Reading #1, from On the Sacred Disease, Hippocrates, 400 B.C.
Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows, griefs, despondency, and lamentations. And by this, in an especial manner, we acquire wisdom and knowledge, and see and hear, and know what are foul and what are fair, what are bad and what are good, what are sweet, and what unsavory; some we discriminate by habit, and some we perceive by their utility. By this we distinguish objects of relish and disrelish, according to the seasons; and the same things do not always please us. And by the same organ we become mad and delirious, and fears and terrors assail us, some by night, and some by day, and dreams and untimely wanderings, and cares that are not suitable, and ignorance of present circumstances, desuetude, and unskillfulness…
I am of the opinion that the brain exercises the greatest power in the man. This is the interpreter to us of those things which emanate from the air, when the brain happens to be in a sound state. But the air supplies sense to it. And the eyes, the ears, the tongue and the feet, administer such things as the brain cogitates. For in as much as it is supplied with air, does it impart sense to the body. It is the brain which is the messenger to the understanding.
Reading #2, from Kenyon Commencement Address,David Foster Wallace, May 21st 2005
There are these two guys sitting together in a bar in the remote Alaskan wilderness. One of the guys is religious, the other is an atheist, and the two are arguing about the existence of God with that special intensity that comes after about the fourth beer. And the atheist says: “Look, it’s not like I don’t have actual reasons for not believing in God. It’s not like I haven’t ever experimented with the whole God and prayer thing. Just last month I got caught away from the camp in that terrible blizzard, and I was totally lost and I couldn’t see a thing, and it was fifty below, and so I tried it: I fell to my knees in the snow and cried out ‘Oh, God, if there is a God, I’m lost in this blizzard, and I’m gonna die if you don’t help me.’” And now, in the bar, the religious guy looks at the atheist all puzzled. “Well then you must believe now,” he says, “After all, here you are, alive.” The atheist just rolls his eyes. “No, man, all that was was a couple Eskimos happened to come wandering by and showed me the way back to camp.”
It’s easy to run this story through kind of a standard liberal arts analysis: the exact same experience can mean two totally different things to two different people, given those people’s two different belief templates and two different ways of constructing meaning from experience. Because we prize tolerance and diversity of belief, nowhere in our liberal arts analysis do we want to claim that one guy’s interpretation is true and the other guy’s is false or bad. Which is fine, except we also never end up talking about just where these individual templates and beliefs come from. Meaning, where they come from INSIDE the two guys. As if a person’s most basic orientation toward the world, and the meaning of his experience were somehow just hard-wired, like height or shoe-size; or automatically absorbed from the culture, like language. As if how we construct meaning were not actually a matter of personal, intentional choice. Plus, there’s the whole matter of arrogance. The nonreligious guy is so totally certain in his dismissal of the possibility that the passing Eskimos had anything to do with his prayer for help. True, there are plenty of religious people who seem arrogant and certain of their own interpretations, too. They’re probably even more repulsive than atheists, at least to most of us. But religious dogmatists’ problem is exactly the same as the story’s unbeliever: blind certainty, a close-mindedness that amounts to an imprisonment so total that the prisoner doesn’t even know he’s locked up.
The Science of Free Will
Prepared remarks for the Unitarian Universalist Congregation of Columbus, Indiana. March 22, 2009
Emerson Pugh once remarked “If the human brain were so simple that we could understand it, we would be so simple that we couldn’t.” Personally, I’m glad our brain is complex, otherwise I’d be out of a job. Having a complex brain allows us to critically assess difficult situations and make moral choices.
Executing a murderer, screening an embryo for genetic defects, legally aborting a fetus, providing health care for an illegal immigrant, waging a preemptive war : reasonable arguments can be made for or against each of these actions. Where do you stand on these issues? Our attitudes to each are shaped by experience, rational consideration and emotion. They require us to make a complex moral choice. How do we make these choices? Do we make them as free-actors, or are they predetermined by our past experience has wired our brain?
Free will, our ability to voluntarily choose our actions, is a fundamental concept in many religions and forms the basis of our legal system. If we freely choose, then the world is what we make of it. If our choices are not predetermined then we can justifiably be punished or rewarded for our errors and successes. Adam chose to eat the apple, so it seems fitting to some that he, and all of humanity by association, should be punished. A Hindu is reincarnated into a higher life if she makes the right decisions. Bernie Madoff deserves to be imprisoned because he chose to defraud people.
Free will is intuitive, it is simply grasped. But is it as simple as it seems?
As science has progressed, it has slowly advanced our understanding not only of the nature of the external world, but also the nature of our own minds. We are now able to describe physical processes in the brain that correlate to perception, deliberation, and choice. Debates over the nature of free will, and its prerequisite consciousness, were made by philosophers and theologians who did not have access to modern scientific discoveries. For a more complete understanding of ourselves, we must integrate this new knowledge, no matter what anxiety it may create regarding our sense of security, predictability and control in a often chaotic world.
Let’s take a deeper look at what science tells about how we perceive the world and make choices.
Rather than start with a complex moral issue, let’s consider with one of the many smaller choices we make throughout a day. Similar mental mechanisms govern the hard choices and the easy choices, and in each we have the impression that our choice is voluntary.
Imagine the decision you might make in a situation I often find myself in. You’ve been working on something all day and finally are finished, ready to relax and perhaps go to bed. You feel a thirst and go to the refrigerator where you see a gallon of milk and a six-pack of beer. You pause, and consider which to consume. The choice is quickly made and you reach for one or the other. How does your brain pick a course of action? A multitude of factors play into this one very simple decision.
What does our brain do during this period?
Of course there is housekeeping. Deep brain regions keep your heart beating and lungs breathing.
More relevant to the decision, the brain acquires sensory input. Information is constantly flowing in through the five senses, plus some others (limb position, gravity). You observe the beer and milk with our eyes. Sniff the milk with your nose. Feel the cool air flowing out of the door with your skin. Perhaps you feel a pang of hunger or of thirst.
As this information flows in from the sensory periphery to the center of the brain, successive brain regions detect features. You recognize the beer is a pilsner and the percentage of milk fat. You determine if the milk smells sour.
Then frontal areas of the cortex, which can access information from many other brain regions, combine the detected patterns to build an internal model of the external world. The cold beer is on the top shelf behind the milk. The milk’s appears to have gone bad.
From this model, the brain anticipates and predicts the consequences of possible actions. The frontal areas of the cortex converse with other areas, such as the dopamine system, that predict punishment and reward. You consider that you might wake up later and be thirsty if you drink the beer, or have an upset stomach if you drink the milk.
These predictions are influenced by your emotional state and your memories. There is an internal conversation between frontal cortex and emotion generating areas. You may feel guilty as you remember the last time you drank beer, stayed up too late and were late to work. You fear that it may happen again. Yet you desire the ice cold refreshment and taste, and the way it quiets self-critical internal voices.
Then, action is planned. To get the beer out you will need to move the milk. Action is executed. Motor control areas of the brain trigger the reaching of the arm and grasping of the hand.
Finally, consequences are observed; the brain does error correction. The processing involved in a decision doesn’t stop once the decision has been made. You evaluate the consequences of your choice over the timescale that the choice could have had an impact. If you wake up thirsty, then you remind yourself not to drink beer before bed. Error correction systems in the brain cause subtle rewiring of the connections within and between brain regions to suppress activity patterns that led to a negative outcome, and enhance activity patterns that led to a positive outcome.
Clearly there is an incredible amount of effort, conscious and unconscious that plays into a simple choice like milk or beer. And this is repeated hundreds of times a day. From things this trivial to highly important, emotional things like whether we should buy a house or shift our retirement accounts, or how provide care for a parent who is losing touch with reality. The time it takes to make these choices varies, but the same brain systems are used.
For a few minutes, I’d like to get a bit technical about the physical mechanisms at play here.
How is the brain organized?
The basic unit of the brain is the neuron, a brain cell. The brain holds 100 billion neurons, each with an average of 10,000 synapses, or connections to other neurons. That is a million times more then the most powerful Intel computer chip. Electrical activity flows through a neuron in a direction. There are input connections and output connections. The neuron can be thought of as a gate through which electrical activity can pass. In general, in the absence of input, a neuron is silent, the gate is closed. If the energy flowing into its inputs is weak or spread out in a disorganized manner, the neuron remains silent and the gate remains closed. But if a lot of energy comes in, or if it has a coordinated pattern that the neuron is tuned to, it will activate the neuron, push the gate open, and electrical energy will be passed onwards.
Neurons are specialized for recognizing specific patterns, which is accomplished by who they are wired to and their shapes. Neurons that are involved in similar processing tasks are clustered together. For example, in vision, light enters the eye, strikes the retina and is transformed into electrical energy. From here neurons pass this electrical message through a series of brain regions. In the first area, neurons are most activated by bright spots surrounded by dark areas. This information is passed to a region where neurons detect edges, then lines of particular angles. Then more complex shapes, like T or cross-shaped intersections are detected at the next level. Another area responds if light is traveling in a particular direction. With these progressive processing steps, each layer discovers features of what we see and passes that information to the next stage. Peculiarities in the circuitry that performs this feature detection cause many optical illusions, like the Scintillating Grid seen on the handout. Similar mechanisms are used for pattern detection in other senses and in combining our senses. Thus our perception, while driven by reality, is sculpted by the circuitry of our brain.
The brain activity associated with thoughts and decisions appears to be distributed across many localized centers, almost like little computer programs, or modules. Each module is connected to a number of related modules. Information, expressed as electrical activity, passes back and forth between them.
The biggest structure in the brain is the cortex, the front and top surface of the brain. The cortex is an area that has expanded greatly throughout the course of evolution. The outer millimeter or two of cortex is what is known as grey matter. It is where we recognize patterns, plan motor actions and weigh complex decisions. Animals with higher cognitive abilities tend to have more cortical surface area. Mice have a smooth cortex, cats have some wrinkles, and ours is highly wrinkled like a crumpled sheet of paper. If your cortex were unfolded, the outer surface could cover a card table. The wrinkles allow it to fit in a smaller space and to minimize the wiring between regions
Internal to the grey matter is the white matter. This is simply the wiring between each area of the cortex and of deeper regions of the brain. Embedded below the white matter are more evolutionarily ancient regions. Some produce our emotional responses. Fear, joy, emotional attachment, and excitement are caused by release of chemicals from specific deep brain areas. Other deep areas provide estimates of where we are in space, the drive for food or sex, expectations of reward or punishment and coordinate the storage of memories.
So where exactly does consciousness lie?
For millennia, people have sought to find the part of the body responsible for our conscious thought, for the seat of our free will and perhaps the soul. Hippocrates was ahead of the curve when he identified the brain as the source of our consciousness. But ancient scholars were not always so perceptive. Aristotle’s view set the field back tremendously. He observed that touching the brain does not cause sensation, thus he concluded that the heart must be the seat of the mind. Descartes, who coined, “cogito ergo sum”, “I think therefore I am”, got things back on track with his extensive studies of the brain and body. Unfortunately, he was convinced that the pineal gland was the seat of consciousness, as it was the only structure of which there were not two copies of in the brain. We now know the pineal gland regulates sleep cycles by excretion of melatonin and is not involved in conscious decision-making.
As modern neuroscience has progressed, no single brain area has been found to be the master control area for conscious thought. Strokes and other focused brain injury have specific effects based on their location and which modules are affected. In strokes, commonly motor control may be lost only on one side or the ability to speak is impaired while other abilities are saved. Prosopagnosia, a condition where people can see clearly, but cannot recognize a face, is caused by damage to a tiny, specific part of the brain called the fusiform face area. A patient named HM who had his hippocampus removed in an experimental therapy lost the ability to make factual memories, but could still learn motor skills. Phinneas Gage’s personality dramatically changed from pious and hardworking to philandering following an accident where a pole was blasted through his head, removing an area of frontal cortex. In all of these cases, there is rarely doubt when talking to the patients that they are conscious and aware and capable of making decisions. But each patient has specific deficits. This points to a distributed nature of consciousness.
So what is consciousness anyway?
We have a general idea of what consciousness is, but it is quite difficult to define precisely. Five people will give you five different answers. Is a dog conscious, if so does it have free will? What about a honeybee? A bee hunts for food, carries it back to the hive and communicates the location and quality of food to its fellow hive members. Are they conscious?
Attention is a key component of consciousness A tremendous amount of information enters the brain. But at any moment we are aware of only a small fraction, what we are paying attention to. Most is filtered out. We can choose what to attend to. If I tell you to think about how tight your shoe feels, maybe you will now notice that your toe itches. If you look down at the handout during the talk you might not remember the next few sentences I say. The sensory signal remains present, but it is not part of our conscious awareness. We can switch attention between things but it is very difficult to attend to two different things at the exact same time. This limitation provides us insight into to the physical mechanisms of conscious thought.
At any given moment, the brain bubbles with spontaneous activity. But often this activity is poorly organized. Remember that neurons like to pass information when they receive energy in a coordinated way. Thus groups of neurons that can activate each other in a coordinated manner are more likely to be able to drive other neurons over their threshold, pushing open their gates. One could imagine that each brain region is a little tribe. The tribes are battling for control of the brain, our conscious perception. Generally the tribes are very disorganized, but when enough of their members band together into a cohesive group they can overpower the disorganized tribes. This could be why the brightly blinking lights of a police cruiser are so quickly able to attract our attention. The neurons in an area of visual cortex are driven in a coordinated manner by the flashers and this cohesive signal then easily propagates to many regions of the brain, demanding our conscious attention, triggering nervousness, a glance at the speedometer, reflexive braking, etc.
A local tribe participates in a thought, but it isn’t a complete one. Neurons from a single brain region, or tribe, usually can only express one type of attribute. They must join together as a coalition with other tribes to form complex thoughts. Depending on the pattern of activity the tribe has produced, other brain regions will be selectively excited. For example, the scent of sour milk will cause a big response in particular neurons of the olfactory cortex. In turn, their activity will open the gates to a region that stores the memory of the last time you had bad milk, another region that causes a feeling of revulsion, and a region that encodes anticipated punishment. The physical representation of conscious thought may be the transient coordinated activity of this coalition of tribes representing multiple brain regions, each expressing a different facet of a thought.
So how do these coalitions of neurons make choices?
In a classic experiment by Libet in the early 80’s, people were told to wait for a random period of time and then move their hand. The researchers found that brain activity steadily increased for almost a full second before the subject had perceived that they had made a choice. This period of increasing activity before the choice may represent the negotiation between various neuronal tribes to form the coalition that triggered the motion.
What about more complex choices? Should I buy a house, what to do about dad, should I screen my baby for Down’s Syndrome? We tend to cycle back to these ideas over and over again before making a decision. However, it is rare that we consider the exact same parameters each time. Rather, each time we consider different perspectives, new wrinkles. Our brain adds or subtracts members to the coalition of neuronal tribes that represent the problem, our possible actions and predicted outcomes. In each cycle, the coalition communicates to those deep brain regions associated with emotions and expected reward and punishment. The resulting emotional responses from these logically constructed scenarios push our brain toward one decision or the other. If two different scenarios are of similar persuasiveness, and if the threshold for action is high, it could take much time and many mental repetitions before one coalition becomes sufficiently strong to trigger the decision.
Neuroscience now can measure some of the physical correlates in the brain of thoughts and choice. We continue to develop and test hypotheses of how the brain circuitry interacts to create our perceptions. But does this understanding provide a satisfactory explanation for the feeling of free will? Few would argue that we do not have a perception of free will, but many would say this perception is an illusion.
Already, with electrical recordings of the brain, we can predict choices a half second before they are made. If we can push this prediction time window back to immediately before we are presented with situation where must make a choice, that would strongly imply that choice is based on the precise state of the brain before a task, rather than an incorporeal ‘will’. It is not unreasonable that technology with this predictive ability will be available within the next decade or two, at least for simple choices.
The feeling of free will may simply be a consequence of spontaneous, essentially random variation in brain activity. For a simple choice, picking milk or beer, we spend little time making the decision, and the result is highly variable. The random processes have more influence. We look back on the event and think, I could have gone either way. But for a difficult choice, one that requires moral distinctions, we consider and reconsider before making the choice. This may reduce the influence of the random fluctuations in brain activity by averaging them out over time. When reflecting back on a hard choice, we tend to say things like, “With what I knew back then, it seemed like the right thing to do,” “It was the choice I knew I had to make”, or “If I had to do it over again, I’d make the same decision.” Doesn’t this indicate that when we reduce the influence of random noise in our brains by lengthy deliberation that our decisions seem less free?
Whether free will is an illusion or not, a recent scientific study indicates our belief in free will influences how ethically we behave. Experimental subjects were given a test and rewarded with cash based on the number of correct answers. Prior to the test, they read passages that strongly promoted or disputed free will. When the tests were observed and graded by a proctor, there was no difference the average score between groups. But when subjects were allowed to take the test privately, score the test themselves, anonymously, those that had read the anti free will passages gave themselves 50% more money than the pro free will readers. Those with a reduced sense of free will cheated more. Thus our belief in our own ability to choose freely, and hence our belief in our capacity for moral decision-making, strongly promotes ethical behavior. Perhaps this is why the assumption of free will is so strongly intertwined with our moral and judicial systems.
As a scientist, I am deeply torn over the nature of free will. On one hand, there is ample evidence that my behavior follows inevitably from the precise state of my brain. My behavior is determined by my past experience, my genetics, my logic and my mood. If my behavior cannot be exactly predicted, that is simply due to current technical limitations. Yet the impression of free choice in my personal life is overwhelming. I am sure that I could have picked the milk, I could have said something differently, I made a free choice. But if this choice were an illusion, it wouldn’t be the first time I have been fooled by my brain.
The atheist philosopher Arthur Schopenhauer said, “Everyone believes himself a priori to be perfectly free, even in his individual actions, and thinks that at every moment he can commence another manner of life. … But a posteriori, through experience, he finds to his astonishment that he is not free, but subjected to necessity, that in spite of all his resolutions and reflections he does not change his conduct, and that from the beginning of his life to the end of it, he must carry out the very character which he himself condemns….” Do you agree with this perspective? What evidence do you have that disputes it? If musing on this statement becomes too depressing, I’ll offer up one more expression as an antidote. The great satirist Ambrose Bierce reworked Descartes’s classic existential argument into “Cogito cogito ergo cogito sum” or “I think that I think, therefore I think that I am.” What do you think?