries and share knowledge, ideas, friendship and spirituality with one another as a matter of coarse, on a level I don't think you could possibly fathom. While people fight wars and choose sides, and use your vaunted science to kill one another and rape and destroy the natural world, artists are the light in the darkness. Without us, humanity would already be dead. What would your rational world be without paintings and music and dance and theater? An ugly, dirty, joyless place at best.
Arrogant? YES. We have every right. Because while we create beauty and encourage honest discourse, you dismiss us as self-aggrandizing and self-righteous braggarts believing we are better than we are. While we give to you, you take without even a thank you most of the time, believing our contributions to be secondary to other "important" matters, like the development of viagra, or the next biological weapon. Uneducated, uninformed, pretending knowledge you don't possess, your conclusions are shallow and devoid of any merit. So yes, arrogant for sure.
Discounting all of the actual chemistry involved in creating the various media used to create art, understanding not only how a certain pigment might react with another based on it's chemical composition, but how it will react to light, humidity and temperature, no there is absolutely no science there. A year dedicated to the study of human anatomy and physiology, learning alongside future doctors, nurses and biologists. Years are given to studying thousands of compositions, learning techniques handed down from master to master over hundreds of years. Our science was a well established fact before yours ever began.
Funny that you should use a work of fiction as a basis for your "logical and rational" argument. David Gamut was in fact a psalmodist; a religious man. Hardly suitable as an example. However, since you used him I'll point out how completely erroneous and misinformed your argument is since music (his chosen art form) is a highly developed form of math. It has structure and form, and is the farthest thing from nonsensical. Just because you don't understand a thing, you have to denigrate it, denying your own failure to comprehend, your own lack of imagination and talent.
The layman likes to throw up arguments like yours because everyone wants to believe that the kitsch crap they buy and stack on their shelves has some artistic merit. It stings that your unsophisticated, untrained eye has you believing that anything someone says is art and throws a big dollar tag on must be worthwhile. You grab it up like a magpie with a piece of colored glass and then squawk when someone points out that your shiny has no real or aesthetic value. Silly bird.