Edge has a fascinating, discursive new interview with the renowned philosopher-of-mind Daniel C. Dennett. As someone who has a deep distrust of the popular metaphor that portrays the brain as a computer, I was struck by something Dennett says near the start:
“The vision of the brain as a computer, which I still champion, is changing so fast. The brain’s a computer, but it’s so different from any computer that you’re used to. It’s not like your desktop or your laptop at all, and it’s not like your iPhone except in some ways. It’s a much more interesting phenomenon.”
Normally, the explanatory power of a metaphor comes from describing a thing we don’t understand in terms of a thing we do understand. But this brain-as-computer metaphor now seems to be diverging from that model. The computer in the metaphor seems to be something very different from what we mean when we talk about a “computer.” The part of the metaphor that is supposed to be concrete has turned into a mystery fluid.
The brain is like a computer!
Cool. What kind of computer is the brain like?
It’s not actually like any computer that’s ever been invented.
So what kind of computer is it like?
It’s like the unique form of a computer that we call a brain.
So the brain is like a brain?
It sounds like it’s time for a new metaphor.
The new explanatory metaphor Dennett is proposing, or at least playing with, doesn’t sound much at all like a digital computer, even if there’s computation of some sort going on:
“We’re getting away from the rigidity of that model, which was worth trying for all it was worth. You go for the low-hanging fruit first. First, you try to make minds as simple as possible. You make them as much like digital computers, as much like von Neumann machines, as possible. It doesn’t work.”
The new metaphor, like the brain itself, is much more interesting:
“Each neuron is imprisoned in your brain. I now think of these as cells within cells, as cells within prison cells. Realize that every neuron in your brain, every human cell in your body (leaving aside all the symbionts), is a direct descendent of eukaryotic cells that lived and fended for themselves for about a billion years as free-swimming, free-living little agents. They fended for themselves, and they survived.
They had to develop an awful lot of know-how, a lot of talent, a lot of self-protective talent to do that. When they joined forces into multi-cellular creatures, they gave up a lot of that. They became, in effect, domesticated. They became part of larger, more monolithic organizations. … [B]ut in the brain I think that (and this is my wild idea) maybe only in one species, us, and maybe only in the obviously more volatile parts of the brain, the cortical areas, some little switch has been thrown in the genetics that, in effect, makes our neurons a little bit feral, a little bit like what happens when you let sheep or pigs go feral, and they recover their wild talents very fast.
Maybe a lot of the neurons in our brains are not just capable but, if you like, motivated to be more adventurous, more exploratory or risky in the way they comport themselves, in the way they live their lives. They’re struggling amongst themselves with each other for influence, just for staying alive, and there’s competition going on between individual neurons. As soon as that happens, you have room for cooperation to create alliances, and I suspect that a more free-wheeling, anarchic organization is the secret of our greater capacities of creativity, imagination, thinking outside the box and all that, and the price we pay for it is our susceptibility to obsessions, mental illnesses, delusions and smaller problems.”
A pack of feral pigs going rogue in a jailhouse: Now, that sounds a lot like my brain. Much more so than does an iMac running Microsoft Office.
As Dennett acknowledges, one of the main reasons we need to rethink the old brain-as-computer metaphor is that it doesn’t mesh well with recent discoveries, made by scientists like Michael Merzenich and Alvaro Pascual-Leone, about the brain’s “tremendous plasticity”:
“The way the brain spontaneously reorganizes itself in response to trauma [or] just novel experience is itself one of the most amazing features of the brain, and if you don’t have an architecture that can explain how that could happen and why that is, your model has a major defect. I think you really have to think in terms of individual neurons as micro-agents, and ask what’s in it for them?
Why should these neurons be so eager to pitch in and do this other work just because they don’t have a job? Well, they’re out of work. They’re unemployed, and if you’re unemployed, you’re not getting your neuromodulators. If you’re not getting your neuromodulators, your neuromodulator receptors are going to start disappearing, and pretty soon you’re going to be really out of work, and then you’re going to die.”
Yes, the metaphor is mixed. But wouldn’t it have to be?
Our understanding of complex, mysterious things always proceeds from metaphor to metaphor. The moment a metaphor changes is an exciting moment because it opens new perspectives that the old metaphor foreclosed.
Photo by jennystiles315.