A Postscript on Free Will
by Francis Crick, physicist and biochemist who collaborated with James D. Watson in the discovery of the molecular structure of DNA, for which they received the Nobel Prize in 1962.
Free Will is, in many ways, a somewhat old-fashioned subject. Most people take it for granted, since they feel that usually they are free to act as they please. While lawyers and theologians may have to confront it, philosophers, by and large, have ceased to take much interest in the topic. And it is almost never referred to by psychologists and neuroscientists. A few physicists and other scientists who worry about quantum indeterminacy sometimes wonder whether the uncertainty principle lies at the bottom of Free Will.
I myself had paid little attention to Free Will until 1986, when I received a letter from an old friend, Luis Rinaldini, an Argentinean cell biologist whom I had first known in Cambridge in the late forties. Luis and his wife now live in Mendoza, a provincial city in Argentina, near the Andes. He was coming to the United States on a visit and wanted to meet and talk over some of his ideas. When we got together in New York he told me that he and a group of friends had formed a discussion group in Mensoza, and that he had become interested in the topic of Free Will. he subsequently wrote to me on the subject in more detail.
Up to that point I was not aware I had a theory of Free Will, but from what he wrote about it I could see that my ideas differed somewhat from his. I there and then wrote out, very briefly, what I discovered I believed and sent it to him. The text occupied less than thirty lines. I showed it to the philosopher Patricia Chruchland, partly for some reassurance that I wasn't being totally silly. she helpfully clarified the wording and added an extra point, telling me that my ideas seemed plausible to her. What follows is a slightly expanded version of what I wrote to Luis.
My first assumption was that part of one's brain is concerned with making
plans for future actions, without necessarily carrying them out. I also
assumed that one can be conscious of such plans -- that is, that they are
subject at least to immediate recall.
My second assumption was that one is not conscious of the "computations"
done by this part of the brain but only of the "decisions" it makes -- that
is, its plans. Of course, these computations will depend
My third assumption was that the decision to act on one plan or another is
also subject to the same limitations. In other words, one has immediate
recall of what is decided but not of the computations that went into the
decision, even though one may be aware of a plan to move. (Professor
Piergiorgio Odifreddi has pointed out to me that one should also
Then, such a machine (this was the word I used in my letter) will appear to
itself to have Free Will, provided it can personify it behavior -- that is,
it has an image of "itself."
The actual cause of the decision may be clear cut (Pat's addition), or it
may be deterministic but chaotic -- that is, a very small perturbation may
make a big difference to the end result. this would give the appearance of
the Will being "free" since it would make the outcome essentially
unpredictable. Of course, conscious activities may also influence the
decision mechanism (Pat's addition).
Such a machine can attempt to explain to itself why it made
This concluded my Theory of Free Will. It obviously depends upon
understanding what consciousness is about (the main topic of this book),
My second assumption was that one is not conscious of the "computations" done by this part of the brain but only of the "decisions" it makes -- that is, its plans. Of course, these computations will dependon the structure of that part of the brain (derived partly epigenetically and partly from past experience) and on its current inputs from other parts of the brain.
My third assumption was that the decision to act on one plan or another is also subject to the same limitations. In other words, one has immediate recall of what is decided but not of the computations that went into the decision, even though one may be aware of a plan to move. (Professor Piergiorgio Odifreddi has pointed out to me that one should alsoassume that there is agreement between decisions and the resulting behavior.)
Then, such a machine (this was the word I used in my letter) will appear to itself to have Free Will, provided it can personify it behavior -- that is, it has an image of "itself."
The actual cause of the decision may be clear cut (Pat's addition), or it may be deterministic but chaotic -- that is, a very small perturbation may make a big difference to the end result. this would give the appearance of the Will being "free" since it would make the outcome essentially unpredictable. Of course, conscious activities may also influence the decision mechanism (Pat's addition).
Such a machine can attempt to explain to itself why it madea certain choice (by using introspection). Sometimes it may reach the correct conclusion. At other times it will either not know or, more likely, will confabulate, because it has no conscious knowledge of the "reason" for the choice. This implies that there must be a mechanism for confabulation, meaning that given a certain amount of evidence, which may or may not be misleading, part of the brain will jump to the simplest conclusion. as we have seen, this can happen all too easily.
This concluded my Theory of Free Will. It obviously depends upon understanding what consciousness is about (the main topic of this book),how the brain plans (and carries out) actions, how we confabulate, and so on. I doubt if there is anything really novel in all this, although some of the details may not have been included in previous explanations.
Where, I wondered, might Free Will be located in the brain? Obviously it involves interactions between several parts of the brain but it was not unreasonable to think that one part of the cortex might be especially concerned. One might expect that this received output from the higher levels of the sensory systems and involved, or fed into, the higher, planning levels of the motor system.
At this point I happened to stumble across an account by Antonio Damasio and his colleagues of a woman with certain brain damage. After the damage, she appeared very unresponsive. She lay quietly in bed with an alert expression. She could follow people with her eyes but did not speak spontaneously. She gave no verbal reply to any questions put to her even though it appeared she understood them because of the way she nodded in reply. She could repeat words and sentences but only very slowly. In short, her few reactions were very limited and rather stereotyped.
after a month she had largely recovered. She said she had not been upset because she had previously been unable to communicate. she had been able to follow conversations but she had not talked because she had "nothing to say." Her mind had been "empty." I immediately thought "she'd lost her Will" -- where was the damage? It turned out to be somewhere in or near (There was also damage to the adjacent supplementary motor area.) a region called the "anterior cingulate sulcus," next to Brodmann's area 24. This is on the inside surface -- the one you'd see if the brain were cut in half -- toward the front (hence anterior) and near the top. I was delighted to learn that this was indeed a region that received many inputs from the higher sensory regions and was at or near the higher levels of the motor system.
Terry Seznowski's group at the Salk Institute has an informal tea on most afternoons of the week. These teas are ideal occasions to discuss the latest experimental results, throw out new ideas, or just gossip about science, politics, or the news in general. I went over to tea one day and announced to Pat Churchland and terry Sejnowski that the seat of the Will had been discovered! It was at or near the anterior cingulate. When I discussed the matter with Antonio Damasio, I found that he also had arrived at the same idea. he filled me in on some of the anatomical connections of that region of the brain. It has strong connections with the corresponding area on the other side of the brain -- you normally have only a single Will at any one moment, although, as we have seen, split brains can have two (se Chapter 12). Moreover, that region on one side projects strongly to the corpus striatum (an important part of the motor system) on _both_ sides of the brain, which is what you might expect from a single Will. It certainly looked rather promising.
Some time later I was reading a paper by Michael Posner in which he mentioned a curious condition, produced by a particular kind of brain damage, known as the "alien hand" syndrome. A patient's left hand, for example, may make movements -- usually rather simple and stereotyped movements -- that the patient denies he himself is responsible for. For example, the hand may spontaneously grasp some object put near it. In some cases the patient is unable to get the hand to let go and has to use his right hand to detach the left hand from the object. One patient found that he could not make his "alien" hand let go by his own willpower, but could make it release its grasp by saying "let go" in a loud voice!
And where was the damage? Again, in or near the anterior cingulate sulcus (on the right side, for and alien left hand) but _also_ in that part of the corpus callosum, so that the region on the left could not give the instructions to the left hand that the damaged region on the right was unable to give. Moreover, as mentioned in Chapter 8, the anterior cingulate is active in certain selection processes, as shown by the increased blood flow there.
So perhaps this aspect of the idea is novel. (Sir john Eccles has previously suggested that an area near area 24, the supplementary motor area, might be the seat of Free Will.) Free Will is located in or near the anterior cingulate sulcus. In practice, things are likely to be more complicated. Other areas in the front of the brain may also be involved. What is needed are more experiments on animals, the careful examination of more cases of the "alien hand" and related conditions, and, above all, a detailed neurobiological understanding of visual awareness and, from that, of other forms of consciousness. And that is why this suggestion is appended to this book.
>From _The Astonishing Hypothesis, The Scientific Search For The Soul_, by