I am very interested in the repetition of history, especially in the repetition of ideas. Two of my favorites are brought up every so often, one by the Right and one by the Left.
The first is the concept of the statistical bell curve as applied to human populations, normally in terms of IQ or some other measurement. Its most recent occurence was in the mid-1990's, reflected in books such as "The Bell Curve", and used to justify things like cuts in social spending, often with reasoning such as "they're poor because they are dumb, they are beyond help".
The second is typically a tool of the left, or of other environmentalists, and is sometimes referred to as simply the carrying capacity of the earth. A recent bestseller on this subject is "The Population Bomb". The concept here is typically doom and gloom - the earth is running out of stuff (food, ninja turtles, whatever) or there are too many people or both, and we're all gonna die for our arrogance.
I'm going to talk about the second one today, partly because I think my liberal leanings are wearing out my welcome on this blog, and partly because it's one of my all time favorite topics.
In 1798 (kind of before 1997), Thomas Malthus wrote his "on the Principle of Population". It is arguable if his ideas were new at the time (a Venetian named Ortes is often credited with preceding Malthus), but they have undoubtedly been repeated since. He postulated that population grows, typically exponentialy. But agricultural production grows linearly. So, you draw a snazzy graph, and the exponential curve eventually crosses the agricultural line and, well, people eat their feet or something. He obviously had a lot more supporting information, but this is the argument at it's heart.
The obvious problem with his analysis is he completely ignores any exponential gains that can be made in agricultural production through technological innovation. Amazingly, Ehrlich does the same in "The Population Bomb". His argument is essentially the same. The thing that worrys me about all this is how often (and in what large numbers) people buy into these re-hashed or warmed over failed ideas. Heck, I worry myself about what bizarro truths I've taken hook, line and sinker; maybe the Fed really is run and owned by an international banking conspiracy!
There is one final aspect of the concepts created by Malthus and rewritten by Ehrlich that I'd like to touch on. Assuming the Universe, or at least the matter and energy in it, are finite, the idea of a limited carrying capacity is essentially true, and there really can be too many people. Unfortunately, people like Malthus or Ehrlich seem to always predict we'll hit the limit in the next week or so. What is that limit? If we can't move to other planets, how many people can really live here? Will we cram them in all underground? Eat a lot of Soylent green? Should we even take living conditions into account, is that even important? I bet if we all could photosynthesize we could cram a lot of people just on the surface.
Ehrlich even wagered on his predictions, and lost.