what is art and who decides?

The audience decides.

No matter what object is presented, it is up to the audience to define and categorize it. Art is whatever its viewer decides to call it. After this course, I have changed half of my answer to this question. At first, I had said that art was expression and that the audience determines that it is art. After everything we’ve talked about, I no longer believe that art always has to be an expression of some kind. "That s not what I meant at all" T.S. Elliot.

since the audio is such a bugger, here's the reflection in writing for now...

Very often in our early educational careers, we are made to compare and contrast various nouns. The dominant vehicle for this exercise is the Venn Diagram. So, when asked to create two textual artifacts that compare two nouns, I couldn't resist the urge to employ the aforementioned visual organizer.
Like the sphere containing their attributes, Modernism and Postmodernism can easily be deemed cyclical, without a determinable beginning or end. They exist to defy a conventional linear structure of art history. The two ideas are undoubtedly interdependent, which makes the use of overlapping circles especially appropriate.
Because the diagram Venn is instantly recognizable by anybody with an elementary American education, its contents are eaily read and understood by many. The effectiveness of this piece is due to it's simplicity and the audience's familiarity with it's structure of information distribution.