The Mystery of Consciousness: Introduction
Consciousness is perhaps the most fundamental unsolved problem in science.
Look at what you are experiencing at this moment.
You are aware of your body, perhaps sitting in a chair, staring at a computer screen.
As you read my words every few moments a competing emotion or sensation
flicks across the screen of your consciousness and distracts your attention.
And, this you are also aware of. Your eyes and attention flick back and forth
between the picture below and the words here.
Or consider this - you, eating a particularly good orange, savoring its sweetness,
its texture, the juice flowing onto your tongue and lips; or this - conversing with friends,
watching their faces, delighting in the dialogue but aware of subtle rippling of your emotions
as you react to their remarks and weigh comments that you consider making.
This is the most fundamental aspect of the human experience - conscious awareness
of self and the world around us: an external world filled with colors, sounds, and textures
and an internal world full of feelings and emotions.
Our capacity to do this defines the human experience. We do it; mice to a lesser extent;
fish, lesser still; trees – I say not; rocks, robots, and the internet - not at all (or so we surmise).
(The wonderful Icelandic landscape above is by Nathan Myhrvold, former CTO of Microsoft.)
Understanding consciousness was my holy grail when I was in my youth at MIT
and in medical school. How does it work? Can it be understood by simply knowing
enough neurobiology? Can it ever be designed into, say, robots? Or, are robots
and other AI projects
destined forever to be fancy clockwork machines devoid of feelings,
vision, and wisdom. (David Gelernter of Yale Computer Science says “robots are just clockwork.”)
Also, might their critical lack of feelings and compassion make it dangerous to build them?
Obtaining a true and complete understanding of consciousness is critically important
to a number of enterprises. First, it would revolutionize psychology and psychiatry
by placing them on firm neuroscientific ground. Second, it would advance the age-old
dictum to "know thyself." What could be more fundamental than knowing who you really are?
Third, it might finally settle key scientific questions concerning the real nature of
the subjective universe (the world as experienced by each of us) as opposed to
the objective world of atoms and physical forces.
Fourth, it might portend an era of consciousness engineering in which we might
if we chose) redesign our conscious selves (or our artifacts) to be more powerful,
more intelligent, more broadly integrated, more world-encompassing, and hence,
wiser and more compassionate. (Consciousness was the subject of a talk I gave
in 2010 at the recent San Francisco Bay Area AI colloquium (video online).)
Of note, one of the most prominent consciousness researchers was Francis Crick,
Nobel laureate and co-discoverer of DNA. Crick devoted the last thirty years of his career
to trying to discover the basis of consciousness, having switched from molecular biology to neurobiology.
At age 78 in 1994 Professor Crick published The Astounding Hypothesis, which relates
his general framework for investigating consciousness. In the very first sentence of the book he
“The Astonishing Hypothesis is that “You,” your joys and your sorrows,
your memories and your ambitions, your sense of personal identity and free will,
are in fact no more than the behavior of a vast assembly of nerve cells and
their associated molecules. As Lewis Carroll’s Alice might have phrased it:
“You’re nothing but a pack of neurons.”
Now, the Astonishing Hypothesis – let’s called it AH! – may strike you as it struck me –
not so astonishing or maybe even obviously true. What else could it be? We think and feel
with our brains, which are made of a vast assembly of neurons. What’s so astonishing about that?
I hope you’re in that camp, because, if you’re not, I’m not going to address your beliefs
in this, or possibly any, of my essays - except right here.
Here is the top-level argument that consciousness, thinking, and feeling
are mediated by
brains and only by brains (and NOT say a divine spirit that
comes to rest in you when you are born and that floats away when you die.)
1) In one minute by injecting an anesthetic into the appropriate nerves I can
make a painful finger, hand, arm, or foot totally disappear from awareness.
2) In less than one minute by injecting an anesthetic intravenously I can take you
from fully alert to comatose. 3) In patients injured by stroke, head trauma, or cancer
there is a tight correspondence between the part of the brain that’s injured
and a change in the person’s capabilities. 4) There is a reliable correspondence
between brain waves (eeg) and state of consciousness (alertness, deep sleep,
dreaming, coma). 5) At death the brain waves cease.
6) There is a reliable spatial and temporal correspondence between
various abilities, images, and thoughts with highly specific regions of the brain
with fMRI and other imaging methods.
Now, you might believe that consciousness exists prior to conception or after death.
Many people and religions espouse that view. Even some transpersonal psychologists
think that’s the case.
Or, you might believe in panpsychism – consciousness is everywhere
in the Universe, including the trees, rocks, water, and stars. Again, you would have
lots of company, including New Age folks and others of a spiritual bent. (I am also
of a spiritual bent, but not in the sense of free-floating apparitions - more in the sense of
a Universe that is inherently generative a la Thomas Berry or Teilhard de Chardin.)
Until the mechanism of consciousness is finally elucidated, who’s to stay
– you might argue – that a rock is not conscious or your computer is not conscious
or that your immortal soul survives the death of your body.
Yes, those propositions might be true, but as scientists we are committed
to reasoning based upon evidence. The evidence that I summarized above, as well as
thousands of neuroscience studies confirm the Astonishing Hypothesis – you’re a pack of neurons!
Get used to it! (but see below - you are also a soul!)
Please note, however, that I don’t really mean just a pack of neurons.
1) The fact that the nervous system is intimately connected to the body and
that the body is situated in the world is hugely important.
2) The phrase pack of neurons is misleading – the actual number is about
one hundred billion neurons with a hundred trillion or more ( > 1000 per neuron).
3) The notion of a synapse as just an on/ off switch is obsolete. According to Stanford
neuroscientist Stephen Smith, each synapse is more like an entire microcomputer
with a kilobit of memory. So, the brain may perhaps be more comparable to the entire internet.
Pack of Neurons vs Soul: Emergence
And now for an almost 180 degree shift ...
When is a pack of neurons not a pack of neurons?
When it's a soul! (Here for the moment the equation is
soul = consciousness .)
Might that network of neurons be so vast and so elaborate that it would be
a gross conceptual error to identify the whole with the sum of its parts.
Yes! Consciousness is exactly that - a property that somehow EMERGES
from the operation of many parts and yet is quite distinct from them.
EMERGENCE is found many times in science
and in the history of the Universe. It most obviously occurs when atoms
bind together to form molecules. There is nothing in the properties of the gases
hydrogen and oxygen that would in any way suggest what the properties
of water might be. Water is completely different from the sum of its parts
despite being composed of only three atoms. Water is stunningly complex.
And, even water has emergent properties as its phase changes from ice
to water to steam.
It was only in 2007 that the properties of water were finally modeled.
Table salt - sodium chloride - is an even more dramatic example,
composed of one atom each of an explosive metal and a deadly gas
In more complex systems such as living matter the emergent properties
are even more unpredictable. While it is possible to model some aspects of
living systems with computers, modeling entire systems is not possible.
One well known example is the protein-folding problem. Every living organism
is made from proteins - long strings of amino acids. However, proteins can only work
if they are folded into precise 3D configurations (which they do themselves).
This process is so complex that it can only be modeled for small proteins
by the world's most powerful computers. Modeling the complete
function of an entire organism - like a bacterium - is just not possible.
When it comes to organisms with nervous systems, the complexity
that results from the multi-way interaction of billions of components is far
beyond current computational feasibility. As an example, the 1 millimeter
round worm, Caenorhabditis Elegans, has only 302 neurons and 6000 synapses
in its transparent body. The structure of its nervous system has been known
for two decades, and yet it has proven impossible to model and predict its behavior.
With human brains it is clear that multi-way, time-varying interactions
among its trillions of synapses are the norm. If emergence occurs in a
water molecule with its three atoms, the notion that consciousness = soul
can be reduced to "just a pack of neurons" seems exceedingly unlikely.
That does not mean that neuroscience is not making progress.
It does mean that it has a long ways to go.
Zombie vs Sentient: Do Atoms Have Feelings?
The real question, of course, is “how does consciousness emanate from
the workings of a pack of neurons?” Until we show how it actually happens,
some skepticism about the validity of the AH! may be justified.
Suppose neuron A fires neuron B, which, in turn, fires neuron C, etc. So what!
How and where does the actual seeing and feeling occur? Where does consciousness arise?
Entire collections of neurons in our bodies can fire, and we are completely unaware of them.
The thirty billion neurons in the cerebellum produce no imprint on consciousness whatsoever.
Similarly, millions of neurons may fire in the spinal cord or the gut of which we are unaware.
What is the purpose of consciousness? What does it do?
It is easy to imagine building a robot that does some or perhaps all of what we do
but which is totally unconscious. That is,
it works but there is "no one home."
It feels like nothing to be that robot.
That is David Gelernter's position,
and it is also mine. Enlightenment scientist Leibniz (co-inventor of calculus)
posited the same thing in 1714.
"Suppose we had a windmill whose construction enabled it to think, to sense,
and to have perceptions. Upon visiting this machine and walking around inside,
one would find only parts pushing one another and never anything to explain perception."
Philosophers regularly discuss the possibility of a zombie - a human being that
does everything we do but who completely lacks sentience.
The zombie does not see,
hear, feel, or have any emotions but otherwise can do everything we do. One can imagine
building that sort of robot - but a robot that actually sees and feels? How does one do that?
Furthermore, what exactly is consciousness - actual seeing, actual feeling?
Is it made out of atoms or electrochemical forces
or is it something entirely different?
Philosopher David Chalmers and neuroscientist Giulio Tononi say consciousness = information,
but what is that? Does that mean my computer might be conscious or my thermostat?
I briefly addressed the beliefs of those of a religious bent above.
However, more interesting to me than the religious stance is the stance and
skepticism of some of my friends who are engineers and scientists (not in brain science).
Their question is “how do we even know that consciousness is real?”
I know that I am conscious, but how can I ever show that YOU are conscious?
My scientist friends may also take the following tack.
Since consciousness is forever subjective, and therefore not objectively verifiable,
it cannot be attacked scientifically.
In the strictest sense they may be right. If my own consciousness is something
that only I can observe, then how can it ever be verified or measured?
My hunch is that as the neural correlates of consciousness become known
in greater detail the issue will become clearer. Meanwhile it seems to me that
1) the world of consciousness is all we really know directly; 2) that any description
of the world that leaves it out is glaringly incomplete; and 3) that this is at least
as important a scientific problem as
current attempts at grand unification of forces.
Our attempts to engineer consciousness
into machines will be stymied until
its nature is understood. (And for now, understanding ourselves, is the most important
reason to try to build conscious machines. (There is a far grander purpose, as well.))
Meanwhile, let’s accept Crick’s Astonishing Hypothesis (AH!) for now.
Armed with just the AH! there is a hugely important corollary:
Subjective Reality is All There Really Is! (SRIATRI)
If everything we know, think, and feel IS due to the precise state of our brain,
then we have no direct contact with the world outside. Instead, we are just
information processing machines that get our knowledge of the outside world in
just the same way that robots, computers,
and other machines do – from an array of sensors.
Now, just like the AH!, the SRIATRI corollary may strike you as being just as trivial
and self-evident. However, my sense of SRIATRI is that it is deeply profound.
In the movie The Matrix, the hero, Neo, takes the red pill, and wakes up
to the absolute tangible, first hand knowledge that his entire life and all his beliefs
have been a computer- induced hallucination. That is – in a milder form –
the actual state of affairs in the real world.
My perception of myself is that I am staring out at the world through my eyes,
looking at a world filled with colored objects. In reality, the whole entity is
an elaborately constructed delusion (albeit a pivotally useful one). But, this
constructed me has absolutely no conscious access to the mechanisms
that are generating the illusion, eg the neural spikes traveling in my
retinal ganglion cells that convey - via
one million optic fibers - the
totality of my visual world. The whole thing is an elaborately engineered illusion.
Instead of a body in a vat plugged into The Matrix, what we actually have is a brain,
floating in cerebrospinal fluid in a totally dark, calcified box connected to
a sensor array by a collection of cables (the spinal cord and cranial nerves).
Of course, the resulting hallucination has great correspondence with the outside world,
otherwise none of our ancestors would have survived to reproduce.
The hallucinatory life that Neo normally leads (the blue pill / normal reality) is what
cognitive scientists and philosophers call NAÏVE REALISM . Naïve realism is
the patently false belief that “the way I experience the world is the way it actually is.” It is NOT!
Science tells us that what's actually out there is a collection of atoms
and photons electromagnetically interacting according to the laws of quantum mechanics.
On the other hand I experience a world of solid objects with my eyes and hands.
Not only do we not experience the atoms and photons, the sight and touch of
solid objects is different for each of us. And if that is the case, then each of our experiences
of intangible objects and events – what it’s like to live life, what’s important in the world,
what we think of other people and places is hugely subjective.
So, every shred of experience is SUBJECTIVE. Naive realism is out!
In fact, it’s dangerously naive (less so if you're a child, more so if you possess
weapons of mass destruction.)
Now, nobody who has studied neurobiology accepts naive realism;
so rejecting it is not new. Psychologists and neurobiologists accept that
the brain constructs and stores a WORLDVIEW which is a map of the
organism's external reality and that we live and die by that worldview.
(and, that the map is not the same as the territory.)
SRIATRI means nobody is in touch with absolute reality. It’s not possible.
The best any of us can do is to plug into consensus reality – the world described
by our culture at large, including all its scientists, teachers, opinion leaders, politicians,
writers, artists, and media people. Of course, consensus reality is constantly changing and evolving.
(My favorite examples are the big paradigm shifts like those described by Thomas Kuhn,
for example, theory of evolution, quantum mechanics, plate tectonics, the role of
asteroid impacts in evolution, and so.)
By the way, the world’s population is about 7 billion. My guess is that
all those folks are naïve realists. So, there is a lot of work for teachers in
every country on Earth. That is why the internet, Wikipedia, and One-Laptop-Per-Child
are so important.
(I just caught myself in an error that I must immediately clarify.
Naïve realism and global consciousness are really about states of knowledge
and not about consciousness in the sense of the Icelandic waterfall above.
Those are two quite distinct uses of the word, and it is really the sense that pertains
to direct vision or hearing that I am predominantly addressing here, not its meaning
as in the phrase “higher consciousness.”
Here, I’ve just introduced the importance of the consciousness problem,
that is, the mind/body problem. The real question is how precisely does it work?
How does the conscious or subjective world arise from the brain? In my future articles
I'll try to give you a sense of how far neuroscience has gotten in providing an explanation.
Copyright 2009 Robert L. Blum