6 Jun 2009
The Ghost in the Machine
There are countless ingredients that make up the human body and mind, like all the components that make up me as an individual with my own personality. Sure, I have a face and voice to distinguish myself from others, but my thoughts and memories are unique only to me, and I carry a sense of my own destiny. Each of those things are just a small part of it. I collect information to use in my own way. All of that blends to create a mixture that forms me and gives rise to my conscience.
(from the film “Ghost in the Shell”)
Do we need the Mind-Body Dualism ?
The phrase “ghost in the machine” was introduced by the British philosopher Gilbert Ryle (1900-76) to criticize René Descartes’ mind-body dualism. It was mentioned in Ryle’s book “The Concept of Mind” (1949) to highlight the perceived absurdity of dualist systems like Descartes’ where mental activity carries on in parallel to physical action, but where their means of interaction are unknown. Ryle argued that there is no hidden “ghost” entity inside the body.. It is quite ironic that Gilbert Ryle, who coined the term “a ghost in the machine” actually dismissed the idea of a ghost, soul or self altogether.
One generation after Ryle, his scholar Daniel Dennett makes exactly the same argument in his popular book “Consciousness explained” which was published 1991, fourty years after Ryle’s book “The Concept of Mind”. There are too many philosophers who still cling to century old ideas, and too little philosophers who try to express the mind in terms of modern neuroscience. How many say that a mental state is just an activation pattern or profile in the neural networks of the brain?
Similarly, Richard Dawkins says in his god delusion book that god does not exist. In principle, the claims from Ryle, Dennett and Dawkins contain some truth, but this does not mean that we don’t need the concepts at all, as I wrote earlier about the evolution of religions. Similarly, Steven Pinker says we don’t need the term soul in the sense of a ‘Ghost in the Machine’, which reads the TV screen of the senses and pushes buttons. Yet the idea of a soul is so old, that there must be some value to it. It provides guidance and comfort in a chaotic world. And it helps making sense of incredibly complex items acting in a complex world. Rather than to explain how the behavior results as the product of physical processes in the brain, which consists of a 100 billion neurons connected by 100 trillion synapses, it is more useful to explain social systems and processes, and it is the basic byproduct of acquiring self-consciousness. Without this convenient illusion, no one of us would really be sure of the own existence.
The idea of dualism is well-known and goes back to Plato. Plato argued that, as the body is from the material world, the soul is from the world of ideas and thus immortal. He believed the soul was temporarily united with the body and would only be separated at death where it would then go back to the world of forms. As the soul does not exist in time and space like the body, it can access universal truths from the world of ideas. In principle, Plato has got it right.
Religions picked this idea up and developed it further, maybe a bit too far. Most religions claim that immortal souls occupy an independent “realm” of existence distinct from that of the physical world. There is some truth in this claim (but also a big deception). Others argue that there are no souls at all and there is some truth in this claim, too. Although a soul is not a physical substance and a mind does not exist in space, the idea of a soul or mind is a good abstraction or first-order approximation of the existing complex physical system. Ryle is right there is no hidden unified entity called “the mind” inside the physical system called “the body”. But there are distributed parts of “the mind” which are implemented in the connections of the neurons. The work of the mind is not an independent mechanism which governs the work of the body, because the mind is “implemented” or hard-wired in the body.
An organization, company or university can have a ‘soul’, too. A complete university is not only consisting of the buildings, libraries, and campuses, it includes and encompasses also the staff, students, standards and traditions. There are indeed completely different worlds, for example the world of biological, mathematical, alphabetical objects which belong to different worlds (mathematics, biology, language, etc.). Mathematics is pure abstract “mind stuff”. The elements and entities of each world can exist independently from each other. To be human means to be a mixture of two worlds, the biological and the cultural. This is the dualism Descartes has observed: life/culture, matter/mind, material/virtual subtance, physical/mental form, body/soul, unique composition of genes/memes, molecules/ideas and thoughts.
The two substances from Plato and Descartes correspond to two different evolutionary systems, the complex adaptive systems which are based on genetic and memetic replicators. Genes give rise to genetic bodies with a physical form, strength, appearance, and certain physical properties: skin and hair color, height, etc. Memes encode memetic bodies or minds with a personality, experience, knowledge and particular mental properties: kindness, openness, personality, ..
In the book “The Self and Its Brain” by Karl R. Popper and John C. Eccles (Springer, 1977), Karl Popper argues that a trialism is better than a dualism: he says the mind-body problem becomes clearer if we introduce a tripartite division in three distinct worlds, the real or material world 1 of the physical environment, the neural world 2 of the brain where neural assemblies live and interact with each other in the different sensoric and motoric systems, and the immaterial or abstract world 3 of the mind where stories, ideas, and theories live. The concept of the self arises from a combination (or collision) of all three worlds.
It is not the mind-body dualism itself which is completely wrong (although a trialism may be better to describe the phenomena), it is the “THE SELF IS A PERSON” metaphor associated with self-consciousness which causes many of the difficulties and inconsistencies. The mind-body dualism is the right choice if we want to describe someone in terms of systems. And it is much better than nothing, as long as we don’t understand the whole neural dynamics underlying complex behaviors. Even the mysterious mind-body connection is not as elusive as it might appear to be.
The mind-body connection I – The Emotions
One major problem with dualism was the question of causal interaction: how can an immaterial mind interact with a physical entity? How is it possible that a mental substance arise out of physical substance, and how can neurons and interactions between neurons give rise to something completely different which “hovers” over the brain? In short, how does the ghost fit into the machine? Philosophers since Descartes found it difficult to find an explanation. Well, the solution is simple, and everyone knows it. Every child knows it. In principle, babies know nothing else.
Usually two independent worlds remain independent from each other, even if one (virtual) world is embedded in a another (real) world. The mind is simply what the brain does, but neurons alone do not produce minds on their own. Our “minds” are made of ideas and experiences – stuff which came from the outside by adaptation and learning, and which did not arise out of some mysterious physical interaction. Our bodies are made of physical stuff, which came from the outside, too. Both worlds remain independent. To affect each other, there must be some kind of interface, adapter or connection, where parts of one world are mapped to parts of the other world. In a 1-1 mapping we would have a kind of mirror, where the systems reflect each other.
These connections exist in animals, there are indeed points in all motile biological live-forms where the body and soul are connected. To major points are pain and pleasure, which happen at the connection between both worlds. Pain is an unpleasant mental event which describes a physical event which is “bad” for the body, an event where the physical integrity of the body is violated or where the resources of the body are depleted. The loss of physical integrity is mirrored by a loss of neural information flow.
Pleasure is the corresponding opposite point. It is a pleasant mental event describing a physical event which is “good” for the body, where the integrity of the body is restored or where the resources of the body are replenished. We derive pleasure from gain of new knowledge in form of insights and gain of new nutrients by food intake. The gain of physical integrity is mirrored by a gain of “neural information flow”.
Pleasure and pain turn objective information into subjective experience. They are two fundamental attributes which are controlled by the brainstem and the limbic system. The limbic system in general serves as a connection between the world of immaterial ideas and the world the material body. Each state of the limbic states is associated with a certain abstract state, action and basic behavior rule (good – do it, bad – don’t do it, danger – flight or flight, etc.). The body states are controlled by neuromodulators and hormones. It is no accident that the limbic system is situated at the border of the cerebral cortex, between the cortex (where the mind is ’embedded’) and the rest of the body. It is the basic connection between mind and body. As an example, consider a thought which arises strong emotional reactions. Usually the thought of something will not deliberately alter the physical state of a body part. The pure thought of Miss Universe in tight clothes could do it without doubt..
If we “give the emperor what belongs to the emperor, and God what belongs to God”, then the remaing interactions turn out to be simple. The fundamental connection between body and soul is not that mysterious at all, and we all know it well since the time we were born. As we grow older, we become aware of ourselves, and things become confusing. We experience that somehow we are able to direct the course of events. How is this possible?
The mind-body connection II – The Self
The metaphors “THE MIND IS AN ENTITY”, “THE SELF IS A PERSON” or “THE SOUL IS AN ACTOR” are conceptual mappings from the social to the “mental” realm. A fundamental feature of metaphors is the insight they provide by understanding one thing in terms of another. This metaphor allows us to understand ourselves as coherent and consistent entity: the self is identified with a single, unique entity which has a voice (the inner voice), the opinion to choose between different actions (the free will), and the ability to formulate thoughts and to make decisions. It offers a crude explanation why thinking is like silent talk and talk like loud thinking, and why we don’t only experience that certain events are occurring, but are also able to direct their course. And it allows us to act deliberately and consciously: instead of being controlled by many spirits (in form of words and commands we hear in your head), one is only controlled by one spirit, the creator of the inner voice and the own train of thought.
Yet there is a price, because another feature about metaphors is that we must tolerate inconsistencies. This double aspect of metaphors is partly responsible for the puzzling feeling caused by self-consciousness, since there is no homunculus inside our brains that controls all thoughts and actions. The neural representation of yourself is distributed among billions of neurons over the entire cortex. This is the part of the “THE SELF IS A PERSON” metaphor which is inconsistent.
Each metaphor describes only an aspect of the real situation, in reality the structures, processes, and interactions are much more complex. In reality there is no mental self except the abstract idea, and there is also no mysterious downward causation from the mind to the body. Yet most of us think they can consciously influence the activities and movements of our body. Who is causing these activities if there is no downward causation? We experience that certain events are occurring, and that we are able to direct their course. The question is why do many of us have the belief that they can move their body in a certain direction if they want to do it voluntarily or consciously? The belief must be based on a perception of a process or interaction. If downward causation is like self-consciousness an illusion, then what kind of stimuli or causal chain precedes a conscious action?
Analyzing neural dynamics underlying complex behavior is still a major challenge in neuroscience and systems neurobiology. The situation may be roughly like this: there are areas inside the somatosensory cortex which are an exact representation of the human body, and these areas are indeed called homunculus. The primary somatic sensory cortex and the primary motor cortex contain a complete neural representation of the physical body, where the cortical arrangement reflects the organization of the body: foot, legs, trunk, arms, elbows, wrist, fingers, and face are represented.
There is a mind-body interface, BUT there is no central self which controls our bodies through this interface. Our intentions which are distributed among many neural assemblies control our low-level behavior, and this low-level behavior which is encoded in the primary motoric regions of the cortex and triggered by the input from the environment controls our body to the mind-body interface.
What kind of stimuli or causal chain precedes a conscious action? The answer is maybe a complex interaction of several causal chains and circuits:
- There is causal chain from the outer world to the brain and back (including the internal stimuli-response or perception-action loop)
- There is a causal chain inside the body from the primary sensoric and motoric regions of the brain to the corresponding body parts
- There is a causal chain inside the mind from the high-level level goals and abstract intentions to the low-level actions and concrete behavior patterns
Now a mental thought occurred, a physical activity of the body happened, and afterwards we witness it. Has the mental thought triggered the physical action? The causal chain which precedes a conscious action goes roughly like this
- The mind formulates an intention and selects a goal, according to the current beliefs and desires (for example “i want to reach a certain region”), which is a complex process itself. Formulating beliefs and intentions belongs to the higher mental processes, but these processes are occur in general automatically without conscious choice or guidance (see this Paper from Bargh and Ferguson On the Automaticity of Higher Mental Processes).
- The body is in a certain state and environment
- The mind perceives the current situation
- The mind triggers a certain action suitable for the current situation and the current goal
- The body is in a new state
Here conscious action is possible through modulation of the causal chain from the outer world to the brain and back according to the current intention. The combination of external stimuli and internal intentions results in the behavior which is experienced as conscious behavior, although it was the intention (and not the self or some conscious process) which caused the modulation of the stimulus-response stream. In agent architectures this is described usually as a perception-reason-action or belief-desire-intention loop. The illusion of downward causation seems to arise through a fundamental attribution error and an interaction of several causal chains.
As explained in the paper Intentionality is the Mark of the Vital from Nicholas S. Thompson and Patrick Derr, it seems to be unnecessary to reconcile the mental with the material if we consider the mental as intentional. It considers the simple case where A did D because A desired (wanted, believed..) [x]. For example I can move my arm because I want to reach a jar of cookies. Here it is the intention to eat the cookies which controls and guides the behavior. It is the intention [x] which causes a kind of downward causation to low-level behaviors inside the mind (from the prefrontal cortex to the premotor areas and the primary motor cortex). Intentional explanations may be the best way to describe the elusive nature of “mental” operations in a biological system: we are able to select certain intentions, and our intentions are able to direct our behavior.
One common view is that mind and body belong to two different realms, fused together in each person like a ‘ghost in the machine’. The view is not completely wrong, and still useful, as long as we have nothing better which can replace it.
If we consider the brain as a giant neural network, where is the connection between mind and body located? First of all in the oldest region of the brain, the brainstem and the limbic system. As we have seen, the limbic system and the emotions are a fundamental interface between mind and body. There is a second interface between mind and body, but no central self which controls it. This mind-body connection resides in the areas of the cortex which have a direct connection to the body, for instance the primary motor cortex and the primary somatosensory cortex.
If we look at the body, we find pure body cells, which act from body to body, for exampe red blood cells. If we look at the higher regions cerebral cortex, where perceptions turn into beliefs and actions into intentions, we find the neurons responsible for abstract reasoning. These are pure “mind” cells, neurons that are connected to other neurons which act from “mind to mind”. In between are the cells and substances which connect mind and body: hormones, the pheromones of the body, neurons of the primary sensory regions (from body to mind) and neurons of the primary motoric regions (from mind to body).
We have seen that conscious and deliberate behavior through this second interface is possible, but it is caused by a complex interaction of several causal interaction chains controls and not by a central self. Intentional explanations may be the best way to describe the elusive nature of “mental” operations in a biological system.
Finally these connections deliver an answer to Descartes’ old question: How can the mind, something non-spatial, inhabit / interact with / influence something spatial, the body? How can a non-physical thinking substance have an impact on the physical world? The interfaces and connections we have considered suggest the following conditions must be fulfilled: a non-physical thinking substance can have an impact on the physical world, on the body, if it is embedded in the physical system, and if there is an interface with a suitable mapping where parts of one system are mapped to parts of the other system.