Positive feedback is a cycle in which something's happening makes its happening again more likely.
Example: Compound interest. When you put a dollar in the bank, the bank is renting your money to invest by loaning it out at interest. So the first year, they put another penny with your dollar. You leave it there, and the second year the bank adds one and one hundredth pennies. In seventy years, you have two bucks, courtesy of positive feedback.
Donella Meadows offers several other examples:
Eroded soil increases erosion because the thinner, poorer soil supports fewer erosion-stopping plants;
"The more high-energy neutrons in the critical mass, they more they knock into nuclei and generate more;"
The more flu sufferers, the more the flu spreads;
The larger the population, the more offspring, which in turn produce even more offspring;
Income from production and trade invested in building more capital to allow the production of more goods for trade.
There are a couple of examples I like, and that Meadows didn't include in this section.
There's methane, a greenhouse gas, frozen in the arctic tundra. As the climate warms, the tundra thaws and releases the mathane, accelerating warming.
The other is the Tom Baker Dr. Who, trying to explain positive feedback to an evil, giant spider that is running some kind of power through some science fiction gadget to get more, more, more, mwahahahaha, unlimited power. Fortunately the Doctor wises up, and bails before the spider goes nova.
Usually a negative feedback loop kicks in, and slows the positive feedback, but Meadows says that we can get quicker results, less threatening to ourselves by slowing the positive loop. Back off the gas before you slam on the brakes. She says this give the existing negative loops time to work. (Meadows was probably thinking of her predictions from the Limits to Growth study.)
She tells us to "look for leverage points around birth rates, interest rates, erosion rates, 'success to the successful' loops, any place where the more you have of something, the more you have the possibility of having more."
What does this have to do with gun violence? It took me a while to get around to writing this, because I was hoping something would come to me. I don't think we get more guns because we have more guns, and I don't believe that conceal-carry laws are adequate or desirable negative feedback. You can't buy a gun in Chicago, but there are high schools there with multiple shootings every year. There was an armed guard at Columbine, and you know somebody in the audience was packing in the Aurora Batman shooting.
We have to intervene in some related system to end mass shootings. Meadows write about five more leverage points, but the next post will be me, going off about what I think is going on.