Neal Stephenson, Anatham ****

Anatham is a 900+ page science-fiction novel whose main theme is epistemology, how we know what we know. There is plenty of action — political intrigue, illegal polar immigration, love affairs, alien spacecraft — but the most pressing concern is whether our knowledge is metaphysically real or constructed in our minds. It presents the most interesting and convincing arguments for the existence of Platonic mathematical entities that I have ever read.

I also enjoyed the world that Stephenson builds on the planet of Arbre. Pure scientists live in convents and only have contact with the outside world once a year (or once a decade or once a century, depending on the order), to prevent their contamination by real-world politics. The details of the society were fascinating to me, although I could imagine others finding them tedious.

For a book so concerned with epistemology, it is ironic that its biggest flaw is that its characters jump to unwarranted conclusions that turn out to be true. It is a common plotting problem that I associate with Dean Koontz: a character learns some small fact, comes up with an outlandish explanation, and immediately starts acting as if that outlandish explanation is established fact ("the mutant child must be telekinetic!"). And it turns out to be right! A few such moments happen in Anatham, notably when our hero Fraa Erasmus and his girlfriend Suur Ala discover an orbiting object that changes direction as it passes across the sun. It must be an alien spaceship! What other explanation is possible? Well, actually, I can think of plenty that comport better with Gardan's Steelyard (to throw in some Arbre jargon).

Another flaw, also common to adventure books, is how the main character and his friends end up at the center of the world-shattering events. They are essentially teenagers, far less qualified than others for the tasks they are given. 

The story includes innumerable philosophical speeches, like an Ayn Rand novel. I imagine most people would identify this as the flaw that bothers them most. But you know, I kinda liked most of the speeches. I found them interesting enough that I could look past their minimal motivation in the story.

Despite these flaws, and despite the length, I enjoyed Anathem. I appreciated the combination of pulp action story with abstract philosophical debate.