In 1967, a budding art critic and PhD student named Michael Fried published the essay in Artforum that would make him famous. “Art and Objecthood” was on the surface a piece that took aim at the Minimalists, then a group of up-and-coming artists led by Donald Judd. But embedded in the critique was a fully-fledged theory of art — in many ways the last of its kind. In the years since,...