What Is Your Favorite Deep, Elegant, or Beautiful Explanation? In a 2012 Edge.org annual question, cognitive scientist Christof Koch argues that the same strategy used to decode DNA's structure could crack the 'neural code' of consciousness, citing Francis Crick's pursuit of the 'second great riddle' in biology. Koch recounts how Crick and James Watson's discovery of the double helix was built on prior localization of genes to chromosomes and DNA, and he defends the approach against philosophers like Colin McGinn who doubt the brain's relevance to consciousness. 2012 : WHAT IS YOUR FAVORITE DEEP, ELEGANT, OR BEAUTIFUL EXPLANATION? /annual-question/what-is-your-favorite-deep-elegant-or-beautiful-explanation Genes, Claustrum, and Consciousness What's my favorite elegant idea? The elucidation of DNA's structure is surely the most obvious, but it bears repeating. I'll argue that the same strategy used to crack the genetic code might prove successful in cracking the "neural code" of consciousness and self. It's a long shot, but worth considering. The ability to grasp analogies, and seeing the difference between deep and superficial ones, is a hallmark of many great scientists; Francis Crick and James Watson were no exception. Crick himself cautioned against the pursuit of elegance in biology, given that evolution proceeds happenstantially—"God is a hacker," he famously said, adding according to my colleague Don Hoffman , "Many a young biologist has slit his own throat with Ockham's razor." Yet his own solution to the riddle of heredity ranks with natural selection as biology's most elegant discovery. Will a solution of similar elegance emerge for the problem of consciousness? It is well known that Crick and Watson unraveled the double helical structure of the DNA molecule: two twisting complementary strands of nucleotides. Less well known is the chain of events culminating in this discovery. First, Mendel's laws dictated that genes are particulate a first approximation still held to be accurate . Then Thomas Morgan showed that fruit flies zapped with x-rays became mutants with punctate changes in their chromosomes, yielding the clear conclusion that the chromosomes are where the action is. Chromosomes are composed of histones and DNA; as early as 1928, the British bacteriologist Fred Griffith showed that a harmless species of bacterium, upon incubation with a heat-killed virulent species, actually changes into the virulent species This was almost as startling as a pig walking into a room with a sheep and two sheep emerging. Later, Oswald Avery showed that DNA was the transformative principle here. In biology, knowledge of structure often leads to knowledge of function—one need look no further than the whole of medical history. Inspired by Griffith and Avery, Crick and Watson realized that the answer to the problem of heredity lay in the structure of DNA. Localization was critical, as, indeed, it may prove to be for brain function. Crick and Watson didn't just describe DNA's structure, they explained its significance . They saw the analogy between the complementarity of molecular strands and the complementarity of parent and offspring—why pigs beget pigs and not sheep. At that moment modern biology was born. I believe there are similar correlations between brain structure and mind function, between neurons and consciousness. I am stating the obvious here only because there are some philosophers, called "new mysterians," who believe the opposite. The erudite Colin McGinn has written, for instance, "The brain is only tangentially relevant to consciousness." There are many philosophers who would disagree, e.g., Churchland, Dennett, and Searle. After his triumph with heredity, Crick turned to what he called the "second great riddle" in biology—consciousness. There were many skeptics. I remember a seminar Crick was giving on consciousness at the Salk Institute here in La Jolla. He'd barely started when a gentleman in attendance raised a hand and said, "But Doctor Crick, you haven't even bothered to define the word consciousness before embarking on this." Crick's response was memorable: "I'd remind you that there was never a time in the history of biology when a bunch of us sat around the table and said, 'Let's first define what we mean by life.' We just went out there and discovered what it was—a double helix. We leave matters of semantic hygiene to you philosophers." Crick did not, in my opinion, succeed in solving consciousness whatever that might mean . Nonetheless, I believe he was headed in the right direction. He had been richly rewarded earlier in his career for grasping the analogy between biological complementarities, the notion that the structural logic of the molecule dictates the functional logic of heredity. Given his phenomenal success using the strategy of structure-function analogy, it is hardly surprising that he imported the same style of thinking to study consciousness. He and his colleague Christoff Koch did so by focusing on a relatively obscure structure called the claustrum. The claustrum is a thin sheet of cells underlying the insular cortex of the brain, one on each hemisphere. It is histologically more homogeneous than most brain structures, and intriguingly, unlike most brain structures which send and receive signals to and from a small subset of other structures , the claustrum is reciprocally connected with almost every cortical region. The structural and functional streamlining might ensure that, when waves of information come through the claustrum, its neurons will be exquisitely sensitive to the timing of the inputs. What does this have to do with consciousness? Instead of focusing on pedantic philosophical issues, Crick and Koch began with their naïve intuitions. "Consciousness" has many attributes—continuity in time, a sense of agency or free will, recursiveness or "self-awareness," etc. But one attribute that stands out is subjective unity: you experience all your diverse sense impressions, thoughts, willed actions and memories as being a unity—not jittery or fragmented. This attribute of consciousness, with the accompanying sense of the immediate "present" or "here and now," is so obvious that we don't usually think about it; we regard it as axiomatic. So a central feature of consciousness is its unity—and here is a brain structure that sends and receives signals to and from practically all other brain structures, including the right parietal involved in polysensory convergence and embodiment and anterior cingulate involved in the experience of "free will" . Thus the claustrum seems to unify everything anatomically, and consciousness does so mentally. Crick and Koch recognized that this may not be a coincidence: the claustrum may be central to consciousness; indeed it may embody the idea of the " Cartesian theater" that's taboo among philosophers—or is at least the conductor of the orchestra. This is this kind of childlike reasoning that often leads to great discoveries. Obviously, such analogies don't replace rigorous science, but they're a good place to start. Crick and Koch may be right or wrong, but their idea is elegant. If they're right, they've paved the way to solving one of the great mysteries of biology. Even if they're wrong, students entering the field would do well to emulate their style. Crick has been right too often to ignore. I visited him at his home in La Jolla in July of 2004. He saw me to the door as I was leaving and as we parted, gave me a sly, conspiratorial wink: "I think it's the claustrum, Rama; it's where the secret is." A week later he passed away. The Scientific Method—An Explanation For Explanations Humans are a story telling species. Throughout history we have told stories to each other and ourselves as one of the ways to understand the world around us. Every culture has its creation myth for how the universe came to be, but the stories do not stop at the big picture view; other stories discuss every aspect of the world around us. We humans are chatterboxes and we just can't resist telling a story about just about everything. However compelling and entertaining these stories may be, they fall short of being explanations because in the end all they are is stories. For every story you can tell a different variation, or a different ending, without giving reason to choose between them. If you are skeptical or try to test the veracity of these stories you'll typically find most such stories wanting. One approach to this is forbid skeptical inquiry, branding it as heresy. This meme is so compelling that it was independently developed by cultures around the globes; it is the origin of religion—a set of stories about the world that must be accepted on faith, and never questioned. Somewhere along the line a very different meme got started. Instead of forbidding inquiry into stories about the world people tried the other extreme of encouraging continual questioning. Stories about aspect of the world can be questioned skeptically, and tested with observations and experiments. If the story survives the tests then provisionally at least one can accept it as something more than a mere story; it is a theory that has real explanatory power. It will never be more than a provisional explanation—we can never let down our skeptical guard—but these provisional explanations can be very useful. We call this process of making and vetting stories the scientific method. For me, the scientific method is the ultimate elegant explanation. Indeed it is the ultimate foundation for anything worthy of the name "explanation". It makes no sense to talk about explanations without having a process for deciding which are right and which are wrong, and in a broad sense that is what the scientific method is about. All of the other wonderful explanations celebrated here owe their origin and credibility to the process by which they are verified—the scientific method. This seems quite obvious to us now, but it took many thousands of years for people to develop the scientific method to a point where they could use it to build useful theories about the world. It was not, a priori, obvious that such a method would work. At one extreme, creation myths discuss the origin of the universe, and for thousands of years one could take the position that this will never be more than a story—how can humans ever figure out something that complicated and distant in space and time? It would be a bold bet to say that people reasoning with the scientific method could solve that puzzle. Well, it has taken us a while but by now enormous amounts are known about the composition of stars and galaxies and how the universe came to be. There are still gaps in our knowledge and our skepticism will never stop , but we've made a lot of progress on cosmology and many other problems. Indeed we know more about the composition of distant stars than many questions about things here on earth. The scientific method has not conquered all great questions - other issues remain illusive, but the spirit of the scientific method is that one does shrink from the unknown. It is OK to say that we have no useful story for everything we are curious about, and we comfort ourselves that at some point in the future new explanations will fill the gaps in our current knowledge, as often raise new questions that highlight new gaps. It's hard to overestimate the importance of the scientific method. Human culture contains much more than science—but science is the part that actually works—the rest is just stories. The rationally based inquiry the scientific method enables is what has given us science and technology and vastly different lifestyles than those of our hunter-gatherers ancestors. In some sense it is analogous to evolution. The sum of millions of small mutations separate us from single celled like blue-green algae. Each had to survive the test of selection and work better than the previous state in the sense of biological fitness. Human knowledge is the accumulation of millions of stories-that-work, each of which had to survive the test of the scientific method, matching observation and experiment more than the predecessors. Both evolution and science have taken us a long way, but looking forward it is clear that science will take us much farther. Boscovich's Explanation Of Atomic Forces A great example how a great deal of amazing insight can be gained from some very simple considerations is the explanation of atomic forces by the 18th century Jesuit polymath Roger Boscovich, who was born in Dubrovnik. One of the great philosophical arguments at the time took place between the adherents of Descartes who—following Aristotle—thought that forces can only be the result of immediate contact and those who followed Newton and believed in his concept of force acting at a distance. Newton was the revolutionary here, but his opponents argued—with some justification—that "action at a distance" brought back into physics "occult" explanations that do not follow from the "clear and distinct" understanding that Descartes demanded. In the following I am paraphrasing reference works. Boscovich, a forceful advocate of the Newtonian point of view, turned the question around: Let's understand exactly what happens during the interaction that we would call immediate contact? His arguments are very easy to understand and extremely convincing. Let's imagine two bodies, one of which is traveling at a speed of, say, 6 units, the other at a speed of 12 with the faster body catching up with the slower one along the same straight path. We imagine what transpires when the two bodies collide. By conservation of the "quantity of motion," both bodies should continue after collision along the same path, each with a speed of 9 units in the case of inelastic collision, or in case of elastic collision for a brief period right after the collision But how did the velocity of the faster body come to be reduced from 12 to 9, and that of the slower body increased from 6 to 9? Clearly, the time interval for the change in velocities cannot be zero, for then, argued Boscovich, the instantaneous change in speed would violate the law of continuity. Furthermore, we would have to say that at the moment of impact, the speed of one body is simultaneously 12 and 9, which is patently absurd. It is therefore necessary for the change in speed to take place in a small, yet finite, amount of time. But with this assumption, we arrive at yet another contradiction. Suppose, for example, that after a small interval of time, the speed of the faster body is 11, and that of the slower body is 7. But this would mean that they are not moving at the same velocity, and the front surface of the faster body would advance through the rear surface of the slower body, which is impossible because we have assumed that the bodies are impenetrable. It therefore becomes apparent that the interaction must take place immediately before the impact of the two bodies and that this interaction can only be a repulsive one because it is expressed in the slowing down of one body and the speeding up of the other. Moreover, this argument is valid for arbitrary speeds, so one can no longer speak of definite dimensions for the particles that were until now thought of as impenetrable, namely, for the atoms. An atom should rather be viewed as a point source of force, with the force emanating from it acting in some complicated fashion that depends on distance. According to Boscovich, when bodies are far apart, they act on each other through a force corresponding to the gravitational force, which is inversely proportional to the square of the distance. But with decreasing distance, this law must be modified because, in accordance with the above considerations, the force changes sign and must become a repulsive force. Boscovich even plotted fanciful traces of how the force should vary with distance in which the force changed sign several times, hinting to the existence of minima in the potential and the existence of stable bonds between the particles—the atoms. With this idea Boscovich not only offered a new picture for interactions in place of the Aristotelian-Cartesian theory based on immediate contact, but also presaged our understanding of the structure of matter, especially that of solid bodies. Commitment It is a fundamental principle of economics that a person is always better off if they have more alternatives to choose from. But this principle is wrong. There are cases when I can make myself better off by restricting my future choices and commit myself to a specific course of action. The idea of commitment as a strategy is an ancient one. Odysseus famously had his crew tie him to the mast so he could listen to the Sirens' songs without falling into the temptation to steer the ship into the rocks. And he committed his crew to not listening by filling their ears with wax. Another classic is Cortés's decision to burn his ships upon arriving in Mexico, thus removing retreat as one of the options his crew could consider. But although the idea is an old one, we did not begin to understand its nuances until Nobel Laureate Thomas Schelling's wrote his 1956 masterpiece: "An Essay on Bargaining". It is well known that thorny games such as the prisoner's dilemma can be solved if both players can credibly commit themselves to cooperating, but how can I convince you that I will cooperate when it is a dominant strategy for me to defect? And, if you and I are game theorists, you know that I know that you know that I know that defecting is a dominant strategy. Schelling gives many examples of how this can be done, but here is my favorite. A Denver rehabilitation clinic whose clientele consisted of wealthy cocaine addicts, offered a "self-blackmail" strategy. Patient were offered an opportunity to write a self- incriminating letter that would be delivered if and only if the patient, who is tested on a random schedule, is found to have used cocaine. Most cocaine addicts will probably have no trouble thinking of something to write about, and will now have a very strong incentive to stay off drugs. They are committed. Many of society's thorniest problems, from climate change to Middle East peace could be solved if the relevant parties could only find a way to commit themselves to some future course of action. They would be well advised to study Tom Schelling in order to figure out how to make that commitment. Why Is Our World Comprehensible? "The most incomprehensible thing about the world is that it is comprehensible." This is one of the most famous quotes from Albert Einstein. "The fact that it is comprehensible is a miracle." Similarly, Eugene Wigner said that the unreasonable efficiency of mathematics is "a wonderful gift which we neither understand nor deserve." Thus we have a problem that may seem too metaphysical to be addressed in a meaningful way: Why do we live in a comprehensible universe with certain rules, which can be efficiently used for predicting our future? One could always respond that God created the universe and made it simple enough so that we can comprehend it. This would match the words about a miracle and an undeserved gift. But shall we give up so easily? Let us consider several other questions of a similar type. Why is our universe so large? Why parallel lines do not intersect? Why different parts of the universe look so similar? For a long time such questions looked too metaphysical to be considered seriously. Now we know that inflationary cosmology provides a possible answer to all of these questions. Let us see whether it might help us again. To understand the issue, consider some examples of an incomprehensible universe where mathematics would be inefficient. Here is the first one: Suppose the universe is in a state with the Planck density r ~ 10