Name: The Causal Angel
ISBN: 9780575088979

Hannu Rajaniemi

With his infectious love of storytelling in all its forms, his rich characterisation and his unrivalled grasp of thrillingly bizarre cutting-edge science Hannu Rajaniemi has swiftly set a new benchmark for SF in the 21st century. And now with his third novel he completes the tale of his gentleman rogue, the many lives and minds of Jean de Flambeur. Influenced as much by the fin de siecle novels of Maurice leBlanc as he is by the greats of SF Rajaniemi weaves, intricate, warm capers through dazzling science, extraordinary visions of wild future and deep conjecture on the nature of reality and story. And now we find out what will happen to Jean, his employer Miele, the independently minded ship Perhonnen and the rest of a fractured and diverse humanity flung through the solar system.

The Causal Angel

Mundy Otto Reimer

TL;DR - A novel that combines Game Theory 🎲 + Tulpas + Replicators Tiling the Multiverse 👾 + Computational Complexity + Viral Spacetime ⏳ + Musica Universalis 🎶+ a discussion of Free-Will & Causality❤️

After finishing up the third and last novel of Hannu Rajaniemi's trilogy, I can honestly say I will treasure the time spent reading these novels and am sad I am finally done.

Like my other reviews, for those seeking novel ideas, Rajaniemi continues to deliver. Concepts dropped such as using fields of flowers as distributed networks of telescopes recording cosmic events, or NP-hard reading of fine print for contracts (brilliant!), or even passwords which are composed of specific unchanging neural configurations that make up the essential core of yourself and are stable across multiple copies of yourself, are fed to the reader in typical Rajaniemi-casual drop fashion (which I love!) Small cultural references also show up in things like the "Gringotts-zoku", and if you are a 90s child like I am then you'll love it even more. And similar to his previous novels, Rajaniemi continues to deliver on his word-smithing abilities and beautifully-crafted phrases like "you grip the katana lightly, like a calligrapher's brush, and prepare to write a haiku of death"...or "keeper-of-the-August-Dragon branch", or "Eden-states", etc. Also, my innate tribalist self really wanted to pick "the best" out of the competing philosophies of the "let's find a cure to Death"-Sobornost, the "Victorian-like cryptoprivacy fanatics" of the Oubliette, the "linguistic-geometric data compression stories" of the people + wildcode of Sirr, and the "game-centric and playful" Zoku, but gosh do I like parts of all of these societies that Rajaniemi worldbuilds. 

However, besides the little things like the above, I thought I really should start this review off with my critique! If there was something I would have done differently, I wish we could have dialed up on the childhood loss of the former main antagonist of this series, chen, and his make-believe friends that he seemed to have spawned into existence like The Flower Prince. I also wish that we made The Great Common Task of eliminating all death that has ever existed into the main point of the story, rather than the "tiling of the universe" scenario that it was morphed into by our more recently explored character, the All-Defector. Personally, I incredibly enjoyed the highly abstract linguistic, Zen-buddhist-like realm and Japanese calligraphy + ink-wash painting aesthetic that characterized the grown-up chen character's inner world, and was disappointed that was not explored more in-depth. Maybe we could have done some sort of *annihilation of the Self*-type scenario that is common in Zen and merge that with the game theory loss of agency plotline? 🤷

Regardless of my personal preferences, there are some really great resolutions in this last book. Our Thief's reason for why he was in the Dilemma Prison to begin with was a nice twist and reveal. The All-Defector character was also a nice game-theoretic touch. Even though I predicted and saw the Theory-of-Mind simulation solution/hack by our Thief a mile-away (I mean the *tulpa-mancing* concept was hinted at quite strongly), I still think the All-Defector character was brilliantly conceived and I really enjoyed the combination of game theory and tiling of the universe scenario. His motives regarding rational actors, defection, replicators, and placing restrictions on the computational complexity and expansion rates of viral spacetime were pretty interesting. And even though I mentioned that I would have liked the chen-thief angle played up more, I really enjoyed the ending with Mieli and the musica universalis or *music-of-the-spheres* concept and all that jazz.

Now let's get a taste of some of the neat philosophical ideas in here, shall we? 
 
First, we have the Zoku! Their society is composed of what you would most likely call the gamers and online netizens of our world today. They view all of life's interactions as games, point systems, leveling-up, and unlocking new achievements. To do this they have a philosophy of quantum "entanglement", where they take the idea of a *social credit score* incredibly seriously, while also inhabiting various realms within realms of game-worlds (called "zoku") designed according to their particular aesthetic or value system. This "entanglement" among your player group scores you positive points when you do things that the rest of the members of your group request. These points then grant you more power, information, and "weight" when it comes to making your own requests towards the group. As such, you can see that they have an inherent monoculture-type mechanism baked into their philosophy and technology, paradoxically granting increased freedom in society the more you are *aligned* to the average majority of that society's desires (kinda scary to those of us who are more individualist-bent). As you can probably correctly point out, this "entanglement" concept is similar to something you might find in modern-day China, or even in precursors elsewhere on the internet where we have thumbs-up/thumbs-down approval & ranking systems on forums or places like Reddit, or even the implicit monoculture-shaping that occurs in something like Facebook or parts of Twitter, or even if you are like some, maybe our market-based monetary-system itself.

And it's interesting how this perspective and technology consequently informs the Zoku's philosophy of Identity and Death. They seem to claim that the identity of an individual solely lies in that individual's values and relationships shared among the rest of the network, and that individual bodies don't matter, rather the network and your relationships found in it are what define You (the Yoneda Lemma from Category Theory anyone?). 

Anyways, some side comments here, I really enjoyed the idea of the Loomers-Zoku, who devote themselves to the intersection of music and matter, translating sound into physical shapes, and where "the volition flashes tend to be requests for brief musings about what sort of Universe would arise from thread-theoretic particle states if you converted a symphony into the Fourier components of creation-annihilation operators". This is definitely my kind of *Sacred Geometry/Harmony*-type Chladni Realm that I would like to inhabit. 

I also really enjoyed a minor character aptly-named "Anti-de-Sitter-times-a-Sphere" who has a sing-song voice and speaks solely in phrases of math-speak like "Filtered Markov chain state: Doom" when talking about feelings toward the future, or "Set Operation: Inclusion" when talking about teamwork, or "Functor: Isomorphism" when expressing the you-are-one-of-us sentiment. Kinda cheesy and geeky, but being the metaphoritician I am, I absolutely love it, haha ❤️

Anyways, back to philosophy and novel perspectives! Another interesting idea was that of Planck-scale computers, where causality itself becomes just another variable. Imagining many possible universes, with different rules, where "causal structures are broken" and "spacetime can rewrite itself". Now combine this with the idea called *Coherently Extrapolated Volition*. Briefly stated, "Coherently Extrapolated Volition" is the concept of what an idealized version of ourselves would want, "if we knew more, thought faster, were more the people we wished we were, had grown up farther together". In essence, a very Virtue Ethics-type perspective on the world. I've been exposed to this idea before, but have never thought about it when thinking of the entire Universe itself being composed of agents within agents, in a very Panpsychism-type philosophical view. When thought of that way, then we can start to ask neat questions such as what would the Universe's Coherent Extrapolated Volition be, and what would that even mean? What would a Universe with its own interests and volition imply? 

Now this concept plays nicely when meshed with Rajaniemi's character, the All-Defector. This character is like the ultimate game-theoretic player, able to simulate perfect Theory of Mind of the other agents/players and win any scenario because of it. What would that mean in a Panpsychist-type perspective? It could possibly entail a desire to "tile the universe" in perfect game-theoretic harmony, and a desire to control the Universe's Coherent Extrapolated Volition. It could also imply that when given knowledge of a potential Multiverse, the Defector would view alternative physics as a type of replicator competition scenario, eating up computational resource complexities of other parallel universes, yielding a type of "viral spacetime". These are all neat ideas that Rajaniemi explores and from which I find myself keep going back to, to mull over the implications of. I really enjoy this type of stuff and it is why I continued to read Rajaniemi's work and now recommend it to others of similar taste. 

And last but not least! Maybe it was because I was never in the "in-crowd" proper of the rationalist-online sphere, but it seems that Hannu Rajaniemi has been in the same causal memetic space of people like Eliezer Yudkowsky, LessWrong, and definitely the Transhumanist/Singularity crowd. The aforementioned 'Coherently Extrapolated Volition' thing (plus the Newcomb's Paradox) were dead giveaways. There seems to be a confluence of interests in these communities and the sci-fi I like to consume and download into me, and last time this happened occurred many years ago when I was reading a bunch into E.T. Jaynes, Bayesianism, and the philosophy of mathematics, from which I am quite thankful for. Honestly, I'm pretty curious now as to whom influenced whom? It is rather spooky the coincidences and similarities I see, and I really find it interesting as to how this memetic-space of ideas was woven. Was this just a Bay Area phenomenon? Did it have roots in earlier common sci-fi influences? Is there like a secret society somewhere (and if so, how do I gain admission 😅)? I mean, I'd like to have some knowledge of the Great Game too!

Anyways, this trilogy ends with high praise from me and bittersweet feelings now that I've completed them. Thank you Rajaniemi :)

A follow-up to The Quantum Thief and The Fractal Prince is set in a post-human future and reveals the ultimate fates of gentleman rogue Jean de Flambeur, his employer Miele and the independently minded ship Perhonnen. 20,000 first printing.