The Irony of Rejection of Knowledge
The humans in the 26th century face a nuclear war-torn globe. For fear of discovering technology even more destructive than atomic energy, they decide to stop pursuing knowledge. Books are banned. Literacy is forgotten. And the people prefer simplicity. This outcome is ironic because knowledge is the only real advancement humankind has ever made. Everything we have ever accomplished has been the result of the evolutionary capacity for comprehension. When we were pre-homonids, we discovered one day that to know something is sometimes better than finding food. Every major technological development after that point has been the result of using knowledge as a finely honed tool. After nuclear warfare the humans basically agreed that they were evil as a species and that they should no longer try to perpetuate their evolution.
The Irony of Simplification
Post nuclear war, people chose simplicity over science. They had witnessed the near total destruction of their species and became terribly afraid. In an attempt to prevent worse incidents, they decide to ban intellectual advancement and all its various vehicles of advancement, namely writing. They hoped to preserve life on Earth by limiting its avenues of evolution. Unfortunately this approach counteracts their goal of preservation because biological evolution is the universe's only known safeguard for the preservation of life. Without passing down knowledge to each generation, the process of evolution among the human species was effectively halted. When they hoped to save humanity, they doomed it to eventual extinction.
The Irony of Religion Preserving Knowledge
The Church becomes the secret vessel for the preservation of the knowledge of the human species. The Catholics take it upon themselves to ensure the salvation of knowledge, devoting entire monasteries to its surreptitious housing. Originally this was the main function of monasteries. They were hubs for intellectual study, conversation, and recording. Most of the records of the ancient world which we possess today are from ancient monasteries. In Miller's timeline the story repeats itself when the Church becomes once more a dominant political power as humans return to their quest for knowledge and advancement. The Church serves the same function it was built to serve, and eventually becomes the vehicle for the salvation of the species after nuclear war once more destroys almost all life on Earth.
The Irony of Isolation As a Result of Knowledge
Brother Joshua and his crew are chosen to preserve the Order's Memorabilia, a.k.a. all of humanity's knowledge recorded in one place. When nuclear weapons are fired to once more destroy biological life, they launch a private rocket into space in order to outlast the radiation. They intend to reunite with other human colonies and to help preserve the species elsewhere, but they end up alone in space. In psychology, intellect is known to create socially isolated individuals who find their knowledge un-relatable to their less-informed peers. Basically the more you know, the more likely you are to have a hard time talking to someone who's worried about the immediate. Brother Joshua and his followers find themselves in the ultimate place of solitude as they float through space carrying an archive of all human knowledge.
The Irony of Repetition
Oddly enough Miller's book is not revolutionary. He's a science fiction master of course, but he envisioned a future based upon the past. The main arch of his plot reflects a commitment to cyclical development. He posits that the future looks like a clear variation of the past. To us who have never experienced nuclear holocaust, establishment of space colonies, or the outlawing of literature, Miller's imagination seems fantastic. Actually he's just repeating patterns of action which have already occurred. For example there's a war, a dark age, a renaissance, and then tension leads to another war. This can be seen multiple times within the book itself and repeatedly throughout all of human history. The irony here is that the most outrageous future world we can imagine still follows the old routines of human civilization's development which we know today.
