National Medal of Science Awarded To Political Scientist Robert Axelrod
Why do we choose to cooperate and how can we promote greater cooperation in world affairs? These are the questions that Robert Axelrod has pursued for more than 40 years. His career has been an interdisciplinary exploration that has encompassed mathematics, political science, and evolutionary biology. Now, his signature achievements in the areas of game theory and complex systems have earned him the highest scientific honor that the United States can bestow: the National Medal of Science.
I first encountered Axelrod’s work during my graduate studies working with great apes. His suggestion that cooperation could evolve as an adaptive strategy was an inspiration for me in a field still dominated by the view that selfish interests were the primary driver of evolution. After several years of watching bonobos – one of our closest evolutionary relatives – as they peacefully shared their resources with groupmates and avoided violence at all costs, I was eager for an alternative explanation.
Axelrod’s publications with the celebrated evolutionary biologist William Hamilton had put the study of cooperation on a new foundation. What’s more, his application of this work to political science offered the potential for an evolutionary framework that could help reduce violence and encourage mutual aid between nations and peoples.
Axelrod first pursued a degree in mathematics before receiving his PhD in Political Science from Yale University in 1969. After brief stints working in the Office of the Secretary of Defense and on Senator Eugene McCarthy’s failed presidential campaign that pledged to end the Vietnam War, Axelrod taught at UC Berkeley before becoming a professor of Political Science and Public Policy at The University of Michigan.
It was Axelrod’s work with computer simulations involving the Prisoner’s Dilemma game that launched his scientific career. In the game, two people who committed a crime are arrested and each is placed in solitary confinement for interrogation. If one betrays the other, the first goes free while the second is sentenced to three years in prison. If they both betray one another, they each receive two years. But if they both keep silent, they receive the minimum penalty of one year each. Under this scenario, the best individual strategy would be to betray the other. However, in actual trials, people were much more likely to cooperate than would be expected under the assumption of rational self-interest. Cooperation and altruism seem to be innate characteristics of the human species.
Axelrod has been able to extend his model of cooperation from animals in nature, down to cancer cells, and up to conflicts involving rival superpowers. His books include The Evolution of Cooperation, The Complexity of Cooperation, and Harnessing Complexity. He has been published in Science, Nature, Proceedings of the National Academy of Sciences, World Politics, and the Journal of Peace Research. During his extensive career, his work on cooperation has been cited more than 9,000 times by researchers across academic disciplines.
It was my distinct honor to talk with Professor Axelrod last week from his current position in the U.S. State Department. In our discussion, he reflected on his work with evolutionary biologist William Hamilton, how cooperation can be promoted within groups, and what this ultimately means for a planet caught in the thrall of competing national powers.
从左至右：Michael D. Cohen, Robert Axelrod, William Hamilton, Arthur Burks, John Holland, Rick Riolo, Michael Savageau, and Carl Simon.
Eric Michael Johnson: To begin with, I would like to talk with you about your work with the evolutionary biologist William Hamilton. In my opinion, this was a model of interdisciplinary collaboration that enriched both fields. How did you end up working with him?
Eric Michael Johnson（以下简称J）：首先，我想和你谈谈你与进化生物学家William Hamilton合著的著作。我认为，这是本跨学科合作的典范，对两个领域均很有促进。你是如何同他建立合作的？
Robert Axelrod: I approached him because I thought that my work on the Prisoner’s Dilemma would have applications to biology. First I got in touch with Richard Dawkins and it was he who suggested Bill Hamilton who, at the time, was visiting The University of Michigan where I was. I didn’t even know he was there.
Robert Axelrod（以下简称A）：我去找他，是因为我觉得我对囚徒困境的研究可能在生物学上得以应用。首先我是跟Richard Dawkins接触，是他推荐的Bill Hamilton。Hamilton当时正访问我所在的密歇根大学。那时候我甚至都不知道他就在那儿。
When I looked him up and told him about my basic idea, he thought it was quite interesting. As you know, before he died of course, he was a world-class evolutionary biologist most noted for showing that animals often cooperate when they are closely related to each other. But my suggestion was a different idea: that cooperation could also be based on reciprocity.
To my delight, Bill immediately saw the value of this approach and he thought we could develop some useful applications for biology. He had already used game theory in some of his work, although he didn’t regard himself as a game theorist. We decided to write an article for Science, which is probably the world’s leading scientific journal.
Bill was able to bring the relevance to biology and speak directly to evolutionary biologists in a way that I could not and I brought the original theory. Then we worked out some of the elaborations together. We were really fortunate in that, not only was the article accepted, it was chosen as the best article of the year in Science magazine. It certainly gave my later work a mark of scientific credibility.
Johnson: What is one of your fondest memories of working with Hamilton? Can you paint a scene of how one of your collaboration sessions played out?
Axelrod: One of the characteristics I remember about him is that when we were talking about an idea he might suddenly stop and think very deeply about it. I learned to keep quiet and let him ponder. Many times he would come up with a really interesting next step. Of course, sometimes he would come up with something completely different because he had given up pondering the topic at hand and his mind had gone off in some other direction. I could never tell which it would be. It was a lot of fun.
Johnson: You were both so generous with one another in how you described your work together. For example, Hamilton wrote in his autobiography that your collaboration added to his own biological insights. Would you say that it also added to your own perspective on political science?
Axelrod: It certainly gave me a deeper sense of the fundamentals that we were studying. It wasn’t something specific like trench warfare, which was one of my examples. I saw that this model could be applied in many different places. For example, as you may know, I later developed another application related to this work as it had to do with cooperation among cancer cells. The same thing happened for him and, several years later, he came up with another idea that he wanted to try out on me related to parasites.
Johnson: This would have been your joint paper on the origin of sex.
Axelrod: Yes, his idea was quite amazing. You see, at the time we did not have a good explanation for the fact that almost all large animals and plants reproduce sexually. This was a serious puzzle because it meant that only half of adults – the females – could reproduce. This is a huge cost in evolutionary terms, so there must be something very valuable about it. The fact that sex is so universal means it must be something that large animals and plants have in common.
Bill’s idea for what they have in common was the need to resist parasites. Parasites evolved to mimic our cells so that our immune system wouldn’t attack them. As a result, they can evolve around thirty times faster than we can since their generation time is so short. If you were to reproduce asexually it would mean you’d have an offspring that was almost identical to you, so the parasites that are adapted to you would also be adapted to your offspring. However, by reproducing sexually our offspring are quite different from us. Therefore, the parasites have to start all over. Bill’s idea was that sexual reproduction is an adaptation to resist parasites. It is just a brilliant idea.
Johnson: How did you end up coauthoring the paper with him?
Axelrod: He said to me that he didn’t have a way of modeling this concept because it inherently involved many genes and, in the formal model, you could only add two or three different genes before the whole thing got too complicated with all of the interaction effects. I used a technique that John Holland at University of Michigan had developed called the genetic algorithm. This was a computer simulation of the genetics and allowed us to handle dozens of genes in one simulation.
This was just what we needed and we developed a simulation to demonstrate that this idea, at least in principle, was viable. It was a lot of fun to first have one idea of mine that I took to Bill only to have him come back with an idea of his own that I helped do simulations on.
Johnson: So it was a meeting of complementary minds. You would build on one another’s ideas and inspiration.
Axelrod: Right. I remember he said in his memoirs that we were both quite serious about aesthetics. We like simple theories and want to get to the fundamentals of things. We both had a background in mathematical modeling and game theory so, even though we came from different disciplines, we had some important things in common.
In addition, I had been fascinated with evolution ever since high school and had taken it quite seriously. I thought a lot about evolutionary biology although I certainly was not a professional. But it meant that he and I could communicate well together because I knew many of the basics in a way that political scientists wouldn’t normally be expected to.
Another thing that he mentioned in his memoirs is that neither one of us had any need to one up the other or establish who had made the biggest contribution. There was never any need to be overly modest just out of the sake of politeness, which I think is common in Britain and something Bill was used to from his time at Oxford. He was simply a delight to work with.
Johnson: You have also taken on other evolutionary questions over the years. One of the debates I have always been interested in is that you have been critical of some evolutionary psychologists, such as Joseph Henrich at University of British Columbia where I am based, who argue that there are specific genes for prosocial traits. Instead you advocate for more general-purpose capabilities such as language and foresight. Do you think there is an overreliance among some evolutionary researchers on genetic mechanisms for understanding the nature of cooperation and altruism?
Axelrod: I think that genetics certainly plays a role. But I am kind of agnostic about just how big the role of genetics is in human behavior. For example, there is no doubt that an important genetic basis exists in both human and nonhuman animals for cooperation with kin. What I was addressing was how specific those genetic components have to be.
Henrich was moving towards the side where they are highly specific and identifiable. My collaborator and I were saying that it could be explained by much more general capacities that were evoked for this purpose. It wasn’t a major difference. Genes are important but I’m not a purist who believes they drive everything. Obviously culture is important too.
Johnson: When Darwin was trying to understand the origin of morality in The Descent of Man he adopted a group selection model where those individuals that displayed selfish tendencies would be punished whereas those that displayed traits benefitting the group would be rewarded. Christopher Boehm followed up on this idea in his book Moral Origins that came out a few years ago. Do you find that the evolution of cooperation has come full circle back to where Darwin originally was?
Axelrod: I think that Darwin’s speculation is quite plausible. At the time he couldn’t really establish it by studying large numbers of societies and identifying those that thrived and those that didn’t.
The idea of group selection, until recently, has had a pretty bad reputation in biology because some non-scientists wildly misused it, saying that if the British were so successful it must be because they were genetically better. But in the last ten years or so biologists have come to agree that, under certain conditions, one can get group selection.
If one small band of humans are better at cooperating than some other band whom they are competing with, the first may well be able to outperform the second either through getting more food or maybe even by fighting and killing them. I think it is a common principle that cooperation is invoked in the service of competition. Cooperation with insiders serves competition with outsiders.
Johnson: You modeled this very process in the journal Nature with what you refer to as tags. You show that cooperation could increase even without reciprocity or high levels of relatedness. If enough individuals with the same tag were in a group they might cooperate simply because they shared these tags. Could you expand on that?
Axelrod: The idea of tags was actually developed by John Holland. Tags are completely arbitrary pieces of information that other people can observe, such as your accent or your skin color or the color shirt you wear. These are signals as to what group a person is a member of and this can lead to ethnocentrism or cooperating with others that are similar to you.
Even if those things are completely arbitrary initially, they can come to take on meaning. They become correlated with traits that include reciprocity. Of course, the question gets tricky and interesting in that somebody else can have this trait or be part of the in-group but then abuse that and not cooperate.
I remember Groucho Marx once said that, “The secret of success is honesty and fair dealing. If you can fake those, you’ve got it made.” One of the purposes of our simulation is to study the conditions under which defectors are not able to take over a population even though, in the short run, they can do well.
Johnson: Do these models suggest that there is room for cultural and institutional change in order to promote cooperation in world affairs? For example, you wrote an article for The New York Times along with Scott Atran about how we should talk to terrorists.
Axelrod: That’s right. As an interesting side note, you may know that this year I am working in the State Department on a fellowship. I was a little worried that I might not get a security clearance because I actually have talked to terrorists. But I have been up front about this so it turned out not to be a problem. I was still able to get my clearance.
Johnson: So is this the kind of thing that could be utilized? By employing various tags and emphasizing shared cultural traits we might enter into closer dialogue that would promote cooperation.
Axelrod: That is the aspiration. But there are some groups, and perhaps ISIL is one of them, where there is not a lot to talk to them about.
Johnson: You noted in one of your autobiographical papers that your father was a painter and that he represented what was important on a given day by what he left out. In your early work you emphasized the Prisoner’s Dilemma because, at the time, the world was in a conflict between rival superpowers. How has the changing world situation altered what you find important and how has that influenced what you include, or don’t include, in your models?
Axelrod: Obviously we’re not in a strict bipolar situation today like the United States and the Soviet Union were in the dominant confrontation during the Cold War. Now there are a number of power centers and, you might say, a two-sided game is only part of the issue.
However, there are still lots of bilateral issues such as between Russia and its neighbor Ukraine. The United States and China also have a complex relationship that has elements of both cooperation and competition. In terms of the U.S.-Chinese relationship, a particularly important feature is that it represents an established power relating to a rising power.
Those situations have often led to war in the past. That has been a difficult relationship to manage. I think it is important that we recognize and promote the cooperative aspects and possibilities, just as President Obama did with the President of China on their agreement over climate change. We should build a cooperative relationship where we both have a common interest in the outcome.
Johnson: So this would still fall into the Prisoner’s Dilemma model. But it seems that there would be a high potential for noise, something that you wrote you wish you had considered more in your earlier work.
Axelrod: That’s right. For our purposes, instead of using the term noise it’s misunderstanding. One side may think it is perfectly reasonable and the other side might think it is breaking the norms that they should be following. An example of this is cyberspace where the United States gets quite angry that the Chinese are stealing industrial secrets and the Chinese don’t regard that as necessarily any different from normal espionage which everybody accepts that other countries do.
Johnson: This would tie in with Elinor Ostrom’s work as it relates to the digital commons and how to manage that.
Axelrod: Right. You have clearly done a thorough job of looking at my vitae. (Laughs)
Johnson: I’ve been reading your work for quite a while.
Axelrod: But you’re right. I think it is important that we sustain the tremendous value of the Internet as a common resource that helps all economies to thrive and helps individuals, businesses, and countries. It is under challenge now because some countries, for example Germany, are promoting the idea that the data generated in their country should stay in their country. This sounds reasonable but it also risks the Balkanization of the Internet and undermining the collective good.
Johnson: You are the first political scientist to be awarded the National Science Medal in United States history. While this award may represent the pinnacle of your career, it certainly is not the end. Where do you plan to go next?
Axelrod: (Laughs) Two things, I have a serious interest in cyber conflict and what we can do to avoid or manage conflict in cyberspace. This could get very serious if one country causes blackouts in another or interferes with the financial system as a way to pressure the other instead of bombing them.
Because we don’t have established norms of what counts as armed conflict there could be a good deal of misunderstanding. One side could think they didn’t escalate very much and the other side could take action that is very serious. We understand the escalation ladder for conventional warfare, for example, but we really don’t have a common understanding for the various types of cyber conflict. I think it has a serious potential for misunderstanding so I’m interested in those issues and have an article in Proceedings of the National Academy of Sciences about the timing of cyber conflict.
The other thing I have been interested in is learning about the State Department, about how organizations make decisions, and how policies develop using this opportunity to see policy formation from the inside.
Johnson: Looking inside the sausage factory.
Johnson: One final question I have for you is that, despite all of the crises in the world today and a seemingly gridlocked political system at home, what continues to give you hope?
Axelrod: One important fact is that we have not had great power wars for a long time. I suppose the last time would have been the United States and China fighting in the Korean War from 1950-53. That was sixty years ago. We have not had a great power confrontation in all that time and even the Korean War was quite limited.
I think it is possible, and it’s certainly hopeful, that major powers can find non-violent ways of dealing with each other and making their interests known to the other side. But it is not guaranteed. The proliferation of nuclear weapons is a serious danger and major differences exist between the United States and Russia in this area. And, of course, jihadism is a serious threat to the world.
But none of these are as serious as World War I or World War II or as dangerous as the Cold War. We could have had hundreds of millions of people dead in a single day if the Cuban Missile Crisis didn’t go well, for example, or if some of the Berlin confrontations had escalated. So I am hopeful that the world is not as dangerous as it was then and that great powers can continue to deal with each other without periodic wars that seemed to be so common in the past.
Johnson: Thank you for taking this time to talk with me. I personally have gained a lot from reading your work over the years and I can’t tell you how thrilled I am that you have received this honor.
Axelrod: Well, thank you very much. I appreciate that. I enjoyed talking with you as well.