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Not sure I understand the reason this kind of model keeps getting spawned every few years. Idealized models with no relevance to empirical observations are nowh

Not sure I understand the reason this kind of model keeps getting spawned every few years. Idealized models with no relevance to empirical observations are nowhere near predicting civilization collapse. They can't even explain the observed past trajectories.

jnurmine 5y ago
During the 1970s the Club of Rome made "The Limits to Growth" with the World3 model and, whatever it predicts, some scenarios like the Business As Usual (BAU) seems to have tracked quite well for ca. 50 years already. The latest check-up is by Gaya Branderhorst in 2020, https://dash.harvard.edu/handle/1/37364868 https://dash.harvard.edu/handle/1/37364868. Of course, one has to understand that such a model doesn't show you "on the year 2028 the population is size 16.2931 billion". That is not the point. The point is to show how something grows, or shrinks, and the interrelations of the tracked variables. As x goes higher, y starts to diminish and soon after z goes through the roof, that kind of thing. The collapse of, for example, industrial output levels might be a form of a Seneca cliff. That is, the growth of the industrial output becomes harder and harder to achieve, while the difficulties compound and actually keep on growing long after the growth of industrial output itself has stagnated or started to drop slightly. This will dramatically increase the inhibitory effect, thus creating a growth curve which starts to slow down and then drops fast ("collapse"). Why dismiss the model? The BAU scenario seems to reflect reality for over 50 years now, so is it not rational to try to understand it? The Limits to Growth is fundamentally a realization that the world has finite resources. It is not illogical to consider this as a truth. At some point there won't be new resources to obtain, and hence growth in systems based on capturing resources will simply slow down (and perhaps even drop fast, "collapse", because difficulties compound). Circular economy and recycling are good but they cannot expand the available resource pool of e.g. raw materials.
jshmrsn 5y ago
I assume these are references to Isaac Asimov’s Foundation.
- shoo 5y ago
  the references to have a read through are not science fiction, but are system modelling studies done in the 70s: > Meadows, Dennis L., William W. Behrens, Donella H. Meadows, Roger F. Naill, Jørgen Randers, and Erich Zahn. Dynamics of Growth in a Finite World. Cambridge, MA: Wright-Allen Press, 1974. > Meadows, Donella H., Dennis L. Meadows, Jorgen Randers, and William W. Behrens. The Limits to Growth. New York 102, no. 1972 (1972): 27. there's lots of people who dismiss this as "doom and gloom". it's worth getting hold of the books and reading through it, and making up your own mind. do you think the modelling assumptions seem reasonable? even if some of the parameters seem difficult to estimate from observed real world data, do you reckon the overall system dynamics behaviour of predicted "overshoot and collapse" seems plausible, even if the timing may be very difficult to predict?
  - rileyphone 5y ago
    I'm reading Donella Meadows' Thinking in Systems right now which I think is a good overview of this line of reasoning. Of course models are idealized, but they're also one of the best ways to understand complex systems. The human brain does something very similar in forming intuitions about the world, but we should recognize that in order to make a better model we will have to make one in silico. Another interesting approach is agent-based modeling, which explores how the decisions of agents with limited information can create emergent patterns.
  - canjobear 5y ago
    Has their model made accurate predictions on held-out data? That's all that matters.
    - dredmorbius 5y ago
      For those curious about the term "held out data", it's a modelling / validation method. https://people.duke.edu/~rnau/three.htm https://people.duke.edu/~rnau/three.htm
    - onethought 5y ago
      Ability to predict a past future doesn’t give any strength to the ability to predict the future future.
spodek 5y ago
Because the data keeps matching their Business as Usual model. I think there's more recent research, but here's a paper from 2014, showing 40 years of reasonable fit: http://sustainable.unimelb.edu.au/sites/default/files/docs/MSSI-ResearchPaper-4_Turner_2014.pdf http://sustainable.unimelb.edu.au/sites/default/files/docs/M.... If we keep matching their model, we'll soon see dramatic population declines. Also, the patterns revealed in their models are useful for understanding patterns in nature and human interaction with it.
- geoalchimista 5y ago
  Just looking at Figure 1 on page 8 of the paper you mentioned, it can go either way because we haven't seen a reversal in any of the trends. That is hardly a prediction. For example, if one looks at the "Services per capita", is there any sign that it will meet an inflection point in the next few years? I know it is always appealing to tell a story with a grand unifying narrative. But sound research must prop it up with empirical evidence. Could there be limits to growth? Probably. But a highly simplistic model not informed by appropriate data or economic understanding is not the way to tell such limits.
  - api 5y ago
    There have to be limits to growth, but we won’t know where they are except in retrospect. We also may never hit them due to fertility decline which occurs in all wealthy societies. Fertility decline plus efficiency increase could cause consumption of some resources to fall. Space migration doesn’t change the equation much on Earth unless you start mining and manufacturing off world and importing product, and that is pretty far off.
  - teabee89 5y ago
    "Could there be limits to growth?" Yes 100% (you cannot extract indefinitely more and more every year from finite resources), the debate is simply when we'll peak for a given ressource (20 years, 100 years, 1 million years) and the size of such an impact on the economy.
  - baq 5y ago
deleted 5y ago
[deleted]
cryptonector 5y ago
Right, because all these models are just that: models, and very simple ones at that. They encode a few functions, often linear, when the thing they model are enormously complex and dynamic. Humans generally fail to grasp the non-linear and the dynamic. The Malthusian model is: more food supply -> more humans -> more food demand -> more food supply -> more humans -> ... A vicious circle. A positive feedback loop. But it's a positive feedback loop operating in machine with negative feedback loops too. It's been over a decade since it's been understood that global human population is going to plateau in just three more decades, then begin declining. Reasons for that are myriad, but if I had to summarize it it would look like this: low child mortality + high life expectancy + high standards of living + high taxes and costs + high retirement costs == low interest in reproduction -- i.e., price signalling works! Who would have thunk it? Not Malthusian modellers, for sure.
- rsj_hn 5y ago
  I remember the Club of Rome was the first to do these models, assuming peak oil and the collapse of western civilization based on resource constraints. They would have these coupled differential equations, similar to predator-prey, calculating cost of extracting resources and the resulting declines in food production and thus population. https://en.wikipedia.org/wiki/Club_of_Rome https://en.wikipedia.org/wiki/Club_of_Rome But I thought all of that had fallen out of fashion by the early 1980s when oil prices fell and it was discovered that you don't have stable relationships or known parameters for most of this stuff.
  - cryptonector 5y ago
    Exactly. You can have very sophisticated, non-linear, dynamic models developed over many years by brilliant people, then still see the models fail miserably.
  - dredmorbius 5y ago
    World3, implemented in the Python module submitted here, is the Club of Rome model.
- coolspot 5y ago

jnurmine 5y ago

During the 1970s the Club of Rome made "The Limits to Growth" with the World3 model and, whatever it predicts, some scenarios like the Business As Usual (BAU) seems to have tracked quite well for ca. 50 years already. The latest check-up is by Gaya Branderhorst in 2020, https://dash.harvard.edu/handle/1/37364868 https://dash.harvard.edu/handle/1/37364868. Of course, one has to understand that such a model doesn't show you "on the year 2028 the population is size 16.2931 billion". That is not the point. The point is to show how something grows, or shrinks, and the interrelations of the tracked variables. As x goes higher, y starts to diminish and soon after z goes through the roof, that kind of thing. The collapse of, for example, industrial output levels might be a form of a Seneca cliff. That is, the growth of the industrial output becomes harder and harder to achieve, while the difficulties compound and actually keep on growing long after the growth of industrial output itself has stagnated or started to drop slightly. This will dramatically increase the inhibitory effect, thus creating a growth curve which starts to slow down and then drops fast ("collapse"). Why dismiss the model? The BAU scenario seems to reflect reality for over 50 years now, so is it not rational to try to understand it? The Limits to Growth is fundamentally a realization that the world has finite resources. It is not illogical to consider this as a truth. At some point there won't be new resources to obtain, and hence growth in systems based on capturing resources will simply slow down (and perhaps even drop fast, "collapse", because difficulties compound). Circular economy and recycling are good but they cannot expand the available resource pool of e.g. raw materials.

jshmrsn 5y ago

I assume these are references to Isaac Asimov’s Foundation.

shoo 5y ago
the references to have a read through are not science fiction, but are system modelling studies done in the 70s: > Meadows, Dennis L., William W. Behrens, Donella H. Meadows, Roger F. Naill, Jørgen Randers, and Erich Zahn. Dynamics of Growth in a Finite World. Cambridge, MA: Wright-Allen Press, 1974. > Meadows, Donella H., Dennis L. Meadows, Jorgen Randers, and William W. Behrens. The Limits to Growth. New York 102, no. 1972 (1972): 27. there's lots of people who dismiss this as "doom and gloom". it's worth getting hold of the books and reading through it, and making up your own mind. do you think the modelling assumptions seem reasonable? even if some of the parameters seem difficult to estimate from observed real world data, do you reckon the overall system dynamics behaviour of predicted "overshoot and collapse" seems plausible, even if the timing may be very difficult to predict?
- rileyphone 5y ago
  I'm reading Donella Meadows' Thinking in Systems right now which I think is a good overview of this line of reasoning. Of course models are idealized, but they're also one of the best ways to understand complex systems. The human brain does something very similar in forming intuitions about the world, but we should recognize that in order to make a better model we will have to make one in silico. Another interesting approach is agent-based modeling, which explores how the decisions of agents with limited information can create emergent patterns.
- canjobear 5y ago
  Has their model made accurate predictions on held-out data? That's all that matters.
  - dredmorbius 5y ago
    For those curious about the term "held out data", it's a modelling / validation method. https://people.duke.edu/~rnau/three.htm https://people.duke.edu/~rnau/three.htm
  - onethought 5y ago
    Ability to predict a past future doesn’t give any strength to the ability to predict the future future.

spodek 5y ago

Because the data keeps matching their Business as Usual model. I think there's more recent research, but here's a paper from 2014, showing 40 years of reasonable fit: http://sustainable.unimelb.edu.au/sites/default/files/docs/MSSI-ResearchPaper-4_Turner_2014.pdf http://sustainable.unimelb.edu.au/sites/default/files/docs/M.... If we keep matching their model, we'll soon see dramatic population declines. Also, the patterns revealed in their models are useful for understanding patterns in nature and human interaction with it.

geoalchimista 5y ago
Just looking at Figure 1 on page 8 of the paper you mentioned, it can go either way because we haven't seen a reversal in any of the trends. That is hardly a prediction. For example, if one looks at the "Services per capita", is there any sign that it will meet an inflection point in the next few years? I know it is always appealing to tell a story with a grand unifying narrative. But sound research must prop it up with empirical evidence. Could there be limits to growth? Probably. But a highly simplistic model not informed by appropriate data or economic understanding is not the way to tell such limits.
- api 5y ago
  There have to be limits to growth, but we won’t know where they are except in retrospect. We also may never hit them due to fertility decline which occurs in all wealthy societies. Fertility decline plus efficiency increase could cause consumption of some resources to fall. Space migration doesn’t change the equation much on Earth unless you start mining and manufacturing off world and importing product, and that is pretty far off.
- teabee89 5y ago
  "Could there be limits to growth?" Yes 100% (you cannot extract indefinitely more and more every year from finite resources), the debate is simply when we'll peak for a given ressource (20 years, 100 years, 1 million years) and the size of such an impact on the economy.
- baq 5y ago

deleted 5y ago

[deleted]

cryptonector 5y ago

Right, because all these models are just that: models, and very simple ones at that. They encode a few functions, often linear, when the thing they model are enormously complex and dynamic. Humans generally fail to grasp the non-linear and the dynamic. The Malthusian model is: more food supply -> more humans -> more food demand -> more food supply -> more humans -> ... A vicious circle. A positive feedback loop. But it's a positive feedback loop operating in machine with negative feedback loops too. It's been over a decade since it's been understood that global human population is going to plateau in just three more decades, then begin declining. Reasons for that are myriad, but if I had to summarize it it would look like this: low child mortality + high life expectancy + high standards of living + high taxes and costs + high retirement costs == low interest in reproduction -- i.e., price signalling works! Who would have thunk it? Not Malthusian modellers, for sure.

rsj_hn 5y ago
I remember the Club of Rome was the first to do these models, assuming peak oil and the collapse of western civilization based on resource constraints. They would have these coupled differential equations, similar to predator-prey, calculating cost of extracting resources and the resulting declines in food production and thus population. https://en.wikipedia.org/wiki/Club_of_Rome https://en.wikipedia.org/wiki/Club_of_Rome But I thought all of that had fallen out of fashion by the early 1980s when oil prices fell and it was discovered that you don't have stable relationships or known parameters for most of this stuff.
- cryptonector 5y ago
  Exactly. You can have very sophisticated, non-linear, dynamic models developed over many years by brilliant people, then still see the models fail miserably.
- dredmorbius 5y ago
  World3, implemented in the Python module submitted here, is the Club of Rome model.
coolspot 5y ago