䷊ Finding Purpose
We’ve already seen that in as much as consciousness is connected with meaning, we have correlates but not a recognized robust model. In biology Searle saw a path already tred.
Well I have another analogy I like to use and that is the history of the debates about life. There was a time, not all that long ago, a century ago when probably near this very spot people debated passionately about the question, can you ever give a scientific account of life? Can you ever give an account of how matter could become alive? Now we can’t feel those passions anymore. That problem has been in large part solved. With understanding the replication of DNA and RNA, we have a pretty good understanding of the biochemical basis of life. We no longer feel that as an issue. And what I’m suggesting is that as our understanding of the brain improves — and we are making progress, I mean I don’t want to give you the idea that we don’t know anything, we know quite a lot — as understanding of the brain improves, I believe that the problem of consciousness as somehow a deep metaphysical problem will be treated as a scientific problem like any other and will be solved in the same way that the problem of life was solved.
Let me introduce Blaise Aguera y Arcas. He’s been reviewing that biological path and pondering where we go next.
In the old days, in the 19th century, we used to think that to be alive meant that there was some vital spirit or vital force that living things have and dead things don’t. And as we started to figure out that the laws of chemistry were the same for living things and dead things, and urea can be synthesized in a test tube and so on, those ideas really went out of fashion. And we went into a very strict materialist kind of perspective where everything is just physics. I was trained as a physicist. I think I believe in physics fully. But I also think that there is more to life, in the sense that if everything is just physics, then you have no way of saying what it means for you or me to be alive. And to understand what that is, what it means to be alive, I think you have to come to grips with the idea of purpose. You have to bring teleology back into the equation.
From my philosopher armchair, I shout:
Life turns efficient cause into final cause! Random motion takes on purpose! Organic molecules don’t just do something, they’re for something! They have specific functions within systems! They mean something!
Arcas notes that von Neumann had a feel for what life requires before relevant discoveries were made.
What von Neumann realized is that in order for self-reproduction to work, you had to have inside yourself a tape with instructions for how to build yourself. And you had to have what he called a universal constructor, which was a machine that would walk along the tape and execute the instructions in order to make whatever is written there. And you had to have a tape copier, a second machine, and the instructions for building the universal constructor and the tape copier had to be on the tape. If all of those things were true, then you would have something that could reproduce. He made all of those predictions in 1950 – before we had discovered the structure and function of DNA, which is indeed exactly that tape, before we had found the ribosome, which is the universal constructor, and before we had discovered DNA polymerase, which is that copier. He was exactly right. But the really cool thing is that he also showed that the universal constructor is a universal Turing machine. They’re one and the same. It’s just a universal Turing machine where the things that it computes with are the actual matter that it is made out of. So it’s an embodied computation. And with that, von Neumann proved that in order to have life, you have to have universal computation. You can’t reproduce without computation. No computation, no life.
We’re probably in a suitable situation now to realize requirements for minds similar to what von Neumann did for life. And we can expect neuroscience to catch up in a few years.
Notice that understanding DNA, ribosomes, and the cell tells us all about how life works now. What about origins? My high school biology only vaguely indicated that some complex organic molecules arise spontanously. With lightning! How do they get organized? How does life get going in the first place?
Arcas looked to model the orgins of life, not with chemicals, but more simply and abstractly starting with random BF programs.
The trick is that we began with a soup of tapes. These tapes are a fixed length, length 64. And rather than just running one tape, tapes are actually run in pairs. So you grab two tapes out of the soup, and you stick them end to end, and you think of that as the tape, and you run it. Everything is self-contained, so it could modify itself. Then you break those tapes back apart, and you put them back in the soup. And that’s it. And you do that over and over. … There’s no fitness function. In other words, there’s no specific function that is saying any tape is better than any other tape. You’re just plucking them out of the soup, sticking them end to end, running, putting them back, and repeating millions of times.
Like chemicals bouncing off each other.
In the beginning, there are about two operations run per interaction and nothing much happens and it looks boring unless you look very closely, but we didn’t look closely till later. And then at some point, a few million interactions in typically, everything will start to change, and it’s very, very sudden. On my computer, when I first ran this, things were scrolling by really fast and suddenly the scrolling stopped and it was going chunk, chunk, chunk and the fan turned on – suddenly a lot of computing was happening. The number of operations running per interaction just leaps from very small numbers to thousands, and if you look at the contents of the tapes, suddenly they are full of instructions. They’re dense with instructions and they’re very complex and moreover, they’re replicating. You find a bunch of copies of different programs and these programs are interacting in complex ways. It’s really quite dramatic.
Quite dramatic!
What’s so cool about this experiment is that it really shows you how life emerges from nothing. And the emergence of life is, in some sense, the emergence of purpose. In this case, what is the purpose of one of these programs? Well, it is to reproduce. If you were to mess with one of those bytes, if you were to change it, you would, in most cases, break the program. And when you break the program, it no longer functions to reproduce. So something that can break is something that is functional or that has purpose.
From nothing? What magic is this? There must be something special. Maybe something subtle?
The thing is, in von Neumann’s model of computation, which is based on cellular automata — based on grid worlds — there is something a little bit new in that conception of computation that isn’t there in Turing’s model, where there is a head that can move back and forth on a tape reading and writing symbols. That’s true, but the thing is, the tape and the head are not made of symbols. So there’s not any sense in which the computation can kind of eat its own tail and generate itself. Whereas in von Neumann’s version of computation, these grid worlds, a computer can literally make another computer. It can copy itself. In other words, it’s embodied. And that is how life works. It’s how life has to work even in order to reproduce. Its states involve the manipulation of the matter that it is itself made out of.
Something something feedback.
Turns out von Neumann computers left to run are a right relevant mechanism for evolution. There’s nothing special about BF among programming languages: Arcas and friends have tried others. A salted-envelope calculation suggests organic molecules are way worse or maybe other special conditions are required. After all, your phone is a von Neumann computer and the bugs aren’t multiplying. I mean they are, but the bugs… the bugs… look, the dominant evolutionary pressure on your phone is called enshitification, and I better not talk about the leviathans responsible for that today.
I remember, a long time ago, an evolutionary biologist friend made the point that most of life’s history on Earth is about evolutionary processes getting better at evolving. He may have been talking about bacteria, pointing out that their evolution is anything but random, and that their DNA is better understood as grandma’s old-world cookbook stuffed with index cards from who-knows-where than as a rigorous set of blueprints.