What are self-correcting systems? They are processes which naturally return toward a “normal” state when they have moved away from that state by a significant distance.

Flickr photo by eutrophication&hypoxia

Population Bomb

For example, when it gets too hot in the afternoons here in Colorado, the clouds form from the hot air rising up over the mountains and cooling, and the rain comes, reducing the temperature. But scientists and so-called scientists often forget or ignore this self-correcting tendency of many systems.

For example, when Paul Ehrlich’s book, “The Population Bomb,” came out in 1968, it opened with; “The battle to feed all of humanity is over. In the 1970s and 1980s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now.” Erlich later wrote in “Ramparts Magazine, “Millions of people will soon perish in smog disasters in New York and Los Angeles… the oceans will die of DDT poisoning by 1979… the U.S. life expectancy will drop to 42 years by 1980, due to cancer epidemics.”

His mistaken predictions were based in part on straight-line projections of the type scientists make too often. The process goes something like this: you plot data, identify a trend, and assume it will continue in the same way. Of course, that ignores the changes which might be made by random chance, or human intervention, or those that might occur naturally in the case of self-correcting systems.

The latter are apparent all over. Coyotes, for example, may grow in numbers in a neat slope on a graph, making it look as thought there will be ten times as many of them in a few years. But at some point the availability of prey is diminished by their own competition with each other, and so more starve and the birth rates decline–you see a population crash on the graph. Then the cycle repeats itself.

Another example, we might see that a man is depleting his savings at a steady rate and predict bankruptcy in two years based on a straight-line projection. But of course as he gets nearer to this fate, his fear of losing everything becomes stronger and more motivating, so he makes changes.

It was 46 degrees Fahrenheit here this morning at six o’clock, and by noon it was 70 degrees. That means the temperature is rising at a rate of six degrees per hour. At that rate, within three days the temperature will be 450 degrees and trees will be bursting into flames.

That may sound silly, but straight-line projections like that are sometimes used when studying self-correcting systems or systems that have other influences which will affect what they do.

If you are interested in the concept, and want to explore it further, here are two questions to get you thinking:

1. What other examples of self-correcting systems can you think of?

2. If straight-line projections do not work with such systems, how do we make predictions about them that are more accurate?