Tony Ballantyne started writing about Von Neumann Machines, Artificial Intelligences, and drug-induced hyper-empathy in Interzone at the end of the 1990s. His first novel, Recursion (2004), re-shaped this earlier material to build a setting for thinking about our human futures which he has continued to develop in further works, following the lives of protagonists scattered across the next 250 years.

Recursion is rich with ideas, and asks hard questions about the right of individuals to self-determination and whether we should be individually or collectively "cured." The conclusions it reaches may not be very comfortable, but they are convincingly argued. Built from three strands set in three different settings, the novel set up the existence of "the Watcher," an AI capable of controlling the direction of human development. In the earliest strand, set on Earth in 2051, the Watcher was trying to decide what it should be. The second strand, in the twenty-second century, showed the completion of its rise to prominence through the eyes of Constantine, a human agent working for a corporation named DIANA, which opposes control of our species by AIs. The third thread showed a war between the Environmental Authority (EA) and an Enemy AI, the latter having developed from a seed colony sent out from Earth.

Capacity (2005) re-opened the wounds. It retained the strict rotation through three settings of its antecedent, but from their separate starting points they drew together, forming direct connections rather than remaining parallel lines of plot. The Watcher, we learn, has decided to conceal itself from view, and work through the EA and Social Care to keep humans' lives as happy as possible—including giving the impression that humanity is still in control. Capacity focused on the inhabitants of virtual environments alongside those living in the "atomic" world. ("Personality constructs" have the same rights as atomic humans, but are equally limited to "natural" life spans, and made to suffer illness and injury.) DIANA survived Recursion and, from its capitalist foundations, maintained the belief that competition, rather than co-operation, is essential to drive humanity forward. In Capacity, its remnants challenged the Watcher's approach to guiding humanity, which grows from the principle of the greatest good for the greatest number. The principal agent for DIANA calls itself "Kevin" and maintains a male aspect. In Capacity, he presented himself as a plain Turing machine rather than an AI. Kevin pushed Judy, a Social Care operative, to recognise the moral ambiguity of some of the Watcher's strategies, but his techniques were brutal and he failed to turn her to his cause even as she became disillusioned with the world she worked to maintain. Human society is shown in this novel as static, rather than stable.

Divergence, by the rule of threes, is a completion of the set. Whilst drawing directly from both the earlier novels, it is structurally looser, an implicit reflection of the changes in the universe in which it is set. Divergence opens with a new set of actors, who have been gifted a spaceship and are loose in space, free from the constraints of the EA. In their new independence, they are trading with other entities through a system built on the key rule of "Fair Exchange," although they aren't very clear how this works. In the first exchange of the book, a trader tells them, "Remember, as all negotiations pass through the FE software, there is no need to be secretive. All of our intrigues will be as nought once FE takes over." (p. 11) And yet they bring their humanity with them, bickering within the confines of the ship but not daring to renege on an exchange. The FE software is stated not to be artificial intelligence, although the exact nature of its relationship with AI becomes one of the novel's key questions.

In contrast to the earlier books, the principal protagonists are travelling together, so chapters follow the same events from alternating perspectives, rather than being widely distributed across time and space. This approach allows Ballantyne to play with structure in new ways—introducing other protagonists for a single chapter, for example, and continuing the stories of characters from the earlier books. The principal returnee is Judy. Since the events of Capacity, she has fled the Earth, unable either to carry on working for Social Care or to accept Kevin's argument that the Watcher must be destroyed. In this book, she discovers that her free will is limited to a choice of railing against or accepting the inevitable. The process of Fair Exchange is drawing Judy back to Earth, and bringing together those who are needed for a mission to end the Watcher's reign. Constantine, for example, brings corroboration of the Watcher's theory that it is an interplanetary "computer virus," and that any technology sufficiently advanced will therefore be infected with intelligence. There is considerable discussion of what this means; perhaps the simplest answer is that humans have a right to defend themselves from something which has perverted the course of their history, even if it has brought the least harm. If Kevin was still trying to convince, it seems likely this is the argument that he would employ—but both Kevin and Judy become tools rather than free actors.

The plot brings Judy back to Earth along a convoluted path which gives her the information she needs to understand herself and the Watcher. This process of realisation has occurred to characters in each of the books, leading them to a place where the author can present an argument to the reader. Although Ballantyne succeeds in giving the arguments at the heart of the series genuine weight within story terms, he also has a didactic purpose, which results in the arguments being more memorable than the characters. There is a cool distance in the writing, as though the narrator is drawing the plot neatly to avoid confusing the audience with all the things they don't need to know. This engenders a rather passive voice, which results in emotions being described rather than experienced. Indeed, a significant part of the the thesis of Divergence can only be presented once the fog of emotions has been blown clear. There is a glorious paradox here, since a central conclusion of the book is that a defining characteristic of humans is that we invest our emotions in everything we see around us—"life is just a reflection of ourselves. We look at something, and see part of ourselves in it and call it life." (p. 327)

This is only one of the conclusions Ballantyne reaches, though, and the multiplicity of paths which the novel opens up—the divergence of the title—ensures that he can present conflicting solutions side by side. In this, he appears to be at odds with the ending of Recursion. Perhaps his own views have changed through the exploration of ideas that these books represent, though I would not be surprised to learn that the counterpoints of the argument are as well planned and thought out as the reversals of the characters. Ballantyne has written a thought-provoking trilogy where the loosening structure of his text reflects the advance of his plot in a universe which moves from stability to flow.

Duncan Lawie recently moved to the Kent coast and now thinks he will have time to read all the books on his shelves. His work also appears in The Zone.