“There was no evolution, no progress,” adds the other.

“We want to set up a new context, a new territory.”

“In the Tate Modern I produced another work of art; it’s a work of art about Yellowism.”

It’s like an Andy Warhol film starring Bill and Ted. But at a time when British contemporary art has seemingly been reduced to an annual cycle of shock, reaction, and dutiful repeat, it is also possible they are onto something. The “new territory” proposed by Yellowism, when you pick apart the impenetrable prose and navigate the conceptual blind alleys, boils down to this: The only avenue left open to the art world is to strip art of meaning; to make it into junk. Which, interestingly, is exactly what the Turner Prize has been accused of doing, as it elevates a procession of young provocateurs into Britain’s Next Big Thing.

In defacing that Rothko, Umanets revealed that even the most transgressive art has its limits—you can take a cudgel to people’s most dearly held beliefs, but leave the £50 million paintings alone.

Nobody would deny that what Umanets did to that Rothko was a bad thing—the museum’s conservation department is working on restoring the canvas, but says that even if it can be restored it’ll take about a year.

The act was also, though, part of a long tradition. Curator Stacy Boldrick, who coincidentally has been helping to put a Tate show together about the history of attacks on art, points out that the impulse in Britain dates back at least to Tudor times, and the systematic obliteration of Catholic artifacts. “It’s about power,” she says, “the struggle over ownership of these images.”

In the modern era, some acts of defacement have come to be seen as more defensible than others. When the suffragette Mary Richardson hacked Velazquez’s “Rokeby Venus” in 1914, she did so in the name of protest, and today her act is viewed with more sympathy than, say, that of Pietro Cannata, the Italian painter who took a hammer to the toe of Michelangelo’s “David” in 1991, and who had no discernible reason for doing so.

It’s only relatively recently that these attacks have been perpetrated in the name of art itself. In 1974, a young artist named Tony Shafrazi walked into New York’s MoMA and sprayed “Kill Lies All” on Picasso’s “Guernica,” calling this an “art action.” In 1994, an artist named Mark Bridger expressed himself by pouring ink into a Damien Hirst tank containing a pickled sheep. In 1996, at MoMA again, an art student vomited onto a Mondrian as part of a performance piece he called “Responding to Art.” Earlier this year, a Houston street artist tagged a Picasso at the Menil Collection.

In Britain, the most infamous example of so-called appropriation occurred in 2003, when the Chapman brothers, Jake and Dinos, drew clown faces on a series of rare Goya prints and called the work “Insult to Injury.” For the most part, the critics and curators responded to this transgression in much the same horrified way they have to Umanets, even though the Chapmans, who bought the prints first, hadn’t broken any laws (one critic went so far as to call the act “evil”).

The reason for this response stems at least in part from a basic principle of democratic society: We are allowed to attack each other’s ideas—we may even have an obligation to do so—but we are not allowed to mess with each other’s stuff. It seems a bit deflating that the anything-goes avant-gardists should also abide by such a ploddingly conventional rule, but there really is no other explanation for the violent revulsion they reserve for people like Vladimir Umanets.

Or maybe there is. In today’s art world, the Yellowists’ impulse to deprive works of context, to strip away the names, accolades, and enormous sums of money changing hands (Hirst raised $198 million at a 1998 Sotheby’s auction) may represent the ultimate act of vandalism, a violation of the last taboo. After all, in the flattening light of Yellowism, Hirst’s “Mother and Child Divided” becomes little more than a dead cow and its calf. It’s just too bad Umanets had to ruin a perfectly good painting to publicize this point.

As much as Spalding disapproves of what Umanets did—“It’s just wrong”—he also suggests that the art world has brought this upon itself. “They’ve created this situation, with this desire to shock,” he says. “The Tate bought a can of [human excrement] for £22,000. And once you’ve bought a can of [human excrement] for £22,000, what else can you do?”