When the towers first fell and, in practically the same moment, so many turned to imagining their replacement, I was appalled. Later, when I started to write about the site, I avoided proposing designs of my own, both because they were banal and impracticable—I thought it would be cool to flood the bathtub—and because I felt such activities were beyond the scope of a responsible critic. I would often say, however—as I think I wrote or at least implied here once—two things: that the ultimate form of the reconstruction was unimportant as long as the process to achieve it, from...