More on Wilson the "science fiction writer"
ILLUMINATUS! became labeled as a work of science fiction very early, apparently when it was acquired by Dell. How this label affected reception of the work, for good and ill, is an interesting question. Neither Robert Anton Wilson nor Robert Shea thought of ILLUMINATUS! as a science fiction novel when they were working on it. (See Wilson's article, here.) Was Kurt Vonnegut Jr. a "science fiction writer"?
See also my interview with former Dell editor David Harris, where Harris says that Wilson resisted dividing the book into three volumes, because Wilson apparently did not understand how works of genre science fiction and fantasy, such as trilogies by Jack Vance or Lin Carter, normally are published. Shea gave a speech at the World Science Fiction Convention in Atlanta, while accepting the Prometheus Hall of Fame award, which is only given to works of science fiction. I met Shea once at another worldcon, one that was held in Boston. Wilson also attended at least some science fiction conventions. According to copyeditor Teresa Nielsen Hayden, Wilson once was booked to serve as the guest of honor for a science fiction convention in San Francisco. The event had to be cancelled because of difficulties with the hotel.