Gazzaniga: Leibnitz raised the question almost 300 years ago with his analogy of the mill. Imagine that you can blow the mill up in size such that all components are magnified and you can walk among them. All you find are individual mechanical components, a wheel here, a spindle there. By looking at the parts of the mill you cannot deduce its function. The physical brain can also be broken into parts and their interactions examined. We now understand neurons and how they fire and a bit about neurotransmitters and so forth. But somehow the mental properties are indivisible and can’t be described in terms of neuronal firings. They need to be understood in another vocabulary.
This is sometimes called the emergent mind. Emergence as a concept in general is widely accepted in physics, chemistry, biology, sociology, you name it. Neuroscientists, however, have a hard time with it because they are suspicious that this concept is sneaking a ghost into the machine. That is not it at all. The motivation for this suggestion is to conceptualize the actual architecture of the layered brain/mind interaction so it can be properly studied. It is lazy to stay locked into one layer of analysis and to dismiss the other.
Cook: How does the mind constrain the brain?
Gazzaniga: No one said this is going to be easy and here is where the going gets tough. Picking up on the last thought the idea: we are dealing with a layered system, and each layer has its own laws and protocols, just like in physics where Newton’s Laws apply to one layer of physics and quantum mechanics to another. Think of hardware-software layers. Hardware is useless without software and software is useless without hardware.
How are we to capture an understanding how the two layers interact? For now, no one really captures that reality and certainly no one has yet captured how mental states interact with the neurons that produce them. Yet we know the top mental layers and the layers beneath it, which produce it, interact. Patients suffering from depression can be aided by talk therapy (top-down). They can also be aided by pharmacological drugs (bottom up). When these two therapies are combined the therapy is even better. That is an example of the mind constraining the brain.
Cook: And how does this idea of the mind and brain interacting bring you to your position on free will?
Gazzaniga: For me, it captures the fact that we are trying to understand a layered system. One becomes cognizant there is a system on top of the personal mind/brain layers which is yet another layer--the social world. It interacts massively with our mental processes and vice versa. In many ways we humans, in achieving our robustness, have uploaded many of our critical needs to the social system around us so that the stuff we invent can survive our own fragile and vulnerable lives.
Cook: You talk about “abandoning” the idea of free will. Can you explain what you mean by this, and how you came to this conclusion?
Gazzaniga: As I see it, this is the way to think about it: If you were a Martian landing on Earth today and were gathering information how humans work, the idea of free will as commonly understood in folk psychology would not come up. The Martian would learn humans had learned about physics and chemistry and causation in the standard sense. They would be astonished to see the amount of information that has accumulated about how cells work, how brains work and would conclude, “OK, they are getting it. Just like cells are complex wonderful machines, so are brains. They work in cool ways even though there is this strong tug on them to think there is some little guy in their head calling the shots. There is not.”
The world is not flat. Before this truth was realized, people use to wonder what happened when you got to the end of the earth-- did you fall off? Once we knew the earth was round, the new perspective, made us see how the old questions were silly. New questions also seem silly many times until a new perspective is accepted. I think we will get over the idea of free will and and accept we are a special kind of machine, one with a moral agency which comes from living in social groups. This perspective will make us ask new kinds of questions.