"Avant-Garde and Kitsch" is the title of a 1939 essay by Clement Greenberg, first published in the Partisan Review, in which he claimed that avant-garde and modernist art was a means to resist the "dumbing down" of culture caused by consumerism.
[1] Greenberg considers kitsch to be "ersatz culture," a simulacrum of high culture that adopts many of its exterior trappings but none of its subtleties.
Greenberg believed that the avant-garde arose in order to defend aesthetic standards from the decline of taste perpetuated by the mass-production of consumer society, and saw kitsch and art as opposites.
He argued this based on the fact that Academic art, such as that in the 19th century, was heavily centered in rules and formulations that were taught and tried to make art into something learnable and easily expressible.
He later came to withdraw from his position of equating the two, as it became heavily criticized.