More on this book
Community
Kindle Notes & Highlights
The system, to a large extent, causes its own behavior! An outside event may unleash that behavior, but the same outside event applied to a different system is likely to produce a different result.
Because of feedback delays within complex systems, by the time a problem becomes apparent it may be unnecessarily difficult to solve.
According to the competitive exclusion principle, if a reinforcing feedback loop rewards the winner of a competition with the means to win further competitions, the result will be the elimination of all but a few competitors.
A diverse system with multiple pathways and redundancies is more stable and less vulnerable to external shock than a uniform system with little diversity.
The behavior of a system cannot be known just by knowing the elements of which the system is made.
A system* is an interconnected set of elements that is coherently organized in a way that achieves something. If you look at that definition closely for a minute, you can see that a system must consist of three kinds of things: elements, interconnections, and a function or purpose.
Systems can be embedded in systems, which are embedded in yet other systems.
A system is more than the sum of its parts. It may exhibit adaptive, dynamic, goal-seeking, self-preserving, and sometimes evolutionary behavior.
Many interconnections are flows of information—signals that go to decision points or action points within a system. These kinds of interconnections are often harder to see, but the system reveals them to those who look. Students may use informal information about the probability of getting a good grade to decide what courses to take. A consumer decides what to buy using information about his or her income, savings, credit rating, stock of goods at home, prices, and availability of goods for purchase.
If a government proclaims its interest in protecting the environment but allocates little money or effort toward that goal, environmental protection is not, in fact, the government’s purpose. Purposes are deduced from behavior, not from rhetoric or stated goals.
Systems can be nested within systems. Therefore, there can be purposes within purposes.
If the interconnections change, the system may be greatly altered. It may even become unrecognizable, even though the same players are on the team. Change the rules from those of football to those of basketball, and you’ve got, as they say, a whole new ball game.
A stock is the foundation of any system. Stocks are the elements of the system that you can see, feel, count, or measure at any given time. A system stock is just what it sounds like: a store, a quantity, an accumulation of material or information that has built up over time.
Stocks change over time through the actions of a flow. Flows are filling and draining, births and deaths, purchases and sales, growth and decay, deposits and withdrawals, successes and failures.
If you understand the dynamics of stocks and flows—their behavior over time—you understand a good deal about the behavior of complex systems.
As long as the sum of all inflows exceeds the sum of all outflows, the level of the stock will rise.
As long as the sum of all outflows exceeds the sum of all inflows, the level of the stock will fall.
If the sum of all outflows equals the sum of all inflows, the stock level will not change; it will be held in dynamic equilibrium at whatever level it happened t...
This highlight has been truncated due to consecutive passage length restrictions.
The human mind seems to focus more easily on stocks than on flows. On top of that, when we do focus on flows, we tend to focus on ...
This highlight has been truncated due to consecutive passage length restrictions.
A stock can be increased by decreasing its outflow rate as well as by increasing its inflow rate.
A stock takes time to change, because flows take time to flow.
Stocks usually change slowly. They can act as delays, lags, buffers, ballast, and sources of momentum in a system. Stocks, especially large ones, respond to change, even sudden change, only by gradual filling or emptying.
Stocks generally change slowly, even when the flows into or out of them change suddenly. Therefore, stocks act as delays or buffers or shock absorbers in systems.
It has taken decades to accumulate the stratospheric pollutants that destroy the earth’s ozone layer; it will take decades for those pollutants to be removed.
