Old dirt, new dirt, old water, new water and Laws of Nature

Thomas Malthus

There is an ongoing battle between the Malthusians and their opponents about whether we can sustain our population agriculturally or whether we inevitably outgrow our means of sustenance.  David Montgomery's book Dirt, about soil erosion and the history of human civilizations, to which we referred in yesterday's post, has some pithy things to think about.

This book says that way before Malthus (who you can friend here), even the classic Romans "exuded confidence that human ingenuity would solve any problems.  Cicero crisply summarized the goal of Roman agriculture as to create 'a second world within the world of nature.' " That's exactly the way technophiles, representatives of science, industry, capitalism, and the status quo argue today:  not to worry, technology will solve all problems!

But like every aspect of complexity in Nature, how right would Malthus have to be to be basically right, and if he's 'mainly right' or 'right in the long run', is his principle a basic principle of Nature?  What kind of evidence would one need to determine if he was 'right' or not? Let's think about this briefly.

There are about 7 billion people alive today, uncountably more than in Malthus' time, much less the time of the ancient civilizations whose dirty habits may have led to their collapse.  Agricultural yield may have petered out here and there due to erosion, salt deposits, and the like.  But worldwide there's far more crop acreage than back then and far more yield per acre.  Instead of dealing always with new dirt from recent growth and new water from rain, we're now living on old dirt (vegetable matter called 'oil') and old water (pumped up from wells).  But we're doing fine, so Malthus must have been not slightly but massively wrong!

Dust bowl, Keota, Colorado
1939

Yes, there are patches of disaster here and there--in northern Africa for example, and our dust bowl last century.  And more people, even if a small percentage of the human species, are starving than ever before, according to statistics we've seen.  But, so? There will always be some areas where things screw up or rapid climate change outpaces people's ability to adapt.  In earlier days, local drought may have meant death, but today there can be airdropped relief packages.  So, yes, some people do outgrow their  land but no, it's not that our whole species is overpopulating.  Technology has, with some bumps in the road, served us well.  Malthus was wrong!

Wait a doggone dirty minute!  If many aspects of science are right, climate change, erosion, and our dependency on fossil-fuel for fertilizer to replace lost topsoil, and on big machines to grow and transport food, will lead us predictably into horrendous Malthusian collapse!  That's why so many are concerned with humans' degradation of the earth, clearing of tropical rainforest (whose soil, thin already, will quickly disappear), and why so many are saying to Eat Local.  And, of course, many are saying as they have been for a while, that there are just too many humans.

Malthus himself was aware of technical advances, but his view was that if technology improved yield, population would grow to catch up and eventually to pass the new capacity.  Montgomery's book basically argues that latter point, and that most civilizations have fallen into decay because of their dirty habits.

Whatever one might say about Malthus, his 'law' was certainly not unexceptionable like the law of gravity, or the ideal gas law, or Ohm's law about electricity.  But then what was it?  Is it a law of Nature at all?  Do such laws have exceptions?  Is it a kind-of-maybe generalization about Nature, beneath which there might be some law(s) acting that we don't know about?

Now, Darwinian evolution that we all love and invoke so much and so often so literally, was largely premised on the Malthusian principle that populations always outgrow their resources.  So, if Malthusian population pressure isn't a Law of Nature, where does that leave natural selection, the cornerstone of Darwinian worldviews and the force that drove it in his mind---and that is so often so blithely invoked?  The reason there was natural selection and only the best in life made it through life was that there was competition for limited resources.  If that weren't so, why, the stumblebums of the living world could do just fine.

Where complexity reins, and observations we make are incomplete on the scale of the events we're trying to understand, what are the criteria we should maintain for understanding, for developing theory, without which science would not be science?

These issues are not just down and dirty, or digging the gossipy society dirt. They also apply to other sciences in which slow non-steady change has to be interpreted if we are to understand both the nature of Nature and the future we and our descendants will face.