The question is, what happens to your ideas about computational architecture when you think of individual neurons not as dutiful slaves or as simple machines but as agents that have to be kept in line and that have to be properly rewarded and that can form coalitions and cabals and organizations and alliances? This vision of the brain as a sort of social arena of politically warring forces seems like sort of an amusing fantasy at first, but is now becoming something that I take more and more seriously, and it's fed by a lot of different currents.A bit later:
It's going to be a connectionist network. Although we know many of the talents of connectionist networks, how do you knit them together into one big fabric that can do all the things minds do? Who's in charge? What kind of control system? Control is the real key, and you begin to realize that control in brains is very different from control in computers. Control in your commercial computer is very much a carefully designed top-down thing.That’s the problem David Hays and I set ourselves in Principles and Development of Natural Intelligence (Journal of Social and Biological Systems 11, 293 – 322, 1988). While we had something to say about control in our discussion of the modal principle, we addressed the broader question of how to construct a mind from neurons that aren’t simple logical switches.
It is by no means clear to me how Dennett, and others of his mind-set, think about the mind. Yes, it’s computational. I can deal with that. But not, as I’ve said, if it’s taken to mean that the primitive operations of the nervous system are like the operations in digital computers, not if it’s taken to imply that the mind is constituted by ‘programs’ written in the ‘mentalese’ version of Fortran, Lisp, or C++. THAT was never a very plausible idea and the more we’ve come to know about the nervous system, the less plausible it becomes.
The upshot is that we need a much more fluid, a much more dynamic, conception of the mind. In Beethoven’s Anvil I talked of neural weather. Here’s how I set-up that metaphor (pp. 71-72):
Thus far we have considered the states of the brain, intentionality, coupling and timing, all while examining the nervous system as a physical system. We can no longer avoid the mind/body problem. I want to approach to this problem in the manner of Gilbert Ryle’s The Concept of Mind. Rather than wonder how the mysterious and ineffable mind can connect with the mysterious but concrete brain, I propose a definition:It’s a simple point, but think about it. The brain is a complex physical system consisting of billions of neurons arranged in a rich and complex structure of functional units. Not only that, but those “coalitions and cabals and organizations and alliances” Dennett talks about change on varying time scales, from seconds to days and months. Mental structure is thus quasi-fluid.Mind: The dynamics of the entire brain, perhaps even the entire nervous system, including the peripheral nervous system, constitutes the mind.The thrust of this definition is to locate mind, not in any particular neural structure or set of structures, but in the joint product of all current neural activity. As such the mind is, as Ryle argued, a bodily process; in the words of Stephen Kosslyn and Olivier Koenig, “the mind is what the brain does.” Whether a neuron is firing at its maximum rate or idling along and generating only an occasional spike, it is participating in the mind.
In asserting this I do not mean, of course, to imply that there is no localization of function in the brain. There surely is. But the mind and the brain are not the same thing, though they certainly are intimately related, as are the dancer and the dance. The fact that the dancer is segmented into head, neck, trunk, and limbs does not mean that the dance can be segmented in the same way. Similarly, we should not think of the functional specialization of brain regions as implying a similar specialization of the mind. It is not at all clear that the mind has “parts” in any meaningful sense.
Back to Beethoven’s Anvil (pp. 72-74):
If the functional proclivities of a patch of neural tissue are not relevant for a current activity, those neurons will not be firing very often, but they will still generate some output. The only neuron that does not generate any output is a dead one. Neurons that are firing at low intensity one moment may well be recruited to more intense activity the next. As Walter Freeman has said, a low level of activity is still a means of participating in the evolving mental state.
The mind, in this view, is thus like the weather. The same environment can have very different kinds of weather. And while we find it natural to talk of weather systems as configurations of geography, temperature, humidity, air pressure etc., no overall mechanism regulates the weather. The weather is the result of many processes operating on different temporal and spatial scales.
At the global level and on a scale of millennia we have the long-term patterns governing the ebb and flow of glaciers which, in one commonly accepted theory, is a function of wobble and tilt in the earth’s spin axis and the shape of the earth’s orbit. At the global level and operating annually we have the succession of seasons, which is caused by the orientation of the earth with respect to the sun as it moves through the year. We can continue on, considering smaller and smaller scales until we are considering the Center or even the breeze coming in through your open window and blowing the papers off your desk.
Weather is regular enough that one can predict general patterns at scales of hours, days, and months, but not so regular that making such predictions is easy and routinely reliable. Above all, there is no central mechanism governing the weather. It just happens.
The flow of information on the internet is much the same. Individual computer users can choose to send messages, send or download files, “surf” the web, and so forth. These decisions send packets of bits flowing through the internet. The specific paths taken by these packets, however, are determined by routers and gateways that are widely distributed. There is no command center regulating overall message traffic on the internet. The global state of internet traffic at any given time is the net effect of independent decisions by many thousands of human and electronic agents.
So it is with the brain. The overall state is not explicitly controlled, at least not at a high degree of precision. Rather, that overall state reflects activities at various levels within the whole system. At the smallest level we have the individual neurons. Neurons are living cells and, as such, act to maintain their existence. Individual neurons, in turn, are grouped into functional units at several levels, with many neurons connected to others at distances ranging from fractions of a millimeter to several centimeters or more. Many of these functional units are coupled together into systems that explicitly control something else—whether it be another system within the nervous system, or something external to it, either elsewhere in the body (the muscles or the viscera) or in the external world. But there is no component of the brain that regulates all of this activity in detail. The overall activity just happens. That overall activity is what I am calling the mind.
Some of the activity may be conscious, some unconscious. Some activity may, in principle, always be outside the reach of consciousness. And, as psychologists from William James to Eleanor Rosch have noted, the “contents” of consciousness certainly vary from moment to moment. No matter, it all contributes to the global state of the nervous system, to the mind. Nor should we think of this division between conscious and unconscious activity as two “parts” of the mind. It simply denotes two different kinds of activity. Just where these are located in the brain is likely to shift from moment to moment.
As a practical matter, many microscopically different states of mind are macroscopically the same. This is true of weather as well. The weather near my apartment while I type this varies from one fraction of a second to the next. The positions, velocities, and directions of air molecules are constantly changing. Each individual change, no matter how small, constitutes a change in the microscopic state of the system. However, for almost all practical purposes, the macroscopic state of the weather is the same from minute to minute, if not hour to hour. Thus the current temperature is about 52 degrees Fahrenheit, it is sunny, there are no clouds in the sky and the wind is calm. The number of microscopic states that fit that macroscopic description is quite large, but we can consider them the same.
So it is with states of mind. For some purposes ordinary wakefulness and dream sleep are perfectly good characterizations of states of mind. Later on we will examine work by J. Allen Hobson aimed at explaining such states. Bette Midler’s heartfelt song and Leonard Bernstein’s ego loss are also macroscopic states of mind. Each is like a macroscopic state of weather, cool and sunny, hot with thunderstorms, etc. Each of these macroscopic states encompasses untold different microscopic ones. The range of things flitting through one’s mind in ordinary wakefulness is, well, mind-boggling. But no less so than what can happen during dreams. Similarly Bernstein can be as lost in a Mozart symphony as in a Stravinsky ballet. Macroscopically the states are the same; microscopically they are not.
But whereas macroscopic states of wakefulness and dreaming recur regularly through the day and seem to be largely under the influence of a particular set of brain mechanisms deep in the core of the brain (concentrated in the reticular formation), we have no reason to believe that Bernstein’s ego loss or Midler’s song is under the strong influence of any particular neural mechanism. It just happens.