What happens when the Singularity leaves you behind--or worse, forcibly uploads a copy of your mind state and then goes off and builds a wormhole using your mind as forced labour?
The Cassini Division asks just these sorts of mind-boggling posthuman questions. Ellen May Ngwethu is a few centuries old, thanks a telomere hack, and living in a post-scarcity society, thanks to nanomachine manufacturing. She has chosen to live on the front lines, literally, and is now a senior member of the eponymous group that watches over the slumbering AIs who built a wormhole out near Jupiter and then lapsed into senescence. Now there are signs that they are back, evolving (or re-evolving), and Ellen and her colleagues aim to do something to stop that.
Ken MacLeod pits humans against machines here, where machines are the evolved intellects of other humans. But this is also a book that attempts to get at heavy issues of philosophy of mind and even economics. MacLeod's characters debate everything from the most efficient decision-making structure to the nature of morality. It's a lot to squish into a three-hundred-some page book, and MacLeod isn't always successful. That being said, it's not a bad effort, and I could see someone else really getting a kick out of this. As far as posthuman SF goes--and you know how lukewarm I feel about that subgenre these days--this is a good one.
Everything regarding the Singularity, AI, mind uploading, etc.--this is where The Cassini Division shines. MacLeod is great at portraying the different opinions regarding mind uploading through his characters. Ellen and many of her allies look down on the idea that consciousness can exist independently of a biological, human brain. To her, an "upload" is just a copy, a stored state, and if it is run on a machine, it is a simulation of a person rather than that actual person's consciousness. Although Ellen and the Division make use of "backups" before they go into dangerous situations, they only load those backups into cloned bodies--and even then, Ellen acknowledges that entity is a copy of the "original" rather than a continuation of that original's identity. The posthumans who became the Outwarders disagree. They believe that consciousness is preserved, that a mind running on a computer (even one where computation speeds up the experience of "consciousness" thousands of times over) is actually conscious and living. Hence, they see this existence as generally superior, although it leads to an evolution in mental capacity and state--the Singularity.
Far from being philosophical discussion without any purpose, this all has very real implications within the story. MacLeod points out that the descendants of Singularity-uploaded humans may not regard regular ol' humans as all that necessary to keep around. We're just taking up space, using valuable matter that can be gobbled up and converted to smart matter. So for Ellen and crew, stopping the posthumans by any means necessary is simply a preemptive means of survival. Her disdain for anything involving electronics and AIs, the way that the Solar Union has stuck with chemical and mechanical computing, despite its speed trade-offs, to avoid computer viruses from the posthumans, is all very fascinating. MacLeod has created a possible future that is interesting, original, but also believable within the Singularity conceit.
Where The Cassini Division starts to falter is its dichotomous depiction of an anarcho-communist Solar Union and the anarcho-capitalist New Martians (along with similar non-cooperatives, nor "non-cos" scattered throughout the Union). It's not so much that I find these social setups unrealistic. But I find the way in which the members of these societies engage in offhand philosophical and economical debates about the relative merits of their systems somewhat stifling. It's almost Heinleinian. I get that you're excited because you have no money any more, but you don't have to point it out all the time. And why is everyone so obsessed with free love? Oh my god, it is a Heinlein novel! Run!
I also didn't care for Ellen all that much. She's not a sympathetic character. Her hard-line stance regarding AIs is interesting, but she just strikes me as uncomfortably genocide-happy. Her amoral adherence to the "True Knowledge" is creepy. I want to think this is intentional on MacLeod's part, just another way of depicting how different this society is. Still, it made me difficult to cheer for Ellen. The rushed resolution, the way she turns out to be right about everything after all and just conveniently manages to "fix" things (maybe) adds to my dissatisfaction.
The Cassini Division is the third book in a series. Nevertheless, it reads fine as a standalone. MacLeod lets you in on the historical details without hitting you over the head with them. I see now that I have the earlier books on my to-read list--but I don't think I'll bother, to be honest. This is the third MacLeod book I've read and the third I haven't enjoyed all that much. It's not the books so much as just my personal experience with his writing and his style, so you might enjoy them. Third time for me, however, proves not to be the charm.