As she tells it, Meadows was at a conference on global trade when it occurred to her that the participants were going about everything the wrong way. Numbers: Constants and parameters such as subsidies, taxes, and standards Buffers:The sizes of stabilizing stocks relative to their flows Stock-and-Flow Structures: Physical systems and their nodes of intersection 9. Delays: The lengths of time relative to the rates of system changes 8. Balancing Feedback Loops: The strength of the feedbacks relative to the impacts they are trying to correct 7.
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As she tells it, Meadows was at a conference on global trade when it occurred to her that the participants were going about everything the wrong way. Numbers: Constants and parameters such as subsidies, taxes, and standards Buffers:The sizes of stabilizing stocks relative to their flows Stock-and-Flow Structures: Physical systems and their nodes of intersection 9.
Delays: The lengths of time relative to the rates of system changes 8. Balancing Feedback Loops: The strength of the feedbacks relative to the impacts they are trying to correct 7. Reinforcing Feedback Loops: The strength of the gain of driving loops 6.
Information Flows:The structure of who does and does not have access to information 5. Rules: Incentives, punishments, constraints 4. Self-Organization: The power to add, change, or evolve system structure 3. Goals:The purpose or function of the system 2. Paradigms: The mindset out of which the system—its goals, structure, rules, delays, parameters—arises.
Transcending Paradigms Solutions Classic How do we change the structure of systems to produce more of what we want and less of that which is undesirable?
We not only want to believe that there are leverage points, we want to know where they are and how to get our hands on them. Leverage points are points of power. But Forrester goes on to point out that although people deeply involved in a system often know intuitively where to find leverage points, more often than not they push the change in the wrong direction.
The classic example of that backward intuition was my own introduction to systems analysis, the World model. Asked by the Club of Rome—an international group of businessmen, statesmen, and scientists—to show how major global problems of poverty and hunger, environmental destruction, resource depletion, urban deterioration, and unemployment are related and how they might be solved, Forrester made a computer model and came out with a clear leverage point: growth.
What is needed is much slower growth, different kinds of growth, and in some cases no growth or negative growth. This model came out at a time when national policy dictated massive low-income housing projects, and Forrester was derided. Since then, many of those projects have been torn down in city after city. Leverage points frequently are not intuitive.
Or if they are, we too often use them backward, systematically worsening whatever problems we are trying to solve. I have come up with no quick or easy formulas for finding leverage points in complex and dynamic systems.
Very frustrating—especially for those of us who yearn not just to understand complex systems, but to make the world work better. It was in just such a moment of frustration that I proposed a list of places to intervene in a system during a meeting on the implications of global-trade regimes. I offer this list to you with much humility and wanting to leave room for its evolution.
What bubbled up in me that day was distilled from decades of rigorous analysis of many different kinds of systems done by many smart people. But complex systems are, well, complex. System states are usually physical stocks, but they could be nonmaterial ones as well: self-confidence, degree of trust in public officials, perceived safety of a neighborhood. There are usually inflows that increase the stock and outflows that decrease it.
River inflow and rain raise the water behind a dam; evaporation and discharge through the spillway lower it. Political corruption decreases trust in public officials; experience of a well-functioning government increases it. Insofar as this part of the system consists of physical stocks and flows—and they are the bedrock of any system—it obeys laws of conservation and accumulation.
You can understand its dynamics readily if you can understand a bathtub with some water in it the stock, the state of the system and an inflowing faucet and outflowing drain. If the inflow rate is higher than the outflow rate, the water gradually rises. If the outflow rate is higher than the inflow, the water gradually goes down. The sluggish response of the water level to what could be sudden twists in the input and output valves is typical; it takes time for flows to accumulate in stocks, just as it takes time for water to fill up or drain out of the tub.
Policy changes take time to accumulate their effects. As systems become complex, their behavior can become surprising. Think about your checking account. You write checks and make deposits. A little interest keeps flowing in if you have a large enough balance and bank fees flow out even if you have no money in the account, thereby creating an accumulation of debt. Now attach your account to a thousand others and let the bank create loans as a function of your combined and fluctuating deposits, link a thousand of those banks into a federal reserve system—and you begin to see how simple stocks and flows, plumbed together, create systems way too complicated and dynamically complex to figure out easily.
Places to Intervene in a System in increasing order of effectiveness Numbers: Constants and parameters such as subsidies, taxes, and standards Think about the basic stock-and-flow bathtub.
The size of the flows is a matter of numbers and how quickly those numbers can be changed. Maybe the faucet turns hard, so it takes a while to get the water flowing or to turn it off. Maybe the drain is blocked and can allow only a small flow. Maybe the faucet can deliver with the force of a fire hose. Some of these kinds of parameters are physically locked in and unchangeable, but many can be varied, making them popular intervention points. Consider the national debt. It may seem like a strange stock; it is a money hole.
The rate at which the hole deepens is called the annual deficit. Income from taxes shrinks the hole, government expenditures expand it. Congress and the president spend most of their time arguing about the many, many parameters that increase spending and decrease taxing the size or depth of the hole. Since those flows are connected to us, the voters, these are politically charged parameters.
Despite all the fireworks, and no matter which party is in charge, the money hole has been deepening for years now, just at different rates. The amount of land we set aside for conservation each year. The minimum wage. The service charge the bank extracts from your account.
All of these are parameters, adjustments to faucets. So, by the way, is firing people and getting new ones, including politicians. Numbers, the sizes of flows, are dead last on my list of powerful interventions.
People care deeply about such variables as taxes and the minimum wage, and so fight fierce battles over them. But changing these variables rarely changes the behavior of the national economy system. Interest rates, for example, or birth rates, control the gains around reinforcing feedback loops. System goals are parameters that can make big differences. These kinds of critical numbers are not nearly as common as people seem to think they are.
Most systems have evolved or are designed to stay far out of range of critical parameters. Mostly, the numbers are not worth the sweat put into them. Buffers: The sizes of stabilizing stocks relative to their flows Consider a huge bathtub with slow in- and outflows. Now think about a small one with very fast flows.
You hear about catastrophic river floods much more often than catastrophic lake floods because stocks that are big, relative to their flows, are more stable than small ones. In chemistry and other fields, a big, stabilizing stock is known as a buffer. The stabilizing power of buffers is why you keep money in the bank rather than living from the flow of change through your pocket.
You can often stabilize a system by increasing the capacity of a buffer. It reacts too slowly. And big buffers of some sorts, such as water reservoirs or inventories, cost a lot to build or maintain. Businesses invented just-in-time inventories because occasional vulnerability to fluctuations or screw-ups is cheaper than certain, constant inventory costs—and because small to vanishing inventories allow for a more flexible response to shifting demand.
Buffers are usually physical entities, not easy to change. The storage capacity of a dam is literally cast in concrete. Stock-and-Flow Structures: Physical systems and their nodes of intersection The plumbing structure, the stocks and flows, and their physical arrangement, can all have an enormous effect on how the system operates.
When the Hungarian road system was laid out so that all traffic from one side of the nation to the other had to pass through central Budapest, that determined a lot about air pollution and commuting delays that is not easily fixed by pollution control devices, traffic lights, or speed limits. The only way to fix a system that is laid out poorly is to rebuild it, if you can.
Amory Lovins and his team at Rocky Mountain Institute have done wonders on energy conservation by simply straightening out bent pipes and enlarging ones that are too small. If we did similar energy retrofits on all the buildings in the United States, we could shut down many of our electric power plants. But often, physical rebuilding is the slowest and most expensive kind of change to make in a system.
Some stock-and-flow structures are just plain unchangeable. The baby-boom swell in the U. Physical structure is crucial in a system, but it is rarely a leverage point because changing it is rarely quick or simple. The leverage point is in proper design in the first place. After the structure is built, the leverage is in understanding its limitations and bottlenecks, using it with maximum efficiency, and refraining from fluctuations or expansions that strain its capacity.
Delays: The lengths of time relative to the rates of system changes Delays in feedback loops are critical determinants of system behavior.
They are common causes of oscillations. It takes several years to build an electric power plant that will likely last thirty years. Those delays make it impossible to build exactly the right number of power plants to supply changing demand for electricity.
Even with immense effort at forecasting, almost every electricity industry in the world experiences long oscillations between overcapacity and undercapacity. For example, the delay between the time when a pollutant is dumped on the land and when it trickles down to the groundwater, or the delay between the birth of a child and the time when that child is ready to have a child, or the time it takes for a price to adjust to a supply-demand imbalance.
Meadows, who worked in the field of systems analysis , proposed a scale of places to intervene in a system. Awareness and manipulation of these levers is an aspect of self-organization and can lead to collective intelligence. Her observations are often cited in energy economics , green economics and human development theory. She started with the observation that there are levers, or places within a complex system such as a firm, a city, an economy, a living being, an ecosystem , an ecoregion where a "small shift in one thing can produce big changes in everything" compare: constraint in the sense of Theory of Constraints. She claimed we need to know about these shifts, where they are and how to use them. She said most people know where these points are instinctively, but tend to adjust them in the wrong direction.
Twelve leverage points
After a yearlong trip from England to Sri Lanka and back, she became a research fellow at MIT , as a member of a team in the department created by Jay Forrester , the inventor of system dynamics as well as the principle of magnetic data storage for computers. She taught at Dartmouth College for 29 years, beginning in Paine Science Education Award in Posthumously, she received the John H. Meadows wrote "The Global Citizen,"  a weekly column on world events from a systems point of view.