Greg Egan’s first novel, An Unusual Angle (1983), attracted little attention. He then wrote a number of stories that successfully combined scientific and metaphysical speculation, such as Quarantine (1993), a novel exploring some of the consequences of the alternate-universes model of quantum theory.
Permutation City has been seen as a fulfillment of these works. The book is a study of artificial intelligence and of whether a computer program matching the steps taken by a human brain is truly thinking or merely simulating thought. The copies think that they are thinking; perhaps, as in René Descartes’ philosophy of cogito ergo sum, that means that they really are.
The novel is in some ways a theological work. In the physical universe where the story begins, there exists a Church of the God Who Makes No Difference. Its religion is a form of Deism in which the Watchmaker God who wound up the universe takes no part in it. In the new Autoverse, the Copies become Gods Who Make No Difference because a fully self-consistent universe has no need for, and cannot encompass, external Creators. They can be said to have been cut out of their universe by Occam’s Razor, which states that among competing theories, the simplest is preferred.
Permutation City also is a treatment of an alternate-universe model in which the universes all coexist and all comprise the same “dust” of individual events. In this version, what seems to be immutable space-time is merely one set of coordinates consciousness imposes on events, and other patterns—other permutations of the same events, perceived by other consciousnesses—could be equally valid. Egan uses the permutation theme skillfully. In the first section, the story threads are given chapter headings, such as “Remit Not Paucity” and “Rip, Tie, Cut Toy Man,” that are permutations of the letters in “Permutation City.” The epigraph presents a set of twenty other permutations that could represent the other realities Paul believes he has lived through.
This is a novel of alternative possibilities. The Copies could be conscious or could be simulating consciousness. Paul could have experienced alternate universes or could be insane. There could be other universes in the dust, or they could be imaginary. The reader is left to assemble the pieces into answers.