As I understand PMism it is a movement which rejects the institutionalised framework which defines what is within the frame as special and valuable. Such assertions, made by a self selecting bunch of approved persons, are intended to separate their mysteriously chosen objects from all the other objects in our culture.
But when the "gallery" applies a price tag to its chosen exhibits it removes that separation from the other objects in the culture. Mops or brake pads say. Or chewing gum.
It is the institutional declaration of the uniqueness and specialness of its chosen objects which gives these esoteric objects their value. If an ordinary mundane object is chosen to be "framed" by the mutual appreciation society, which includes favoured critics, a pile of bricks say, it becomes valuable per se
. PMism questions the legitimacy of this elite to bestow value on objects simply by choosing to do so because it is anti-art and, human nature being no different in these respects in thieves' kitchens or dinner parties and receptions, corruption is inevitable.
The classic case I know of is when the Guggenheim Museum prevented Haacke's "Real Time Social Systems" being in one of their exhibitions. (1971).
It was alleged to trace the connections between some Guggenheim trustees and badly maintained slum tenement ownership and thus called into doubt the respectability of those members. Haacke's work met the same fate with the Wallraf-Richartz Museum in Cologne because it traced a link of a board member to the Nazi party through previous ownership of a picture they exhibited.
PMism challenges any sort of bureaucratic control over art.
Modernism challenged "patron" art because it was made to legitimise the existing power structures. It challenged accepted concepts of beauty in pictures like Picasso's Les Demoiselles d'Avignon and it was content to leave surface representation to photography. Cubism sought to represent the geometrical arrangements that scientists were discovering in matter at the molecular level. The female nude became lumps of flesh and threatening. Representation of underlying reality was sought.
But basically a response to photography.
There was an incident similar to the Haacke one when it was realised that a tapestry copy of Geurnica was hanging on the wall behind Mr Colin Powell when he was speaking in favour of the Iraq war at the United Nations. The tapestry was covered over with a blue cloth and some pretty flower arrangements.
As with football and rock and roll formal training is out of court. When Bob Dylan was asked if he played golf he replied that he didn't because he had heard you had to have lessons. Right there is the difference. Bankers have lessons but the Wall Street wizards play it with brains. No contest eh?