Transcript
Professor Simon A. Levin：
Thank you very much for the introduction. I'm delighted to be here. I thank the Luohan Academy for inviting me and I thank all the funding sources that have contributed to my work. So sustainability of the biosphere, which Katherine alluded to in terms of investing, is the ultimate global challenge.
A crucial feature is that this sustainability really is focusing on macroscopic features. This is similar to if you're going to boil water to make tea, what you are interested in is whether the water boils while recognizing that control of those features rest at lower levels of organization. Just as if you were boiling water or putting the liquid or gas under pressure, you would know that the phase transitions would depend on lots of interactions that were taking place, but you wouldn't attempt to account for each one of those in your analysis.
This implies that there's a need to relate phenomena across scales, for a biologist from cells to organisms, to collective ecological social, technological systems, in which they are embedded. There’s a need to ask: How robust are the properties of those systems? How does that robustness of the macroscopic properties relate to the individual dynamics on finer scales? The sort of agent-based approaches that Doyne is going to talk about. Are systems at critical points about the transition, just like the water that's boiling? And how do we manage the Commons across scales and conflicts of interest? Ecosystems in the biosphere, which is what I work on primarily, are complex adaptive systems. The term originated by John Holland at Santa Fe. They are heterogeneous collections of individual agents that are interacting with each other on a local scale.
The whole system evolves based on the outcomes of interactions and then feeds back to affect them. Not only the ecological systems, but socioeconomic systems, with which we are concerned today and with which they are interlinked. They are complex, adaptive systems, from an ecology, from microbial systems, like the slime molds on the left to the large animal herds that you see on the right (those are wildebeests), to socioeconomic systems. Macroscopic patterns emerge from microscopic interactions. Market dynamics depend on individual traders. Can we learn how to deal with those systems from what we understand about nature? And what can we add? Because we have the capacity to make models, to build predictions, which is not what's going on during the course of evolution.
The challenges of managing these complex, adaptive systems are, first of all, that the dynamics play out on multiple scales; multiple spatial, temporal, and organizational scales. And the systems self organize. That leads to a consequently unpredictability of outcomes. That is the system may have multiple stable states. There's path dependence and hysteresis, meaning if the path from A to B is not the same as the path getting from B back to A.
Now, this is an idea which is illustrated very graphically by CH Waddington's famous landscape of a developing organism, a ball rolling down the landscape, reaching certain decision points in which it goes one way or the other. That's the path dependence of something that Brian Arthur in his seminal work at the Santa Fe Institute through Brian and Kenneth Arrow's leadership began to develop its economics program. Brian emphasized the importance of path dependence in the economy. And associated with that is the potential for sudden flips from one state to the other: contagious spread and systemic risk, and the potential for the destabilization and shifts of regimes through the evolution of variables that are operating on slower time scales.
As an example in 2008, 6 months before the financial crisis and collapse, Bob May, George Sugihara and I wrote a paper in Nature called Ecology for Bankers, in which we say if we analogize from ecological systems to financial systems, we see an increasingly interconnected system. And one, which if we were monitoring an ecological system, would be on the verge of collapse. In fact, we said, who knows, for instance, how the present concern over sub-prime loans will pan out. Unfortunately, we know how that panned out, and we know what we can learn from thinking about complex adaptive systems from one discipline to another, or from the sort of higher level viewpoint that Santa Fe explores.
Critical transitions are widespread and complex adaptive systems. Often they are early warning indicators, Marten Scheffer's book covers the landscape of this topic from natural systems, to economic systems, to physiological systems. When you go to a doctor and the doctor performs an electrocardiogram or some other measure, she or he is trying to anticipate the potential for catastrophic changes in the system. This raises the question more generally of whether we can read the tea leaves. Are there early warning indicators of critical transitions? Marten Scheffer has led a series of working groups. One I happen to have been part of, was on trying to identify what some of the early warning indicators might be in anticipating the transition of a system, like critical slowing down. There are some caveats in over-interpretation of the signals, but these are very promising and exciting areas.
Having covered all those topics in the black dots, I turn now to the last topic which is involving a lot of my energies: what does all this mean for the conflicts between levels? And how do we achieve a sustainable future? How do we sustain public goods and common-pool resources? How do we get the cooperation and collective decision making that's necessary? Public goods problems are widespread in socioeconomic and ecological context, from the sharing scene between oil rigs and fishermen that you see on the left to tumor cells, whose rapid growth leads to the breakdown of the commons. These are all public goods problems. These are all problems that have to do with complex, adaptive systems. On the right. it's the tumor cells of the individual agents that are proliferating without regard for the ultimate demise of their hosts. So the latest challenges we know about, of course antibiotics and their overuse is a problem for society.
In terms of the latest pandemic, we're seeing this problem in terms of individual perceived liberties versus the collective goods in areas like social distancing, vaccination and mask wearing. And interestingly this has been, surprisingly to many, strongly divided along political divisions. And the degree of political polarization in our systems has made it much more difficult to deal with public goods problems. You see the differences here, for example, between Republicans and Democrats in terms of the willingness to get vaccinated.
The maintenance of cooperation, in general, and sustaining the commons was highlighted by Garrett Hardin three-quarters of a century ago, building on the work of William Forster Lloyd, when he talked about the tragedy of the commons and in which the solution had to do with mutual coercion mutually agreed upon. But Hardin was thinking strongly in terms of the need for a government authority to impose those agreements. Lin Ostrom who was involved in Santa Fe, a Nobel Laureate who passed away a few years ago, showed that this could arise from the bottom up, from shared and mutually agreed upon norms. And social norms are crucial to understanding how we achieve cooperation. They are not only problems. They may be the solutions to many of our problems. Social norms can change rapidly: attitudes towards foot binding, smoking in public places, racial equality, gender equality. Maybe we're seeing it now with regard to attitudes towards climate change, sustainability, and the current pandemic. Norms can change rapidly. Can we build on the local, pro-sociality and norms to achieve agreements at the global level on climate change and other environmental problems.
In some of her last work Lin Ostrom talk about what you call the polycentric approach for coping with climate change in which smaller scale agreements would serve as building blocks for the global agreements. This is a problem in complexity economics. With Avinash Dixit and my student Andrew Tillman, we published a paper recently in which we built on the Elinor Ostrom ideas. Divided the population up into sub populations in each of which individuals had concern for each other, and asked whether the pro-sociality in those local groups at least and the leakage of the public goods or public bads from one sub-population to another, could lead to global cooperation and show the conditions under which it could.
In conclusion, I’ve tried to show you that ecology and economics are two sides of the same coin. Therefore, advances in each can inform problems in the other. If you go back to the early work of Charles Darwin or Adam Smith, you'll see very similar themes. Andy Lo and I edited a volume less than a year ago, a special issue of the Proceedings of the National Academy of Sciences， called "Evolutionary Models of Financial Markets". These are adventures in complexity and economics. I think they show, the papers in this issue, the great potential for interfaces across disciplines from complexity theory to economics.
In conclusion, in dealing with complex adaptive systems, we need to understand the multiple scale nature of those systems. We need to develop approaches, I call them statistical mechanics, to identify the potential for multiple stable states and critical transitions to understand what makes these systems resilient and robust. And most crucially, how do we manage the commons across scales and conflicts of interest. So I think we'll see these topics explored in the lectures that will follow. Thank you very much.
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