When someone says "negative feedback loop" instead of "vicious cycle", they just admitted that they didn't really understand the concept of feedback loops. Since these are the folks writing the rules, I'm not about to give them a pass on this mistake. If you're searching for _mines_, I'll give you more credit for finding more mines. However, how do you search for "things likely to exacerbate a chaotic system"? How do you even know the system is chaotic in the first place? How do you find the regions that are chaotic -- before stepping into them? And these folks think that they are knowledgeable and clever enough to design a "systemic regulator"? Re antibiotics & crime: it is well-known/well-understood that there are significant political forces arrayed against eliminating all crime; you wouldn't need policemen, prosecutors, prison guards, etc. We fought & won the war against certain diseases -- primarily through vaccinations -- only to have a certain percentage of the population now refuse to vaccinate their children; these diseases are now coming back. MRSA exists because people refuse to finish their antibiotic regimens, allowing a small % of the bugs to mutate & become resistant. The drug companies have now concluded that _curing_ people of a disease isn't particularly profitable, so they now focus on "managing" the disease, so the patient has to take their medicine for the rest of their lives; at least these companies now have an incentive to keep the patients alive as long as possible! Re stabilizing control through feedback: there is usually a tradeoff between speed of control and instability. If you want your system to be able to react quickly, it has to be closer to the point of instability. If you want to avoid all instability (perhaps impossible), you end up with a very sluggish system. Example: high performance fighter aircraft, which require the ability to quickly change course, are inherently unstable without active (computer) control. There is a point for every system where you are willing to put up with some risk of instability in order for the system to be able to respond more quickly to a changing environment. An analogy can be made to converging sequences. My heuristic is that faster convergence may entail more violent initial swings (Gibbs phenomenon?). Smooth, monotonic convergence may be possible, but is more likely to be slower convergence. (Its been a long time since undergrad days -- is there a theorem about this?) I should have expanded my last point about these regulatory regimes requiring more design tools & testing. If Boeing or Toyota released an airplane or an automobile that hadn't been thoroughly tested & it crashed, there would be a huge demand for heads to roll. Yet politicians & bureaucrats routinely inflict untested theories on the public all the time, leaving immense damage in their wake. They don't even have the courtesy of testing these theories on a small % of the population before inflicting them on everyone simultaneously. It's as if Microsoft (or MacAfee) forced every user to upgrade his systems every night _with the latest untested batch of changes_. At 01:50 PM 5/8/2010, Dan Asimov wrote:
It seems hardly worthy of mention if someone was trying to say "vicious cycle" but instead said "negative feedback loop". <<
This sounds like saying that because our minesweepers are flawed and can't even detect some mines at all, we shouldn't even try to find them. <<
There's certainly some truth to this and closely related ideas. For example, recent studies have shown that often, the more that law enforcement tries to clamp down on violent, powerful drug organizations, the more virulent and powerful they tend to become. (A bit like taking a course of antibiotics for an infection, but stopping before it's fully wiped out. Which is not to say we should engage in a battle to the finish with such drug organizations . . ..) And certainly there are computer-automated trading routines whose behavior in many situations is not known and could be (and could have already been) disastrous. I said *some* truth, because there is much regulation that seems successful, like your most basic law enforcement, laws that make many utilities *public* utilities so we don't end up getting gouged for a glass of water, laws that prevent 51% or the population from tyrannizing the other 49%, etc.