The classic Science advances one funeral at a time refers; and I swear I have at least one other riffing on the theme. And today brings us Population Doomster and False Prophet of Ecological Apocalypse Paul Ehrlich Has Died. Wiki tells me that "statistician Paul A. Murtaugh says that Ehrlich was largely correct" but that is drivel. Michael Mann says he "was a friend and a hero. He will be greatly missed" and whinges that Julian Simon said Ehrlich was an alarmist purveyor of doom and gloom. Sadly, shortage of electrons - could it be anything else - prevents Mann from noting that Simon won the bet.I recall in the dim and distant past discussing Ehrlich on sci.env; and, miraculously, Google Groups turns up this thread, started by Baby Timmy. And I find:
David Friedman wrote:>In article <3cc1...@news.nwl.ac.uk>, w...@bas.ac.uk wrote:>> >...I get>> >an estimated world total deaths due to nutritional deficiency>> >during the 1970s of 5,061,129 or a nice round five million.>> Well, you've done quite a bit of work on that: thanks.>> I'll go with 5M, until something more definitive turns up.
>But those aren't famine deaths. That's coming from an estimate of "deaths>world-wide due to all nutritional deficiencies." Poor nutrition results>in an increase in death rates long before anyone is starving to death.So what. Its an upper bound. If correct, famine deaths were less than 5M,and Erlich was wildly wrong (on this point).Well, you've done quite a bit of work on that: thanks.I'll go with 5M, until something more definitive turns up.
Which I think suffices for the distant past. My recollection of myself, at that time, was of being sympathetic to the kind of stuff the Ehrlich was saying - notice my parenthetical "on this point" -, but perhaps fortunately I was able to read what other people wrote; so many people can't.
I don't think I ever read Ehrlich. I did read the in-the-same-camp Club of Rome, and realised it was all wrong: they simply assume bad things increase exponentially but good things increase polynomially, and so even before the complicated modelling, those assumptions tell you that the bad will eventually overwhelm the good. Inevitably they plot bad-things-happening on a graph with time as the X axis; inevitably people read that time axis as meaningful; their defence is oh-dearie-me-no, the time is just expressive and so of-course-our-predictions-were-not-for-that-actual-time; but that just makes all the modelling even more pointless, because as I've said, the result is baked in from the start1. David Henderson, in his My 1983 Memo on Population Growth, tells us that "This paper is premised on the idea that reducing population growth hastens economic progress. However, the author simply asserts the premise rather than documenting it" and I have a feeling that's true of Ehrlich's work. Malthus makes a similar mistake: to first order, more people will produce more stuff, so food production, as a first guess, should be assumed to increase in line with population.
2026/3/19: Ehrlich dishonestly claimed that all his work was peer reviewed. He was lying: popular books - indeed, books in general - aren't peer reviewed the way academic papers are.
Refs
* Me from 2023 reffing ACX on Ehrlich.
* Capital maintenance requires real sacrifice. Under capitalism, private owners do it because they capture the gains. Under democracy? Public infrastructure tends to be neglected in pursuit of votes.
Notes
1. Somewhere I believe I have a post saying this, but I cannot now find it.
No exponential growth can continue forever. Doesn't matter what is growing.
ReplyDeleteYeast in a fermentation vat, humans. Eventually it stops, often before consuming all the atoms in the Universe.
Yeast growth will hit a limit, and if we started with malted barley and hops, we might have beer. Or if we start with grapes or more barley, we might have wine. But the growing yeast population peaks rather sharply. In the first case, the yeast run out of food. In the second case, alcohol produced by the yeast makes the environment poisonous for yeast.
Picture a yeast cell carrying a sign denying beer is in the future. It might be correct if there is enough food to make enough alcohol. Then we end up with wine or barley wine.
Human population might be limited by society. A population limit was imposed in China by the Chinese state, and has likely been a major factor in China's rapid economic growth.
Human population can not be limited by individual choice. Those that choose to reproduce less for what ever reason would soon be outnumbered by those that choose to reproduce more. The current slowdown in population growth is temporary. See "Tragedy of the commons".
Mathus was wrong on the details. So was the yeast cell protesting beer.
I did read Ehrlich, and I found him quite inconsistent. Well worded sections mixed with sections of utter dribble.
"Those that choose to reproduce less for what ever reason would soon be outnumbered by those that choose to reproduce more. The current slowdown in population growth is temporary."
ReplyDeleteI guess we'll see. But as long as urbanization continues and large families change from being an asset to a cost, low population growth--or even decline--may be the new normal.
The horse-and-buggy-driving New Order Amish population doubles about every twenty years.
ReplyDeletehttps://groups.etown.edu/amishstudies/amish-population-profile-2025/
Math question.
If the Amish population in the USA and Canada is 410,955 in 2025, how long is it before the Amish population is the majority, assuming that the population of the USA and Canada is stable at about 381,399,587?
The Amish are rural and growing. If that trend continues, the future is deurbanization.
https://en.wikipedia.org/wiki/Counterurbanization
Or the quiverfull movement.
Or our neighbors that decided on 6 children. What will their children do? Not religious, just like to raise babies.
There are many smaller groups with higher population growth rates, some very religious and some not.
Well, the Amish aside, the urban population of the world has grown from 35% in 1960 to 58% in 2024, according to the World Bank and that trend doesn't show any sign of stopping soon.
ReplyDeleteOther than that, how did you enjoy the play, Mrs Lincoln?
ReplyDeleteShould we care about the world after 2100?.
ReplyDeleteI know you don't. You don't get to decide for everyone.
ReplyDeletePhil, I don't know why you would say that. Really I don't. I have corresponded on various weblogs with our host for over a decade. We have fought bitter fights and called each other names. But I have never seen any evidence that he is uncaring about the fate of the world. Did you get up on the wrong side of the bed this morning?
ReplyDeleteDr Connolley's answer to caring is: "answer is a qualified no; we should not care-as-change." We "should care, in the sense of being benignly interested."
ReplyDeleteIf you think I've misunderstood this, please correct me.
I feel like Leviathan. But I shall try: the doubling of the Amish will sort itself out peacefully, with no help needed from you or me; it will cause no problems to the world, much like the horseshit catastrophe in turn-of-century London. Ehrlich's error was to take similar unproblematical situations and declare them harbingers of disaster. You are wise enough to draw no explicit conclusions and just use innuendo.
ReplyDeleteThe Amish may or may not be sorted out peacefully. You have no idea, and neither do I.
ReplyDeleteThat whooshing sound? Oh, never mind.