(“Metatheorics”, I should say)
Most Neal Stephenson fans probably read his book Anathem last fall, but I just finished. There are many reviews available, so I won’t add one here, but I got a big charge out of some of the philosophical ideas Stephenson put in the book.
In the course of the novel, Stephenson proposes an interesting relationship between platonic truths, the multiverse, and human rationality/consciousness, which I have enjoyed comparing to my own ideas (discussion below the fold).
The main idea is that the platonic realm is not a single transcendent world out there, but rather the source of platonic ideas is to be found in the multiverse (called the “polycosm” in the book; the overall theory is called “complex protism” where protism=Platonism and “simple protism” would be the positing of a single platonic realm).
The core of this idea is one I endorse here in the non-fictional realm, and it was very cool to see it in the novel. Modal judgments about what is possible and what is necessary play a crucial role in our reasoning. At the same time, both philosophers and theoretical physicists have proposed that our world is one member of a set of many possible worlds. If we propose that the logical possibilities we explore with our minds are identical with real possibilities present in the multiverse, then the multiverse can be seen as the source of our rationality, and of our knowledge of abstract truths. (The philosophical term for the match-up between logically possible worlds and metaphysically possible worlds is modal rationalism).
But how does a human mind access the multiverse? First, let me note that the type of multiverse being proposed in the book is inspired by the many-worlds interpretation (MWI) of quantum mechanics (QM). So the solution is to have the mind exploit the quantum realm. There’s a dialogue between the characters Orolo and Erasmus (pp. 543-548) where they discuss how the presence of the same person’s brain in multiple adjoining and interfering worlds gives the brain access to possibilities. Stephenson’s characters later make the point (which I liked) that it isn’t that the human brain is the only thing which is in contact with possibilities; one should assume everything in the world experiences some contact, but it is in our own brains that we can best see the evidence manifested (pp. 690-92).
I’ve come at this in similar spirit, with one apparent difference when it comes to interpreting QM. I believe that our world is comprised of quantum measurement “collapse” events, which each embody the actualization of one of many possibilities. The fact that we humans are ultimately grounded in quantum-level events gives us a kind of direct acquaintance with possibilia in everything we do. That makes our ability to have modal knowledge intelligible, even though we don’t yet know the manner in which our brain/body system leverages this presumably micro-level contact into macro-level knowledge.
It appears Stephenson’s idea is to try to preserve the MWI (which attempts to do away with measurement events), while allowing contact between parallel worlds to be exploited by the mind. MWI would not typically be seen as allowing any contact. Also, usually in MWI, worlds branch (what we think of as a measurement is a splitting of worlds), whereas Stephenson wants to keep worlds in parallel. Of course, positing contacts between parallel worlds is very helpful for the creating the exciting parts of the novel which involve characters and spaceships moving between worlds.
The other aspect of Stephenson’s multiverse which is interesting is that the informational contact between worlds has a flow, where some worlds are upstream or downstream from one’s own world. It seems he places a single purely platonic world at the source of the information flow (whereas I would follow the usual philosophical tradition of identifying logical and mathmatically necessary truths to be those things true in all worlds). I’m not sure this makes sense or was philosophically motivated, but it was a neat twist.
There are allusions to many other philosophical and scientific ideas in the book, and Stephenson discusses many of the sources which inspired these in this acknowledgments page on his website. There’s more to follow up on there – one philosopher he discusses who I have not read is Edward N. Zalta.
[I have a number of old posts on related topics, including
Making Abstract Truths Intelligible
Modal Realism, Modal Rationalism
Multiverses -- Physical and Metaphysical]