Key Concepts: Visual and Narrative Models of Important New Thinking
FRAME: Leverage Points to Provoke Change in Complex Systems
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Places to Intervene in a System (In Increasing Order of Effectiveness)
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by Donella H. Meadows
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Introduction
difficult it is to figure out how the system works.
For example, switching to a reasonable diet does not
First we need to understand a few concepts about
how a system works.
result in immediate weight loss, nor does the start of
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an exercise program result in immediate gain in
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All systems and their components have system
muscle mass.
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“states,” which refers to the amount of something -%'/#38'#/3)23#%5#)&#'Q'261/'#72%@2)9#2'/4(3#1&#199'B
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(physical or non-material) that’s on hand—like
Components of the Model
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items a store might keep in stock for sale. One state # Following is a list and brief description of the
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of a bathtub might be the amount of water in it.
components of the model
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We might answer on a survey that our amount, or
Numbers
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“stock” of happiness (how happy we are today) is a # The least effective place to intervene is by
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9 out of 10. That’s a non-material state.
arbitrarily changing various parameters. These are
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things we can measure, but which don’t really
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Stocks change over time based on flows—inflows
represent an important state of the system. Changing
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and outflows. The amount of water in a bathtub
the temperature inside the passenger compartment
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changes based on how much water flows into it or 342'#1&/1-'#38'#7)//'&@'2#6%97)239'&3#%5#)#6)2#9)"#
of a car may be easy, but it won’t help reduce the
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how much water drains out of it. Heat flows out of
temperature of an overheating engine. We also try
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often to make changes to numbers without
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opening the hot water tap.
understanding how the system that creates them
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works. Therefore, a manager might demand that
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If
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want
to
take
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bath,
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have
in
mind
a
goal
next year’s sales figures exceed $1,000,000. Simply
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for the depth and temperature of the water. You plug 'Q6''-#SI>JJJ>JJJ+#L197("#.2131&@#)#&'.#&49!'2#
writing a new number down won’t make it happen.
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up the drain (thereby setting the outflow to zero)
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and turn on the faucets using a combination of hot # Material Stocks and Flows
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and cold water. Then you watch the water rise, and <#(%,.#"'/()$=&'#+5'>")?&'
The next least effective place to intervene is by
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use your hand to test the temperature. If it’s too hot, K8'#&'Q3#(')/3#'55'631<'#7()6'#3%#1&3'2<'&'#1/#!"#)-B
adjusting the plumbing and arrangement of the
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you’ll use that information and cut back on the hot M4/31&@#38'#7(49!1&@#)&-#)22)&@'9'&3#%5#38'#/3%6:/#
stocks and flows. Although some systems are just
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water tap. If the water is too high, you’ll open the )&-#5(%./+#;(38%4@8#/%9'#/"/3'9/#)2'#M4/3#()1-#%43#
laid out wrong and the only way to get them to work
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drain to let a little out.
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That’s feedback. You take
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information regarding the
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state of the system and use
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it to adjust the flows that
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affect that state.
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Feedback isn’t always
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immediate. When you first
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in your house, you
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probably don’t get hot
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water immediately. It may
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take a while. The amount
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of time between making a
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change to a flow and
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seeing the change affect
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the stock it’s connected to
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is called lag. The longer
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Key Concepts: Visual and Narrative Models of Important New Thinking
better is to change the way that people and
processes are connected to one another and in what
order, changing the way things are connected to one
another is often expensive (like moving two
departments closer together so they can
communicate better with one another).
Regulating Negative Feedback Loops
A thermostat is the classic example of a negative
feedback subsystem. The user sets a goal by
entering a target temperature. The thermostat
compares room temperature to the target, and then
compensates for any difference by either turning on
the air conditioning or the furnace. Negative
feedback loops self-correct. If some stock is out of
whack with our goal for it (like our weight) chances
are it’s because there’s a inadequate or weak
negative.
Driving Positive Feedback Loops
Positive feedback is self-reinforcing. Imagine a
small group of rabbits that breed to have baby
rabbits, who grow up to breed and create yet more
rabbits. The increasing rabbit population is
governed by positive feedback —rabbits create
more rabbits and more rabbits create even more
rabbits. The reproductive cycle is a positive
feedback loop. So is investing money in a bank at a
constant rate of interest with reinvestment. These
loops drive growth. They can also precipitate
collapse. A virus that infects one rabbit is
transmitted to two, who transmit it to four others,
and then to eight and so on. (An immune system is a
negative feedback loop.) Finding ways to either
create positive feedback loops (like fashion crazes)
or to impede them is a very powerful way to
influence what is happening in a system.
Information Flows
Often we don’t have the information we need in
order to know what to change in a system. It’s like
trying to fill a bathtub to the right level without
either being able to look at the bath or to use your
hand to gauge the amount of water that’s already in
it. Sometimes just showing people information
about the state of a stock (how much cash they have
in the bank), or the rate of a flow (how fast their
cash is entering the bank through income or leaving
the bank through expenses) is enough to get them to
make the necessary changes to improve the system
For more information contact:
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(925) 934-1786
they’re working with (cut down on eating out or
find a little higher paying job).
The Rules of the System
The rules relate to incentives, punishments and
constraints, including a system’s scope and
boundaries. The tax code of the IRS is an example
of a complex body of rules that radically influences
the behavior of corporations and individuals. A
subsidy is another example of a rule that influences
behavior. The cost of water and gasoline in the
United States are both heavily subsidized. If the
subsidies were removed, and people had to pay the
true cost of these things, their behavior would likely
be altered. Rules change behavior. Power over rules
is real power.
The Power of Self-Organization
Self-organization shows up as evolution and
revolution. This is an extremely powerful type of
change. New systems are successful if they evolve
to be more fit in their environment than the systems
they are replacing. The replacement of horses by
automobiles is an example. The introduction of the
car required the evolution of whole new systems
and subsystems like gas stations, paved roads,
petroleum refinement, and mass production
techniques. Both evolution and revolution have a
common impetus— diversity. To increase the
chances of creating a new type of system that
replaces a less efficient one, allow for more
diversity of ideas and experiments to take place.
The Goals of the System
Goals influence everything further down the list. If
the overall goal is to take a whirlpool bath instead of
just a normal one, major components of the system
must be changed—like the addition of air jets and
the controls for how forceful they are, as well as the
size of the tub.
The Mindset or Paradigm
The highest place to intervene—the most effective
and the most difficult—is how we think about the
systems we are trying to change. Egyptians built
pyramids because they believed in an afterlife. We
build skyscrapers because we believe that
downtown space is extremely valuable. We engage
in capitalism because we agree with Adam Smith
that the selfish actions of individual players in
markets wonderfully accumulates to the common
good.