Finally we come to the penultimate chapter of the book and the primary aim of the book. How does all of this relate to the mind and the brain? Ellis says “The main claim will be that one cannot begin to understand the brain properly without taking top-down causation into account…This is top-down causation from the social milieu to detailed aspects of brain structure.” He intends to show that just as in all the other examples given in this book so far, the brain is a combination of bottom-up and top-down causation. In this way, “physics can underlie the extraordinary nature of the functioning of the mind.” He underscores however that he is not claiming to have solved the problems of free will or of consciousness but rather to have outlined critical features that any such approach must include.
His view of the organization of the brain is summarized in this table:
Ellis emphasizes the role that symbolism and language, purpose and meaning, and our system of values and ethics plays in affecting our brain which in turns affects our higher level decision process and actions. He also notes that “The mind can discover unchanging eternal relationships and possibilities that were always there and exist independently of the human mind: that is, they can reasonably be called Platonic entities.”
Ellis embarks on a detailed description of the biology of the brain. A key point that he makes is illustrated by his quote of Alwyn Scott discussing the Hodgkin-Hawley equations that describe action potential in neurons: “One cannot derive these laws from physics and chemistry because they depend upon the detailed organization of the intrinsic proteins that mediate sodium and potassium current across the membrane and upon the geometric structure of the nerve fibres.”
In other words, this is genuine emergence. The physics and chemistry of the atoms and molecules within the neuron is constrained or bounded by higher level parameters from the environment. This is a true top-down causality with the emergence of new features that require new equations to describe.
“A key question, of course, is how the brain gets to be what it is…The primary point is that the brain is not developed in a predetermined way through genetic influences: rather it adapts to the environment in which it finds itself. Brain plasticity at the micro-level allows adaptation at the macro-level. This development is guided by experience, evaluated on the basis of the primary emotional systems.”
“Minds cannot be understood on their own: we have a distributed cognition that is not contained solely within the head of the individual…The human mind is unlike any other on this planet, not because of its biology, which is not qualitatively unique, but because of its ability to generate and assimilate culture, which provides us with symbolic tools such as language that then shape the way we see reality.”
“David Sloan Wilson remarks that the transition from bottom-up to top-down dominated causation in the relation of mind to the society in which it is imbedded is a major evolutionary transition in the historical development of humanity, resulting in the emergence of the social order as a higher level entity in its own right, and a consequent change in the nature of the evolutionary processes at work.”
“Interlevel causation, both bottom-up and top-down, is key to brain function. Evolution has selected for it to occur. The underlying physics is channeled and constrained to enable this to happen.”
“…this process faces a problem of infinite recursion: where does the next higher level of selection criteria come from? At some point we have to draw a line and say, this is where I stand: these are my founding principles, this is the purpose in my life. That is where one makes value choices based on one’s view of meaning…These are abstract ideas that shape what one does, and thereby act down to muscles, neurons, and genes, and on to electrons and atoms as we try to fulfil these goals and purposes.”
“[Consciousness] is an emergent property of a dynamic core of neurons. It is a higher level process enabled by the properties of the underlying neurons and genes, in turn enabled by the properties of the underlying molecules and physics, but it is not reducible to them, among other things because it is deeply meshed into ongoing interactions with the physical, ecological, social, and intellectual environment.”
The above selected quotes are just a small portion of the many that are worth reading and pondering. Ellis emphatically demonstrates the many ways in which top-down causation works in concert with bottom-up causation to create the mind. This is how physics underlies the mind. It is the bottom level that causes the higher levels to exist and to function. But that physics is constrained and guided by the top-down causation of the higher levels. He shows how the highest levels involve large-scale interaction with our environment—our peers, our culture, and even Platonic entities. In this way, the mind emerges from the brain, an awesome interaction both vertically and horizontally.